Vitamin D is actually a steroid hormone that controls over 1,000 genes! Our primary source of Vitamin D is UVB irradiation from the sun. While many are deficient in Vitamin D, there continues to be new information about the positive effects it has on our well-being.

What Impacts Our Vitamin D Levels?

Sunscreen: The main reasons why Vitamin D levels have decreased over the last few decades is due to more sunscreen use and spending less time outdoors. Anything that blocks UVB rays such as sunscreen will also prevent your skin from making Vitamin D.

Skin Color: The darker the skin (the more melanin) the more difficult to absorb Vitamin D. The CDC estimates that only 30% of light skinned Americans have at least 30 ng/ml levels of Vitamin D (U.S. Endocrine Society identifies 30 ng/ml at the lowest level of adequate), and dark skinned Americans fare even worse.

Age: As we age our bodies become less efficient at producing Vitamin D, so that a 70 year old produces 4 times less Vitamin D than a 20 year old.

Body Fat: The bioavailability of Vitamin D is reduced by body fat, so the more fat you have the more Vitamin D is being stored in the fat and the less of it is being released into the blood stream.

Genetics: Normal variations in the sequence of DNA exist with several different genes involved in the Vitamin D pathway. If we have a variation that makes a particular "Vitamin D impacting" gene less efficient at doing its’ job, then we’ll see less 25-hydroxy Vitamin D being converted in the kidneys. This means that certain individuals will have to take more vitamin D in order to achieve “sufficiency.”

What Are The Benefits?

Slows Aging: According to a study of twins, being in the lowest quartile of Vitamin D levels correlated with 5 extra years of aging. It is thought that the anti-inflammatory properties of Vitamin D are partly responsible for delaying the process of shortening your telomeres, which in turn slows the aging process.

Mood and Brain Function: Dr. Rhonda Patrick's work, suggests that Vitamin D may be important to producing serotonin in the brain from tryptophan. Serotonin regulates a broad range of cognitive functions and behaviors, including: social behavior, impulse control, decision making, anxiety, memory, impulse aggression, and more.

Gut and Autoimmunity: Gut inflammation is also linked to serotonin...not the serotonin in the brain, rather serotonin that is produced in the gut. Vitamin D probably stops the conversion of tryptophan into serotonin, therefore, Vitamin D deficiency may lead to excessive immune cell activation and gut inflammation. Patrick's research, also demonstrates that Vitamin D may be regulating autoimmunity through this same gut-serotonin pathway. If a gene is hyperactive because there is low Vitamin D, it means less tryptophan is available to the pathway that is essential to keeping autoimmunity at bay.

Cardiovascular Disease: Metabolic Syndrome (MetS), a common cluster of conditions that heighten the risk of heart disease, stroke and diabetes, is found to have a strong association with Vitamin D deficiency. One of the benefits discovered is that Vitamin D appears to positively impact blood vessel health by increasing their flexibility and reducing inflammation. Another study found that Vitamin D improves the heart pumping function. Finally, a recent study found that participants with blood D levels that were above 30 ng/ml had one-third of the risk of type-2 diabetes and those with levels above 50 ng/ml had one-fifth of the risk of developing diabetes.

Cancer: Higher Vitamin D levels have been associated with a reduced risk of colon, lung, breast, pancreatic, bladder, prostrate, and ovarian cancers (just to name a few). Women with levels of 40 ng/ml or greater had a 67 percent lower risk of cancer than women with levels of 20 ng/ml or less.

Bone Health: According to Dr. Cauley, who has spent many years investigating the physical changes that take place in postmenopausal women the risk of hip fractures was 77 percent higher among women whose D levels were at the lowest concentrations. On the other hand, stress fractures are a potential risk for runners, especially female runners. A Scandinavian study showed mild Vitamin D supplementation was able to reduce stress fracture rates by over 20%.

Infections: Vitamin D is thought to protect against respiratory infections such as the common cold and flu, by boosting levels of a natural antibiotic-like substances in the lungs. In fact, supplementation has been discovered to cut the risk of these infections by as much as 50%! Overall, the reduction in risk of these infections induced by Vitamin D was on a par with the protective effect of the injectable flu vaccine!

