Many of us suffer from Seasonal Affective Disorder or S.A.D during winter. I also see more patients with insomnia, anxiety and mood disorders in winter time. People tend to put more weight on in the winter and complain of lack of energy. So why are we happier, more active and feel healthier during summer? The answer to this question may be found in the sunshine vitamin and its deficiency in the winter months. Living in Northern climates such as in Canada we have very long and grey winter months. Also we need to cover up while outside. This leads to very little sun exposure, a necessity to produce vitamin D in the body.

Vitamin D deficiency symptoms

Vitamin D deficiency may be characterized by muscle pain, weak bones/fractures, low energy and fatigue, lowered immunity, depression and mood swings, and sleep irregularities. What’s more, evidence from studies that track the prevalence of disease by geography and nationality shows links between vitamin D deficiency and obesity, insulin resistance, heart disease, and certain cancers. Also individuals with renal problems or intestinal concerns (such as IBS or Crohn’s disease) may be vitamin D deficient because they can neither absorb nor adequately convert the nutrient.

Researchers are discovering that D also promotes normal cell growth and differentiation throughout the body, a key factor in maintaining hormonal balance and a healthy immune system. It appears that calcitriol actually becomes part of the physical composition of cells, assisting in the buildup and breakdown of healthy tissue - in other words, the process that keeps you well.

Your body can’t create vitamin D on its own. Instead, it’s designed to make it through sun exposure. In theory, you can make an ample supply of vitamin D with as little as a couple of hours per week in the sun. You can also ingest D through food, especially eggs and certain fish. So vitamin D deficiency should be an easy problem to solve, right? But the truth is we’re just not getting enough.

The consideration is, not all forms of vitamin D are the same - some are more usable (bioavailable). Our bodies can naturally synthesize more than 20,000 IU of vitamin D in just 20 minutes of sun exposure without ill effect. That’s because we have a natural check-and-balance mechanism that shuts off the synthesis when we get enough. This doesn’t happen when we eat sources of vitamin D - the same 20,000 IU of vitamin D taken as an oral supplement could be toxic.

Most milk suppliers fortify their products with vitamin D in the form of ergocalciferol (also called D2). Some orange juice makers are doing the same, and like many food fads, you can soon expect to see lots of other products claiming to be good for you because they’re fortified with vitamin D. While the amount in these beverages is enough to ward off malnutrition, you’d have to drink four or five glasses a day to reach optimal levels; that’s just too much milk or juice for most adults.

Vitamin D, menopause and osteoporosis

As we age, our bodies slowly lose the ability to mobilize vitamin D, a process that lowers our calcium absorption rates. This creates a higher risk of osteoporosis, particularly in post-menopausal women.

We’re not sure how sex hormones affect vitamin D conversion, but women seem to have a harder time stimulating the mechanism that builds bone tissue when their estrogen levels are reduced. Calcium is clearly an important co-factor to vitamin D, and may lose efficacy if vitamin D is deficient or estrogen levels are low, as vitamin D appears to be the more critical factor in bone health. A recent study by scientists at the University of Massachusetts found that a diet rich in calcium and vitamin D can help control some symptoms of PMS, such as tearfulness, anxiety, and irritability.

This is more evidence that all the systems of the body are connected and we can’t look for easy answers in one place.

Vitamin D and weight loss

Some studies have shown that weight loss does occur with an increase in calcium intake, while others appear to refute this. According to a study published in the Journal of Clinical Nutrition in January 2007, Consumption of calcium+D during a weight-loss intervention enhanced the beneficial effect of body weight loss on the lipid and lipoprotein profile in overweight or obese women with usual low daily calcium intake.

Moreover, people who have a reduced capacity to mobilize vitamin D often weigh more and have more body fat than those with full capacity. In the past 20 years multiple studies have shown a correlation between higher blood levels of vitamin D and leaner body mass.

Vitamin D and cancer

Evidence is mounting that vitamin D may protect against some cancers, particularly breast cancer, prostate cancer, and colorectal cancers. In fact, over 60 years of research have shown vitamin D supplementation or sunlight-induced vitamin D conversion to be associated with lower incidence of cancers.

There is also a higher incidence of breast cancer in northern climates, but whether that is associated with lower levels of vitamin D is still speculation. Vitamin D deficiency most certainly affects your immune system because calcitriol actually helps regulate cell division, so adequate levels may help sustain normal cell growth. And stress and other physiological markers can disrupt the function of vitamin D receptors, among others, making us more susceptible to unusual cell activity.

Vitamin D and depression

Another area of vitamin D research is its relationship to depression. Seasonal affective disorder, or SAD, is a situational mood disorder brought on by decreasing daylight in the winter months. High doses of vitamin D during these months have proven to be a very effective natural remedy for SAD, leading most practitioners to believe that normal neurotransmitter function depends in part on adequate vitamin D synthesis.

Vitamin D levels are inversely related to those of melatonin, another mood-regulating hormone. Melatonin helps modulate your circadian rhythms, with darkness triggering melatonin secretion by the pineal gland within your brain, bringing you down gently at night for sleep. Insomnia, mood swings and food cravings are influenced by melatonin. Sunlight shuts melatonin production off, while triggering release of vitamin D - that’s why it is recommend getting outdoors as a remedy for jet lag.

Most of us can sense the positive influence of sunlight in our own lives by the immediate lift we get from taking a walk outdoors on a beautiful sunny day. Now there may be many factors at work that brighten our mood in such cases, but sun exposure is almost certainly a critical piece. Soaking in the warmth of the sun is one of the most relaxing activities we share with all living creatures - just watch a cat dozing in a beam of sunlight.

Is healthy sunbathing possible?

Our bodies are remarkably efficient. During the summer months, even as little as 15 minutes in the sun (without sunblock!) in the early morning and late afternoon is enough for most light-skinned individuals to create an ample supply of vitamin D. Skin with more pigment (melanin) may require up to 40 minutes.

To practice safe sun exposure, you should not be out in the sun unprotected for more than 15 minutes, twice a day, early in the morning and late afternoon. If you begin to turn red before 15 minutes, cover up completely or go inside. It is never a healthy practice to burn your skin. Always protect your face and scalp by wearing a hat and during the sun’s peak hours (11 AM – 2 PM) by using a lotion with SPF–15 or more, preferably PABA–free. Melanoma is a serious condition, and I’m not in favor of increasing your risk with unhealthy sun exposure. It is also not safe to use tanning beds as a source of vitamin D.

What you can do to prevent vitamin D deficiency

The best way to protect yourself from any deficiency is to build your health from the bottom up and let your body balance itself. We acknowledge the controversy over whether our primary source of vitamin D should be the sun, diet, or supplements. Which combination is best for you depends on such variables as your age, nutritional status, and geographic location. With attention to the importance of Vitamin D in our daily lives and our likelihood of being deficient, we need to consider all our options. With this in mind I recommend the following steps to prevent vitamin D deficiency:

• Eat a diet rich in whole foods and complex carbohydrates. Nutrient-dense, fatty fish like mackerel and sardines are good sources of vitamin D. Eggs, fortified organic milk and other dairy products, and Cod liver oil are also good natural sources of D.
• Take a top-quality multivitamin every day to fill in any nutritional gaps, preferably one that includes pure and certified fish oil. Your supplement should have a minimum dose of 200 IU of vitamin D. To be on the safe side, it should not exceed 2000 IU daily, to avoid vitamin D overdose.
• Allow yourself limited, unprotected sun exposure in the early morning and late afternoon (no more than 15 minutes for light-skinned individuals, 40 minutes for darker skin) - particularly between May and September if you live in northern regions.
• Check with your healthcare professional about vitamin D testing. If you think you may be suffering from vitamin D deficiency, get a blood test and ask for the results. I like to see an optimal value of 50–100 ng/ml of 25 hydroxyvitamin D. Discuss adding a vitamin D supplement to your diet during the winter months or if you get inadequate sun exposure. This is especially important for women over 50. Then be sure to get follow-up testing to monitor your response. Vitamin D is a fat soluble vitamin and over dose can have adverse health risks.

Keep in mind that in the end, optimal health is never about just one thing. Vitamin D is just one component of an ever-changing picture - your health is a work in progress that needs your consistent attention and support.

Vitamin D may be an important element in improving and optimizing our health, but what matters most is how you feel and what works for you. I encourage you to investigate your personal vitamin D level with your medical practitioner as part of a comprehensive approach to your whole health.