Metabolic syndrome and high blood pressure can be helped by sleep apnea treatment

Posted on January 22, 2012 by Dr. Jonathan

Summary: the stress of oxygen starvation that occurs with sleep disordered breathing (sleep apnea and hypopnea) contributes to metabolic syndrome and high blood pressure. CPAP (continuous positive airway pressure) can help .

I have been finding that people coming to our practice who have been struggling with the depredations of metabolic syndrome including overweight, hypertension, elevated lipids and HgbA1c, etc. have not been evaluated for sleep disordered breathing. A study recently published in The New England Journal of Medicine offers evidence that treatment for sleep apnea can provide significant benefit. The authors state:

“Obstructive sleep apnea is associated with an increased prevalence of the metabolic syndrome and its components…In our double-blind, placebo-controlled trial, we randomly assigned patients with obstructive sleep apnea syndrome to undergo 3 months of therapeutic CPAP followed by 3 months of sham CPAP, or vice versa, with a washout period of 1 month in between.”

They measured anthropometric variables, blood pressure, fasting blood glucose levels, insulin resistance, fasting blood lipids, glycated hemoglobin, carotid intima–media thickness, and visceral fat before and after the real and sham CPAP interventions. Their data showed a worthwhile effect:

“A total of 86 patients completed the study, 75 (87%) of whom had the metabolic syndrome. CPAP treatment (vs. sham CPAP) was associated with significant mean decreases in systolic blood pressure (3.9 mm Hg), serum total cholesterol (13.3 mg per deciliter), non–high-density lipoprotein cholesterol (13.3 mg per deciliter), low-density lipoprotein cholesterol (9.6 mg per deciliter), triglycerides (18.7 mg per deciliter), and glycated hemoglobin (0.2%). The frequency of the metabolic syndrome was reduced after CPAP therapy (reversal found in 11 of 86 patients [13%] undergoing CPAP therapy vs. 1 of 86 [1%] undergoing sham CPAP).”

Clinicians should not fail to consider the possibility of sleep disordered breathing when managing hypertension, overweight and other components of metabolic syndrome. Do you snore or wake in the morning unrefreshed and fall asleep inappropriately during the day? If so, a screening may be appropriate. The authors conclude:

“In patients with moderate-to-severe obstructive sleep apnea syndrome, 3 months of CPAP therapy lowers blood pressure and partially reverses metabolic abnormalities.”

Understanding obesity as an inflammatory condition

Posted on November 23, 2011 by Dr. Jonathan

Summary: chronic low-grade inflammation is both a damaging result of and a fundamental cause promoting obesity. Management of both weight loss programs and the medical complications of obesity should address the inflammatory component.

An important paper was recently published in the Journal of Clinical Investigation that discusses the role of inflammation in obesity, obesity-related disorders, and metabolic dysfunction. The chronic inflammatory response associated with obesity is has been termed metainflammation:

“Over the past decade, the search for a potential unifying mechanism behind the pathogenesis of obesity-associated diseases has revealed a close relationship between nutrient excess and derangements in the cellular and molecular mediators of immunity and inflammation. This has given birth to the concept of “metainflammation” to describe the chronic low-grade inflammatory response to obesity.”

The authors describe characteristics of the metainflammation of obesity:

“The chronic nature of obesity produces a tonic low-grade activation of the innate immune system that affects steady-state measures of metabolic homeostasis over time. Childhood obesity may place individuals at risk for lifelong metainflammation, since inflammatory markers are elevated in obese children as young as 3 years old. Superimposed on this chronic inflammation are recurrent acute episodes of nutrition-related immune activation induced by nutrient availability (fasting or high-fat meals)…Non-biased assessments of gene expression networks in adipose tissue identify a robust pattern of overexpressed inflammatory genes associated with obesity and metabolic disease and enriched for macrophage genes…While transient inflammatory states such as sepsis can have multi-organ effects, few other chronic inflammatory diseases are characterized by the features of pancreatic, liver, adipose, heart, brain, and muscle inflammation as is seen in obesity.”

Importantly, inflammation itself induces insulin resistance that further promotes obesity:

“Multiple inflammatory inputs contribute to metabolic dysfunction, including increases in circulating cytokines, decreases in protective factors (e.g., adiponectin), and communication between inflammatory and metabolic cells. For example, direct and paracrine signals from M1 classically activated macrophages can impair insulin signaling and adipogenesis in adipocytes…Similar effects on adipocyte inflammation and glucose transport are generated by signals from activated conventional T cells such as IFN-γ. In parallel, dysregulated macrophage-myocyte and macrophage-hepatocyte signaling can influence insulin sensitivity.”

They discuss the fascinating observation that obesity is associated with an imbalance of immune regulation characterized by the dominance of Th1 (cell-mediated, with a classical proinflammatory macrophage activation state = M1) over Th2 (antibod-mediated, M2) immune inflammatory activity:

“While ATMs [adipose tissue macrophages] likely assume a number of states along the M1/M2 spectrum depending on fat depot location and nutritional status, increasing adiposity results in a shift in the inflammatory profile of ATMs as a whole from an M2 state to one in which classical M1 proinflammatory signals predominate.”

Most importantly there are a number points where we may intervene to ‘perturb the system’ in the direction of more balanced immune function, thus reducing inflammation and supporting weight loss:

“…maintaining metabolic homeostasis requires a balanced immune response and an integrated network of multiple cell types. Adipose tissue also contains potent tolerogenic CD4+ Tregs that are downregulated by obesity, a potential initiating event in metainflammation. Likewise, there appear to be innate systems by which nutrient signals are utilized to self-limit inflammation. For example, the obesity-induced increase in expression of GPR120, an omega-3 fatty acid (FA) receptor on macrophages capable of attenuating M1 macrophage activation and increasing M2 gene expression, limits inflammation…”

Also of great interest is the role of brain inflammation in promoting obesity:

“The effects of brain inflammation on the metabolic function of peripheral tissues are broad. Independent of obesity, hypothalamic inflammation can impair insulin release from β cells, impair peripheral insulin action, and potentiate hypertension. Many of these effects are generated by signals from the sympathetic nervous system, which is also capable of inducing inflammatory changes in adipose tissue in response to neuronal injury…The dynamic interplay between hypothalamic inflammation and obesity suggest additional targets for antiinflammatory therapies in obesity. A key extension of these observations is the potential that antiinflammatory pathways may counteract these CNS inflammatory events and improve leptin sensitivity.”

