October 2011 - Volume 5, Issue 10
In this issue...
- Study linking vitamin E with prostate cancer sparks controversy
- "Vitamins Kill" headlines misleading, say researchers
- Lipoic acid improves glucose metabolism in diabetics
- Glutamine protects tissue after radiation therapy
- Risk of colon cancer affectd by timing and dose of folate
- High dietary B6 linked to lower breast cancer risk
- Evidence that birth control pills impact B vitamin status is reviewed
CLINICAL UPDATE - Study linking vitamin e with prostate cancer sparks controversy
Over 34,000 men were divided into four groups: those taking vitamin E only, selenium only , both or neither. After several years of follow-up on the named SELECT study (Selenium and Vitamin E Cancer Prevention Trial), researchers concluded that taking vitamin E supplements increased the risk of prostate cancer by 17%. Critics of the study argue that the supplement was a synthetic vitamin E containing only one of the eight naturally occurring forms of vitamin E (alpha-tocopherol) and that taking large doses of this form of vitamin E may possibly cause deficiencies or imbalances in other forms of the vitamin – namely tocotrienols, which are also important physiologically.
(Journal of the American Medical Association, October 2011)
LINK to ABSTRACT Vitamin E and the risk of prostate cancer: the Selenium and Vitamin E Cancer Prevention Trial (SELECT).
CLINICAL UPDATE - "vitamins kill" headlines misleading, say researchers
In the Iowa Women’s Health Study, over 38,000 women were asked via questionnaire about their use of supplements. Authors of the study concluded that many commonly used dietary supplements increase mortality, causing such headlines as “your vitamins may be killing you” in mainstream media. The study implies vitamins to be dangerous, when in reality the study reinforces the need for targeted versus blind supplementation. The “more is better” philosophy can be dangerous when it comes to supplements , since blind supplementation can cause imbalances, create pro-oxidant effects and actually induce deficiencies in other nutrients as a side effect.
(Archives of Internal Medicine, October 2011)
LINK to ABSTRACT Dietary Supplements and Mortality Rate in Older Women: The Iowa Women's Health Study.
CLINICAL UPDATE - lipoic acid improves glucose metabolism in diabetics
A small group (n=57) of type 2 diabetics were given either 300 mg of alpha lipoic acid daily or placebo for two months. Fasting blood glucose levels and insulin resistance were significantly lower in the supplemented group. Antioxidant status was improved in the supplemented group as well.
(Saudi Medical Journal, June 2011)
LINK to ABSTRACT Effect of alpha-lipoic acid on blood glucose, insulin resistance and glutathione peroxidase of type 2 diabetic patients.
CLINICAL UPDATE - glutamine protects tissue after radiation therapy
Cancer patients who have had radiation therapy in the pelvic region often have significant damage to their bladders. In this animal study, supplementation with the amino acid glutamine prevented damage to the bladder wall after radiation therapy.
(Nutrition, August 2011)
LINK to ABSTRACTGlutamine supplementation prevents collagen expression damage in healthy urinary bladder caused by radiotherapy.
CLINICAL UPDATE - risk of colon cancer affected by timing and dose of folate
In the Nurses’ Health Study, the use of multivitamins containing folate reduced the risk of colorectal cancers and adenomas (benign tumors), but only when used for more than 15 years. In a more objective study that measured actual serum folate concentrations in 458 people (versus food frequency questionnaire), researchers concluded that at serum levels of 8.0 ng/mL, the risk of colon tumors was significantly reduced. However, the risk of colon tumors in people with folate concentrations above 8.0 ng/mL did not differ, reinforcing the notion that “more is not necessarily better” when it comes to vitamin supplementation.
(American Journal of Clinical Nutrition, April 2011)
(Clinical Nutrition, May 2011)
LINK to ABSTRACT Folate intake and risk of colorectal cancer and adenoma: modification by time.
LINK to ABSTRACTDetermination of the minimal essential serum folate concentration for reduced risk of colorectal adenoma.
CLINICAL UPDATE - higher dietary b6 linked to lower breast cancer risk
In a study on dietary intake of B vitamins as determined by food frequency questionnaire, researchers found that higher dietary intake of vitamin B6 was associated with reduced risk of breast cancers. In the paper, potential mechanisms of action are addressed, particularly the role of B6 in DNA repair and methylation.
(Journal of Epidemiology, September 2011)
LINK to ABSTRACT Dietary Intake of Vitamin B(6) and Risk of Breast Cancer in Taiwanese Women.
CLINICAL UPDATE - evidence that birth control pills impact b vitamins status is reviewed
A review of studies on the use of oral contraceptives concluded they may negatively affect vitamin B6 status but their impact on folate and vitamin B12 is not significant.
(Nutrition Reviews, October 2011)
LINK to ABSTRACT Oral contraceptive use: impact on folate, vitamin B(6), and vitamin B(12) status.