When it comes to COVID-19, research suggests that there is an association with vitamin D levels and the impact of the infection. First, consider the factors that are known to increase the risk of death due to COVID-19...hypertension, obesity, male sex, advanced age, living at a northern latitude, and bleeding disorders. Notably, poor vitamin D levels is associated with many if not all of these factors. Recently we learned that in a small study involving COVID-19 patients treated in the intensive care unit (ICU) all patients under the age of 75 were vitamin D deficient.

Death among COVID-19 patients is commonly the result of "pro-inflammatory molecules" being released in a "cytokine storm". Another new study suggests that vitamin D could reduce the risk of developing a cytokine storm and therefore decrease COVID-19 mortality by strengthening our immune response while reducing the chances of over-responding. Also, elevated blood levels of CRP (c-reactive protein) are seen in severe COVID-19, and getting adequate amounts of vitamin D reduces CRP levels and results in being nearly 16% less likely to have severe COVID-19 than those with a vitamin D deficiency. Finally, data suggest that staying out of the deficient zone of 20 ng/mL will reduce COVID-19 infection risk about 42%! The above suggests that Vitamin D could reduce the chance of getting COVID-19 and reduce the disease severity but it is agreed that more research is needed to determine if we are looking at an association or a cause.

At this point the overall benefits give good reason to make sure our levels are in a healthy range!

How Much Do I Need?

Its important to note, both too high and too low Vitamin D levels cause the same premature aging, meaning there is an optimal Vitamin D concentration. Meta-analyses of studies done ranging from 1966-2013 have shown that people with Vitamin D levels between 40-60 ng/ml have the lowest all-cause mortality. The National Institute of Medicine sets a tolerable level of Vitamin D at 4,000 IU/day, while data compiled from several different studies reveal that toxicity is obtained at doses higher than 10,000 IU/day. On average, for every 1,000 IU of Vitamin D3, you will raise serum levels by about 5 ng/ml.

“Meta-analyses of studies done ranging from 1966-2013 have shown that people with Vitamin D levels between 40-60 ng/ml have the lowest all-cause mortality. ”

Dietary sources sidestep challenges with skin synthesis. While fish is the richest source of Vitamin D (Salmon contains 530 IU/3.5 oz), if your Vitamin D levels are low, food will help, but it won’t suffice. And if you are trying to obtain adequate levels of Vitamin D from fortified foods (i.e. whole milk, orange juice etc.) you would have to consume incredibly large amounts. For many, supplementation is necessary! Vitamin D3 supplementation is a good way to ensure you get adequate amounts.

Here Are Some Important Guidelines When Supplementing:

Take oil-based gelcaps with fat containing food (or fish oil), to ensure absorption, because Vitamin D is fat-soluble.
Make sure it is the human form (D3 )! The prescription form is the non-human form (D2) and yields different effects. Also note, D2 is usually the form added to foods such as dairy products!
Supplement in the morning, because for some, Vitamin D can impact your ability to sleep.
Take it with fish oil but NOT with calcium because calcium supplementation alone has been associated with increased cardiovascular risk. Also note, that excessive levels of Vitamin D will generally result in higher serum levels of calcium, which in some, can lead to toxicity!
Get enough magnesium! According to The Journal of the American Osteopathic Association, Vitamin D remains stored and inactive for as many as 50 percent of Americans. Without enough magnesium, Vitamin D is not really useful, In fact, a person may suffer from vascular calcifications if their magnesium levels are low and they are taking Vitamin D supplements.
Most importantly, it is best to get your Vitamin D levels routinely tests in order to make sure you are in the "sweet spot"of 40-60 ng/ml. For the reasons stated above, when you have your levels tested ask for 25-hydroxy AND calcium!

“Most importantly, it is best to get your Vitamin D levels routinely tests in order to make sure you are in the ”sweet spot”of 40-60 ng/ml. For the reasons stated above, when you have your levels tested ask for 25-hydroxy AND calcium!”

I remember many years ago my dermatologist saying that she had started to check Vitamin D levels, because "living in Minnesota, you could lie naked on your roof top and still not get enough Vitamin D." Turns out...of the four in our family, three of us were well below 30 ng/ml!

Wendy Dellis is a certified wellness coach. She joins years of training and work in the area of behavior change, experience as a fitness instructor and run club coordinator with a passion for adventure and people. She lives in Minnesota with her husband, Jay, and two sons.

The information contained on this page is for general information purposes only. Nothing here should be construed as medical or healthcare advice, but only topics for discussion. No physician-patient relationship exists; please consult your physician before making changes in diet or lifestyle.