No need to caution the portion of nuts – eating nuts does not lead to weight gain

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By Lisa Yates Advanced Accredited Practising Dietitian and Program Manager, Nuts for Life

For many, the low-fat diet mantra of the 80s and 90s has taken root and many fear that eating nuts, rich in healthy fats, will result in weight gain; but this is not the case. The 2013 Australian Dietary Guidelines reported that 65-100g of nuts a day does not lead to weight gain; at least in the short term (1). This is supported further by more recent research. Health professionals should be encouraging nut consumption and here’s why.

What quantity of nuts are we eating?

The Australian Health Survey (2011-13) uncovered that Australians on average are eating just 6g of nuts a day (2) – well short of the 30g serving size recommended in the Australian Dietary Guidelines(1). In the dietary modelling that underpins the Guidelines, nuts were included as a separate food group. In the various meal plans, depending on age, gender and life stage, from four serves of nuts a week to 21 serves a week (a serve is 30gm) is advised (3). Recommending a simple 30g handful a day, however, is a much simpler take-home message.

Although nuts appear in the “protein” food group with legumes, eggs, fish, chicken and red meat – a 30g serve of nuts is not equivalent in protein compared with other serves of protein foods in this food group. For instance two 30g handfuls of nuts contains on average 28g of protein(4), similar to a 65g serve of red meat. Vegetarians will need to eat larger serves of nuts.

Nuts and heart health

A regular daily handful of nuts has been well researched with clear positive outcomes for health. It is now common wisdom that regular nut consumption reduces the risk of coronary heart disease and cardiovascular disease (CVD) (5-8), and reduces CVD and all cause mortality (5,9-14). This is because regular nut consumption reduces total and LDL cholesterol and/or triglycerides (15,16), reduces blood pressure (17,18) and reduces the impact of oxidative stress and inflammation on endothelial function(19) – all risk factors for CVD.

Nuts and Weight

A systematic literature review of some 100 clinical trials has found regular nut consumption (30g a day) as part of a healthy diet contributes to heart health without weight gain.(20) The epidemiological evidence suggests regular nut consumption does not cause weight gain and if swapped in place of other snacks in an energy-controlled diet can lead to weight loss.(21-23) Nuts are high in protein and fibre which help satisfy the appetite, they increase intestinal satiety hormones signalling fullness, increase fat oxidation, increase excretion of fat in stools (fat is trapped in the fibrous structure of nuts unavailable for absorption), (24,25) and help control blood glucose and improve insulin sensitivity(26-27).

Nuts and Diabetes

Regular nut consumption reducing the risk of type 2 diabetes is more controversial, however, with several meta analyses published in the last 12 months with opposing results.(6,7,13,25,28-30) Daily nut consumption does appear to be beneficial for those with existing type 2 diabetes by: helping to reduce CVD risk(31,32), assisting with blood glucose control and improving glycosylated haemoglobin (HbA1c) through reduced postprandial glycemia (25-27) and improving insulin sensitivity(27).

Are you eating enough nuts?

In a recent survey of GPs just 4% reported eating 30gs of nuts every day and 60% reported that whenever they consume nuts they generally have a 30g handful of nuts, just not every day. Similarly 5% of consumers reported eating a 30g handful of nuts every day.(33)

So while the epidemiological evidence suggests a daily 30g serve of nuts, results from meta analysis of clinical trials suggest 30-60gs a day especially for those with high cholesterol or blood glucose.(15,26) Generally the benefits increase with each additional weekly serving of nuts.(34,35)

#nuts30days30ways campaign

To encourage more regular consumption of a 30g serve of nuts, Nuts for Life – a health education program from the Australian Tree Nut Industry and Horticulture Innovation Australia - has developed a new campaign for March 2016. They are encouraging everyone to take the #nuts30days30ways challenge and eat a 30g healthy handful of nuts every day as a snack or as ingredients in meals. Health professionals can take the challenge and encourage clients and patients to do the same and see how well their cholesterol, glucose and weight responds.

For recipe inspiration search #nuts30days30ways on instagram and facebook or visit http://nutsforlife.com.au/nut-recipes and for more information on the health benefits of nuts read The Nut Heart Weight Report summary here http://nutsforlife.com.au/resources/literature-reviews-summaries

Lisa Yates has a Bachelor of Science (majoring in Biochem and Pharmacol) and a Master of Nutrition and Dietetics. She consults to Nuts for Life, a health education initiative co-funded by the Australia Tree Nut Industry and Horticulture Innovation Australia with Australian Government matched funding.

