Should I be taking Vitamin D?

We all have heard the buzz on vitamin D and its various health benefits. Vitamin D has been associated with cardiovascular health, mental health, immunity, energy levels and bone health among other things. So, lets get to know Vitamin D, its actual benefits and whether you should be taking any supplemts.

What is Vitamin D:

Vitamin D is a fat solube micronutrient that is essential in various body functions. Receptors for vitamin D are found in many organ cells such as the endothelium (cells lining blood vessels), neurons, pancretaic cells, bone cells and immune cells. Hence their presumed association with vairous health benefits. Vitamin D's best studied and established role is for bone health. Vitamin D is essential for calcium and phosphorous absorption, two main elements of bone formation. Vitamin D is also associated with improved immune response. But randomized controlled studies have failed to show any direct link between vitamin D supplementation and cardiovascular, mental or endocrine health.

Vitamin D sythesis:

Naturally, vitamin D is made through a complex process: sunlight converts cholesterol in skin cells to an inactive form of vitamin D (D3). D3 is then converted by the liver to 25-OH Vitamin D, this is the vitamin D we can store. It is also what we measure clinically, its value indicates the total available Vitamin D in the body. The liver releases small amounts of 25-OH vitamin D into the bloodstream based on daily requirements. The kidneys in turn activate this storage form into the final, active Vitamin D.

So, to make natural vitamin D we need dietary cholesterol, exposed skin to the sun, a healthy liver and kideny.

How do I get Vitamin D precursors:

As you can see from the above diagram there are two ways to obtain vitamin D: Naturally through sun light or supplements.

1) Sun Light:

Healthy individuals can make and store enough vitamin D from about 10-30 minutes of direct sun light exposure per day. The body surface needed is combination of hands, arms, legs and face. The best hour for this is 10am to 3pm, when UV light B is the predominant UV light. UVB is the frequency that breaks down the cholesterol to Vit D. The other sun light, UVA, is responsible for the DNA damage and risk of skin cancer, but it does not help with vitamin D synthesis.

Lighter color people tend to need less exposure (closer to 10 minutes) while darker skin people need more. In addition, sunblock does reduce the amount of UVB exposure. We all should apply sun block to prevent skin cancer (UVA), but this also means we may spend a little more time outside (closer to the 30 minutes) for the full exposure of UVB.

Another factor that affects the ratio of UVB in daily sunlight is the latitude on earth and distance/angle from the sun. Sadly for us Clevelanders, we do not get the UVB from around November to April. So, even if you are brave enough to be out in shorts and shirt, and get a sunny day, you are still not getting effective sunlight exposure during those months.

2) Foods with vitamin D:

Wild caught salmon: about 600 units, enough for a daily intake.

Farm raised salmon: about 200-300 units, half of daily requirement.

Tuna: 200 units (about 30% of daily value).

Egg yolk: 40 units per egg (about 8% of daily value).

Beef liver: high level of vitamin D, remember, this is where vitamin D is stored.

Fortified juices: I hope by now you have read enough of my blogs and you are not drinking these.

3) Supplements:

For individuals with no vitamin D deficiency, 600 units of daily supplement is enough. For those with deficiency, 1000 units daily suffices once the deficiency has been replenished. For those with deficiency, there will be a period of higher dose (5000 units daily) to replete followed by a higher maintance dose (1000 units).

So, when should you take Vitamin D? According to the naional health guidelines Vitamin D supplementation is not indicated except for those who have osteopenia or osteoporosis, pregnant women and children. But these guidelines are based on population studies across the board; people from sunny states all the way to us gloomy Clevelanders. When I practiced in Boulder/CO I rarely saw a patient with vitamin D deficiency. I rarely see anyone in Cleveland who has adequate numbers. Just because there are no trials done to demonstrate the benefit of supplementation it does not mean that there is no benefit. In addition, taking healthy amounts of supplements has no risks.

So, my personal recommendation is to take 600 units of vitamin D3 daily from October to April, and let the sun shine on you from May to September. Over the counter D3 is readily available at all pharmacies. If you are taking a multivitamin be sure that it has 600 units (most do not).

Normal Vitamin D level is the same across populations and age groups. But some may require higher daily levels to achieve a normal level. This includes children, elderly, pregnant women and endurance athelets. So, if you are a at risk person be sure to get your levels checked.

One caveat on taking supplements: This is one of those things where too much of a good thing is not a good thing. Too much Vitamin D can lead to high Calcium levels (Hypercalcemia). Hypercalcemia can have dangerous health consequences including nerve damage, kideny stones and arrythmias. So only take 600 units daily or 1000 units if you had prior deficiency and be sure to check your levels once a year.

Knowing your Vitamin D levels:

Deficiency: less than 20 ng/ml

Insufficiency: less than 30 ng/ml

Normal: 30 and above