Nutritional cost of 'health' campaigns

Dr Carrie Ruxton

There continues to be an increasing number of so-called ‘awareness’ weeks and months encouraging us to turn to a vegetarian or vegan diet or eat less red meat due to the risk of over consumption. Often these campaigns vilify meat, and more often than not incorrectly identify red meat as a cause of chronic health conditions. 

As detailed in the National Diet and Nutrition Survey, vegetarian diets are currently followed by just 2 - 4% of the population and, in many cases, include eggs, cheese and fish. While avoidance of meat can work for the committed vegetarian who is prepared to source a variety of protein-rich alternatives, this is not the case for others and research shows that meat-free diets are low in zinc, calcium, iron, manganese, selenium, and copper_[1].
 
Vegan and vegetarian diets restrict opportunities for vitamin D intake_[2],[3] and following these types of diets greatly reduces intakes of long-chain omega-3 fatty acids which are found in both oily fish and certain meats_[4]. Another key nutrient, vitamin B12, is a major issue for vegans as it is only present in foods of animal or microbiological origin_[5].

While iron is found in small amounts in some non-meat foods, such as beans, pulses and fortified foods, it is of the ‘non-haem’ variety which is poorly absorbed. Indeed, only 10% of non-haem iron is absorbed compared with up to 30% of haem iron from red meat_[6]. Interestingly, the presence of haem iron in foods increases the absorption of non-haem iron.

A final point is that humans are naturally omnivorous which means that we evolved to include meat in the diet. Evidence from fossilised bones, gut physiology and the diets of contemporary hunter-gatherer societies suggests that two thirds of calories in the diet of ancient man came from animal products_[7].

Therefore lean red meat is second to none as a source of bioavailable nutrients.

 

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[1] Freeland-Grave-J (1988) Mineral adequacy of vegetarian diets. The American Journal of Clinical Nutrition  48:859-62

[2] Calvo Ms, Whiting SJ, Barton CN (2005) Vitamin D intake: a global perspective of current status. Journal of Nutrition 135 310-6

[3] Laskowska-Kilta T, Chelchowska M, Ambroszkiewicz J, Gajewska J, Klemarczyk W (2011) The effect of vegetarian diet on selected essential nutrients in children 15:318-25

[4] Welch AA, Shakya-Shrestha S, Lentjes MA, Wareham NJ, Khaw KT (2010) Dietary intake and status of n-3 polyunsaturated fatty acids in a population of fish-eating and non-fish-eating meat-eaters, vegetarians, and vegans and the product-precursor ratio [corrected] of a-linolenic acid to long-chain n-3 polyunsaturated fatty acids: results from the EPIC-Norfolk cohort. The American Journal of Clinical Nutrition 92:1040-51

[5]Ambroszkiewicz J, Klemarczyk W, Chelchowska M, Gajewska J, Laskowska-Klita T (2006) Serum homocysteine, folate, vitamin B12 and total antioxidant status in vegetarian children.Advances in medical science 51:265-8

[6] SACN (2010). Iron and health. London: The Stationery Office. Available at: www.sacn.gov.uk/pdfs/sacn_iron_and_health_report_web.pdf

[7] Cordain L et al. (2002) The paradoxical nature of hunter-gatherer diets: meat-based, yet non-atherogenic. Eur J Clin Nutr 56: S42-52.