Nuts reduce inflammation and all-cause mortality
Nuts 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."
"...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
A 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.