A new study, conducted by prominent medical scientists from New Zealand, suggests that vitamin D supplements do not provide any benefit to the bones of healthy adults. A number of experts continue to urge patients to take their supplements, however, believing additional factors to play a part in maintenance of bone density.
The Bone Study
The study was spearheaded by Professor Ian Reid, of the University of Auckland’s Bone Research Group. The group found that vitamin D supplements had no influence upon bone mineral density in healthy adults that already had normal vitamin D levels.
Bone mineral density is an indication of bone strength. As individuals begin to age, this density begins to decline (osteopenia), due to the rate of manufacture of bone (by osteoclast cells) lagging behind the rate at which bone is broken down (by osteoblast cells). Loss of calcium, and a variety of other essential minerals, takes its toll on the integrity and strength of these bones, causing them to become porous and less dense. As the condition progressively worsens, osteoporosis can occur, with patients at increased risk of developing bone fractures.
The research team combined their results from a systematic review and meta-data analysis to study the effects of vitamin D supplements in 4,000 healthy individuals. A total of 23 randomized trials were performed, the results of which were published in the latest issue of The Lancet medical journal.
Professor Reid briefly expounded up the knowledge gained from his new study. He states that the data collected from the review yielded “little evidence” of any benefit from administering vitamin D to most healthy grownups:
“Most healthy adults do not need vitamin D supplements… Our data suggest that the targeting of low-dose vitamin D supplements only to individuals who are likely to be deficient could free up substantial resources that could be better used elsewhere in healthcare.”
When interpreting the 23 individual studies, the group monitored the changes in bone mineral density across different parts of the subject’s body, after administering a concentration of 800 IU of hydroxyvitamin D, per day.
Bone mineral density measurements were taken at various sites, including the femoral neck, forearm, lumbar spine, total hip and trochanter. After monitoring the group that was given vitamin D supplements for two years, there was no perceived improvement in the bone mineral density of participants at any of the afore-mentioned sites, apart from the femoral neck.
The group found that vitamin D-takers had a statistically significant increase in density in the femoral neck of just 0.8%; however, the group theorize this subtle, localized change to be of no clinical importance.
Vitamin D Supplements in “At Risk” Groups
Reid accepts there are certain at risk group that require these vitamin D supplements, particularly those who receive limited exposure to sunlight; this includes people who inhabit areas with infrequent sunlight, as well as those who wear veils and work indoors for protracted periods. In addition, Reid singles out the elderly and infirm as particularly high risk groups, as well as people with darker skin.
Individuals who purchase these supplements should also be aware of the impact of taking excessive quantities of vitamin D. Vitamin D is required within the bloodstream in sufficient quantities to promote absorption of calcium in the gut and resorption of bone, using cells called osteoclasts. However, excessive levels of vitamin D within the blood can actually cause bone density to wane, and can also potentially lead to liver and kidney damage.
Dr. Clifford J Rosen, of the Maine Medical Research Institute, states that scientific understanding of vitamin D supports the team’s conclusions for the majority of healthy individuals, but not everyone. He agrees that supplementation is not necessary for healthy people, but remains an effective means of preventing hip fractures in the elderly.
Clifford also suggests that monitoring bone density in middle-aged females may no longer be the most effective prognostic indicator of osteoporosis.
Recent investigations in 2012, performed by Stuart T. Haines and Sharon K. Park, based at the University of Maryland School of Pharmacy in Baltimore, highlighted a potential benefit to musculoskeletal health when taking doses of between 800 and 5000 IU/day.
Meanwhile, additional studies suggest that vitamin D could play a role in protection against muscle weakness, dozens of cancers, cardiovascular disease, multiple sclerosis and type 1 diabetes mellitus; the Institute of Medicine claims there is no evidence to support these correlations, however.
Other studies have focused upon the safety implications of vitamin D supplementation. Armin Zitterman and colleagues, of the Heart and Diabetes Center at Ruhr University Bochum, Germany, suggested that more accurate dosing should be based upon body weight to avoid vitamin D intoxication. One of the hallmarks of taking too much vitamin D is hyperglycemia, which can lead to further health issues.
However, a study performed by Prentice et al., (2013) found that a combination of both calcium and vitamin D supplements could reduce the chances of postmenopausal women in the U.S. developing hip fractures and colorectal cancer.
Speaking to the Daily Mail, Claire Bowring, who works for the National Osteoporosis Society, summarizes her conclusions on the study. Bowring explains that the best source of vitamin D, for the majority of people, is from “… safe summer sunlight exposure.”
Professor Reid states that use of vitamin D supplements in healthy adults represents a drain on finances and resources, and should only be reserved for those that have been classified at risk. He vehemently asserts, based upon his study’s findings, that vitamin D pills provide no benefit to the bones of healthy adults.
By: James Fenner
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University of Auckland Press Release
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