Recent studies report that diets which exclude animal foods result in significantly lower intakes of vitamin B12, omega-3 fatty acids, iron, zinc and selenium.
A US review of 40 observational studies showed that the general prevalence of vitamin B12 deficiency among infants reached 45% (1). While the deficiency rates among children and adolescents reached up to 33%, deficiency among pregnant women ranged from 17 to 39%, dependent on the trimester, and among adults and elderly individuals a deficiency rate of up to 86% was reported. With few exceptions, all analyzed studies documented relatively high deficiency prevalence among vegetarians. Vegans who do not ingest vitamin B12 supplements were found to be at especially high risk. An observational study from Australia with 308 young women (mean age 23 years) showed that the majority of participants did not meet the national recommendations for servings of vegetables, meat and fish (2). Avoidance of animal foods was reported in 23% of women and resulted in significantly lower intakes of omega-3 fatty acids, vitamin B12, iron, zinc and selenium compared to non-avoidance.
The researchers concluded that vegetarians, especially vegans, should give strong consideration to the use of supplements to ensure adequate micronutrient intakes. Vegetarians, regardless of the type of vegetarian diet they adhere to, should be screened for micronutrient deficiencies. A sustained low intake of micronut- rients may lead to adverse health effects in the longer-term, such as compromised immune function and iron deficiency anaemia.