Obesity must be understood as an active agent, both as cause and result, in the web of chronic inflammation. The greatest clinical success in managing weight loss and chronic inflammatory disorders comes from determining and treating the pro-inflammatory factors involved according to each individual case.

Kidney disease is another reason to prevent metabolic syndrome

Posted on October 26, 2011 by Dr. Jonathan

Summary: the insulin receptor resistance and higher insulin levels of metabolic syndrome are a significant risk factor for kidney disease.

We’ve long known that the kidneys are exquisitely sensitive to damage from higher levels of insulin. A study recently published in the Clinical Journal of the American Society of Nephrology further reveals the contribution metabolic syndrome to chronic kidney disease. Since MetS is on the rise, chronic kidney may too. The authors state:

“Observational studies have reported an association between metabolic syndrome (MetS) and microalbuminuria or proteinuria and chronic kidney disease (CKD) with varying risk estimates. We aimed to systematically review the association between MetS, its components, and development of microalbuminuria or proteinuria and CKD.”

The authors undertook an analysis of eleven studies encompassing 30,146 subjects that reported the development of microalbuminuria or proteinuria and/or CKD in subjects with MetS, with attention to eGFR (estimated glomerular filtration rate, a metric for kidney function). Their data present a clear picture:

“MetS was significantly associated with the development of eGFR <60 ml/min per 1.73 m2 [impaired kidney function]. The strength of this association seemed to increase as the number of components of MetS increased. In patients with MetS, the odds ratios for development of eGFR <60 ml/min per 1.73 m2 for individual components of MetS were: elevated blood pressure 1.61, elevated triglycerides 1.27, low HDL cholesterol 1.23, abdominal obesity 1.19, and impaired fasting glucose 1.14. Three studies reported an increased risk for development of microalbuminuria or overt proteinuria with MetS.”

The ‘take home’ message for clinicians and patients is don’t wait until the onset of type 2 diabetes; bear in mind the authors’ conclusion and take decisive action before delicate kidney tissue is irrevocably lost:

“MetS and its components are associated with the development of eGFR <60 ml/min per 1.73 m2 and microalbuminuria or overt proteinuria.”

Diabetes is a significant risk factor for all-cause dementia and Alzheimer’s disease

Posted on October 24, 2011 by Dr. Jonathan

There has been a burst of papers drawing further attention to the damage that glucose and insulin dysregulation does to the brain. A study just published in the journal Neurology investigates specifically…

“…the association between glucose tolerance status defined by a 75-g oral glucose tolerance test (OGTT) and the development of dementia.”

The authors subjected 1,017 community-dwelling dementia-free subjects 60 years and older to an oral glucose tolerance test, then followed them for 15 years. The outcome measure was clinically diagnosed dementia. What did their data show?

The age- and sex-adjusted incidence of all-cause dementia, Alzheimer disease (AD), and vascular dementia (VaD) were significantly higher in subjects with diabetes than in those with normal glucose tolerance. These associations remained robust even after adjustment for confounding factors for all-cause dementia and AD, but not for VaD (all-cause dementia: adjusted hazard ratio [HR] = 1.74; AD: adjusted HR = 2.05; VaD: adjusted HR = 1.82). Moreover, the risks of developing all-cause dementia, AD, and VaD significantly increased with elevated 2-hour postload glucose (PG) levels even after adjustment for covariates, but no such associations were observed for fasting plasma glucose (FPG) levels: compared with those with 2-hour PG levels of <6.7 mmol/L [120.6 mg/dl], the multivariable-adjusted HRs of all-cause dementia and AD significantly increased in subjects with 2-hour PG levels of 7.8 to 11.0 mmol/L [140.4 to 198 mg/dl] or over, and the risk of VaD was significantly higher in subjects with levels of ≥11.1 mmol/L [199.8 mg/dl].”

This is striking. The risk of all-cause dementia doubled for those with diabetes, and there was a significant increase in the risk of all-cause dementia and Alzheimer’s disease with a 2 hour post-glucose load level of 140.4 mg/dl or more. Moreover, fasting glucose levels did not reveal the danger that was disclosed only by the functional OGTT. I always risk desensitizing my patients to the damage done to the brain by glucose and insulin dysregulation; better to let the authors’ conclusion do the talking:

“Our findings suggest that diabetes is a significant risk factor for all-cause dementia, AD, and probably VaD. Moreover, 2-hour PG levels, but not FPG levels, are closely associated with increased risk of all-cause dementia, AD, and VaD.”

Meanwhile, a time study just published in the journal Diabetic Medicine also examines the association of diabetes with Alzheimer’s disease. The authors’ intent was to determine…

“…whether diabetes mellitus influences functional status in patients with Alzheimer’s disease.”

They studied 608 community-dwelling patients with Alzheimer’s disease, assessing diabetes at the beginning. Functional status was examined twice yearly with the Activities of Daily Living scale. Each patient also had a baseline functional disability determined if their Activities of Daily Living score was less than 6. Decreases in these metrics over four years of follow-up exams was used to define worsening of functional disability due to AD. Their data also reveal the ruination of the brain by glucose intolerance:

“At baseline, diabetes was present in 63 participants (10.4%) and, compared with those without diabetes, was associated with functional impairment [age- and sex-adjusted OR = 2.73]. After controlling for confounders, the association remained significant [OR = 2.04]. Follow-up demonstrated a significant interaction between duration of Alzheimer’s disease and diabetes, which was associated with progression of functional impairment in patients who had been diagnosed with Alzheimer’s disease for less than 1 year, but not in those who had been diagnosed with Alzheimer’s disease for more than 1 year. Abnormal one-leg balance, polymedication and obesity seem to be important factors explaining the association between diabetes and functional status.”

Clinicians (non-neurologists), how often do you check one-leg balance? The authors’ data suggests that a year after a clear-cut Alzheimer’s diagnosis the damage is too extensive to discriminate the effect of diabetes, thus they conclude:

“At baseline, the presence of diabetes significantly increases the risk of functional disability in patients with Alzheimer’s disease; our longitudinal data confirm that in patients with a recent diagnosis of Alzheimer’s disease (but not in those who have had Alzheimer’s disease for longer than 1 year), diabetes continues to worsen functional status.”

