A body of evidence tells us that eating patterns in which plants take centre stage are associated with lowering the risk of type 2 diabetes, cardiovascular disease (CVD), hypertension, obesity, metabolic syndrome and all-cause mortality (1).

Taking this a step further, research suggests a reduced risk of disease when protein comes from plants, such as nuts, grains and beans, instead of from animal sources.

The most compelling evidence, from systematic literature reviews and meta-analyses of intervention studies, is that a diet high in plant protein (>50% of total protein intake from plant sources), in substitution for animal protein, is protective against a range of CVD markers (2-5).

What’s so special about nut protein? 

Traditionally, the benefits of nuts have been attributed to their healthy mono- and poly-unsaturated fatty acids, dietary fibre, and other nutrients and bioactives, such as vitamin E, magnesium and phytosterols.

But nuts also provide significant amounts of protein, and it is likely this plays at least some part in many of the health benefits linked with eating nuts.

Of the common sources of plant protein that Australians eat – grains, legumes, nuts and soy – nuts generally have the highest plant protein content per 100g (6). For instance, almonds and pistachios have 20g plant protein per 100g, compared to soybeans at around 14g, tofu at 12g, chickpeas at 6g, and oats with 2-3g.

The protein digestibility (or ‘protein quality’) of tree nuts is similar to many other plant protein sources (7-9).

Evidence suggests that protein from nuts and seeds may be the most effective for heart health.

The well-known Adventist Health Study 2, a large cohort of more than 81,000 US-based adults, found protein from ‘nuts and seeds’ was associated with a 40-60 per cent reduced risk of death from heart disease (10). No such links were found for protein from ‘grains’, or ‘legumes, fruits and vegetables’, suggesting that nuts and seeds are unique among sources of plant protein.

A number of possible mechanisms have been suggested to explain the favourable effects of plant and nut protein on health, including the differing amino acid profiles of plant and animal proteins (11). The exact mechanisms, however, are unclear – with more research needed in this area.

The bottom line

Given their high level of plant protein, including a daily handful of nuts (30g) may be an effective and yet easy way for Australians to embrace plant-based eating patterns – a win for our health (and that of our planet).

Want to learn more?

Nuts for Life asked Nutrition Research Australia (NRAUS) to scope the science, published in the past 20 years, on the effect of plant and nut protein on health. This uncovered new insights into the unique contribution of nut protein to health.

References

  1. Lonnie M., Johnstone AM. The public health rationale for promoting plant protein as an important part of a sustainable and healthy diet. Nutrition Bulletin, 2020. 45:281-93.
  2. Bergeron N., et al. Effects of red meat, white meat, and non-meat protein sources on atherogenic lipoprotein measures in the context of low compared with high saturated fat intake: A randomized controlled trial. Am J Clin Nutr, 2019. 110(1):24-33.
  3. Li SS., et al. Effect of plant protein on blood lipids: A systematic review and meta-analysis of randomized controlled trials. J Am Heart Assoc, 2017. 6(12).
  4. Zhao H., et al. Effects of plant protein and animal protein on lipid profile, body weight and body mass index on patients with hypercholesterolemia: A systematic review and meta-analysis. J Acta Diabetologica, 2020. 5:1-12.
  5. Anderson JW., Major AW. Pulses and lipaemia, short- and long-term effect: Potential in the prevention of cardiovascular disease. Br J Nutr, 2002. 88 Suppl 3:S263-71.
  6. Food Standards Australia and New Zealand (FSANZ). Australian Food Composition Database - Release 1.0: FSANZ; 2019. Available at: https://www.foodstandards.gov.au/
  7. Loveday SM. Food proteins: Technological, nutritional, and sustainability attributes of traditional and emerging proteins. Annu Rev Food Sci Technol, 2019. 10:311-39.
  8. Boye J., et al. Protein quality evaluation twenty years after the introduction of the protein digestibility corrected amino acid score method. Br J Nutr, 2012. 108(S2):S183-S211.
  9. Freitas JB., et al. Edible seeds and nuts grown in Brazil as sources of protein for human nutrition. Food Nutrition Sciences, 2012. 3(6):857-62.
  10. Tharrey M., et al. Patterns of plant and animal protein intake are strongly associated with cardiovascular mortality: The Adventist Health Study-2 cohort. Int J Epidemiol, 2018. 47(5):1603-12.
  11. Mariotti F. Animal and plant protein sources and cardiometabolic health. Adv Nutr, 2019. 10(Suppl_4):S351-66.
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