I was inspired to write this post because over the last year I’ve been working on improving my vitamin D level. I spend most of my free time outdoors whenever the weather is warm and the sun is out, and I incorporate vitamin D rich foods into my diet (wild-caught salmon and sardines 2-4 times a week). I was happy to hear that my vitamin D level is within the top 90% of the patients my doctor sees, and while it was just below his recommended optimal level, I was advised to supplement during the winter. What was shocking to hear was that most people have vitamin D levels FAR less than mine and it is my assumption that most people don’t know it, nor do they know the possible consequences.
Can’t wait for the next sunny sky? The sun improves our mood, sleep, and just feels great! Could there be a biological reason for that? Perhaps our innate desire to be in the sun is our body’s way of telling us we need our sunshine vitamin, our vitamin D fix.
Photo Credit: temporalata / Creative Commons
Vitamin D is crucial for normal functioning of SO many of our biological processes. It’s responsible for the absorption of calcium and phosphorus in our bones thereby promoting bone growth and strength and preventing osteoporosis. Even with adequate amounts of calcium and phosphorous obtained from diet, without enough vitamin D our body can’t absorb them. Vitamin D is an important factor in muscle, heart, lung and brain health, and is vital in activating our immune defenses. Deficiency on the other hand is linked to various types of cancer, heart disease, depression, Alzheimer’s, Multiple Sclerosis, and a long list of other diseases.
Sources of Vitamin D.
Vitamin D is so important that our body makes it itself, but it can’t do so without the aid of sunlight. A moderate amount of UV exposure is the best, and safest, way to obtain what we need. Have you ever wondered how we absorb vitamin D from the sun? Most people don’t know that vitamin D isn’t actually a vitamin. It functions as a steroid hormone and is manufactured in our body not acquired:
Sun UVB rays convert the cholesterol in our skin into vitamin D
Where you live, season of the year, time of day, skin exposure, sunscreen use, and skin pigmentation determines how much sunlight exposure is needed. The more north of the equator you are and the darker your skin is, the greater the exposure you need. At most latitudes outside of the tropics however, there are substantial portions of the year, such as the winter months, during which vitamin D cannot be obtained from sunlight. Additionally, environmental factors including pollution can also reduce the availability of UVB light. What is remarkable to me is that our bodies are brilliantly smart. Our body knows how vital vitamin D is to our health that it stock piles any excess it makes for times when sun exposure is limited. Get the recommended amount during the summer months and you should have a reserve that lasts you through winter. Conversely, when enough vitamin D is synthesized from the sun our bodies have a built in regulatory system that turns off production.
Photo Credit: Catherine Day / Creative Commons
What happens if you can’t get enough sun? Unfortunately, natural food sources containing vitamin D are limited and are found mainly in animal-based foods such as cod liver oil, wild-caught fatty fish (wild salmon, tuna and sardines), pasture-raised eggs, grass-finished beef liver etc. Additionally, you have to eat a lot of it. There isn’t enough vitamin D to obtain adequate amounts from food alone, unless you want to turn into a sardine.
Interesting note: With the exception of mushrooms, which also contain vitamin D, there is typically a correlation between foods that are rich in vitamin D and cholesterol (i.e. foods highest in vitamin D are often also high in cholesterol, like eggs). That’s because cholesterol is needed to make vitamin D. Consequentially, low cholesterol REAL food diets are inherently low in vitamin D.
Don’t Get Enough?
Vitamin D deficiency often goes undiagnosed or untreated. It is estimated that up to 50% of Americans aren’t getting enough vitamin D. Deficiency could be caused by numerous factors such as:
- limited sun exposure
- the amount of pigment in one’s skin
- malabsorption (Crohn’s & celiac disease could be attributing factors)
- age (as we age, the less we’re able to make vitamin D from the sun)
- deficiency in calcium (when calcium levels are low our body uses vitamin D to restore levels by increasing calcium absorption from food or by taking calcium out of our bones)
Many of us today live a lifestyle predominately indoors, I for one work in an office every day, so this is not surprising. What is most important is to get tested to determine if an increase in sun exposure and modification in diet is needed. If both of those are not adequate enough, you may have to take a daily supplement.
Photo Credit: Bradley Stemke / Creative Commons
Get Too Much?
When vitamin D levels are too high, high levels of calcium can develop in the blood, a condition called hypercalcemia. Unlike our regulatory mechanism that controls vitamin D storage from the sun, there is no regulatory system for vitamin D consumed. If large doses are taken for a prolonged period of time or a huge dose for a short period of time, it could accumulate in the body in unhealthy excess. Fortunately, vitamin A and K2 protect against vitamin D toxicity and vice versa. Vitamins A, D and K2 exist synergistically and should be consumed in adequate amounts. When supplementing with vitamin D, know your entire nutritional profile to include vitamin A, K2 and calcium levels, and take a supplement(s) that puts you in proper balance.
How Much Do I need?
There is no good way to standardize how much everyone needs, and studies recommending optimal dosage are varied; there are just too many individualized factors. Getting mid-day summer sun exposure several times a week without sunscreen is enough for many people. This could be 10-15 minutes for fair skinned individuals or a couple of hours for darker skin. Without proper testing though, you will not be able to figure out how much you need, or whether the sun exposure you get or the supplements you take, are sufficient.
The Vitamin D Council is a great resource for more information about vitamin D deficiency, supplementation, sun exposure, and testing, and was used as a reference for much of this post.
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Lauren Brinkac, founder of DC Healthy Bites, received a dual BS in Biology and Biochemistry from Syracuse University and a MS in Bioinformatics from George Mason University. She is currently a Lead Bioinformatics Analyst conducting bacterial genomics research of infectious disease at The J. Craig Venter Institute. Lauren hopes to use her scientific background and the latest in scientific research to guide others in making informed dietary choices to optimize their own personalized health. Click here to read Lauren’s Story.