Beta-carotene and vitamin A
Vitamin A is essential for normal growth and development, immune system, vision and other functions in the human body. National survey data show that the intake of preformed vitamin A (retinol) – as such only present in animal products (especially liver) – is often critically low and does not meet the recommendations. As beta-carotene can be converted by the body to vitamin A, the carotenoid contributes significantly to balance inadequate vitamin A intake in large parts of the population. The bioavailability of beta-carotene is influenced by food-related factors including linkage strength in the food, food processing, dosage, and fat in the meal. Additionally, consumer-related factors such as vitamin A status, gut integrity and genetic variations determine the amount of beta-carotene used as vitamin A source.
The extent to which beta-carotene is converted to vitamin A is highly variable between well-nourished healthy individuals. Recent research has shown that almost 50% of women have a genetic variation which reduces their ability to produce sufficient amounts of vitamin A from beta-carotene. Such ‘poor converters’ seem to have a polymorphism in the gene coding the key enzyme responsible for beta-carotene conversion. Younger women carrying the genetic variation may be at particular risk as they tend to eat not enough vitamin A-rich foods relying heavily on the beta-carotene form of the nutrient.
Experts speculate that approximately 40 percent of all Europeans possess a gene variant that restricts the amount of beta-carotene their bodies can convert into vitamin A. If the gene-related restrictions are taken into account, the intake recommendations for beta-carotene would need to be increased for those who carry the genetic variation, they suggest. Further investigations in this direction are currently underway.