The Role of Plant-based Foods
Both national and international dietary guidelines, from Public Health England (PHE) and the World Health Organization (WHO), are now actively encouraging the consumption of more plant proteins and fewer animal proteins as part of a healthy diet. What’s more, the role of nuts (including walnuts) is becoming increasingly central to the plant-based eating conversation. Click here for a full list of studies referenced on this page.
Official line: more plants, fewer animal proteins
The latest government dietary guidelines, published in the Eatwell Guide, are now aligned with international dietary recommendations.1-4 Two major changes have been incorporated into these new guidelines.
Firstly, foods that are considered high in saturated fats, salt and/or sugars have been removed altogether from the plate model. They now sit outside the main image, emphasising the message that they are not a necessary part of a healthy diet, and should only be consumed occasionally and in small amounts.
Secondly, plant foods have taken a much more central role, with foods such as beans and pulses being encouraged over red and processed meat as a main protein source. Although animal proteins needn’t be cut out of the diet altogether, the majority of the plate model is now made up of plant foods including nuts, seeds, wholegrains and starchy carbohydrates, fruit and vegetables, beans and pulses, and plant-based meat and dairy alternatives.
More plant-based foods for a healthier nation
Dietary patterns based on plant foods have been associated with numerous positive health outcomes relating to heart health, cancer and body weight.5-10 The health benefits associated with walnut consumption could be attributed to their unique, plant-based nutritional profile. Specifically, this includes their lower content of saturated fats, as well as their provision of heart healthy unsaturated fats, vitamins, minerals and fibre.
Unsaturated fats in plant-based foods
Primary sources of saturated fat in the UK diet include meat and processed meats, milk and dairy, and cereals and cereal products (e.g. pizza, cake and pastries). Although these foods still have a place in the diet, the UK public continues to consume saturated fat in excess of national and global heart health recommendations (≤10% total energy (≤11% food energy) or approx. 20g per day).11,12 UK adults aged 19-64 years currently consume on average 25.2g of saturated fat per day, which equates to 12.1% of total energy (12.7% of food energy).13
Plant foods are naturally lower in saturated fats than some popular processed snack foods like chocolate bars and sausage rolls. For example, a 30g handful of walnuts provides 100% of the UK Dietary Reference Value (DRV) for polyunsaturated fat for adult women and 78% for men, and around 10% and 7% respectively of the UK DRV for saturated fat.14
The importance of omega-3 fatty acids
Walnuts, like most tree nuts, are rich in unsaturated fats, but what makes them unique is their polyunsaturated fatty acid (PUFA) content – specifically, of essential omega-3 fatty acid, alpha-Linolenic acid (ALA).14 100g of walnuts provide 7.5g ALA, while a daily handful of 30g provides 2.24g of ALA.14 ALA is associated with several heart health benefits, including maintenance of normal cholesterol levels and improved endothelial function.15-16 Walnuts in particular have been shown to improve endothelial function, partly due to their ALA content.15,17
Replacing saturated fats with polyunsaturated fats
It is well established that the replacement of energy from saturated fats with polyunsaturated fats is most effective at reducing low-density lipoprotein (LDL) cholesterol levels, a primary modifiable risk factor for heart disease.6, 18-20 Substituting 5% saturated fat energy with polyunsaturated fats has been associated with a 0.26mmol/L reduction in LDL-C, overall improvements to HDL cholesterol ratio and a 10% reduced CHD risk.21
- PHE. Guidance: The Eatwell Guide. Gov.UK. March 17, 2016. Available at: https://www.gov.uk/government/publications/the-eatwell-guide. Accessed March 2017.
- WHO. WHO Global Strategy on Diet, Physical Activity and Health.: WHO; 2004.
- WHO. WHO Technical Report Series 916 Diet, Nutrition & the prevention of chronic diseases. Geneva: WHO; 2003.
- WCRF International. Cancer Prevention and Survival. Summary of global evidence on diet, weight, physical activity and what increases or decreases your risk of cancer. London: WCRF International; 2016. Continuous Update Project.
- Richter C, Skulas-Ray A, Champagne C. Plant protein and animal proteins: do they differentially affect cardiovascular disease risk? Adv Nutr. 2015;6(6):712-728.
- Hooper L, Martin N, Abdelhamid A, et al. Reduction in saturated fat intake for cardiovascular disease (Review). Cochrane Systematic Review. June 2015:(6):CD011737.
- WCRF / AICR. Continues Update Project Report: Diet, Nutrition, Physical Activity, and Breast Cancer Survivors. WCRF International – Breast Cancer Survivors. 2014. Available at: http://www.wcrf.org/int/research-we-fund/continuous-update-project-findings-reports/breast-cancer-survivors. Accessed June 2017.
- Barnard N, Levin S, Yokoyama Y. A systematic review and meta-analysis of changes in body weight in clinical trials of vegetarian diets. J Acad Nutr Diet. 2015;115(6):954-969.
- Farmer B. Nutritional adequacy of plant-based diets for weight management: observations from the NHANES. Am J Clin Nutr. 2014;100(Supp 1):365S-368S.
- Estruch R, Ros E, Salas-Salvadó J. Primary prevention of cardiovascular disease with a Mediterranean diet. N Engl J Med. 2013 Apr 4;368(14):1279-90. April 2013;368(14):1279-90.
- PHE. Government Dietary Recommendations: Government recommendations for food energy and nutrients for males and females aged 1 – 18 years and 19+ years. London: PHE; 2016.
- ESC/EAS. Guidelines for the management of dyslipidaemias. Eur Heart J. 2011;32:1769-1818.
- PHE, FSA, MRC. Official Statistics: NDNS results from years 5 and 6 (combined) of the rolling programme 2012-2013 & 2013-2014. Gov.UK. September 9, 2016. Available at: https://www.gov.uk/government/statistics/ndns-results-from-years-5-and-6-combined. Accessed May 2017.
- Dietplan7. The UK Nutrient Databank: Forestfield; 2017.
- EFSA. Commission Regulation (EU) No 432/2012 of 16 May 2012 establishing a list of permitted health claims made on foods, other than those referring to the reduction of disease risk and to children’s development and health;L 136:1-40.
- Egert S, Stehle P. Impact of n-3 fatty acids on endothelial function: results from human interventions studies. Curr Opin Clin Nutr Metab Care. March 2011;14(2):121-131.
- Ros E. Nuts and novel biomarkers of cardiovascular disease. Am J Clin Nutr. 2009;89(Suppl):1649S–56S.
- Astrup A, Dyerberg J, Elwood P, et al. The role of reducing intakes of saturated fat in the prevention of cardiovascular disease: where does the evidence stand in 2010. Am J Clin Nutr. 2011;93:684-688.
- Briggs M, Petersen K, Kris-Etherton P. Saturated fatty acids and cardiovascular disease: replacements of saturated fat to reduce cardiovascular risk. Healthcare. June 2017;5(23):pii: E29.
- Sanders T. Reappraisal of SFA and cardiovascular risk. Proc Nutr Soc. November 2013;72(4):390-398.
- Mozaffarian D, Micha R, Wallace S. Effects on Coronary Heart Disease of Increasing Polyunsaturated Fat in Place of Saturated Fat: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. PLoS Med. 2010;7:e1000252.
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