These days you might be preparing for winter like I am — bringing in the firewood and lawn chairs, locating the snow tires and antifreeze. But is your vitamin D level readied for the short, dark days of winter?
If you’re like most folks, the answer is probably no. Recent nationwide studies suggest that only 1 of 5 individuals have adequate vitamin D blood levels, and the incidence of vitamin D insufficiency has doubled over the last 10 years.
We depend on a small band of UVB sunlight for over 90% of our vitamin D. During the winter, this narrow range of solar radiation is not available in latitudes roughly above Atlanta (due to the slant of the sun). So the dark days of winter challenge our vitamin D reserves, and most folks dip into even greater vitamin D inadequacy by the end of winter.
The active hormonal form of vitamin D we produce from sunlight exposure interacts with almost every cell in the body, directly or indirectly targeting up to 2,000 genes. A drop in your vitamin D level may be associated with increased flu and viral infections, more depression, and increased fractures. Low vitamin D levels have also been linked to osteoporosis, heart disease, muscle weakness, MS and autoimmune diseases, periodontal disease, and diabetes among others.
Here’s what you can do to be sure your vitamin D is adequate as we spend less time in the sun:
Your winterization plan
1. Test your vitamin D levels in the fall. This will give you your “end-of-summer vitamin D reading.” Most likely this will be the highest level you will attain all year, and you will draw on these vitamin D reserves during the winter. Be sure to use the 25(OH) vitamin D test. Minimal adequacy is 32 ng/mL, but 50-60 ng/mL is more ideal, and up towards 100 ng/mL is too much. Your doctor can order a vitamin D blood test for you, or you can order a test kit through the Vitamin D Council.
2. If you are substantially below 32 ng/mL, your physician will likely prescribe high dose vitamin D (say 4,000 to 7,000 IU a day) for 8 weeks and then retest your level. Or many physicians prescribe one of the 50,000 IU pills of vitamin D a week for eight weeks and then retest.
3. If you are at or only slightly above 32 ng/mL, know that your vitamin D level would likely raise 10 ng/mL for every 1,000 IU of vitamin D you add to your supplement program per day.
4. Test your vitamin D level in mid-winter to see how your vitamin D reserves are holding up. You will see if you need to increase your vitamin D dose during the winter. If you do follow-up testing, remember it takes about 8 weeks to see the full impact of a new dose of vitamin D.
5. If you cannot obtain a vitamin D test, you might try 1,000 to 2,000 IU of vitamin D per day and then test your levels when you have a chance to see if this intake is enough.
Keep in mind that individuals with a hypersensitivity to vitamin D or with any of the following health concerns should use vitamin D only under the supervision of their physician:
Hypercalcemia (high blood calcium)
Be well and enjoy the winter. Hibernate a bit and rest up some — Nature seemed to intend it that way! If you’d like to find out more about vitamin D, read my article on the many benefits of vitamin D.