The importance of β-carotene as a source of vitamin A with special regard to pregnant and breastfeeding women

Manuela Strobel, Jana Tinz, Hans-Konrad Biesalski

Vitamin A is essential for growth and differentiation of a number of cells and tissues. Notably during pregnancy and throughout the breastfeeding period, vitamin A has an important role in the healthy development of the fetus and the newborn, with lung development and maturation being particularly important. The German Nutrition Society (DGE) recommends a 40% increase in vitamin A intake for pregnant women and a 90% increase for breastfeeding women. However, pregnant women or those considering becoming pregnant are generally advised to avoid the intake of vitamin A rich liver and liver foods, based upon unsupported scientific findings. As a result, the provitamin A carotenoid beta-carotene remains their essential source of vitamin A. Basic sources of provitamin A are orange and dark green vegetables, followed by fortified beverages which represent between 20% and 40% of the daily supply. The average intake of beta-carotene in Germany is about 1.5-2 mg a day. Assuming a vitamin A conversion rate for beta-carotene for juices of 4:1, and fruit and vegetables between 12:1 and 26:1; the total vitamin A contribution from beta-carotene intake represents 10-15% of the RDA. The American Pediatrics Association cites vitamin A as one of the most critical vitamins during pregnancy and the breastfeeding period, especially in terms of lung function and maturation. If the vitamin A supply of the mother is inadequate, her supply to the fetus will also be inadequate, as will later be her milk. These inadequacies cannot be compensated by postnatal supplementation. A clinical study in pregnant women with short birth intervals or multiple births showed that almost 1/3 of the women had plasma retinol levels below 1.4 micromol/l corresponding to a borderline deficiency. Despite the fact that vitamin A and beta-carotene rich food is generally available, risk groups for low vitamin A supply exist in the western world. It is therefore highly critical to restrict the beta-carotene supply from diet, particularly from sources of beta-carotene with high consumer acceptance such as fortified juices (e.g. "ACE juices") or dietary supplements (e.g. multivitamins for pregnant women). For the part of the population unable to meet vitamin A requirements according to the DACH recommendations, sufficient intake of beta-carotene may be crucial to help improve and maintain adequate vitamin A status and prevention of developmental disorders. At this time it has to be urgently advised against restricting the beta-carotene supply or putting warning labels on beta-carotene fortified products. It is, however, highly recommended to improve the available data on nutrient intakes in Germany, especially for pregnant and breastfeeding women. For them, recommendations to be aware of potential nutrient intake inadequacies might prove useful.