Regarding mechanisms, an interesting paper just published in Current Diabetes Reviews examines recent findings illuminating the link between IGF-1 signaling and diabetes-associated dementia. The authors state:

“Patients with type 2 diabetes (T2DM) have a two- to three-fold increased risk for Alzheimer’s disease (AD), the most common form of dementia. Vascular complications might explain partially the increased incidence of neurodegeneration in patients with T2DM. Alternatively, neuronal resistance for insulin/insulin-like growth factor-1 (IGF-1) might represent a molecular link between T2DM and AD, characterizing AD as “brain-type diabetes”.”

They describe recent research findings that suggest decreased IGF-1 signaling (IIS) in the brain is a compensatory attempt to reduce the accumulation of toxic β-amyloid (Aβ):

“According to this hypothesis, brains from AD patients showed substantially downregulated expression of the Insulin receptor (IR), the IGF-1 receptor (IGF-1R), and the insulin receptor substrate (IRS) proteins…suggesting that decreased IIS [insulin/IGF-1 signaling] might be involved in the pathogenesis of both T2DM and AD. In contrast, type 2 diabetic patients suffering from AD accumulate less β-amyloid (Aβ) compared to non-diabetic AD patients raising the question, whether the changes in IIS are cause, consequence, or compensatory counterregulation to neurodegeneration. Recent data in C. elegans showed that reducing IIS decreases Aβ toxicity. This effect is accomplished via two transcription factors…suggesting that Insulin/IGF-1 transmitted signals influence Aβ proteotoxicity.”

This important point should not go unnoticed by those who are contemplating therapies that increase IGF-1—they may increase risk factors for Alzheimer’s disease and dementia.

And another paper recently published in Neurology highlights the damage done to the brain by advanced glycation end products due to poor glucose tolerance. The authors observe:

“Several studies report that diabetes increases risk of cognitive impairment; some have hypothesized that advanced glycation end products (AGEs) underlie this association. AGEs are cross-linked products that result from reactions between glucose and proteins. Little is known about the association between peripheral AGE concentration and cognitive aging.”

They studied 920 elders without dementia, 495 with diabetes and 425 with normal glucose, and examined baseline AGE concentration by urine pentosidine in association with performance on the Modified Mini-Mental State Examination (3MS) and Digit Symbol Substitution Test (DSST) at baseline and repeatedly over 9 years. What did the data show?

“On both tests, there was a more pronounced 9-year decline in those with high and mid pentosidine level [more AGEs] compared to those in the lowest tertile. Incident cognitive impairment was higher in those with high or mid pentosidine level than those in the lowest tertile.”

We are probably just beginning to understand the ways that glucose and insulin regulation, whose profound leverage on the physiology is evolutionarily preserved from relatively primitive organisms to humans, has on the brain. Regarding damage done by excessive glucose interaction with tissues, it is not necessary for glucose dysregulation to have progressed to diabetes as the authors conclude:

“High peripheral AGE level is associated with greater cognitive decline in older adults with and without diabetes.”

Dietary macronutrient composition for weight loss and weight maintenance

Posted on October 22, 2011 by Dr. Jonathan

Summary: When designing a dietary strategy for weight loss and maintenance the individual patient’s functional and genetic constitution must be carefully considered, but there is an accumulation of evidence indicating that a high protein, low carbohydrate regimen is a good starting point.

There is a large body of evidence that can instruct us in how to fashion an eating plan to promote both short and long-term success in weight loss and healthy body composition. As a paper published in the journal Obesity demonstrates, the way many Americans eat—referred to as a ‘cafeteria diet’ (CF)—is worse than a diet high in lard. The authors note:

“Obesity has reached epidemic proportions worldwide and reports estimate that American children consume up to 25% of calories from snacks. Several animal models of obesity exist, but studies are lacking that compare high-fat diets (HFD) traditionally used in rodent models of diet-induced obesity (DIO) to diets consisting of food regularly consumed by humans, including high-salt, high-fat, low-fiber, energy dense foods such as cookies, chips, and processed meats.”

They investigated the effects on weight gain and inflammation of a cafeteria diet (CAF) compared to a lard-based 45% HFD by feeding their rodent models either HFD, CAF or a chow control for 15 weeks. Their data clearly show that even consuming almost half the diet in lard is better than the lethal mix that many now consume:

“Body weight increased dramatically and remained significantly elevated in CAF-fed rats compared to all other diets. Glucose- and insulin-tolerance tests revealed that hyperinsulinemia, hyperglycemia, and glucose intolerance were exaggerated in the CAF-fed rats compared to controls and HFD-fed rats.”

Moreover, the cafeteria diet was markedly worse in promoting inflammation:

“It is well-established that macrophages infiltrate metabolic tissues at the onset of weight gain and directly contribute to inflammation, insulin resistance, and obesity. Although both high fat diets resulted in increased adiposity and hepatosteatosis, CAF-fed rats displayed remarkable inflammation in white fat, brown fat and liver compared to HFD and controls. In sum, the CAF provided a robust model of human metabolic syndrome compared to traditional lard-based HFD, creating a phenotype of exaggerated obesity with glucose intolerance and inflammation.”

A study published in The New England Journal of Medicine examined specific dietary factors that stand out in their contribution to obesity noting that they…

“…may affect the success of the straightforward-sounding strategy “eat less and exercise more” for preventing long-term weight gain.”

They performed investigations involving 120,877 U.S. women and men who were free of chronic diseases and not obese at baseline for as long as twenty years. Relationships between changes in lifestyle factors and weight change were evaluated every four years. There were several factors that stood out:

“Within each 4-year period, participants gained an average of 3.35 lb. On the basis of increased daily servings of individual dietary components, 4-year weight change was most strongly associated with the intake of potato chips (1.69 lb), potatoes (1.28 lb), sugar-sweetened beverages (1.00 lb), unprocessed red meats (0.95 lb), and processed meats (0.93 lb) and was inversely associated with the intake of vegetables (−0.22 lb), whole grains (−0.37 lb), fruits (−0.49 lb), nuts (−0.57 lb), and yogurt (−0.82 lb)…Other lifestyle factors were also independently associated with weight change, including physical activity (−1.76 lb across quintiles); alcohol use (0.41 lb per drink per day), smoking (new quitters, 5.17 lb; former smokers, 0.14 lb), sleep (more weight gain with <6 or >8 hours of sleep), and television watching (0.31 lb per hour per day).”

Potatoes are clearly ‘sugar grenades’, but in my opinion further studies are required to examine the difference between red meat from animals treated with hormones and fed a grain diet versus those that are free of growth-stimulating medications and eat mainly grass.

With the most egregious insults to a metabolically healthy diet out of the way, we can proceed to the roles of glycemic index and glycemic load on weight loss as examined in a study published recently in the Journal of Nutrition:

“This study assessed the effect of changes in glycemic index (GI) and load (GL) on weight loss and glycated hemoglobin (HbA1c) among individuals with type 2 diabetes beginning a vegan diet or diet following the 2003 American Diabetes Association (ADA) recommendations.”

99 subjects with type 2 diabetes were randomized to follow 1 of 2 diet treatments for 22 weeks. Glycemic index and glycemic load changes were assessed and their relationships with changes in weight and HbA1C were calculated. (Glycemic index is a metric for rate which a food will cause blood sugar to rise. Glycemic load is determined by multiplying the glycemic index by the amount of carbohydrate in grams provided by a food and dividing the total by 100; this amounts to the sum of the glycemic loads for all foods consumed in the diet.) Interestingly, glycemic index predicted weight gain while glycemic load did not:

“…the vegan group reduced GI to a greater extent than the ADA group, but GL was reduced further in the ADA than the vegan group. GI predicted changes in weight, adjusting for changes in fiber, carbohydrate, fat, alcohol, energy intake, steps per day, group, and demographics, such that for every point decrease in GI, participants lost ~0.2 kg (0.44 lb)…Weight loss was a predictor of changes in HbA1C. GL was not related to weight loss or changes in HbA1C.”

Thus glycemic index takes precedence over glycemic load in choosing foods for weight loss and blood sugar regulation. Also notable was the finding regarding GI and HbA1C:

“GI was not a predictor for changes in HbA1C after controlling for weight loss.”

Every wonder why a patient’s HbA1C didn’t go down even though they were eating a low GI diet? This shows that if they don’t lose weight as a result, the the HbA1C will tend to stay the same. The authors conclude:

“A low-GI diet appears to be one of the determinants of success of a vegan or ADA diet in reducing body weight among people with type 2 diabetes. The reduction of body weight, in turn, was predictive of decreasing HbA1C.”

The interesting difference between the effects of glycemic index and glycemic load revealed here help to explain the inconsistency noted in a review published earlier in journal IUBMB (International Union of Biochemistry and Molecular Biology) Life:

“Recently, due to its possible link to appetite control and metabolism, several clinical studies have assessed the effect of low glycemic index (GI) and glycemic load (GL) diets on weight loss. To determine the application of GI/GL in the prevention and treatment of obesity, we searched several databases and identified 23 clinical trials that examined low GI/GL diets and weight loss as the primary outcome measure.”

Here the pooling of GI and GL seems to have obfuscated the issue. The authors conclude:

“Over the past decade, the body of research that links low GI/GL diets to weight loss has grown rapidly and significantly. While there is a significant amount of inconsistency in the current findings, the majority of studies found a trend that favored low GI/GL diets in weight loss.”

Moreover…

“…the benefits of low GI and GL diets extend beyond weight loss and have favorable effects on obesity-related risk factors such as heart disease and diabetes by mechanisms that are independent of weight loss.”

What about protein versus carbohydrate for weight loss? A number of investigators have examined this question, but an interesting study published recently in the Nutrition Journal corrects some important limitations in earlier work:

“Studies have suggested that moderately high protein diets may be more appropriate than conventional low-fat high carbohydrate diets for individuals at risk of developing the metabolic syndrome and type 2 diabetes. However in most such studies sources of dietary carbohydrate may not have been appropriate and protein intakes may have been excessively high. Thus, in a proof-of-concept study we compared two relatively low-fat weight loss diets – one high in protein and the other high in fiber-rich, minimally processed cereals and legumes – to determine whether a relatively high protein diet has the potential to confer greater benefits.”

They eighty-three overweight or obese women to either a moderately high protein (30% protein, 40% carbohydrate) diet (HP) or to a high fiber, relatively high carbohydrate (50% carbohydrate, > 35 g total dietary fiber, 20% protein) diet (HFib) for 8 weeks. During that time their energy intakes were reduced by 478 to 955 calories per day to achieve weight loss of between 0.5 and 1 kg per week. Which diet resulted in better weight loss?

“Participants on both diets lost weight (HP: -4.5 kg and HFib: -3.3 kg), and reduced total body fat (HP: -4.0 kg and HFib: -2.5 kg, and waist circumference (HP: -5.4 cm and HFib: -4.7 cm), as well as total and LDL cholesterol, triglycerides, fasting plasma glucose and blood pressure. However participants on HP lost more body weight (-1.3 kg) and total body fat (-1.3 kg). Diastolic blood pressure decreased more on HP (-3.7 mm Hg).”

High protein wins out over high carbohydrate, even when the carbohydrate is high fiber. The authors conclude:

“A realistic high protein weight-reducing diet was associated with greater fat loss and lower blood pressure when compared with a high carbohydrate, high fiber diet in high risk overweight and obese women.”

Importantly, the benefits of a high protein to carbohydrate ratio diet include the slowing of tumor growth and prevention of cancer initiation as described in an excellent paper (you may wish to read it in its entirety) published recently in the journal Cancer Research. It includes a significant consideration for reducing carbohydrate by increasing protein rather than fat. The authors state:

“Since cancer cells depend on glucose more than normal cells, we compared the effects of low carbohydrate (CHO) diets to a Western diet on the growth rate of tumors in mice. To avoid caloric restriction–induced effects, we designed the low CHO diets isocaloric with the Western diet by increasing protein rather than fat levels because of the reported tumor-promoting effects of high fat and the immune-stimulating effects of high protein.”

They were able to formulate diets that demonstrated that the tumor inhibiting effects were due to factors other than weight loss from calorie restriction (CR):

“To exploit the fact that cancer cells rely more heavily on glycolysis than normal cells, we designed low CHO, high protein diets to see if we could limit BG and tumor growth. In designing our diets, we wanted to avoid NCKDs [no calorie ketogenic diets] because of the difficulty in achieving long-term compliance with no CHO diets in potential future human studies and because Masko and colleagues recently reported that a 10% or 20% CHO diet slows tumor growth as effectively as NCKDs. Following early studies with 8% CHO diets, using 10% and 15% CHO, high protein diets in which 70% of the CHO was in the form of amylose, we found that, compared with a Western diet, they were indeed capable of reducing BG, insulin, and lactate levels and, importantly, in slowing the growth of implanted murine and human tumors, with little or no effects on mouse weight.”

There is good reason to apply these finding to human case management:

“Consistent with the notion that reducing BG in humans can be beneficial, there is a wealth of epidemiologic evidence showing a clear association between BG and/or insulin levels (which are determined by BG levels) and the incidence of human cancers. Thus, although our studies were conducted, out of necessity, with mice, the fact that human BG can be significantly reduced with low CHO diets and the association of many cancers with high BG levels suggest that our findings are very likely relevant to human cancers as well, particularly in cancers that have been associated with higher baseline BG and/or insulin levels, such as pancreatic, breast, colorectal, endometrial, and esophageal cancers.”

This also has application to prostate cancers:

“In addition to these cancers, a low CHO diet may also be beneficial in early-stage prostate cancer, even though it is not typically detectable by PET. This is because the metastases of these tumors kill the patients and, given the pivotal role of lactate in promoting metastasis, our low CHO diets could significantly reduce metastasis by reducing tumor-associated lactate levels.”

Regarding concerns about the impact on kidney function…

“In terms of macronutrient composition, even though high protein has been shown to promote satiety—thus reducing obesity, BG, and insulin levels—and enhance both antitumor immunity, through amino acid supplementation, and life span, we were concerned, based on the literature, that high protein levels might cause kidney damage. More recent data, however, suggest that this may only occur in individuals with existing chronic kidney disease and that in normal people, the increase in glomerular filtration rate and kidney cellularity that occur with long-term high protein consumption may be a normal response.”

Incidentally, amylose starch prevents DNA damage in the colon that may otherwise be caused by red meat:

“Interestingly, colonic cancer-inducing damage caused by red meats may be avoided with high amylose, low CHO diets. These studies suggest that macronutrient sources and combinations are very important…”

The authors conclude:

“Our study, herein, shows that a high amylose containing low CHO, high protein diet reduces BG, insulin, and glycolysis, slows tumor growth, reduces tumor incidence, and works additively with existing therapies without weight loss or kidney failure. Such a diet, therefore, has the potential of being both a novel cancer prophylactic and treatment, warranting further investigation of its applicability in the clinic, especially in combination with existing therapies.”

Regarding weight loss, what if exercise is added to the program? Will high protein still beat high carbohydrate. A study published in the journal The Physician and Sports Medicine studies this question as the authors set out to…

“…determine whether sedentary obese women with elevated levels of homeostatic model assessment (HOMA) insulin resistance (ie, > 3.5) experience greater benefits from an exercise + higher-carbohydrate (HC) or carbohydrate-restricted weight loss program than women with lower HOMA levels.”

221 women who participated in a 10-week supervised exercise and weight loss program were assigned low-fat (30%) diets that consisted of 1200 kcals per day for 1 week (phase 1) and 1600 kcals per day for 9 weeks (phase 2) with either high carbohydrate (HC) or higher protein (HP). Fasting blood samples, body composition, anthropometry, resting energy expenditure, and fitness measurements were obtained at the beginning and end. Again we see high protein win out over high carbohydrate:

“Subjects in the HP group experienced greater weight loss (−4.4 ± 3.6 kg vs −2.6 ± 2.9 kg), fat loss (−3.4 ± 2.7 kg vs −1.7 ± 2.0 kg), reductions in serum glucose (3% vs 2%), and decreases in serum leptin levels (−30.8% vs −10.8%) than those in the HC group.”

The authors conclude:

“A carbohydrate-restricted diet promoted more favorable changes in weight loss, fat loss, and markers of health in obese women who initiated an exercise program compared with a diet higher in carbohydrate. Additionally, obese women who initiated training and dieting with higher HOMA levels experienced greater reductions in blood glucose following an HP diet.”

Regarding the use of vegetable or fruit juices in programs designed for weight loss, a study published in the journal Obesity demonstrates that this is counter-productive:

“Beverage consumption has been implicated in weight gain, but questions remain about the veracity of the association, whether the relationship is causal and what property of beverages is responsible. It was hypothesized that food form is the most salient attribute. Thus, a randomized controlled trial of food form was conducted. Energy-matched beverage or solid forms of fruits and vegetables were provided to 34, lean or overweight/obese adults for two 8-week periods with a 3-week washout interspersed.”

During the solid food arm of the study the lean group had no significant weight change while the overweight/obese group had weight gain, but during the juice phase…

“In contrast, incomplete dietary compensation and weight gain occurred in both the lean (43%) and overweight/obese (61%) groups during the beverage arm…These data demonstrate energy consumed as beverages may be especially problematic for weight gain.”

And for the carbohydrates that are consumed, a curious study also published in Obesity offers evidence that eating them mainly at dinner further aids in weight loss, satiety and more:

“This study was designed to investigate the effect of a low-calorie diet with carbohydrates eaten mostly at dinner on anthropometric, hunger/satiety, biochemical, and inflammatory parameters. Hormonal secretions were also evaluated. Seventy-eight police officers (BMI >30) were randomly assigned to experimental (carbohydrates eaten mostly at dinner) or control weight loss diets for 6 months. On day 0, 7, 90, and 180 blood samples and hunger scores were collected every 4 h from 0800 to 2000 hours. Anthropometric measurements were collected throughout the study.”

Amazingly…

“Greater weight loss, abdominal circumference, and body fat mass reductions were observed in the experimental diet in comparison to controls. Hunger scores were lower and greater improvements in fasting glucose, average daily insulin concentrations, and homeostasis model assessment for insulin resistance (HOMAIR), T-cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) levels were observed in comparison to controls. The experimental diet modified daily leptin and adiponectin concentrations compared to those observed at baseline and to a control diet.”

Wow…all that just from shifting carbohydrates to dinner. The authors conclude:

“A simple dietary manipulation of carbohydrate distribution appears to have additional benefits when compared to a conventional weight loss diet in individuals suffering from obesity. It might also be beneficial for individuals suffering from insulin resistance and the metabolic syndrome.”

The scientific data addressing various aspects of dietary fat is treated in a separate post, but it’s suitable here to consider a study published in The Journal of Clinical Endocrinology & Metabolism offering evidence that a low carbohydrate diet is equivalent to a low fat diet for weight loss:

“Overweight and obese men and women (24–61 yr of age) were recruited into a randomized trial to compare the effects of a low-fat (LF) vs. a low-carbohydrate (LC) diet on weight loss…Subjects on the LF diet consumed an average of 17.8% of energy from fat, compared with their habitual intake of 36.4%, and had a resulting energy restriction of 2540 kJ/d [585 calories]. Subjects on the LC diet consumed an average of 15.4% carbohydrate, compared with habitual intakes of about 50% carbohydrate, and had a resulting energy restriction of 3195 kJ/d [763 calories].”

At the end of the study period the LC group lost as much weight and had better insulin regulation:

“Both groups of subjects had significant weight loss over the 10 wk of diet intervention and nearly identical improvements in body weight and fat mass. LF subjects lost an average of 6.8 kg and had a decrease in body mass index of 2.2 kg/m2, compared with a loss of 7.0 kg and decrease in body mass index of 2.1 kg/m2 in the LC subjects. The LF group better preserved lean body mass when compared with the LC group; however, only the LC group had a significant decrease in circulating insulin concentrations.”

The authors conclude:

“”These data suggest that energy restriction achieved by a very LC diet is equally effective as a LF diet strategy for weight loss and decreasing body fat in overweight and obese adults.”

Bottom line: When designing a dietary strategy for weight loss and maintenance the individual patient’s functional and genetic constitution must be carefully considered (inflammation, immune regulation, insulin sensitivity, allergy, intestinal permeability, sleep disordered breathing and hormonal function are fundamentals); but there is an accumulation of evidence suggesting that a high protein, low carbohydrate regimen is a good starting point.

A middle path in the debate over PSA testing for prostate cancer

Posted on October 10, 2011 by Dr. Jonathan

Summary:

The use of PSA as a screening tool for aggressive prostate cancer (PCa) is not supported by scientific studies of its effectiveness.
Many men are subject to disabling, sometimes even fatal, interventions based on PSA tests when they would never have developed aggressive prostate cancer.
The U.S. Preventive Services Task Force has prepared a draft recommendation to stop screening in those who have not been diagnosed with prostate cancer.
There are many who, having benefited from PSA screening for PCa, feel strongly that this recommendation by the USPSTF is irresponsible.
A broader understanding of the underlying causes of elevated PSA and PCa offers a ‘middle path’ of judicious PSA screening, with a meaningful action plan that doesn’t corner patients and doctors into risky invasive procedures or the anxiety of doing nothing. Factors such as insulin resistance and estrogen-testosterone balance are of vital importance for prostate and general health.

Anyone reading this is surely aware of the controversy swirling around the draft recommendation statement of the U.S. Preventive Services Task Force (USPSTF) that…

“…recommends against prostate-specific antigen (PSA)-based screening for prostate cancer…This recommendation applies to men in the U.S. population that do not have symptoms that are highly suspicious for prostate cancer, regardless of age, race, or family history.”

The Task Force did not evaluate the use of the PSA test for men with highly suspicious symptoms or those with a diagnosis prostate cancer. This recommendation is based on a number of studies finding that PSA (including PSA velocity, the rate at which PSA goes up) is a poor predictor of prostate cancer in general and aggressive prostate cancer in particular, and the assertion that widespread screening has resulted in many unnecessarily invasive and debilitating procedures that themselves can be disabling and even fatal. Feelings are riding high as a large body of public health statistics is pitted against those who feel that a PSA test may have saved their life or the life of a patient. But practitioners and patients face more than a quandary—the debate as it’s currently framed is flawed by a glaring omission.

The PSA discussion is presently structured to assume that the response to a rising PSA can only be ignored (in favor of ‘watchful waiting’) or acted on with invasive biopsies that can seriously damage quality of life and aggressive therapies for what may in fact be indolent, slow growing tumors. That’s it, the clinical decision-making path would appear to fork into only those two roads. Here’s the problem: there is a surprising blind spot for the extensive body of science done on the underlying causes of prostate cancer that offer important opportunities to benefit. Bear in mind that inflammation or enlargement of prostate tissue caused by various disrupting factors can elevate PSA. These can often be treated with lifestyle or wholesome, non-invasive measures that also reduce the risk of other conditions like diabetes and cardiovascular disease. You may wish to read earlier posts on this topic by typing ‘prostate’ in the search box above. For now consider a couple of the most glaring omissions:

To ignore the role of insulin resistance and metabolic syndrome in prostate disease is gigantic clinical error. Consider just one paper published recently in Nature Reviews Urology in which the authors state:

“The metabolic syndrome is common in countries with Western lifestyles. It comprises a number of disorders—including insulin resistance, hypertension and obesity—that all act as risk factors for cardiovascular diseases. Urological diseases have also been linked to the metabolic syndrome. Most established aspects of the metabolic syndrome are linked to benign prostatic hyperplasia (BPH) and prostate cancer. Fasting plasma insulin, in particular, has been linked to BPH and incident, aggressive and lethal prostate cancer.”

Moreover…

“Overall, the results of studies on urological aspects of the metabolic syndrome seem to indicate that BPH and prostate cancer could be regarded as two new aspects of the metabolic syndrome, and that an increased insulin level is a common underlying aberration that promotes both BPH and clinical prostate cancer.”

This is so important yet has been so ignored. Here it is again:

“Key points

The metabolic syndrome is a cluster of disorders, including type 2 diabetes, atherosclerotic disease manifestations, hypertension, obesity and dyslipidemia, and is prevalent in countries with Western lifestyles

The most important common underlying endocrine aberration of these disorders is an increased insulin level, which is also linked to benign prostatic hyperplasia (BPH) and prostate cancer

Most aspects of the metabolic syndrome are risk factors for BPH and prostate cancer, which seems to suggest that these tumors are themselves aspects of the metabolic syndrome”

Insulin at high levels due to receptor resistance damages sensitive tissues and can act as a tumor promoter. The authors conclude:

“Urologists need to be aware of the effect that the metabolic syndrome has on urological disorders and should transfer this knowledge to their patients.”

Another of the most egregious omissions in prostate cancer management and prevention is attendance to the role played by estrogens in PCa development and progression. Consider a paper published in 2007 in the Journal of Cellular Biochemistry in which the authors observe:

“Prostate cancer is the commonest non-skin cancer in men. Incidence and mortality rates of this tumor vary strikingly throughout the world. Although several factors have been implicated to explain this remarkable variation, lifestyle and dietary factors may play a dominant role, with sex hormones behaving as intermediaries between exogenous factors and molecular targets in development and progression of prostate cancer.”

Furthermore…

“Human prostate cancer is generally considered a paradigm of androgen-dependent tumor; however, estrogen role in both normal and malignant prostate appears to be equally important. Aberrant aromatase expression and activity has been reported in prostate tumor tissues and cells, implying that androgen aromatization to estrogens may play a role in prostate carcinogenesis or tumor progression…In animal model systems estrogens, combined with androgens, appear to be required for the malignant transformation of prostate epithelial cells.”

After reviewing other aspects estrogen stimulation of prostate tissue including the opposing role of ERα and ERβ receptors, the authors conclude:

“In summary, although multiple consistent evidence suggests that estrogens are critical players in human prostate cancer, their role has been only recently reconsidered, being eclipsed for years by an androgen-dominated interest.”

The authors of a review published subsequently in European Urology recognized the dual role of estrogen receptors in prostate cancer when they set out to…

“…examine mechanisms of how oestrogens may affect prostate carcinogenesis and tumour progression.”

They report evidence for the effects of estrogenic stimulation of prostate tissue:

“The human prostate is equipped with a dual system of oestrogen receptors (oestrogen receptor alpha [ERα], oestrogen receptor beta [ERβ]) that undergoes profound remodelling during PCa development and tumour progression. In high-grade prostatic intraepithelial neoplasia (HGPIN), the ERα is upregulated and most likely mediates carcinogenic effects of estradiol as demonstrated in animal models…The partial loss of the ERβ in HGPIN indicates that the ERβ acts as a tumour suppressor…The progressive emergence of the ERα and the oestrogen-regulated progesterone receptor (PR) during PCa progression and hormone-refractory disease suggests that these tumours can use oestrogens and progestins for their growth.”

Moreover…

“The TMPRSS2-ERG gene fusion recently reported as a potentially aggressive molecular subtype of PCa is regulated by ER-dependent signalling.”

The authors also conclude:

“Oestrogens and their receptors are implicated in PCa development and tumour progression. There is significant potential for the use of ERα antagonists and ERβ agonists to prevent PCa and delay disease progression.”

A paper just published in the journal Endocrinology and Metabolism Clinics of North America echoes the theme:

“The mainstay targets for hormonal prostate cancer (PCa) therapies are based on negating androgen action. Recent epidemiologic and experimental data have pinpointed the key roles of estrogens in PCa development and progression. Racial and geographic differences, as well as age-associated changes, in estrogen synthesis and metabolism contribute significantly to the etiology.”

The authors go on to report on how estrogens and estrogen mimics contribute to development of PCa, and the roles of the different estrogen mediators in the process.

As is often the case, the principle of balance comes into play as examined in a fine paper published in The Journal of Steroid Biochemistry & Molecular Biology on the estrogen:androgen ratio in the prostate gland. The authors state:

“Although androgens and estrogens both play significant roles in the prostate, it is their combined action – and specifically their balance – that is critically important in maintaining prostate health and tissue homeostasis in adulthood. In men, serum testosterone levels drop by about 35% between the ages of 21 and 85 while estradiol levels remain constant or increase. This changing androgen:estrogen (T:E) ratio has been implicated in the development of benign and malignant prostate disease.”

They review the role of the aromatase enzyme in the production of estrogens from androgens, and the fact that its aberrant expression plays a critical role in the development of malignancy in a number of tissues. In the case of PCa, it leads to an altered T:E ratio that is associated with the development of disease. And since we do have for treatment purposes wholesome modulators of estrogen receptor function as well as aromatase enzyme inhibitors…

“The role of estrogen and the T:E balance in the prostate is further complicated by the differential actions of both estrogen receptors, α and β. Stimulation of ERα leads to aberrant proliferation, inflammation and pre-malignant pathology; whereas activation of ERβ appears to have beneficial effects regarding cellular proliferation and a putative protective role against carcinogenesis.”

Clinicians who manage, support patients with, or endeavor to prevent prostate cancer must bear their conclusion in mind:

“Overall, these data reveal that homeostasis in the normal prostate involves a finely tuned balance between androgens and estrogens. This has identified estrogen, in addition to androgens, as integral to maintaining normal prostate health, but also as an important mediator of prostate disease.”

A more comprehensive perspective on the use of PSA

There far more evidence for the application of these and other factors in prostate cancer development and expression that are equally important for conditions ranging from cardiovascular disease and diabetes to dementia than can be presented in this post. It is clear, however, that we must go beyond the fascination with the false promise of ‘silver bullet’ medications and lure of lucrative procedures to properly examine and treat the more complex web of underlying factors that support prostate cancer. In the judicious hands of a skilled clinician who has the knowledge and experience to evaluate the risk of prostate cancer in the context of the total health of their patient, observing an elevation of PSA offers more than a specter of indecision over the stark choices of invasive procedures or doing nothing. It is an opportunity to intervene in positive and wholesome ways that advance the overall, not just prostate, health of the patient in their care.

Dairy reduces inflammation and oxidative stress in metabolic syndrome

Posted on September 3, 2011 by Dr. Jonathan

More evidence that dairy foods contain agents with antiinflammatory and antioxidant properties is presented in a study published recently in The American Journal of Clinical Nutrition showing reductions in damaging inflammatory biomarkers. The authors state:

“Oxidative and inflammatory stress are elevated in obesity and are further augmented in metabolic syndrome. We showed previously that dairy components suppress the adipocyte- and macrophage-mediated generation of reactive oxygen species and inflammatory cytokines and systemic oxidative and inflammatory biomarkers in obesity…The objective of this study was to determine the early (7 d) and sustained (4 and 12 wk) effects of adequate-dairy (AD) compared with low-dairy (LD) diets in subjects with metabolic syndrome.”

Their forty overweight or obese subjects with metabolic syndrome were randomly assigned to receive either an ‘adequate dairy diet’ (defined as 3.5 daily servings) or ‘low dairy diet’ (less than half a daily serving) form of weight-maintenance diet for 12 weeks. They measured oxidative and inflammatory biomarkers at the start and after 1, 4, and 12 weeks as primary outcomes, along with body weight and composition to start and after 4, and 12 weeks as secondary outcomes. Their data showed a dramatic difference for the ‘adequate dairy’ diet:

“AD decreased malondialdehyde and oxidized LDL at 7 d (35% and 11%, respectively), with further decreases by 12 wk. Inflammatory markers were suppressed with intake of AD, with decreases in tumor necrosis factor-α at 7 d and further reductions through 12 wk (35%); decreases in interleukin-6 (21%) and monocyte chemoattractant protein 1 (14% decrease at 4 wk, 24% decrease at 12 wk); and a corresponding 55% increase in adiponectin at 12 wk. LD exerted no effect on oxidative or inflammatory markers. Diet had no effect on body weight; however, AD significantly reduced waist circumference and trunk fat, and LD exerted no effect.”

While these findings don’t obviate the need to attend to the possibility of dairy allergies or the quality of dairy foods consumed, this is strong evidence that there agents in an ‘adequate dairy’ diet that can do more than a low dairy diet even when the same amount of weight is lost.

“Data from this study show that an increase in dairy intake from suboptimal to adequate levels (≈3.5 servings/d) significantly attenuates both oxidative and inflammatory stress in metabolic syndrome. Notably, although these effects may result, in part, from reductions in adiposity on higher dairy diets, the rapid onset (within the first 7 d of dietary change) suggest that there is an adiposity-independent effect as well. This is further supported by our previous evidence that showed direct effects of dairy components on adipocyte cytokine expression and secretion.”

GGT is an important predictor of diabetes and cardiovascular risk

Posted on September 1, 2011 by Dr. Jonathan

I always include GGT (Serum γ-Glutamyltransferase) in our basic screening blood panel, but find often that this is not included in lab work that patients bring from elsewhere. A study recently published in the journal Obesity shows that, besides being associated with fatty liver, GGT is an important metric for predicting metabolic syndrome, diabetes and hypertension. The authors state:

“Serum γ-glutamyltransferase (GGT) is associated with oxidative stress and hepatic steatosis. The extent to which its value in determining incident cardiometabolic risk (coronary heart disease (CHD), metabolic syndrome (MetS), hypertension and type 2 diabetes) is independent of obesity needs to be further explored in ethnicities.”

They examined a cohort of 1,667 adults from a general population age 52 to 63 with 4 year’s follow-up, measuring GGT activity in association with metabolic syndrome (identified by Adult Treatment Panel-III criteria modified for male abdominal obesity) and multiple markers for cardiovascular disease. Their data bolsters the use of GGT for case management:

“Median GGT activity was 24.9 U/l in men, 17.0 U/l in women…while smoking status was not associated, (male) sex, sex-dependent age, alcohol usage, BMI, fasting triglycerides and C-reactive protein (CRP) were significant independent determinants of circulating GGT. Each 1-s.d. increment in (= 0.53 ln GGT) GGT activity significantly predicted in each sex incident hypertension (hazard ratio (HR) 1.20), and similarly MetS, after adjustment for age, alcohol usage, smoking status, BMI and menopause. Strongest independent association existed with diabetes (HR 1.3) whereas GGT activity tended to marginally predict CHD independent of total bilirubin but not of BMI.”

Interestingly…

“Higher serum total bilirubin levels were protective against CHD risk in women.”

While not any stronger a risk predictor for coronary heart disease (CHD) than body mass index (BMI), GTT is a valuable and underutilized marker to use for the case management of cardiometabolic disorders. The authors conclude:

“We conclude that elevated serum GGT confers, additively to BMI, risk of hypertension, MetS, and type 2 diabetes but only mediates adiposity against CHD risk.”

Metabolic syndrome doubles the risk of liver cancer

Posted on August 5, 2011 by Dr. Jonathan

A sound personalized strategy for eating, exercise and evidence-based supplementation to support healthy insulin regulation decreases the risk for a host of diseases. A paper just published in the journal Hepatology identifies metabolic syndrome as a major risk factor for liver cancer. The authors state:

“Incidence rates of hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC) have increased in the United States. Metabolic syndrome is recognized as a risk factor for HCC and a postulated one for ICC. The magnitude of risk, however, has not been investigated on a population level in the United States. We therefore examined the association between metabolic syndrome and the development of these cancers.”

They examined the data for 3649 HCC cases and 743 ICC cases in comparison with 195,953 control subjects for the prevalence of metabolic syndrome (taking into consideration other risk factors for HCC (hepatitis, alcoholic liver disease, etc) and ICC (biliary cirrhosis, cholangitis, hepatitis, alcoholic liver disease, inflammatory bowel disease, etc). What did the data show?

“Metabolic syndrome was significantly more common among persons who developed HCC and ICC than the comparison group. In adjusted multiple logistic regression analyses, metabolic syndrome remained significantly associated with increased risk of HCC (odds ratio = 2.13) and ICC (odds ratio = 1.56).”

In other words, the adjusted odds ratio for hepatocellular carcinoma (HCC) was 213% (more than double) and 56% for intrahepatic cholangiocarcinoma (ICC). And very significantly, 43% of the patients with liver cancer had no other previously established risk factors for it. Considering that both HCC and ICC are on the increase, the authors’ conclusion is notable:

“Metabolic syndrome is a significant risk factor for development of HCC and ICC in the general U.S. population.”

Intermittent hypoxia (low oxygen) of sleep apnea exacerbates insulin resistance and inflammation

Posted on August 2, 2011 by Dr. Jonathan

New research just published in the journal Obesity contributes to the evidence for weighty metabolic consequences of the hypoxia (reduced oxygen saturation) that occurs with sleep disordered breathing. The authors state:

“The main aim of this study is to evaluate the effects of chronic intermittent hypoxia (CIH), a hallmark of sleep apnea, on IR [insulin resistance] and NAFLD [non-alcoholic fatty liver disease] in lean mice and mice with diet-induced obesity (DIO).”

They fed the study subjects either a high fat or regular diet for 12 weeks, after which they were exposed to CIH or normal room air as a control condition for 4 weeks. Then they measured fasting blood glucose, insulin, homeostasis model assessment (HOMA) index, liver enzymes, and performed an intraperitoneal glucose tolerance test. Their data paints an interesting picture:

“In DIO mice, body weight remained stable during CIH and did not differ from control conditions…Compared to lean mice, DIO mice had higher fasting levels of blood glucose, plasma insulin, the HOMA index, and had glucose intolerance and hepatic steatosis at baseline. In lean mice, CIH slightly increased HOMA index, whereas glucose tolerance was not affected. In contrast, in DIO mice, CIH doubled HOMA index, and induced severe glucose intolerance. In DIO mice, CIH induced NAFLD, inflammation, and oxidative stress, which was not observed in lean mice.”

In other words, even though hypoxia did not further increase the body weight of the subjects with diet induced obesity, the metabolic effects including glucose intolerance, inflammation, fatty liver disease and oxidative stress were severe. I often find that the possibility of sleep disordered breathing has been overlooked in the work-up of patients with overweight or metabolic syndrome. This research adds to the compelling evidence that clinicians should bear this in mind.

“In conclusion, CIH exacerbates IR and induces steatohepatitis in DIO mice, suggesting that CIH may account for metabolic dysfunction in obesity.”