Vitamin Supplements - Part 2

Read Vitamin Supplements - Part 1 right here.

Vitamin A

Dietary deficiency of vitamin A is uncommon in healthy people, except in older age groups. A is needed to absorb calcium, effects intestinal flora, and synthesizes body proteins. Although vitamin A is important for the function of the immune system, concerns about birth defects and bone loss, people should not take over 10,000 IU of supplemental vitamin A in the form of retinol without consulting a doctor.

Beta-carotene

Beta-carotene is a precursor to vitamin A, and may have a separate role in human health. Controlled research has shown that beta-carotene supplements can increase the numbers of some white blood cells and enhance cancer-fighting immune functions in healthy people who take 25,000–100,000 IU per day. (However, some studies of smokers have reported that supplements of synthetic beta-carotene increased the risk of both heart disease and lung cancer, this may or may not be correlational, a third variable is needed to suggest or presume this potential empirically). Other trials found no positive or negative effect of synthetic beta-carotene on the risk of many other diseases, including several types of cancer, angina pectoris, diabetes, age-related eye disease or intermittent claudication. Natural beta-carotene, though very similar to synthetic, was found in one preliminary study to reverse pre-cancerous changes, while synthetic beta-carotene did not. Further study is needed about the effects of synthetic beta-carotene.