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The Role of Nuts in Plant-Based Diets

By Sharon Palmer, RD

Tree nuts, including almonds, brazil nuts, cashews, hazelnuts, macadamias, pecans, pine nuts, pistachios, walnuts, and peanuts, are a nutrient-rich plant food that can provide important vitamins and minerals for people following plant-based diets. A recent increase in interest regarding plant-based eating patterns has been observed: Four percent of adults described themselves as vegetarian and 1% as vegans, yet 47% reported that they frequently eat vegetarian meals.1

Plant-based diets are associated with many health benefits, such as a lower risk of death from ischemic heart disease; lower BMI, LDL cholesterol, and blood pressure; and lower rates of overall cancer, hypertension, and type 2 diabetes. In fact, increased intake of nuts, as well as fruits, vegetables, whole grains, and soy products, are protective components within a plant-based diet.2 The Dietary Guidelines for Americans, interpreted in MyPlate, now suggest consuming a plant-based diet, with recommendations to fill at least three-fourths of the plate with plant foods and include more plant protein foods in the diet, such as nuts.3

Nutrient Contributions of Nuts
Several studies indicate that regular nut consumption may protect against cardiovascular disease risk, and emerging research suggests that nuts may play a protective role in cognitive function, bone health, weight control, and diabetes management, though more studies are needed to confirm benefits in these areas.4

Nuts are dense in diverse nutrients, including macronutrients, vitamins, and minerals. Various nuts also contain specific phytochemicals. For example, walnuts contain very high levels of ellagic acid, gamma-tocopherol, and melatonin, and peanuts and pistachios contain resveratrol, the potent antioxidant compound found in red wine. Oxidative stress reduction through dietary intake of antioxidants from plant foods may reduce oxidative damage that can lead to disease, such as cardiovascular disease and cancer.5

While studies show that plant-based diets, such as vegetarian eating patterns, tend to have higher levels of dietary ﬁber, magnesium, potassium, vitamins C and E, folate, carotenoids, ﬂavonoids, and other phytochemicals compared with diets based on animal foods, other nutrients may be of concern, including omega-3 fatty acids and protein; nuts can provide good sources of protein and walnuts are rich in plant-based omega-3s.2

Walnuts are one of the few foods that provide an excellent source (more than 2.5 g/oz) of alpha-linolenic acid (ALA), the plant form of omega-3 fatty acids. Research suggests that ALA may have protective benefits against nonfatal myocardial infarction.3,6 The Dietary Reference Intake recommends levels of 1.6 g and 1.1 g of ALA per day for men and women, respectively. People who consume little if any omega-3 fatty acids through fish may need to consume additional dietary ALA food sources, such as walnuts.2

Starring Role in the Mediterranean Diet
Nuts also play an important role in the Mediterranean diet, one of the most widely investigated plant-based eating patterns.

The diet, with its focus on whole grains, legumes, nuts, fruits, vegetables, olive oil, moderate wine consumption, fish, and moderate intake of dairy products, has been linked with several health benefits, including lower risk of cardiovascular disease and type 2 diabetes, associated with higher levels of circulating antioxidants, reduced oxidative stress, and modulation of inflammation.7,8

Data from 1,224 participants in the PREDIMED randomized clinical trial found that a traditional Mediterranean diet enriched with 30 g/day of nuts lowered the incidence of the metabolic syndrome.9

Optimal Plant-Based Protein Choice
Nuts provide a nutrient-rich protein source for plant-based diets. Studies suggest that choosing nuts at meals instead of animal foods may offer a variety of health benefits.

In a recent randomized, crossover study, 25 subjects received either a control diet, a diet incorporating 1.5 oz of walnuts (per 2,400 kcal) six days per week, or a diet including two 4-oz servings of salmon per week. After four weeks, the ratios of total cholesterol to HDL cholesterol, LDL to HDL cholesterol, and apolipoprotein B to A-I were lower in those on the walnut diet compared with the control and fish diets.10

And a Harvard study, which looked at two cohorts including more than 83,000 women and 37,000 men, found that regular consumption of red meat was associated with a 13% increased risk of mortality. However, replacing one serving of red meat with one serving of nuts reduced mortality risk by 19%.11

Studies suggest that everyone can benefit from consuming a 1-oz serving of nuts per day, but perhaps plant-based eaters have even more reason to include one to two servings of this nutritious food in their diets daily.

— Sharon Palmer, RD, is a plant-based diet expert, the author of The Plant-Powered Diet and the forthcoming Plant-Powered for Life, the editor of the Environmental Nutrition newsletter, and a contributing editor at Today’s Dietitian.

Common Nuts, Calories, and Protein Content

Nuts (1-oz portion)	Calories	Protein (g)
Almonds	164	6
Brazil nuts	186	4
Cashews	157	5
Hazelnuts	178	4
Macadamia nuts	204	2
Peanuts	161	7
Pine nuts	191	4
Pistachios	159	6
Walnuts	185	4

— Source: USDA

References

1. Stahler C. How often do Americans eat vegetarian meals? And how many adults in the U.S. are vegetarian? The Vegetarian Resource Group Website. http://www.vrg.org/blog/2012/05/18/how-often-do-americans-eat-vegetarian-meals-and-how-many-adults-in-the-u-s-are-vegetarian/. May 18, 2012. Accessed March 3, 2014.

2. Craig WJ, Mangels AR; American Dietetic Association. Position of the American Dietetic Association: vegetarian diets. J Am Diet Assoc. 2009;109(7):1266-1282.

3. US Department of Agriculture, US Department of Health and Human Services. Dietary Guidelines for Americans, 2010. 7th ed. Washington, DC: US Government Printing Office; 2010.

4. Banel DK, Hu FB. Effects of walnut consumption on blood lipids and other cardiovascular risk factors: a meta-analysis and systematic review. Am J Clin Nutr. 2009;90(1):56-63.

5. Halvorsen BL, Carlsen MH, Phillips KM, et al. Content of redox-active compounds (ie, antioxidants) in foods consumed in the United States. Am J Clin Nutr. 2006;84(1):95-135.

6. Geleijnse JM, de Goede J, Brouwer IA. Alpha-linolenic acid: is it essential to cardiovascular health? Curr Atheroscler Rep. 2010;12(6):359-367.

7. Dai J, Jones DP, Goldberg J, et al. Association between adherence to the Mediterranean diet and oxidative stress. Am J Clin Nutr. 2008;88(5)1364-1370.

8. Chrysohoou C, Panagiotakos DB, Pitsavos C, Das UN, Stefanadis C. Adherence to the Mediterranean diet attenuates inflammation and coagulation process in healthy adults. The Attica study. J Am Coll Cardiol. 2004;4(1):152-158.

9. Salas-Salvado J, Fernandez-Ballart J, Ros E, et al. Effect of a Mediterranean diet supplemented with nuts on metabolic syndrome status: one-year results of the PREDIMED randomized trial. Arch Intern Med. 2008;168(22):2449-2458.

10. Rajaram S, Haddad EH, Mejia A, Sabate J. Walnuts and fatty fish influence different serum lipid fractions in normal to mildly hyperlipidemic individuals: a randomized controlled study. Am J Clin Nutr. 2009;89(5):1657S-1663S.

11. Pan A, Sun Q, Bernstein AM, et al. Red meat consumption and mortality: results from 2 prospective cohort studies. Arch Intern Med. 2012;172(7):555-563.