Health authorities around the world recommend eating more plant foods for good health: good for the body and for the environment.

Nuts are like nature’s own vitamin supplement – a small package containing a combination of at least 28 different essential nutrients.

Regularly eating nuts has been shown to contribute to heart health, reduce overall mortality and the risk of developing type 2 diabetes, assist with weight management, reduce the risk of cancer, improve sperm quality, reduce depression and overall promote good health.

Introduction 

Recent scientific evidence concludes that a diet rich in plant-based foods and with fewer animal source foods confers both improved health and environmental benefits [1]. The EAT-Lancet report suggests that transforming to healthy diets by 2050 requires global substantial shifts, including more than doubling consumption of healthy foods like nuts, fruit and vegetables, and legumes. The traditional Mediterranean way of eating, which includes plenty of plant foods and nuts, is considered to be one of the healthiest in the world. 

Nuts have long been associated with good health. Their role in heart health was established over 20 years ago following the publication of four major population studies [2-5]. Since then, nuts have been associated with a number of health outcomes including: 

  • reduced risk of cardiovascular and coronary heart disease [6]
  • preventing type 2 diabetes [7], and managing existing diabetes [8]
  • reduced risk of overweight and obesity [9]
  • reduced all-cause mortality (death) [6]
  • reduced risk of cancer [10]
  • improvements in brain health, including cognition, learning and memory [11-13]
  • improvements in sperm quality [14]
  • decreased risk of depression [15].

So, what is it about nuts that contributes to these benefits?

Tree nuts are a nutrient dense food, rich in numerous essential vitamins, minerals, mono- and polyunsaturated fatty acids, protein and fibre. 

Generally, nuts contain:

  • Fats, especially the healthy mono- and polyunsaturated fats – essential for regulating blood cholesterol and serve as a carrier of fat-soluble vitamins.  The majority of the fat in nuts is unsaturated, averaging over 85% of total fat.
  • Omega-3 polyunsaturated fats. Omega-3 alpha linolenic acid (ALA) is an essential fat which must be obtained from the diet and is necessary for growth and development, brain and nerve function, maintaining cell membranes and in regulating inflammation.  
    • Walnuts are particularly rich in ALA, with smaller amounts in pecans, hazelnuts and macadamias.
  • Protein – required throughout life to create, maintain and renew our body cells. It also plays a role in satiety, helping to satisfy hunger.
    • Nuts provide approximately 10-20g of protein per 100g
  • Fibre – essential for maintaining a healthy bowel, helping to satisfy hunger, managing blood glucose levels and helping to lower blood cholesterol.
    • Nuts provide approximately 8g of fibre per 100g
  • Vitamin E – an antioxidant that helps protect tissues from damage.
    • An average 30g serve of nuts provides around 20% of the RDI
    • Folate, a B-group vitamin associated with heart health, and involved in cell structure.
  • Magnesium – a mineral essential for good nerve and muscle function.
  • Zinc – a mineral required for a strong immune system and healing and protecting the skin.
  • Iron – a mineral involved in various bodily functions, including the transport of oxygen in the blood.

In addition, most tree nuts provide phytochemicals – the biologically active compounds found in plants.

The important phytochemicals present in tree nuts include polyphenols, carotenoids, phytosterols, phytates, and lignans. Studies have shown that these phytochemicals have antioxidant, anti-inflammatory, anti-mutagenic, and anti-cancer properties. This broad range of bioactivity of phytochemicals helps in preventing or slowing down aging and age-related diseases [16]. 

In addition to polyphenols, the presence of phytosterols, tocopherols, folic acid, L-arginine, low sodium, high calcium, magnesium, and potassium, and a good ratio of omega-3/omega-6 fatty acids among many other nutrients in tree nuts contribute to enhanced health and an increased lifespan.

How many nuts do we need?

Many studies on nuts and health have investigated a one ounce serving, or increments of an ounce serving of nuts (where an ounce is equivalent to 28g). A recent review conducted by Aune et al in 2016 [6], concluded that a minimum of around 20g of nuts per day is associated with most of the disease risk reduction. Given the Australian Dietary Guidelines define a serving of nuts as 30g, and putting this into context, it is appropriate to aim for a 30g serving of nuts every day. 

References

  1. Willett, W., et al., Food in the Anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems. The Lancet, 2019. 393(10170): p. 447-492.
  2. Fraser, G.E., et al., A possible protective effect of nut consumption on risk of coronary heart disease. The Adventist Health Study. Arch Intern Med, 1992. 152(7): p. 1416-24.
  3. Ellsworth, J.L., L.H. Kushi, and A.R. Folsom, Frequent nut intake and risk of death from coronary heart disease and all causes in postmenopausal women: the Iowa Women's Health Study. Nutr Metab Cardiovasc Dis, 2001. 11(6): p. 372-7.
  4. Hu, F.B., et al., Frequent nut consumption and risk of coronary heart disease in women: prospective cohort study. BMJ, 1998. 317(7169): p. 1341-5.
  5. Albert, C.M., et al., Nut consumption and decreased risk of sudden cardiac death in the Physicians' Health Study. Arch Intern Med, 2002. 162(12): p. 1382-7.
  6. Aune, D., et al., Nut consumption and risk of cardiovascular disease, total cancer, all-cause and cause-specific mortality: a systematic review and dose-response meta-analysis of prospective studies. BMC Med, 2016. 14(1): p. 207.
  7. Afshin, A., et al., Consumption of nuts and legumes and risk of incident ischemic heart disease, stroke, and diabetes: a systematic review and meta-analysis. Am J Clin Nutr, 2014. 100(1): p. 278-88.
  8. Viguiliouk, E., et al., Effect of tree nuts on glycemic control in diabetes: a systematic review and meta-analysis of randomized controlled dietary trials. PLoS One, 2014. 9(7): p. e103376.
  9. Li, H., et al., Nut consumption and risk of metabolic syndrome and overweight/obesity: a meta-analysis of prospective cohort studies and randomized trials. Nutr Metab (Lond), 2018. 15: p. 46.
  10. Wu, L., et al., Nut consumption and risk of cancer and type 2 diabetes: a systematic review and meta-analysis. Nutr Rev, 2015. 73(7): p. 409-25.
  11. O'Brien, J., et al., Long-term intake of nuts in relation to cognitive function in older women. J Nutr Health Aging, 2014. 18(5): p. 496-502.
  12. Arab, L. and A. Ang, A cross sectional study of the association between walnut consumption and cognitive function among adult US populations represented in NHANES. J Nutr Health Aging, 2015. 19(3): p. 284-90.
  13. Gignac, F., et al., Maternal nut intake in pregnancy and child neuropsychological development up to 8 years old: a population-based cohort study in Spain. Eur J Epidemiol, 2019.
  14. Salas-Huetos, A., et al., Effect of nut consumption on semen quality and functionality in healthy men consuming a Western-style diet: a randomized controlled trial. Am J Clin Nutr, 2018. 108(5): p. 953-962.
  15. Sanhueza, C., L. Ryan, and D.R. Foxcroft, Diet and the risk of unipolar depression in adults: systematic review of cohort studies. J Hum Nutr Diet, 2013. 26(1): p. 56-70.
  16. Rusu, M.E., et al., Anti-aging potential of tree nuts with a focus on the phytochemical composition, molecular mechanisms and thermal stability of major bioactive compounds. Food Funct, 2018. 9(5): p. 2554-2575.
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