Tags: nuts, nut, almond, walnut, diabetes, heart, weight, obesity, mortality

References

1. National Health and Medical Research Council (2013) Australian Dietary Guidelines. Canberra: National Health and Medical Research Council 
2. ABS 4364.0.55.007 - Australian Health Survey: Nutrition First Results - Foods and Nutrients, 2011-12 
3. National Health and Medical Research Council Modelling System to Inform the Revision of the Australian Guide to Healthy Eating 2011 
4. Nuts for Life 2016 Nutrient Composition Ready reckoner http://nutsforlife.com.au/resources/nutrient-composition
5. Mayhew AJ et al. A systematic review and meta-analysis of nut consumption and incident risk of CVD and all-cause mortality. Br J Nutr. 2016 Jan;115(2):212-25.
6. Zhou D et al. Nut consumption in relation to cardiovascular disease risk and type 2 diabetes: a systematic review and meta-analysis of prospective studies. Am J Clin Nutr. 2014;100(1):270-7.
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):278-88.
8. Heffron SP et al. Greater frequency of nut consumption is associated with lower prevalence of peripheral arterial disease. Prev Med. 2015;72:15-8.
9. Gopinath B et al. Consumption of nuts and risk of total and cause-specific mortality over 15 years. Nutr Metab Cardiovasc Dis. 2015;25(12):1125-31.
10. Bao Y et al. Association of nut consumption with total and cause-specific mortality. N Engl J Med. 2013;369(21):2001-11.
11.Grosso G et al. Nut consumption on all-cause, cardiovascular, and cancer mortality risk: a systematic review and meta-analysis of epidemiologic studies. Am J Clin Nutr. 2015;101(4):783-93.
12.Luu HN et al. Prospective evaluation of the association of nut/peanut consumption with total and cause-specific mortality. JAMA Intern Med. 2015;175(5):755-66.
13.Luo C et al. Nut consumption and risk of type 2 diabetes, cardiovascular disease, and all-cause mortality: a systematic review and meta-analysis. Am J Clin Nutr. 2014;100(1):256-69.
14.Guasch-Ferré M et al. Frequency of nut consumption and mortality risk in the PREDIMED nutrition intervention trial. BMC Med. 2013;11:164.
15.Del Gobbo LC et al. 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):1347-56.
16.Blanco Mejia S et al. Effect of tree nuts on metabolic syndrome criteria: a systematic review and meta-analysis of randomised controlled trials. BMJ Open. 2014;4(7):e004660.
17.Mohammadifard N et al. The effect of tree nut, peanut, and soy nut consumption on blood pressure: a systematic review and meta-analysis of randomized controlled clinical trials. Am J Clin Nutr. 2015;101(5):966-82.
18.Guo K et al. Meta-analysis of prospective studies on the effects of nut consumption on hypertension and type 2 diabetes mellitus. J Diabetes. 2015;7(2):202-12.
19.Barbour JA et al. Nut consumption for vascular health and cognitive function. Nutr Res Rev. 2014;27(1):131-58.
20. Neale. E, Nolan Clark D and Tapsell LT. The effect of nut consumption on heart health: a systematic review of the literature. Nuts for Life North Sydney 2015. (unpublished). Summary 
21.Jackson CL, Hu FB. Long-term associations of nut consumption with body weight and obesity. Am J Clin Nutr. 2014;100 Suppl 1:408S-11S.
22. Martínez-González MA, Bes-Rastrollo M. Nut consumption, weight gain and obesity: Epidemiological evidence. Nutr Metab Cardiovasc Dis. 2011;21 Suppl 1:S40-5.
23. Tan SY et al. A review of the effects of nuts on appetite, food intake, metabolism, and body weight. Am J Clin Nutr. 2014;100 Suppl 1:412S-22S.
24. Mattes RD. The energetics of nut consumption. Asia Pac J Clin Nutr. 2008;17 Suppl 1:337-9.
25. Ibarrola-Jurado N et al. Cross-sectional assessment of nut consumption and obesity, metabolic syndrome and other cardiometabolic risk factors: the PREDIMED study. PLoS One. 2013;8(2):e57367.
26. 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):e103376.
27. Kendall CW et al. Acute effects of pistachio consumption on glucose and insulin, satiety hormones and endothelial function in the metabolic syndrome. Eur J Clin Nutr. 2014;68(3):370-5.
28. Pan A et al. Walnut consumption is associated with lower risk of type 2 diabetes in women. J Nutr. 2013;143(4):512-8.
29. 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):409-25.
30. Liu Z et al. Is nut consumption associated with decreased risk of type 2 diabetes? Am J Clin Nutr. 2014;100(5):1401-2. doi: 10.3945/ajcn.114.093302.
31. Nishi SK et al. Nut consumption, serum fatty acid profile and estimated coronary heart disease risk in type 2 diabetes. Nutr Metab Cardiovasc Dis. 2014;24(8):845-52.
32. Li TY et al. Regular consumption of nuts is associated with a lower risk of cardiovascular disease in women with type 2 diabetes. J Nutr. 2009;139(7):1333-8.
33.Nuts for Life Market Research 2015 Consumer Insights. (unpublished)
34. Ma L et al. Nut consumption and the risk of coronary artery disease: a dose-response meta-analysis of 13 prospective studies. Thromb Res. 2014;134(4):790-4.
35. Kelly JH Jr, Sabaté J. Nuts and coronary heart disease: an epidemiological perspective. Br J Nutr. 2006;96 Suppl 2:S61-7.