Vitamin D Levels and the End of Summer

Labor Day marks the traditional end of summer. With fall around the corner, I wanted to share some thoughts about Vitamin D and the end of Summer. This is important to maintaining a good health and as a gynecologist I am routinely finding deficiencies. There is a lot of talk and a lot of press about healthy Vitamin D Levels. First let’s cover a a few facts about Vitamins in general.

 

Definition(s)

Vitamins are any of a group of compounds that are essential for normal growth and nutrition and are not typically synthesized by the body.

Vitamin D is actually synthesized in our skin when ultraviolet B light is absorbed by 7-dehydrocholesterol that transforms it to pre-vitamin D₃, which is then converted to Vitamin D₃. Vitamin D₃ is metabolized in the liver to 25-hydroxyvitamin D₃ and then in the kidney to its biologically active form, 1,25-dihydroxyvitamin D₃. Vitamin D is unique among vitamins in that it is also a hormone since it is manufactured in one organ and exerts its effects at a distance upon other organs. Asheville enjoys about the same number of sunny days throughout the year, but most of us are likely to be outdoors more during the summer months.

 

RDA (Recommended Daily Allowance) is the amount of vitamin intake that would meet the healthy requirements for 97.5 percent of the population. The Institute of Medicine website explains the method for determining the RDA for Vitamin D.

 

Sun Exposure

Although chronic sun exposure increases the risk of nonmelanoma skin cancer; complete avoidance of sun exposure increases our risk of vitamin D deficiency. This can have serious implications including associations with cancers, osteoporosis, high blood pressure, heart disease, mood disorders, and some autoimmune diseases. Remember that darker skinned individuals require more sun exposure to produce the same amount of Vitamin D as fairer skinned individuals.

Healthy Vitamin D Levels

The amount of sun exposure that causes our skin to turn just a little red produces about 10,000 to 25,000 international units (IU). Effective UV protection significantly reduces our risk of skin cancers, but also can reduce our production of Vitamin D substantially. Another factor that can affect our health is that as we age our ability to produce Vitamin D declines. In addition, some individuals whose religious or social customs require them to remain covered are at higher risk of developing Vitamin D deficiency because of their almost complete blockade of the sun.

As fall approaches we are less likely to be out in the sun and the need to supplement our diet to maintain healthy and adequate Vitamin D levels becomes more important.

 

Dr. Mark Hyman recently posted a blog in which he reports that “Two recent studies in The Journal of Pediatrics found that 70 percent of American kids aren’t getting enough vitamin D, and this puts them at higher risk of obesity, diabetes, high blood pressure, and lower levels of good cholesterol. Low vitamin D levels also may increase a child’s risk of developing heart disease later in life.”

 

Vitamin D Regulates Functions

Vitamin D has widespread effect in on health and the function of our cells. It regulates cellular growth and proliferation and is important in the differentiation of cells into specific types of tissue. This may account for its importance in reducing the incidence of various types of cancer including cancer of the colon, prostate, breast, and ovary. It is thought to be an inhibitor of these cancers.

 

Dr. Michael Holick, a Boston University School of Medicine researcher, recommends intakes of up to 2,000 IU a day. This is likely to achieve blood levels of 25 hydroxy vitamin D at between 75 to 125 nmol/L (nanomoles per liter). The government recommends 2,000 IU as the upper limit for vitamin D₃ .

 

6 Tips for Getting the Right Amount of Vitamin D

How much Vitamin D you should take will depend on your age, how far north you live, how much time you spend in the sun, the time of the year, and to a smaller extent your dietary intake. Many people report feeling better when they achieve optimal levels of Vitamin D.

 

Dr. Mark Hyman offers the following advice for getting optimal levels of vitamin D:

1. Get tested for 25 OH vitamin D. The current ranges for “normal” are 25 to 137 nmol/L or 10 to 55 ng/ml. These are fine if you want to prevent rickets – but NOT for optimal health. In that case, the range should be 100 to 160 nmol/L or 40 to 65 ng/ml. In the future, we may raise this “optimal” level even higher.

 

2. Take the right type of vitamin D. The only active form of vitamin D is vitamin D3 (cholecalciferol). Look for this type. Many vitamins and prescriptions of vitamin D have vitamin D2 – which is not biologically active.

 

3. Take the right amount of vitamin D. 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 because of differences in vitamin D receptors, living in northern latitudes, indoor living, or skin color.

 

4. Monitor your vitamin D status until you are in the optimal range. If you are taking high doses (10,000 IU a day) your doctor must also check your calcium, phosphorous, and parathyroid hormone levels every 3 months.

 

5. Remember that it takes up to 6 to 10 months to “fill up the tank” for vitamin D if you’re deficient. Once this occurs, you can lower the dose to the maintenance dose of 2,000 to 4,000 units a day.

 

6. If you eat fish, try to eat dietary sources of vitamin D. These include:

• Fish liver oils, such as cod liver oil. One tablespoon (15 ml) = 1,360 IU of vitamin D
• Cooked wild salmon. (3.5) ounces = 360 IU of vitamin D
• Cooked mackerel. (3.5) ounces = 345 IU of vitamin D
• Sardines, canned in oil, drained. (1.75) ounces = 250 IU of vitamin D
• One whole egg = (20) IU of vitamin D

 

I welcome your comments—but remember, this site does not offer personal medical advice and is not intended to replace consultation with your physician.