The evidence that vegan and vegetarian diets come up short on specific nutrients

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My attention was recently caught by research carried out in Kenya which shows that supplementing children’s diets with meat assisted their growth, and also led to improvements in their performance in problem-solving and intelligence tests. As a result of this and other research, the lead researcher of this study has described brining up children as strict vegans as unethical�. Personally, I think this sort of judgement is a bit strong, but this recent study does I think highlight the fact that vegan, and also vegetarian, diets tend to be low in specific nutrients required for healthy growth, development and general well-being. I thought I’d look this week at the sort of nutrients such diets tend to be low in, and what can be done to beef them up.

Protein: in years gone by, dieticians would stress the importance of protein for proper growth and development in children. However, a general trend towards emphasising the value of carbohydrates in kids’ diets has seen protein slip off the menu of late. Recently, Danish researchers decided to give the role of protein in childhood growth another look. The results of this study, published in the American Journal of Clinical Nutrition, showed that higher levels of protein in the diet were associated with increased height and weight in 10-year-old kids. There was no association found between protein intake and body fat percentage. This suggests the increased weight associated with a good intake of protein was not the result of excess fat, but due to an increase in the amount of non-fatty body tissues such as muscle and bone. This study confirms that adequate protein is important for optimal growth in children.

Protein-rich foods to include in their diet include meat, fish, eggs, yoghurt, nuts, beans and lentils.

Protein is composed of molecules known as amino acids. Amino acids that come from protein in the diet are used as building blocks in the manufacture of many structures and tissues in the body including bone and muscle. There are 22 amino acids, most of which can be made in the body and therefore do not, strictly speaking, need to be provided in the diet. However, children are unable to make 10 amino acids, and their presence in the diet is therefore crucial to optimum health. These are referred to as the essential amino acids.

Meat and fish are very good sources of protein, as are eggs and dairy products such as milk, cheese and yoghurt. Some non-animal foods, such as beans, peas and nuts and seeds, are also good sources of protein. Some foods provide a good balance of essential amino acids and are generally regarded as superior sources of protein than those foods that may be lacking in one or more essential amino acids. In general, animal-derived proteins are regarded as more ‘complete’ in terms of their component amino acids than vegetables sources of protein. For this reason, those who do not eat animal foods generally do well to eat a broad range of protein-containing foods including beans, pulses, nuts, seeds and perhaps soya based products (e.g. soya milk and tofu) too.

In addition to the issue with protein, vegan diets tend to be low in specific nutrients including vitamin B12, vitamin B2, calcium, iron, zinc and iodine. Even a vegetarian diet may be low in some of these nutrients, notably iron, vitamin B12 and iodine. Foods the eating of which can help counter these deficiencies include green leafy vegetables (calcium), calcium fortified non-dairy milks such as soya and rice milk, nori seaweed (vitamin B2 and iodine), nuts (calcium) and dark chocolate (calcium). For vegetarians, eggs offer good quality protein, in addition to some iron and vitamin B12. Vegans are very prone indeed to B12 deficiency, and are generally recommended to supplement with this nutrient.

While I am a great believer in the health giving properties of a healthy diet, it can nonetheless be hard for vegetarians and vegans to cover their nutritional bases.

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