26 April 2010
Seniors with higher blood levels of vitamin D are also likely to have better physical function, suggests a new study.
03 January 2012
The recommended vitamin A intake in general cannot be reached by consuming preformed vitamin A alone, suggests a new review.
Available intake data from 11 studies was analyzed, to estimate the contribution of beta-carotene to vitamin A (retinol) supply in industrialized countries; altogether, 8 countries and 121,256 participants made up the basis for analysis (1). The results showed that preformed vitamin A only accounted for nearly 65% of total vitamin A intake and carotenoids made up 35%. Studies from single countries showed varying results. No statistical differences between men and women in total intake of retinol were observed.
The researchers concluded that in general the recommended level of vitamin A intake cannot be reached by consuming one component (vitamin A or beta-carotene) alone, even in Western countries where animal products are commonly available. Furthermore, they stressed that the mean preformed vitamin A intake cannot reach recommendations without provitamin A carotenoids. In the Western world, supplement use significantly contributes to the carotenoid and vitamin A intake.
Preformed vitamin A is present only in animal products, such as liver, kidney, fatty fish, dairy products and eggs. Vitamin A may also be converted in the human body from its dietary precursors: provitamin A carotenoids such as beta-carotene (recommended daily intake: 2–4 mg) are an additional major dietary source of vitamin A for most of the world’s population (2). Populations with highly restrictive diets, who have a strong dietary regime or exclude certain types of food for example, might be at risk of vitamin A insuffi-ciency, even in developed countries. The recommended total vitamin A intake levels vary from 700 mcg/day (UK) to 1000 mcg/day (Germany, Austria, Switzerland) for men and from 600 mcg/day (UK) to 900 mcg/day (Germany, Austria, Switzerland) for women. Vitamin A is indispensable for cell differentiation, embryonic development and vision, to name only a few of its many other roles.