Vitamin D supplementation lowers fracture risk

The May 11 2005 issue of the Journal of the American Medical Association published the results of a meta-analysis of 12 clinical trials involving vitamin D supplementation in the prevention of fracture. The analysis concluded that supplementation with higher than the commonly recommended 400 international unit (IU) doses of vitamin D reduces the risk of hip and nonvertebral fractures in older individuals.

The vitamin D studies included a total of 19,114 men and women aged 60 and older. The trials used the form of the vitamin known as cholecalciferol, or vitamin D3, which, according to studies cited in the current review, may be much more effective than the dietary form of the vitamin.

The researchers found that doses of 700 to 800 IU of vitamin D3 per day reduced the risk of hip fracture by 26 percent and nonvertebral fracture by 23 percent. Studies that used 400 IU vitamin D3 or less found no significant benefit for either type of fracture.

The role of additional calcium supplementation could not clearly be defined from the studies, but it appears that at least 700 milligrams calcium per day may also be necessary for nonvertebral fracture prevention.

Vitamins E and C confirmed safe by leading experts

In a new article published in the April issue of the American Journal of Clinical Nutrition, fourteen leading safety and antioxidant experts reviewed the available scientific literature on vitamin E and C and concluded that high dosages commonly used in supplements are safe for the general population.

In reviewing the available scientific literature on vitamins E and C, the scientists evaluated clinical trials as well as epidemiological studies in humans, including the recent, controversial meta-analysis on vitamin E from Johns Hopkins University. Based on the 95 studies analyzed, the experts determined there was sufficient information from human data to support a conclusion on safety. The experts concluded that evidence of potential adverse effects of high vitamin E intakes in humans is not convincing and that supplements appear safe for most adults in amounts up to 1,600 IU.

With regard to vitamin C, the authors noted that other than occasional gastrointestinal upset or mild diarrhea, there is no pattern of evidence to support concerns about safety in dosages commonly consumed.

Vitamins E and C are among the most popular dietary supplements. Many studies suggest that these antioxidant supplements, either alone or in combination with other supplements, can help promote overall good health and be helpful in lowering the risk of certain chronic degenerative diseases.

American Journal of Clinical Nutrition, Vol. 81, No. 4, 736-745, April 2005

CoEnzyme Q10 reduces oxidative damage to nerve cells

In a recent study published in the April 2005 volume of Neurobiology of Disease, researchers investigated the role of CoEnzyme Q10 in protecting nerve cells from oxidative damage.

Nerve cells depend on optimal mitochondrial function for energy. This study demonstrated that external oxidative stress causes mitochondria to increase production of free radicals, leading to nerve cell damage and destruction. Since CoEnzyme Q10 is a component of the mitochondrial energy process and is a potent anti-oxidant, CoEnzyme Q10 was evaluated as a neuroprotective agent.

In this study, CoEnzyme Q10 inhibited the production of free radicals by the mitochondria, suggesting that CoEnzyme Q10 acts to stabilize the mitochondrial membrane when nerve cells are subjected to oxidative stress. CoEnzyme Q10 may therefore have a potential benefit as a therapeutic intervention for neurodegenerative diseases.

Long-term vitamin E use slows cataract development

The April 2005 issue of the journal Archives of Opthalmology reports that long- term use of vitamin E supplements and an increased intake of the B vitamins thiamin and riboflavin are associated with a reduction in the progression of cataracts.

Researchers from Harvard and Tufts Universities analyzed data from 408 participants in the Nurses' Health Study between the ages 52 to 74. The association of cataract development with B vitamins thiamin, riboflavin and niacin, vitamins C and E, and carotenoids was evaluated. Computer-assisted image analysis was used to determine the amount of lens nuclear opacification (cloudiness) that occurred during the duration of the study.

Long-term vitamin E supplement use, and higher intakes of thiamin and riboflavin were associated with a reduced progression of opacities. Niacin additionally appeared to have an effect, although it was smaller than that of the other B vitamins.

The current research is consistent with prior studies which documented an association between long-term vitamin E supplement use and a lower risk of cataracts.