Combating the Winter Blues this Winter? Start With Vitamin D

If you’re susceptible to mood changes in the winter, this one’s for you.

The winter blues, seasonal depression, or seasonal affective disorder (SADs): Whatever you want to call it, it’s a real thing that affects more of us than you might realize. It can make us feel low-energy, sad, lethargic and unmotivated to leave the house, let alone to train hard at the gym.

While it depends on the source, a 2011 study (1) suggests 41.6 percent of the US population is deficient in Vitamin D, with even higher rates found among minority groups. Other research (2) has pegged this number as high as 75 percent. Meanwhile, those of us who carry a gene called 5-HTTLPR (3) are even more predisposed to SAD, as this gene helps regulate how serotonin gets removed from the brain. 

Editor’s note: The content on BarBend is meant to be informative in nature, but it shouldn’t take the place of advice and/or supervision from a medical professional. The opinions and articles on this site are not intended for use as diagnosis, prevention, and/or treatment of health problems. Speak with your physician if you have any concerns or feel you may be suffering from any disorder. 

A Quick Serotonin 101 

Often called the happiness neurotransmitter, serotonin is at the heart of the SAD matter. Low serotonin levels are linked to low energy, low mood, low sex drive, anxiety and depression, including the winter blues.

It is believed that one of the biggest contributors to healthy serotonin levels is a good dose of Vitamin D, which you get from the sun. More specifically, sunlight helps your body produce Vitamin D3 out of the cholesterol in your skin. Then, Vitamin D converts the amino acid tryptophan into serotonin.

Secondly, sunlight reduces the amount of serotonin that gets removed from the brain. This means when you’re not getting enough sunlight—most commonly during the long autumn and winter months in many places of the world—serotonin levels can start to decline.  

Luckily, there are a handful of measures you can take to give you the best chance of staying happy this winter. Of course, if you are experiencing strong symptoms of a mood disorder, it’s highly recommended you first speak with your individual medical professional. 


1. Vitamin D

Vitamin D deficiency can lead to other symptoms beyond just feeling low in the winter, including muscle weakness and bone loss. 

It’s hard to figure out exactly how much Vitamin D you should be taking, as different sources recommend different amounts. That being said, at least 600 IUs seems to be a relatively agreed upon minimum amount. 

The Dieticians of Canada (4) for example, suggests both men and women consume between 600 and 4,000 IUs of Vitamin D per day. The Endocrine Society (5) recommends adults take between 1,500 and 2,000 IUs a day and the Mayo Clinic (5) suggests at least 600 IUs.

What does this look like in practice?

Some food sources high in Vitamin D include:

  • Cod liver oil: 100 grams has 10,000 IUs of Vitamin D
  • Salmon: 100 grams has 526 IUs of Vitamin D
  • Mackerel: 100 grams has 1,006 IUs of Vitamin D
  • Trout: 100 grams has 635 IUs of Vitamin D
  • Egg yolks: 100 grams has 218 IUs of Vitamin D

In light of the above, if you’re not a meat eater or a seafood lover, a Vitamin D supplement is often recommended, but talk to your doctor before changing up your supplement routine.

2. Light Therapy

Though the evidence is weaker for this one than for Vitamin D, there’s some who believe half-an-hour of light therapy (6)—also known as bright light therapy or phototherapy—can help boost mood and energy levels. 

It can be as simple as buying your own light therapy box (7), which exposes you to artificial light and tricks your body into thinking it’s getting sun. Before you considering purchasing a light therapy box, however, it’s best to consult your doctor or health professional.   

3. Fish Oil

Other research (8) suggests Omega-3 deficiencies can lead to SAD and other forms of depression. 

The thinking stems from the fact that Omega-3 fatty acids help serotonin get through cell membranes more efficiently. One of the best ways to get plenty of Omega-3s is through a fish oil supplement, especially if you don’t eat a lot of fish in your diet.

4. B Vitamins

Vitamin B6 and Vitamin B12 have also been linked to lower symptoms of depression, (9) especially in older adults, while Vitamin B6 helps support the production of serotonin in the brain. Foods high in B Vitamins include dark, leafy green vegetables, such as broccoli and spinach, nuts and seeds, such as sunflower seeds and almonds, we well as red meat, poultry, fish and eggs. 

5. Sun vacation

While not realistic for everyone, it might be worth considering booking a vacation in a reliably sunny and hot location in mid to late-January. 

At the very least, commit to buying the right warm clothes and accessories to handle the elements this season, so you can continue to get outside for hikes or walks even in the cold, the snow or the rain.

Bottom line: Don’t hibernate this season. At the very least, prioritize seeing some sun and consuming ample Vitamin D.


1. Forrest KY, Stuhldreher WL. Prevalence and correlates of vitamin D deficiency in US adults. Nutrition Research. 2011.
2. Jordan Life. Vitamin D deficiency soars in the U.S., study says. Scientific American. 2009.
3. Noreen Goldman, Dana A. Glei, Yu-Hsuan Lin, Maxine Weinstein. The Serotonin Transporter Polymorphism (5-HTTLPR): Allelic Variation and Links with Depressive Symptoms. Depress Anxiety. 2010.
4. Food Sources of Vitamin D. Dieticians of Canada. 2017.
5. Liza Torborg. Mayo Clinic Q and A: How much vitamin D do I need? Mayo Clinic. 2017.
6. Light Therapy. Mayo Clinic. 2017.
7. Seasonal affective disorder treatment: Choosing a light therapy box. Mayo Clinic. 2016.
8. Alan C Logan. Omega-3 fatty acids and major depression: A primer for the mental health professional. Lipids in Health and Disease. 2004.
9. Kimberly A Skarupski, Christine Tangney, Hong Li, Bichun Ouyang, Denis A Evans, Martha Clare Morris. Longitudinal association of vitamin B-6, folate, and vitamin B-12 with depressive symptoms among older adults over time. The American Journal of Clinical Nutrition. 2010.