According to a new study, healthy adults do not need to take vitamin D supplements.
The study published in The Lancet found the subjects had no beneficial effect on bone density, a sign of osteoporosis.
Experts say many other factors could be at play and people should not stop taking supplements.
University of Auckland researchers analyzed 23 studies involving more than 4,000 healthy people.
The New Zealand research team conducted a meta-analysis of all randomized trials examining the effects of vitamin D supplementation on bone mineral density in healthy adults up to July 2012.
The supplements were taken for an average of two years by the study participants.
Healthy adults do not need to take vitamin D supplements
Bone mineral density is a measure of bone strength and measures the amount of bone mineral present at different sites in the body. It is often seen as an indicator for the risk of osteoporosis, which can lead to an increased risk of fracture.
The trials took place in a number of different countries including the UK, the US, Australia, Holland, Finland and Norway.
Although the results did not identify any benefits for people who took vitamin D, they did find a small but statistically significant increase in bone density at the neck of the femur near the hip joint.
According to the authors, this effect is unlikely to be clinically significant.
Prof. Ian Reid, lead study author, from the University of Auckland, said the findings showed that healthy adults did not need to take 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.”
Writing about the study in The Lancet, Clifford J. Rosen from the Maine Medical Research Institute agrees that science’s understanding of vitamin D supports the findings for healthy adults, but not for everyone.
“Supplementation to prevent osteoporosis in healthy adults is not warranted. However, maintenance of vitamin D stores in the elderly combined with sufficient dietary calcium intake remains an effective approach for prevention of hip fractures.”
The Department of Health currently recommends that a daily supplement of vitamin D of 10 micrograms (0.01 mg) should be taken by pregnant and breastfeeding women and people over 65, while babies aged six months to five years should take vitamin drops containing 7 to 8.5 micrograms (0.007-0.0085 mg) per day.
A major study results showed that vitamins and other dietary supplements taken by 50+ women may actually put them at more risk.
According to scientists, there is little evidence the vitamins and dietary supplements do any good and in fact some could be causing serious harm.
The study involved nearly 39,000 women and has found multivitamins, vitamin B, folic acid, iron, magnesium and copper supplements all increased the statistical risk of premature death.
Most of the popular pills include multivitamins, vitamin A, C and E, iron, folic acid and calcium – which are all thought to improve long-term health and ward off illnesses.
Scientists from U.S., Finland, Norway, and South Korea looked at the long-term health effects of common vitamin and minerals supplements on 38,772 women aged 55 to 69.
Women had been asked to record any supplements they regularly took over an 18-year period.
A major observational study, which involved nearly 39,000 women, has found multivitamins, vitamin B, folic acid, iron, magnesium and copper supplements all increased the statistical risk of premature death
The study results, which were published in the Archives of Internal Medicine, found copper increased the risk of dying prematurely by 18%. Folic acid – which pregnant women are told to take to protect their child against spina bifida – increased risk of death by almost 6%, while iron raised the risk by nearly 4%.
The study also showed that multivitamins raised the risk of premature death in 50+ women by 2.4%, vitamin B6 by 4%, magnesium by 3.6% and zinc by 3%.
However, the researchers said they do not fully understand how supplements may trigger early death among 50+ women, but supposed they may interfere with the body’s natural defenses.
The scientists said the vitamins and dietary supplements should only be taken by patients who are malnourished and only under the supervision of a doctor. All other people should ensure they eat a balanced diet to get adequate vitamins and minerals.
Jaakko Mursu, from the University of Eastern Finland, said:
“Based on existing evidence, we see little justification for the general and widespread use of dietary supplements.
“We recommend that they be used with strong medically-based cause, such as symptomatic nutrient deficiency disease.”
The new study results back up another major study carried out at the University of Copenhagen, Denmark in 2008 which found some vitamin supplements increase the risk of dying early by 16%.
Yesterday, when scientists dismissed the latest findings, they claimed many patients took supplements to treat underlying health problems – for example iron for anaemia – so were more likely to die early anyway.
Dr. Glenys Jones, from the Medical Research Council’s Human Nutrition Research unit in Cambridge, said: “This observational study is interesting, but it does not show supplement use causes women to die earlier.”
