Health effects of vegetarian diets and associated dietary guidelines

ANSES is responsible for establishing dietary guidelines for the French population. These guidelines provide scientific bases for public health policies and recommendations on nutrition as part of the National Health and Nutrition Programme. It has already issued such guidelines for the general adult population and for specific population groups such as children, the elderly and pregnant women.

Following on from this work, to take account of changes in eating habits, ANSES decided to undertake an expert appraisal specifically dedicated to adults on a vegetarian diet. The term ‘vegetarian’ refers to diets that exclude the consumption of any animal flesh (meat, fish, molluscs, crustaceans, etc.). It includes lacto-ovo vegetarians, who consume eggs and dairy products, as well as vegans, who exclude all foods of animal origin.

These new dietary guidelines intended for people on a vegetarian diet aim to help them meet all their nutritional requirements while reducing exposure to contaminants and the risk of chronic disease.

Health effects of vegetarian diets

The aim of the first expert appraisal was to identify epidemiological links between health and various types of vegetarian diets, by conducting a systematic review of the scientific literature. Although the level of evidence was moderate, this review showed that the risk of developing type 2 diabetes is lower with vegetarian than with non-vegetarian diets.

ANSES also observed, albeit with a low level of evidence, that vegetarians are less likely than non-vegetarians to develop certain diseases, such as ischaemic heart disease, ovulation disorders, certain types of cancer (prostate, stomach, blood) and certain ophthalmological and gastro-intestinal diseases. However, they are at greater risk of bone fractures and hypospadias (congenital malformation of the urethra), also with a low level of evidence.

Lastly, the epidemiological studies undertaken showed that vegetarians have a less favourable nutritional status in iron, iodine and vitamins B12 and D, and a poorer calcium and phosphorus balance than non-vegetarians. Vegans also have a less favourable nutritional status in vitamin B2.

Guidelines to adjust the diets of vegetarians

In its second expert appraisal, ANSES established dietary guidelines to enable vegetarians to better meet their nutritional needs without significantly altering their eating habits. Like for the general population, it used an optimisation tool combining consumption data, dietary reference values and food contamination data.

This optimisation work showed that it is difficult for vegetarians in general to meet their nutritional needs for certain omega-3 fatty acids (EPA, DHA) and for vitamin D; for vegans specifically, it is difficult for men to meet their nutritional requirements for vitamin B12 and zinc. These findings may contribute to the ongoing European work on management measures relating to food supplements and the fortification of food.

More generally, the presence of contaminants in food is a major issue that affects the entire population, regardless of their diet. ANSES stresses that it is necessary to reduce emissions of human-induced contaminants in order to reduce exposure to the most persistent substances in the environment, especially metals.