by Paula H. Mendelsohn, MPH, RD, LD, CCN
Not too long ago, I had the privilege of hearing Dr, Michael Hollick speak at the Florida Dietetic Association annual state meeting. Dr. Hollick is considered to be the “Father” of the Vitamin D and sunlight movement. He shocked us with pictures of iguanas raised as pets inside the home with broken legs and fractured pelvises. He explained that without sunlight, these animals were basically being raised to have rickets and osteoporosis, their bones had become too fragile to support their weight. We all know iguanas love to bask in the sun, keeping them indoors was unnatural and deprived their bodies of the ability to make vitamin D.
Then he shocked us even more, when he explained that humans also used to thrive outdoors naked in the sunlight. By becoming ‘civilized and industrialized’, covering ourselves with clothing and living indoors and now with fears of skin cancer, coating our surfaces with sunscreen, we are becoming as the pet iguanas, at risk of vitamin D deficiency and the consequences, some of which include various cancers and auto-immune diseases.
I was inspired to share this information with my clients and students, and motivated to communicate a sufficient understanding of the situation, they would know how to protect themselves and prevent (and possibly reverse) the potential problems. When I asked my people to please have their vitamin D levels checked, we were very surprised to see almost everyone was deficient, and the average levels being measured were in the range of 17-24. And this was in south Florida, the “sunshine state”!
We now know that vitamin D is much more than just the vitamin that protects our bones. Vitamin D, (real name “cholecalciferol”) actually acts more like a hormone than a vitamin. Humans (and animals) can synthesize vitamin D from the action of ultraviolet light from the sun on the cholesterol just under our skin’s surface. We change the cholesterol into a new compound called 7-dehydrocholesterol. This new form then cycles through our liver and our kidney, each organ adding a tiny piece of chemical called a ‘hydroxyl group’. The newly formed fully functional vitamin D is referred to a 1,25-dihydroxy-cholecalciferol. (The test for vitamin D is called 25-hydroxy vitamin D3 (subscript), this is the circulating form of vitamin D that is the best indicator of health status.)
What surprised scientists when they started to examine humans more closely, is that there are receptors for vitamin D in every tissue in our body, not just in our bones. We need vitamin D in order to have healthy brains, breasts, colons, livers, etc…everywhere in our bodies, the bones were just the ‘tip of the iceberg’. So what are people supposed to do, go back to being naked and living outdoors? Obviously that’s not practical, however, it is recommended that to the best of our ability, we get about 20 minutes worth of direct sunlight several times per week on exposed skin. Just enough to turn pink, not to burn. How much vitamin D you make depends on your age, how much skin is uncovered, and your skin tone. Without sunblock and with arms and legs exposed, skin will make 10,000 to 15,000 units of vitamin D in one pinking sun exposure, on average. (Sunblock with an SPF of more than 15 blocks 100% of vitamin D production in the skin.)
If sun exposure is not an option, due to work or immobility or living so far north of the equator that direct sunlight is only available during a very few months of the year, then our primary tool is to supplement. Even choosing foods that are good sources of vitamin D, will still not give us enough to stay healthy and prevent deficiency conditions without either direct sunlight or supplementation or both.
This brings up some interesting questions: How much vitamin D is recommended? What’s the best kind to take if we choose supplements? Is anyone at particular risk who may need extra?
One of the issues that compounds the situation is our laboratories are still using older levels as the ‘norms’, so when people get their vitamin D levels tested, they are told they are ‘normal. Well, heart disease, cancers of the colon, lung, and breast, and muscle/bone pain have also become ‘normal’ nowadays. All of these conditions would be improved and possibly prevented with adequate levels of vitamin D.
Another compounding issue is there are two commercially available forms of vitamin D. The regular prescription form and some over the counter versions are Vitamin D2 (subscript), called “ergocalciferol”. This is the plant form of vitamin D and is a good match up for plant receptors. The best form for humans and animals (even our pets may need supplementation if they are kept indoors) is the cholecalciferol form, D3 (subscript). Using the standard Vitamin D2 (subscript) form, takes an extra long time to restore vitamin D levels, even in the 50,000 IU dosage!
The following chart shows the levels and potential consequences of deficient and sufficient vitamin D:
< 10 ng/mL Severely deficient
< 15 ng/mL
- Risk of rickets
< 20 ng/mL
- 75% greater risk of colon cancer
< 30 ng/mL Deficient
- Increased calcium loss from bones, osteoporosis
- Poor wound healing
- Increased muscle pain
- Increased joint and back pain
- Greater risk of depression
- Increased diabetes
- Increased schizophrenia
- Increased migraines
- Increased autoimmune disease (lupus, scleroderma)
- Increased allergies
- Increased preeclampsia
- Increased inflammation
30–50 ng/mL Suboptimal levels
< 34 ng/mL
- Twice the risk of heart attack
< 36 ng/mL
- Increased high blood pressure
< 40 ng/mL
- Three times the risk of multiple sclerosis
50–80 ng/mL Optimal levels
> 50 ng/mL
- 50% reduction in breast cancer, decreased risk of all solid cancers
- Slowing of cancer growth in patients with cancer
> 100 ng/mL Possible increased risk of toxic symptoms (hypercalcemia)
With my patients, I recommend 2000 IU of vitamin D if their levels are between 40 and 50, 5000 IU if levels are between 27 and 39, and 10,000 IU of vitamin D3 if levels are below 26. People of color, people with digestive challenges such as colitis or gluten sensitivity, and very obese people may require even more intervention to raise their Vitamin D to a protective-preventive level.
Paula Mendelsohn is a consulting nutritionist with Boca Wellness & Nutrition Services and the nutrition professor for the Lynn College of Nursing at Florida Atlantic University, both in Boca Raton.