By Dr. Glen Matejka

Wintertime is commonly a time when darker moods tend to creep in; a phenomenon linked to a decline in sunlight. Seasonal affective disorder (SAD) affects an estimated 6 percent of the U.S. population, while a milder form, known as the “winter blues,” affects about 14 percent.1 As noted in the Evening Standard:2

“According to the DSM [diagnostic and statistical manual of mental disorders], people who have SAD are excessively fatigued, lose interest in their hobbies, tend to crave more starches and sweets, may gain seasonal weight, and have difficulty concentrating during darker months.”

That said, longer, darker days tend to influence the behavior of most people, even if you don’t feel outright depressed and depleted. This is because your health and mood are actually intricately tied to exposure to sunlight, even irrespective of vitamin D. For example, your serotonin levels (a hormone associated with mood elevation) rise when you’re exposed to bright light.

Your melatonin level also inversely rises and falls with light and darkness. When it’s dark, your melatonin levels increase, which is why you may feel tired when the sun starts to set (and in the heart of winter, this may be at as early as 4 p.m.) which mimics the natural light from the sun, has been shown to be effective remedy for SAD, and may even be preferable for major depression.

Vitamin D supplementation can also be quite helpful for depression and/or the winter blues if you’re vitamin D deficient, which a vast majority are at this time of year. Research shows having a vitamin D level below 20 nanograms per milliliter (ng/mL) may raise your risk for depression by as much as 85 percent, compared to having a vitamin D level greater than 30 ng/mL.

Have You Checked Your Vitamin D Level Yet?

My recommendation is to get your Vitamin D tested twice a year, when your level is likely to be at its lowest (midwinter) and highest (midsummer). This is particularly important if you’re pregnant or planning a pregnancy, or if you have cancer. That means right about now is a good time to get your level checked, to identify your low point. Based on the research done and data collected by GrassrootsHealth, 40 ng/mL is the cutoff point for sufficiency to prevent a wide range of diseases, including cancer.

For optimal health and disease prevention, a level between 60 and 80 ng/mL appears to be ideal.3 The American Medical Association claims 20 ng/mL is sufficient, but research suggests 20 ng/mL is not even adequate for the prevention of osteomalacia. As for dosage, you need to take whatever dosage required to get you into the optimal range, with 40 ng/mL being the low-end cutoff for sufficiency.

Research4 suggests it would require 9,600 IUs of vitamin D per day to get a majority (97.5 percent) of the population to reach 40 ng/mL, but individual requirements can vary widely. If you’ve been taking a certain amount of vitamin D3 for a number of months and retesting reveals you’re still not within the recommended range, then you know you need to increase your dosage.

Vitamin D Sufficiency Lowers All-Cause Mortality and Risk of Diabetes

The Health and Medicine Division of the National Academies of Sciences, Engineering and Medicine (formerly IOM) has also reported an association between vitamin D and overall mortality risk from all causes, including cancer.17,18 Additional studies can be found on GrassrootHealth’s vitamin D*Action breast cancer page,19 where you can also enroll in the D Action Breast Cancer Prevention Project which includes both vitamin D and omega-3 testing.

GrassrootsHealth D*Action + Omega-3 Project is the largest project in the world that allows scientific researchers to study the links between these nutrients. Participating in the project is an inexpensive way to take control of your health while simultaneously helping to advance nutritional science.

Considering vitamin D is required for healthy genetic expression, and vitamin D receptors are found throughout your body, cancer is not the only disease risk that can be directly impacted by your vitamin D status. For example, an analysis20 by GrassrootsHealth reveals people with a median vitamin D level of 41 ng/mL have a diabetes rate of 3.7 per 1,000. Contrast that to those with a median serum level of just 22 ng/mL, among whom the diabetes rate was 9.3 per 1,000.

In other words, vitamin D sufficiency may lower your risk of Type 2 diabetes by as much as 60 percent, even after taking confounding factors such as age, gender, race and bodyweight into account. Abdominal obesity in combination with low vitamin D may also “synergistically influence” your risk of insulin resistance.  According to this study, 47 percent of the increased odds of insulin resistance can be explained by the interaction between insufficient vitamin D levels and a high body mass index.

The Importance of Vitamin D During Pregnancy

Maintaining vitamin D sufficiency is particularly important during pregnancy, since it’s not just your own health that is at stake but that of your child as well.22 Protect Our Children NOW! is a GrassrootsHealth campaign launched in 2015 to combat vitamin D deficiency among pregnant women worldwide.

Research conducted through this project reveals up to 59 percent of preterm births — which are responsible for 28 percent of newborn deaths during the first month of life — could be prevented simply by raising pregnant women’s vitamin D to a level of 40 ng/mL.

As of 2015, the U.S. had a preterm birth rate of 9.6 percent, meaning nearly 1 in 10 babies were born prematurely. The U.S., while one of the most advanced countries in the world, ranked No. 130 in preterm births out of 184 countries in 2010.

Protect our Children NOW! is a cost-effective, reproducible program that protects children by ensuring pregnant mothers are vitamin D sufficient, and could go a long way toward improving these abysmal statistics. Among non-Caucasian women (among whom vitamin D deficiency is more common and prominent) the reduction in risk was even greater.

In this group, the preterm rate prior to the start of the study was 18 percent. Those who achieved a vitamin D level of 40 ng/mL by their second test had a 78 percent lower preterm birth rate — reducing the preterm birth rate to just 4 percent!

To learn more visit Dr. Glen Matejka’s website: