Nuts reduce inflammation and all-cause mortality

Asia Pacific Journal of Clinical NutritionNuts have been shown to confer multiple health benefits, so it’s disconcerting to see  some apparently popular paleo diet plans that forbid them. In the absence of a nut allergy it’s a shame to forgo the benefit of such a healthful and convenient food. The intent of the paleo diet is to reduce inflammation, so it’s worth considering a paper published in the Asia Pacific Journal of Clinical Nutrition offering evidence that nuts reduce inflammation. The authors note:

“Several large epidemiological studies have associated the frequency of nut consumption with reduced risk of coronary heart disease (CHD), CVD, myocardial infarction, sudden death, and all causes of mortality, Type 2 diabetes (T2D) and other chronic disease.

Nuts are anti-inflammatory

Key inflammatory markers including CRP and IL-6 are reduced by nut consumption:

“Epidemiological and clinical studies suggest that some dietary factors, such as n–3 polyunsaturated fatty acids, antioxidant vitamins, dietary fiber, L-arginine and magnesium may play an important role in modulating inflammation. The relationship observed between frequent nut consumption and the reduced risk of cardiovascular mortality and type 2 diabetes in some prospective studies could be explained by the fact that nuts are rich in all of these modulator nutrients. In fact, frequent nut consumption has been associated with lower concentrations of some peripheral inflammation markers in cross-sectional studies. Nut consumption has also been shown to decrease the plasma concentration of CRP, IL-6 and some endothelial markers in recent clinical trials.”

Nuts also benefit cholesterol and lipids

“In the last two decades, a considerable number of clinical trials have consistently demonstrated beneficial effects on blood lipids and lipoproteins, primarily a decrease in Low-density lipoprotein (LDL) cholesterol, a classical CHD risk factor. This effect has been demonstrated consistently in different population groups, using different types of nuts (walnuts, hazelnuts, almonds, pecan, pistachio and macadamia nuts) and study designs. The favourable effects of tree nuts or tree nut oils on plasma lipid and lipoprotein profiles is a mechanism that appears to account for some of the cardio protective effects observed in the epidemiological studies.”

Nuts and olive oil are a great combination for cardiovascular risk:

“…in a cross-sectional study we evaluated the association between components of the Mediterranean diet and circulating markers of inflammation in a large cohort of asymptomatic subjects with high risk of cardiovascular disease. Subjects with the highest consumption of nuts and virgin olive oil showed the lowest concentrations of VCAM-1, ICAM-1, IL-6 and CRP; although this difference was statistically significant for ICAM-1 only in the case of nuts and for VCAM-1 in the case of olive oil.”

After reviewing several other studies documenting improvements in inflammation and endothelial function the authors conclude:

“In conclusion, nuts are complex food matrices containing diverse nutrients and other chemical constituents that may favourably influence human physiology. These sub- stances may inhibit the activation of the innate immune system, probably by decreasing the production of proinflammatory cytokines such as CRP, IL-6, TNF-α or IL-18, and increase the production of antiinflammatory cytokines such as adiponectin. This may improve the proinflammatory milieu, which in turn ameliorates endothelial dysfunction at the vascular level, and ultimately decreases the risk of insulin resistance, type 2 diabetes and coronary heart disease. The capacity of nuts to modulate inflammation may explain at least in part why frequent nut consumption is associated with reduced risk of diabetes and cardiovascular disease in epidemiological studies.”

Nut consumption reduces total and cause-specific mortality

New England Journal of MedicineA paper published earlier this year in The New England Journal of Medicine add more extensive data presenting evidence that eating nuts reduces death from cancer, heart disease, respiratory disease and ‘all causes’.

“Observational and intervention studies of nut consumption have also shown reductions in various mediators of chronic diseases, including oxidative stress, inflammation, visceral adiposity, hyperglycemia, insulin resistance, and endothelial dysfunction. In prospective cohort studies, increased nut intake has been associated with reduced risks of type 2 diabetes mellitus, the metabolic syndrome, colon cancer, hypertension, gallstone disease, diverticulitis, and death from inflammatory diseases.”

To extend the data to encompass the effects of eating nuts and all causes of death the authors:

“…examined the association of nut consumption with total and cause-specific mortality in two large, independent cohort studies of nurses and other health professionals. These studies provide repeated measures of diet (including separate data on peanuts and tree nuts), extensive data on known or suspected confounding variables, 30 years of follow-up, and data on more than 27,000 deaths for analysis.”

Their data suggest that nuts are among the healthiest foods to eat:

“In two large prospective U.S. cohorts, we found a significant, dose-dependent inverse association between nut consumption and total mortality, after adjusting for potential confounders. As compared with participants who did not eat nuts, those who consumed nuts seven or more times per week had a 20% lower death rate. Inverse associations were observed for most major causes of death, including heart disease, cancer, and respiratory diseases. Results were similar for peanuts and tree nuts, and the inverse association persisted across all subgroups.”

