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One thing is for certain, the human body needs vitamin D. More Americans are coming to understand how important vitamin D is for optimal health, but how should we be getting our vitamin D? Should we be getting it through food, supplements, or sun exposure? What is the most effective way to ensure we're getting the vitamin D that our bodies need to maximize our health?
You guessed it, sun exposure. Today, we're going to explore why vitamin D should be received from the sun, and specifically why vitamin D supplements are not a substitute for sensible sun exposure.
When it comes to getting vitamin D through our diet, foods like beef, calf liver, cod liver oil, canned sardines in oil, and salmon are all rich in vitamin D. But, the reality is that vitamin D does not occur naturally in most foods.
There are foods, like cereals and milk, that are enhanced with vitamin D. This enhancement process is called “fortification,” and it's a good thing. In fact, most of the vitamin D consumed in the United States diet comes from fortified foods, but 70% of the US population is suffering from vitamin D deficiency.
Fortification is clearly not enough.
We simply can't get the recommended amount of vitamin D that our bodies need from food alone. This is one of the reasons why we see many people turn to vitamin D supplements. But are supplements really the answer? Will supplements help us address the vitamin D deficiency that plagues our nation?
As more people come to understand the importance of vitamin D to our health, the idea of vitamin D supplementation has become quite popular. While many of us know that sun exposure is the best way to get our vitamin D, we've been taught - maybe even programmed through public health messaging - to avoid the sun. But, people have believed in health benefits from the sun since the most ancient civilization. Plus, there are more benefits to sensible sun exposure than just vitamin D.
The first scientifically proven health benefit of sun exposure was the discovery in 1919 that sunlight cured ricketts, a bone disease that crippled millions of children at the beginning of the Industrial Revolution.
Then in 1931, scientists discovered that the active ingredient in sunlight that healed ricketts was a previously unknown molecule, soon to be named “vitamin D.”
Both of these discoveries occurred more than a hundred years ago. Since then, as scientists discovered more health benefits correlated to sun exposure, they assumed the health benefits were all attributable to vitamin D. This led to a robust vitamin D supplement market. However, little actual research was done during the 20th century to determine if this assumption was correct.
As the years went by, some doctors began advising their patients to take large doses of vitamin D supplements up to 5,000 international units daily. This is compared to the recommended daily reference intake (DRI) of 200 IUs per day. Other doctors became concerned about possible overdosing on vitamin supplements.
In 2009, the US and Canadian governments asked the prestigious Institute of Medicine of the National Academies of Science to undertake a comprehensive review of all of the science related to vitamin D. The purpose of the study was to determine the proper dietary reference intake (DRI) for vitamin D supplements.
The results of the review were published in a 1,000 page report in 2010. The review identified many health benefits correlated to the level of 25 hydroxy vitamin D in the blood, which is a precursor to vitamin D produced in the body, principally by sun exposure. But, it found that vitamin D supplements have been shown to be effective only for bone health, and the proper DRI, or dietary reference intake, for bone health was 600 IUs per day.
This raised the prospect that many of the benefits of sun exposure were the result of substances other than the vitamin D produced in the body by sun exposure. This hypothesis was confirmed by subsequent studies.
The fact that 90% of the 25 hydroxy vitamin D and the body is produced by sun exposure means that the level of this biomolecule in the blood is a metric for sun exposure, as well as for vitamin D status.
This has led to a lot of confusion and misleading marketing related to the health benefits of vitamin D. This is because the correlation of a low level of 25 hydroxy vitamin D in the blood with increased risk of various diseases could indicate that the problem is insufficient vitamin D, or it could indicate that the problem is insufficiency of some other biomolecule produced by sun exposure.
For example, it's recently been discovered that sun exposure produces nitric oxide in the blood and produces the following health benefits.
Lowers blood pressure
Protects the heart
Stimulates the brain
Kills bacteria
Sun exposure also acts as a gatekeeper of blood flow to different organs. It activates nerve sales, modulating many functions like the movement of food and waste to the gastrointestinal system.
Nitric oxide is only one biomolecule discovered to be produced by sun exposure. Others include melatonin, serotonin, beta endorphin, and dopamine just to name a few.
These studies show sensible sun exposure has significant and distinct health benefits that are actually independent of vitamin D. Therefore, they can't be replicated with oral vitamin D supplements.
The benefits of sun exposure are so much more than vitamin D. Cancer, autoimmune conditions, heart disease, hypertension, diabetes, bone fractures are just a few of the health conditions known to be positively impacted by sun exposure - but, not specifically vitamin D.
More studies are showing that vitamin D alone in supplements cannot replace the protective benefits that come from sun exposure. For example, a 2017 study published in the European Heart Journal reported that vitamin D supplements did not reduce mortality in patients with advanced heart failure.
Another 2017 study found that high doses of vitamin D supplements were not beneficial for overweight vitamin D deficient patients who were diagnosed with type two diabetes. The authors of that study concluded that it would be unlikely that vitamin D supplements would be an effective strategy for reducing diabetes risk, even in vitamin D deficient populations.
Even vitamin D's reputation for independently helping bone development has been questioned. A report from the United States Preventive Services Task Force, an independent group which makes health policy recommendations, concluded that there's not enough evidence to recommend for or against vitamin D supplementation preventing bone fractures. Other studies have yielded similarly disappointing results when it comes to vitamin D supplements.
The human body is intricately created to carefully regulate its production of vitamin D, so you can't overdose on vitamin D through sun exposure. However, overconsumption of vitamin D through supplements is a concern.
It can lead to vitamin D toxicity, or hypervitaminosis D, which can lead to calcium buildup in the blood. This build up gives rise to a number of health issues, such as heart attacks, strokes, and kidney failure.
Studies also show that an excess of vitamin D supplementation could cause autism and infants. Researchers have found that countries where infants are not fed vitamin D supplements show fewer cases of autism, giving rise to the possibility that vitamin D supplements are indeed a risk factor for autism in infants.
Today, scientists believe the best source of vitamin D is by exposing your skin to sunlight. However, given our indoor lifestyles, many are turning to vitamin D supplements. As we've discussed here, numerous studies show that vitamin D supplements are not all they've been marketed to be.
Vitamin D deficiency is a widespread and serious public health problem. For Black Americans, it's been called the “hidden epidemic” and vitamin D supplements may not be the best approach to resolving this issue.
We hope this article empowers you to make healthier, more informed choices for you and your family.