Back to Mery's Notes


The Importance of Vitamin D

With the long days of the summer finally here, it seems suitable to spend a little time talking about the “Sunshine Vitamin,” vitamin D. This is actually a funny name for this compound, as it’s actually a hormone and not a nutrient, but for the sake of brevity, I’ll stick to calling it a vitamin. 
Many of us are not getting enough of this essential compound, but the good news is that summertime makes it all the more possible.

You might be wondering why we even need to worry about vitamin D. If it’s a hormone, our bodies should just produce enough of it, right? Actually, no. It’s called the Sunshine Vitamin because our skin contains a certain type of cholesterol, that when stimulated by UVB rays from the sun, forms vitamin D3. It then goes through additional processes in the body, like conversions in the liver and kidneys, to form various derivatives that benefit that body. This process can be inhibited in many ways: time of day, location, cloud cover, season, age, and skin color can all influence your vitamin D production. 

I’d also like to point out that this is just one of the many necessary functions within the body in which cholesterol plays a part—it’s not the evil villain it’s been made out to be. 
There are many reasons we need vitamin D. It’s essential for a powerful immune system, strong bones and teeth, cardiovascular health, and hormonal balance. These are the benefits we most often hear about. But, new research is revealing even more positive impacts of vitamin D on health. 

A recent Japanese study looked at more than 30,000 men and women over the course 16 years. Higher vitamin D levels were associated with a 20% lower relative risk for overall cancer and a 30-50% lower relative risk for liver cancer. Other research has found similar results, such as a reduction in all types of cancer in women who took vitamin D supplements with calcium. When compared to the both calcium alone and placebo groups, low vitamin D status was considered a significant predictor for cancer risk.

Another study from the University of California San Diego School of Medicine and Seoul University looked at the relationship of vitamin D to diabetes. Those who had “adequate levels,” identified as 30 ng/ml, had one-third the risk of developing diabetes. Those with levels over 50 ng/ml had one-fifth the risk. 

We’ve also seen that low vitamin D levels correlate with increased all-cause mortality.
It’s clear that there is much more to vitamin D than just bone health and cold and flu prevention. From cancer to diabetes, it may protect us from much greater health risks. 

So how can we get more of it? Well you know I always turn to food first. While the sun is still the best source, you can get some vitamin D from liver, cod, herring, and sardines. Mushrooms and eggs also contain vitamin D. 

Those living north of the line drawn from San Francisco to Richmond are at a greater risk of vitamin D deficiency, as the fall and winter months greatly decrease our chances of getting enough. Getting outside in the sun (without sunscreen) for just 10 to 15 minutes a day, with light hitting the arms and legs, can generate enough for most of us. While you’ll need to prioritize your sun exposure for optimal vitamin D synthesis, it’s important to be careful to avoid over-exposure that can lead to skin damage. You do not need to burn or even tan for vitamin D synthesis to occur; it only takes about half the time spent in sunlight that it would take for your skin to burn during that season in that location. 
Since it can be difficult to eat enough food sources of vitamin D and get the correct amount of sunshine, supplements are another option. Just be sure to get a product containing vitamin D3, preferably in capsule or drop form. 

If you have a deficiency, you should correct it with 5,000 to 10,000 IU of vitamin D3 a day for 3 months — but only under a doctor’s supervision. For maintenance, take 2,000 to 4,000 IU a day of vitamin D3. Some people may need higher doses over the long run to maintain optimal levels.

To improve absorption, vitamin D should be taken with food that contains some fat, since it is fat soluble. It’s also important to note that vitamin D works synergistically with other nutrients, so be sure to talk to your practitioner to make sure you’re getting what you need with it. 

When supplementing, have your levels rechecked every three months to know you’re within a proper range. And remember, vitamin D is a hormone, so it fluctuates for everyone differently, and obviously seasonal changes affect it as well.

There are many different “optimal ranges” being recommended from the medical and scientific experts. I personally recommend following the guidelines of the Vitamin D Council, you definitely want it over 40 ng/ml but not more than 80 ng/ml, with 50 ng/ml being an ideal level. This number can vary with health conditions, such as autoimmunity, but it’s a useful range for the general public. If you are an athlete, you can run your level of vitamin d D to 120ng/ml (Mery Zanutto).

Extract from Mark Hyman, MD