Health benefits of nuts

The health benefits of nuts are widely accepted in many cultures. Most traditional cuisines incorporate nuts in one way or another. Nuts are part of many dietary patterns, including vegan (raw or regular), vegetarian, pescetarian, paleo, keto, Mediterranean, etc.

Tree nuts and peanuts

Tree nuts include walnuts, almonds, macadamia nuts, etc. Peanuts are botanically legumes, but are considered in the “nut” category due to its similar nutritional profile. Sadly, they also share the potential to cause food allergy. Both tree nuts and peanuts are in the list of top ten food allergens that must be declared in food packaging (read more about food allergy here).

Most scientific studies include peanuts when analysing nut consumption. Likewise, the Australian Dietary Guidelines consider peanuts in the nut category.

Nutrients in nuts

Nuts are energy-dense due to their high fat content. Depending on the type of nut, they also provide some protein and fibre. This make them ideal for controlling hunger. See table below for average values per 100g of raw nuts (1).

Different nuts have different proportions of the main kinds of fatty acids: saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA). See table below for average content per 100g of nuts (1). MUFAs and PUFAs are less stable than SFAs, hence the proclivity of nuts to become rancid. The human body requires a mixture of fatty acids, and, in general, it is better to obtain them from whole foods such as nuts.

Nuts also contain micronutrients such as polyphenols, which also confer health benefits.

Diabetes

The analysis of a large cohort study found that people who consumed walnuts had lower relative risk of diabetes compared to people who didn’t consume nuts at all (2).

Almonds, pistachios and peanuts may help control blood sugar and insulin (3).

Body composition

The UK Women’s Cohort Study found that higher nut consumption was associated with lower body weight, body mass index (BMI) and waist circumference. The researchers also analysed the results grouped by food preferences. Some of the benefits seemed to be more pronounced for omnivores than vegetarians and vegans (4).

Almonds and peanuts increase satiety, allowing for better intake control. In addition, peanuts may help improve fat oxidation (3).

Cardiovascular risk

The same study also found higher nut consumption was also associated reduced blood pressure and blood cholesterol. Participants who ate more nuts also had less prevalence of heart attack, diabetes and gallstones (4).

Walnuts in particular have been linked to improvements in blood lipids and endothelial function (3, 5). The phytosterols, unsaturated fatty acids and fibre in nuts seem play a role in the former, and alpha-linolenic acid (ALA), a PUFA that contributes 10% of the energy in walnuts, may be responsible for the latter (5).

Pistachios have also been associated with favourable changes in blood lipids and vascular function (3).

Nuts also contain potassium, which seems to counteract the effects of excess sodium on elevating blood pressure (5).

Inflammation and oxidative stress

An analysis of 2 large cohort studies found that higher nut consumption was associated with lower concentrations of the following inflammatory markers: C-reactive protein (CRP) and interleukin-60 (IL-6), but not tumor necrosis factor receptor 2 (TNFR2). This association also was noted when 3 servings of nuts replaced the same number of servings of red meat, processed meat, eggs or refined grains. The same relationship was found for CRP when nuts replaced potatoes and potato chips (6).

Walnuts contain g-tocopherol, a potent antioxidant that aids in reducing inflammation (3, 5). A type of polyphenol in walnuts, called ellagitannins, have also been linked to antioxidant and antiinflammatory activities (5).

Brazil nuts are rich in selenium, which has antioxidant properties (3).

Recommendations

• If you have a nut allergy, make sure you let people know in restaurants, airplanes, functions, etc. It’s better to be safe than sorry.
• As a general rule, a reasonable intake of nuts is around 30g per day. This may be adjusted based on age, gender, body mass, activity level, etc.
• Raw, dry roasted and “activated” (soaked, then dried) nuts are best
• When possible, keep nuts in the freezer or fridge to protect the fatty acids
• Don’t eat nuts that taste or smell rancid
• Eat a variety of nuts to ensure a wide exposure to beneficial nutrients
• If you don’t like to eat nuts on their own, try adding them to salads, yoghurt, etc.
• If you struggle with portion control and/or want to lose weight, the following strategies can be useful:
  • Buy single-serve packages or use small containers to portion your daily snack
  • Buy nuts in the shell and shell them before eating
  • Choose whole nuts instead of nut butters
  • Avoid making treats with nut meal or butter

References

1. Food Standards Australia New Zealand. AUSNUT 2011–13 – Australian Food Composition Database. 2014 [Available from: http://www.foodstandards.gov.au].
2. Arab L, Dhaliwal SK, Martin CJ, Larios AD, Jackson NJ, Elashoff D. Association between walnut consumption and diabetes risk in NHANES. Diabetes/metabolism research and reviews. 2018;34(7):e3031.
3. de Souza RGM, Schincaglia RM, Pimentel GD, Mota JF. Nuts and Human Health Outcomes: A Systematic Review. Nutrients. 2017;9(12).
4. Brown RC, Gray AR, Tey SL, Chisholm A, Burley V, Greenwood DC, et al. Associations between Nut Consumption and Health Vary between Omnivores, Vegetarians, and Vegans. Nutrients. 2017;9(11):1219.
5. Ros E, Izquierdo-Pulido M, Sala-Vila A. Beneficial effects of walnut consumption on human health: role of micronutrients. Current opinion in clinical nutrition and metabolic care. 2018;21(6):498-504.
6. Yu Z, Malik VS, Keum N, Hu FB, Giovannucci EL, Stampfer MJ, et al. Associations between nut consumption and inflammatory biomarkers. The American Journal of Clinical Nutrition. 2016;104(3):722-8.

[Photo by Tom Hermans on Unsplash]

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