If you live in northern latitudes and your moods tend to hover at the low end of the emotional spectrum, this time of year may be especially tough to get through. Seasonal Affective Disorder (SAD) is becoming a familiar term, but there’s still a lot we don’t understand about it.
Most people know SAD has something to do with winter’s weakened sunlight taxing our spirits. Increasingly, researchers are linking the season’s trademark low mood with our bodies’ diminished capacity to manufacture Vitamin D – “the sunshine vitamin.”
Indeed, low levels of vitamin D have been linked to depression in a number of clinical studies. Now, psychiatric researchers at UT Southwestern Medical Center working with the Cooper Center Longitudinal Study have confirmed this connection in what is believed to be the largest such investigation ever undertaken.
According to a write-up of the study in Science Daily:
“The scientists have not determined the exact relationship — whether low vitamin D contributes to symptoms of depression, whether depression itself contributes to lower vitamin D levels, or chemically how that happens. But vitamin D may affect neurotransmitters, inflammatory markers and other factors, which could help explain the relationship with depression, said Dr. Brown, who leads the psychoneuroendocrine research program at UT Southwestern.”
This finding has special significance at this time of year. Shorter days and cold winter weather urge residents of the northern hemisphere to spend more time indoors, curtailing their exposure to sunshine necessary for Vitamin D production.
Could a Vitamin D supplement be the answer?
A daily dose of vitamin D may just be what people in northern climates need to get through the long winter, according to researchers at Loyola University Chicago Marcella Niehoff School of Nursing.
Says Loyola Professor Sue Penckofer, “Vitamin D deficiency continues to be a problem despite the nutrient’s widely reported health benefits. Chicago winters compound this issue when more people spend time away from sunlight, which is a natural source of vitamin D.”
In his best-selling book “Spontaneous Healing,” natural health guru Dr. Andrew Weil advises supplementing with Vitamin D, a solution he calls effective and inexpensive. In fact, the lack of Vitamin D is, Weil believes, the second most common and serious nutritional deficiency in our population (next to omega-3 fatty acids):
“Receptors for Vitamin D occur throughout the brain, and it appears to play an important role in the development and function of that organ, including the activity of neurotransmitters that affect mood. High vitamin D levels may protect against age-related cognitive decline. Low levels are associated with impaired cognitive function (especially in the elderly), seasonal affective disorder, depression, and even psychosis.”
Choosing to supplement: How much and how often
The best possible way to boost your Vitamin D levels is through skin exposure to sunlight. However, most of us, even if we live closer to the equator, fall short of optimal exposure. Why? Many factors diminish Vitamin D synthesis: obesity, dark pigmented skin, sunscreen, time of day, degree of latitude, clothing, exposure through glass, medications.
Vitamin D deficiency can be measured only through a blood test. Many health sources peg the normal range Vitamin D serum level at 32-50 nanograms per milliliter (ng/mL). This “normal” range is extremely conservative, according to the Vitamin D Council which strongly advocates that it should begin at a minimum of 50, rather than 32.
The widespread incidence of Vitamin D deficiency has become better known in recent years, prompting more health-care providers to screen their patients.
So, when it comes to supplements, how much is enough?
The Vitamin D Council reports that a healthy human body utilizes around 3,000-5,000 IU of vitamin D per day for proper functioning. Considering that current recommended intakes are in the range of 600 IU, the Council has come out with a statement that the current recommended intakes are not high enough to raise and/or maintain the vitamin D levels necessary for proper health.
Based on the body’s indicated daily vitamin D usage, Vitamin D Council recommends the following amounts of supplemental Vitamin D3 per day in the absence of proper sun exposure.
- Healthy children under the age of 1 year – 1,000 IU.
- Healthy children over the age of 1 year – 1,000 IU per every 25 pounds of body weight.
- Healthy adults and adolescents – at least 5,000 IU.
- Pregnant and lactating mothers – at least 6,000 IU.
How much is too much?
The U.S. Government’s Tolerable Upper Intake Level (UL) for vitamin D is set at 4,000 IU per day. The Vitamin D Council cites the opinion of many experts in the field that advise a maximum supplementation level of 10,000 IU. The Council’s official statement is as follows:
“Current expert consensus is that the U.S. Government UL for vitamin D is too low and that it should be raised to 10,000 IU per day. Since this is the amount one would naturally produce in their skin from sun exposure, it is considered safe.”
In most cases, patients with a deficiency are advised to take 10,000 IU of Vitamin D for several weeks, tapering off to 5,000 as blood serum levels return to normal. Thereafter, a daily supplement of 2,000 to 5,000 IU is recommended.
Low Vitamin D Levels Linked to Depression, Psychiatrists Report (Science Daily, Jan. 5, 2012).
Vitamin D Lifts Mood During Cold Winter Months, Researchers Say (Science Daily, March 3, 2010).
Vitamin D Supplementation, Vitamin D Council website.
Weil, Andrew M.D., “Spontaneous Happiness.” Little, Brown and Company, 2011.