Emerging research on vitamin D has linked the nutrient to strengthening the immune system and reducing the risk of a multitude of health conditions from asthma to prostate cancer. But, despite the recent studies, researchers can't say for sure if high doses of vitamin D really make people healthier or if healthy people simply live a lifestyle that results in high levels of vitamin D.
Some of these questions and others may be answered during a major study over the next five years, according to Well:
The nationwide clinical trial is recruiting 20,000 older adults, including men 60 and older and women 65 and older, to study whether high doses of vitamin D and omega-3 fatty acids from fish-oil supplements will lower risk for heart disease and cancer.
Until the study results are published, however, the question remains: Should you be taking daily vitamin D supplements?
To shed some light on the subject, I asked Stanford endocrinologist David Feldman, MD, who has been studying vitamin D for the past 30 years. He says:
It's important to note that current research on vitamin D deficiency doesn't prove a cause and effect relationship it proves an association. So a person might have a disease such as multiple sclerosis and be deficient in vitamin D but the deficiency is not necessarily the cause of the disease. However, the mounting amount of basic evidence of beneficial actions of vitamin D together with the associations uncovered provide a strong indication that vitamin D deficiency increases risk of disease.
There is a lot of basic science work in cells, animal models and epidemiology studies that show that vitamin D deficiency is bad and taking vitamin D or calcitriol, the hormone created when the body converts vitamin D, can improve certain health conditions. This has yet to be shown in prospective trials in humans. But the bottom line is there is a lot of research suggesting that vitamin D offers certain health benefits and the data continues to get stronger and stronger.
It is important to recognize that vitamin D is not really just a vitamin but the precursor to a very potent hormone, calcitriol, that acts on every tissue in the body. The actions discovered in basic science research indicate that calcitriol inhibits cell growth, improves cell function, regulates the immune system and is anti-inflammatory. These findings are based on substantial research carried out in literally hundreds of experiments around the world that provide the underpinning for the hypothesis that vitamin D would be useful to treat and/or prevent myriad diseases from multiple sclerosis to cancer.
The fact that many people, even in sunny regions, are vitamin D deficient has recently been recognized. This may occur because there are very few foods with good amounts of vitamin D. Most vitamin D comes from the action of the sun on our skin. However, because we have become leery of sun damage, for good reason, many individuals are deficient in vitamin D. Current research suggests that this deficiency may increase their risk for many diseases. Because of this, many researchers in the vitamin D field recommend individuals have their vitamin D blood levels tested and that people with deficient levels take vitamin D supplements.
Currently, there is a lot of debate about the recommended daily does of vitamin D for adults and children. There is a growing consensus that most healthy people should take 1,000 IUs a day. But that may not be enough if a person is very deficient. I would advise everyone to be tested for vitamin D deficiency, which is a relatively inexpensive blood test, and then talk to a doctor about how much of the nutrient to consume based on the patient's levels.
Photo by Daquella manera