Some nuts every day was the best:

“Our results are consistent with the findings in previous, smaller studies. The Adventist Health Study showed that, as compared with nut consumption less than once per week, consumption five or more times per week was associated with reduced total mortality among whites, blacks, and elderly persons, with hazard ratios ranging from 0.56 to 0.82. Similarly, a study of a U.K. cohort, the Iowa Women’s Health Study, the Netherlands Cohort Study, and an earlier analysis of the NHS all showed significant inverse associations between nut intake and total mortality. Finally, in a recent secondary analysis within the PREDIMED (Prevención con Dieta Mediterránea) trial, a hazard ratio for death of 0.61 (95% CI, 0.45 to 0.83) was found for consumption of more than three servings of nuts per week, as compared with no nut consumption.”

Bottom line: ‘paleo’ and ‘autoimmune’ paleo diets can be fine healing diets for many, but like everything else should not be applied dogmatically or in a ‘rubber stamp’, ‘one-size-fits-all’ manner. In the absence of allergy, the evidence supports the consumption of nuts as wholesome foods with anti-inflammatory and metabolic benefits, exactly what paleo diets intend to accomplish.

The tape measure: a powerful predictive ‘instrument’ for mortality

More research recently published in the Archives of Internal Medicine further validates the power of waist circumference measurements to predict death from all causes. This study provides evidence that its accuracy is far superior to body mass index (BMI).

Waist circumference (WC), a measure of abdominal obesity, is associated with higher mortality independent of body mass index (BMI). Less is known about the association between WC and mortality within categories of BMI or for the very high levels of WC that are now common.”

The authors examined the association between WC and mortality among 48 500 men and 56 343 women between 1997 and 2006, during which 9315 men and 5332 women died. Considering the adverse metabolic and hormonal activity of visceral (intra-abdominal versus subcutaneous) fat, their data is not surprising:

“After adjustment for BMI and other risk factors, very high levels of WC were associated with an approximately 2-fold higher risk of mortality in men and women…The WC was positively associated with mortality within all categories of BMI.”

Very high levels of WC means 47 inches for men and 43 inches for women. Waist circumference is a more reliable indicator than weight or BMI. If you’re losing weight without your WC getting smaller, you’re probably losing more muscle than fat. As the authors state in their conclusion:

“These results emphasize the importance of WC as a risk factor for mortality in older adults, regardless of BMI.”

Even modest visceral fat gain causes blood vessel dysfunction

An interesting study just published in the Journal of the American College of Cardiology offers evidence that even a modest amount of fat around your waist prevents blood vessels from dilating properly. But there is good news too. The authors refer to endothelial function (the endothelium is the inner lining of the blood vessel; it regulates constriction and dilation):

“The aim of this study was to determine the impact of fat gain and its distribution on endothelial function in lean healthy humans…Endothelial dysfunction has been identified as an independent predictor of cardiovascular events.”

Study subjects were assigned to either gain weight or maintain the same weight while a number of functional indicators were tracked along with body composition. The metric for endothelial function was brachial artery flow-mediated dilation [FMD]. The weight gainers then lost the added weight for the final measurements. What did the data show? First the bad news, then the good:

FMD decreased in fat gainers but recovered to baseline when subjects shed the gained weight.

Subcutaneous fat gain did not degrade endothelial function. The authors sum up their findings by concluding:

“In normal-weight healthy young subjects, modest fat gain results in impaired endothelial function, even in the absence of changes in blood pressure. Endothelial function recovers after weight loss. Increased visceral rather than subcutaneous fat predicts endothelial dysfunction.”

So ‘it’s not over until the fat lady loses the weight around her waist.’

Fructose even worse than glucose for fat and insulin

Journal of Clinical InvestigationThis is why the ubiquitous high-fructose corn syrup is such a disaster for public health. The authors of this study published in The Journal of Clinical Investigation note that “Studies in animals have documented that, compared with glucose, dietary fructose induces dyslipidemia and insulin resistance.” When they examined the effect in humans they found that all the following were increased markedly in the subjects on fructose but not glucose: visceral adiposity (fat around the organs), plasma triglycerides, fat in the liver, small dense LDL, oxidized LDL, fasting glucose and fasting insulin. At the same time insulin sensitivity decreased in the subjects consuming fructose but not glucose. The authors conclude: “These data suggest that dietary fructose specifically increases DNL, promotes dyslipidemia, decreases insulin sensitivity, and increases visceral adiposity in overweight/obese adults.” [DNL = de novo lipogenesis which means making fat from scratch in the liver.] An accompanying commentary in the same journal states: “In the event that any readers harbor some remaining skepticism, an unprecedented thorough analysis in close to 900,000 participants from almost 60 prospective studies was very recently published, proving beyond any possible doubt that progressive excess mortality is caused by increased body adiposity…Stanhope and colleagues provide major scientific progress by demonstrating marked differences in the metabolic effects of these two major sugars with respect to their ability to promote intraabdominal lipid deposition and hepatic lipid production, while shifting cholesterol metabolism in an unfavorable manner and diminishing insulin sensitivity in humans.” Public health is groaning under a burden of overweight/obesity; how much disease could we prevent just by cutting out most of the sweet drinks (including most fruit juices) for children and adults?