Vitamin A & Autism -- (12/17/2017)
Giving vitamin A to young children with autism spectrum disorders and low blood levels of vitamin A (as retinol) seemed to improve some symptoms of ASD, according to a pilot study. For details, see the "What It Does" section of the Vitamin A Supplements Review >>
Latest Supplement Recommendations -- (11/17/2013)
New draft recommendations on vitamin and mineral supplement use were published this week by the U.S. Preventive Services Task Force
. The recommendations apply only to healthy adults without nutritional deficiencies
. They focus only on the use of supplements for the prevention of cardiovascular disease and cancer at doses not exceeding tolerable upper intake levels
. The recommendations are based on existing science and are generally consistent with information already presented in ConsumerLab.com’s Product Reviews. We have summarized the recommendations below, with links to more information in ConsumerLab.com’s reports:
and Vitamin E
: Supplementation with either does not provide a benefit. Vitamin E does not pose a risk of harm, but beta-carotene increases the risk of lung cancer in people at risk for lung cancer.
- Other Single Vitamins, Minerals, Pairs, and Multivitamins
: There is inadequate evidence regarding a benefit or a risk of harm.
The task force stressed that at excessive doses
(above tolerable upper intake levels) there is evidence of harm with supplementation, such as with vitamin A
and vitamin D
Antioxidants: Too Much of a Good Thing? -- (8/25/2013)
A new, long-term study of Americans found the risk of dying over the course of the study (about 14 years) was lowest when antioxidant levels in the blood were above the lowest levels (the bottom 20% of the population). However, for people in the top 20% of blood levels for vitamins A and E, the risk of death increased compared to people with moderate levels. For selenium and beta-carotene, there was no significant difference in the death rate between moderate and high levels, although for vitamin C some additional benefit was seen at high, but not the highest, levels.
The results suggest that antioxidant supplements may be useful for those who are nutritionally deficient, but, as noted by the researchers, "beyond a certain threshold, higher levels do not lead to additional benefit, and may potentially be toxic." More details (including specific serum levels) are found in the linked updates to the following reviews, which include our test results and quality ratings of products:
Lower Melanoma Risk with Vitamin A -- (3/18/2012)
A study of people ages 50 to 76 found the risk of developing melanoma (over an average of 6 years) was 40% lower
among those who took a vitamin A supplement than among those who did not. The protective effect appeared strongest and most statistically significant among women, and only occurred with vitamin A from retinol and, not beta-carotene. For details, including the dose (which matters), see the updated information in the Vitamin A Supplement Review
. More >>