Are nuts part of a healthy diet?

NutritionLifestyle Medicine
Written By Paul Martin
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Seventy to ninety-five percent of the calories in nuts come from fat! That’s a lot of fat, which is the main reason why nuts have been maligned and confined to occasional use...and often shunned when trying to lose weight.

However, an extensive body of scientific evidence beginning with a landmark Adventist Health Study paper published in 1992(1) has changed all that. Nuts are now prescribed as a daily part of a healthy diet. Here’s why.

General nutritional characteristics

Yes, nuts are fat-rich, but the majority of that fat is “good” fat: mono and polyunsaturated fat. Nuts are cholesterol and trans-fat free, providing about 2 grams of fiber and 5 grams of protein per one-ounce serving (28 grams). Nuts are also a good source of the amino acid, L-arginine, which is converted into nitric oxide, a powerful vasodilator that helps reduce the risk of cardiovascular disease.(2) They provide vitamin E and 5 different B vitamins, including folate. Nuts are a mineral source, supplying calcium, potassium, magnesium, as well as the trace minerals iron, zinc, manganese, copper and selenium. Nuts contain phytosterols, plant substances so similar in structure to cholesterol that they block cholesterol reabsorption, helping lower cholesterol levels. Finally, nuts contain an abundant array of health-promoting antioxidants and phytochemicals, including phenolic acids, ellagic and gallic acids, flavonoids, isoflavones and carotenoids.(3),(4)

Nuts’ complex package of nutrient and non-nutrient substances act synergistically to provide a wealth of health benefits associated with regular consumption.

Health benefits

  1. Frequent nut consumption is associated with a strong cardioprotective effect: 

    • A dose-response decreased risk of coronary heart disease (CHD), the greatest risk reduction associated with eating nuts more than 5 times/wk,(5)

    • A decreased risk of CHD death,(5)

    • The beneficial effects are similar for different clinical outcomes: nonfatal myocardial infarction, fatal CHD, sudden cardiac death,(1),(5)

    • Lowers total cholesterol, LDL cholesterol, apo B and triglycerides,(5) (6) 

    • Is significantly associated with decreased inflammatory markers, CRP, IL-6 and fibrinogen.(5)

    • The fiber in nuts is associated with decreased: body mass index, waist-to-hip ratio, apoB and fasting glucose.(5)

  2. The fiber and polyphenols in nuts improve the guts microbiome by providing fermentable substrate for beneficial bacterial species.(7)

  3. There is strong evidence that frequent consumption of nuts is associated with a decreased risk of diabetes in women.(5)

  4. Frequent nut consumption is associated with a decreased risk of gallstone formation in men and women, even though nuts have a high fat content.(5)

  5. Even though nuts are high-calorie foods, frequent nut consumption is not associated with weight gain or becoming overweight or obese.(5)

  6. Dietary patterns that include nuts are associated with positive health outcomes, including decreased risk of high blood pressure and stroke.(5),(8)

  7. Regularly eating nuts is associated with lower cardiovascular disease and mortality in people with diabetes.(9)

  8. Regular nut consumption, especially almonds, hazelnuts and walnuts, may be protective against Alzheimer’s disease.(10)

  9. Higher weekly nut consumption in the middle-aged and elderly (>= 55yrs) is associated with: 1) decreased risk of all-cause and cause-specific morbidity and mortality, including risk of type 2 diabetes, obesity, stroke and incidence of cardiovascular events, 2) lower levels of total cholesterol, LDL cholesterol, triglycerides, apoB and all markers of cardiovascular morbidity and mortality, 3) decreased: fasting and postprandial blood sugars, fasting insulin, HbA1c, insulin resistance and BMI, 4) decreased inflammatory markers, CRP and IL-6, 5) decreased risk of several cancers, 6) increased cognitive performance and decreased cognitive decline, 7) improving the gut microbiome by increasing various species of beneficial bacteria.(11)

Recommendations

In order to optimize your health, enjoy 1-2 one-ounce servings of nuts most days of the week, unless your doctor tells you not to.

Nuts are different sizes, therefore, the number of nuts in an ounce varies with the nut; (information is provided in Table 1). If you prefer not to count or measure, a simple guideline is to have one small handful a day. Mix it up; eat a variety of nuts from day-to-day to profit from the nutritional benefits unique to each kind of nut. 

Table 1: Number of nuts per ounce

  1. Fraser GE, Sabaté J, Beeson WL, Strahan TM. A possible protective effect of nut consumption on risk of coronary heart disease. The Adventist Health Study. Arch Intern Med. 1992;152(7):1416-1424.

  2. Bondonno CP, Croft KD, Hodgson JM. Dietary Nitrate, Nitric Oxide, and Cardiovascular Health. Crit Rev Food Sci Nutr. 2016;56(12):2036-2052. doi:10.1080/10408398.2013.811212

  3. Alasalvar C, Bolling BW. Review of nut phytochemicals, fat-soluble bioactives, antioxidant components and health effects. Br J Nutr. 2015;113 Suppl 2:S68-S78. doi:10.1017/S0007114514003729

  4. Bolling BW, Chen CY, McKay DL, Blumberg JB. Tree nut phytochemicals: composition, antioxidant capacity, bioactivity, impact factors. A systematic review of almonds, Brazils, cashews, hazelnuts, macadamias, pecans, pine nuts, pistachios and walnuts. Nutr Res Rev. 2011;24(2):244-275. doi:10.1017/S095442241100014X

  5. Joan Sabaté, Yen Ang, Nuts and health outcomes: new epidemiologic evidence, The American Journal of Clinical Nutrition, Volume 89, Issue 5, May 2009, Pages 1643S–1648S, https://doi.org/10.3945/ajcn.2009.26736Q

  6. Del Gobbo LC, Falk MC, Feldman R, Lewis K, Mozaffarian D. Effects of tree nuts on blood lipids, apolipoproteins, and blood pressure: systematic review, meta-analysis, and dose-response of 61 controlled intervention trials. Am J Clin Nutr. 2015;102(6):1347-1356. doi:10.3945/ajcn.115.110965

  7. Lamuel-Raventos RM, Onge MS. Prebiotic nut compounds and human microbiota. Crit Rev Food Sci Nutr. 2017;57(14):3154-3163. doi:10.1080/10408398.2015.1096763

  8. Chiavaroli L, Viguiliouk E, Nishi SK, et al. DASH Dietary Pattern and Cardiometabolic Outcomes: An Umbrella Review of Systematic Reviews and Meta-Analyses. Nutrients. 2019;11(2):338. Published 2019 Feb 5. doi:10.3390/nu11020338

  9. Liu G, Guasch-Ferré M, Hu Y, et al. Nut Consumption in Relation to Cardiovascular Disease Incidence and Mortality Among Patients With Diabetes Mellitus. Circ Res. 2019;124(6):920-929. doi:10.1161/CIRCRESAHA.118.314316

  10. Gorji N, Moeini R, Memariani Z. Almond, hazelnut and walnut, three nuts for neuroprotection in Alzheimer's disease: A neuropharmacological review of their bioactive constituents. Pharmacol Res. 2018;129:115-127. doi:10.1016/j.phrs.2017.12.003 

  11. Rusu ME, Mocan A, Ferreira ICFR, Popa DS. Health Benefits of Nut Consumption in Middle-Aged and Elderly Population. Antioxidants (Basel). 2019;8(8):302. Published 2019 Aug 12. doi:10.3390/antiox8080302  

 
Paul Martin
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