By: John Muller, MD candidate
Winter is coming.
With the clocks falling back this weekend, we finally accept that summer is over and sadly enter colder, darker days. Less sun means less vitamin D. Less vitamin D means lower mood.
Vitamin D3 is made in the skin from a cholesterol base (7-dehydrocholestrol) under the influence of UV light in a two-step process. Both UVB intensity and skin pigmentation level contribute to the rate of vitamin D3 formation.
Vitamin D2 (ergocalciferol) is derived from plants (the plant sterol ergosterol). Thus, this form of vitamin D can be obtained from the diet.
Vitamin D, or 1,25-dihydroxyvitamin D if you want to impress, is the active hormonal form that is created after a series of steps that occurs in the liver and kidneys.
The active form of vitamin D is critical for your health. It affects calcium and phosphate regulation, thus affecting your bones, the immune system, your metabolism, and the cardiovascular system, to name a few.
Importantly, vitamin D affects your mood
Multiple studies show the effect of vitamin D deficiency on mood. One such study found that in in older adults, vitamin D deficiency was associated with low mood and with impairment on two of four measures of cognitive performance.
Research suggests that vitamin D supplementation may decrease depressive symptoms during winter months. In order to test this, a study administered the Beck Depression Inventory before and after vitamin D3 supplementation and found that supplemental vitamin D3 reduces depressive symptoms.
Finally, certain cognitive domains are more affected in persons with vitamin D deficiency. A study found that higher vitamin D levels appear to be associated with better cognition, especially in areas of executive function and mental flexibility.
These are but a few of the many studies that have found a relationship between vitamin D level and mood.
The National Institutes of Health (NIH), which provides great fact sheets on many topics, states that for males and females aged 19-50, the recommended dietary allowance is 600 IU (15 mcg).
So how can you increase your vitamin D levels?
Sun Exposure
Even in the winter, take advantage of those sunny days. Go for a walk and make sure at least some of your skin is uncovered as clothing prevents UVB from penetrating the skin. Additionally, sunscreens of SPF 8 or more appear to block UVB. But take caution not spend too much time in the sun unprotected. UV damage can cause numerous skin problems. UV lamps may be a costly option as well.
Diet
Very few foods in nature contain vitamin D; however, in the American diet a majority of foods are fortified. Some food sources of vitamin D, listed from highest to lowest, include cod liver oil, swordfish, salmon (sockeye), mushrooms, canned tuna fish, orange juice fortified, milk, yogurt, eggs, cereal and swiss cheese.
Supplements
As mentioned earlier, the two main forms are D2 and D3, with D2 coming from plants and D3 often from animals (I see you vegans). Although research does suggest D3 may be more effective, both do the job. Remember, a majority of supplements in the United States are not regulated. Generally, 1,000 to 4,000 IU is considered a safe daily dose. Make sure that if you are taking a multivitamin or other supplements, they do not also contain vitamin D as you may be getting too much.
Of course, if you are concerned about your vitamin D levels, you should see your primary care provider who can test your blood levels.