Vitamin D had been gaining a reputation as a ”wonder supplement.” Studies have suggested it can help bone and heart health, ease mild depression, and lower the risk of cancer. Others have suggested it might help people with fibromyalgia, multiple sclerosis, and other chronic diseases.
Now comes a different finding. Researchers who looked at dozens of studies say that vitamin D supplements do not lower the risks of heart attacks, strokes, cancer, or fractures by more than 15% in generally healthy people. This was true whether or not the supplements included calcium.
Bottom line: For most healthy adults, vitamin D supplements are not worth it, the researchers say in The Lancet Diabetes & Endocrinology.
Not everyone agrees, and the debate is far from done. Here, two experts address the most common questions about vitamin D supplements.
Are vitamin D supplements losing their luster?
“I believe so,” says Doug Campos-Outcalt, MD, of the University of Arizona College of Medicine, Phoenix. He recently wrote a review of vitamin D for The Journal of Family Practice.
Evidence shows that vitamin D helps bone health, he says. But early studies that show vitamin D may help in other areas, such as heart health and cancer prevention, are not convincing.
“Information on the health benefits of vitamin D is difficult to sort out,” he writes in the review. He cites a report from the Institute of Medicine, an independent organization that provides health advice. The institute looked at studies of vitamin D to protect against cancer, heart disease, diabetes, and autoimmune diseases such as lupus. Except for bone health, it found no evidence that vitamin D helped with any other diseases.
Robert R. Recker, MD, director of osteoporosis research at Creighton University School of Medicine in Nebraska, disagrees. He cites research finding vitamin D lowers the risks of colon, breast, and other cancers, and improves how the immune system works.
On the other hand, other experts say low vitamin D levels may be a result of illness, not the cause.
What do we know for sure about vitamin D?
What it does: Experts agree on the basics. Vitamin D helps the body absorb calcium, and that is good for bone health. Vitamin D also helps reduce inflammation in our cells. Inflammation can trigger disease.
What are the main areas of disagreement about Vitamin D?
How much is needed: At the center of the debate is how much vitamin D is enough. “We need more vitamin D than what we are getting [from diet and sun exposure],” Recker says. “What is not agreed upon is how much more.”
The Institute of Medicine recommends that most Americans need no more than 600 international units (IU) of vitamin D a day. People 71 and older may need 800 IU, it says. This level is enough for bone health, it says.
Vitamin D is found in some foods, including fatty fish like salmon and tuna, beef liver, fortified dairy products, cheese, and egg yolks. Except for those, getting enough vitamin D from your diet isn’t easy. As examples, a 3-ounce serving of salmon provides 447 IU, and 3 ounces of tuna fish offer 154 IU.
Meanwhile, our skin makes vitamin D when exposed to natural sunlight. This helps vitamin D levels in our blood. But Recker says only people who live at the equator get a large amount of D from sunlight.
Testing: Experts disagree on whether healthy people need routine testing to detect low vitamin D blood levels.
How much is enough: Experts also disagree on how much vitamin D we need in our blood to be healthy.
Which groups of people might benefit more from higher levels of D?
Older adults who are frail, Campos-Outcalt says. Getting 800 IU a day may help them prevent falls and fractures.
Recker says older people who are healthy can also benefit from the higher levels, ”because the skin loses the ability to make vitamin D” as people age. Some older people also stay indoors more as they age, he says.
Other people may also need to pay close attention to vitamin D in their foods. Among them are people on corticosteroids and other medications that can affect bone health, Recker says.
What are the potential harms of excess vitamin D supplements?
Very high doses of vitamin D can cause extremely high levels of calcium in your blood, which can lead to heart rhythm problems, kidney stones and damage, and severe muscle weakness. This calcium excess usually happens if you take 40,000 IU per day for a couple of months or longer, or take a very large one-time dose.
Vitamin D ‘helps beat symptoms of asthma’: Supplements could soon be used as treatment alongside other drugs
Vitamin D has the potential to significantly cut the symptoms of sufferers.
Scientists at King’s College London made the discovery.
The ‘sunshine’ vitamin resulted in lower levels of a natural chemical in the body that aggravates symptoms in asthma patients
Vitamin D could help asthma patients breathe more easily, claim British researchers.
Scientists at King’s College London have discovered vitamin D has the potential to significantly cut the symptoms of sufferers. They say it may one day be prescribed as a treatment alongside conventional steroids, but reducing the need for medication. A new study found the ‘sunshine’ vitamin resulted in lower levels of a natural chemical in the body that aggravates symptoms in asthma patients and cuts the effectiveness of steroids. More than five million Britons suffer asthma, including 1.4 million children, and the disease causes 1,400 deaths each year. Asthma is an inflammatory disease of the airways, causing them to constrict and resulting in attacks of breathlessness and wheezing which can be fatal.
Severe asthma is currently treated with steroid tablets which can have harmful side effects. Many sufferers have a steroid resistant variation of the condition making it even more difficult to treat and putting them at greater risk of hospitalisation from severe, even life-threatening, asthma attacks. In a study funded by Asthma UK charity, a team of scientists at King’s identified a mechanism through which Vitamin D can reduce asthma symptoms, providing a potential target for future treatments. IL -17A is a natural chemical which helps to defend the body against infection, but is known to exacerbate asthma and reduce responsiveness to steroids when produced in larger amounts.
The team examined the production of IL-17A and levels of the chemical in cells from 18 steroid resistant asthma patients and 10 patients who responded to steroids, as well as a control group of 10 healthy people. Results showed that patients with asthma had much higher levels of IL-17A than those without asthma and patients with steroid resistant asthma expressed the highest levels of IL-17A. Further tests showed that while steroids were unable to lower the production of IL-17A in cells from patients with asthma, vitamin D significantly cut the production of IL-17A in cells from all patients studied. The results demonstrate that vitamin D could potentially provide an effective add-on treatment for all asthma sufferers, reducing the amount of steroid-based medicines prescribed. There is growing evidence that vitamin D deficiency may be responsible for triggering a range of diseases, including several cancers. The body makes most of its vitamin D from sunlight, although oily fish is a good dietary source. Professor Catherine Hawrylowicz from the Medical Research Council & Asthma UK Centre in Allergic Mechanisms of Asthma at King’s, who led the study, said the findings were ‘very exciting’.
She said ‘They show that Vitamin D could one day be used not only to treat people with steroid resistant asthma but also to reduce the doses of steroids in other asthma patients, reducing the risk of harmful side effects. ‘The results are so positive that we are testing this in a clinical trial in steroid resistant asthma patients to further research the possibilities of vitamin D as a potential treatment.’ The study is published in the Journal of Allergy and Clinical Immunology. Malayka Rahman, Research Analysis and Communications Officer at Asthma UK, said: ‘For the majority of people with asthma, current available medicines are an effective way of managing the condition but we know that they don’t work for everyone, which is why research into new treatments is vital. ‘We also know that many people with asthma have concerns about the side effects of their medicines so if vitamin D is shown to reduce the amount of medicines required, this would have an enormous impact on people’s quality of life. We look forward to the results of the clinical trial.’