How Two Common Supplements May Help Tackle Seasonal Mood Changes (2024)

As winter approaches, it means shorter days and a dwindling amount of sunlight. This seasonal change can bring on symptoms of seasonal affective disorder (SAD), which affects about one in 20 Americans.

SAD is a form of depression—with symptoms that can affect daily functioning—and is prompted by shorter daylight hours during the winter.It’s different from the “winter blues,” where cold weather and little sunlight can bring on feelings of sadness or decreased interest in activities.

Some social media influencers claim that you can counteract these symptoms with a combination of vitamin D3 and vitamin K2 supplements.

“You need to buy vitamin D before seasonal depression hits, before the sun goes away for months on end,” said TikTok user Cirena Wilson. “And make sure you get the one with K2.”

SAD symptoms often overlap with those of depression. Common signs include persistent feelings of sadness or depression, a loss of interest in activities you once enjoyed, and excessive sleeping.

SAD is believed to be triggered by shorter daylight hours, which can affect your “internal clock.”These changes to your circadian rhythm can affect melatonin and serotonin levels, which can lead to classic symptoms of depression.

Can Vitamin D and Vitamin K Help With Seasonal Depression?

Vitamin D and vitamin K are key nutrients that everyone needs to stay healthy.But is there evidence that vitamin D and vitamin K can actually help with symptoms of SAD?

A recent study published in Nutrients examined whether vitamin D can help alleviate symptoms of SAD. While the findings were inconclusive, the authors suggested that vitamin D deficiency, specifically, may increase the risk of developing SAD.

“Vitamin D is involved in the pathways of production of melatonin and is believed to play a key role in serotonin activity, which further links serotonin, melatonin, and light exposure, but mainly deficiency of vitamin D and SAD,” the study authors wrote.

Certain health organizations, including the U.K.’s National Health Service and the U.S. National Institute of Mental Health, do list vitamin D as a treatment option for people with SAD but don’t mention the addition of vitamin K.

There has been some evidence that vitamin D may help people living very far north where there is little sun exposure in the winter, said Maya Vadiveloo, PhD, RD, FAHA, an associate professor of nutrition at the University of Rhode Island College of Health Sciences. But generally, the research doesn’t support vitamin D supplements for SAD.

“Broadly, I think that while there isn’t a strong evidence base to support dietary supplementation for prevention/treatment of SAD, there is good support to adhere to diets rich in fruits and vegetables, whole grains, nuts, seeds, legumes, and heart-healthy oils while limiting less healthy foods high in added sugars, salt, and saturated fats,” Vadiveloo said.

Also, the studies that have shown positive results with vitamin D supplements and SAD aren’t very strong, Taylor Wallace, PhD, CFS, an adjunct associate professor at the Friedman School of Nutrition Science and Policy at Tufts University said.

“There are some studies [and small clinical trials] that show vitamin D may affect mood in this regard,” Wallace said. “But they are mostly observational and the effects haven’t held true in larger clinical trials.”

It’s not clear that vitamin K would be beneficial in helping boost vitamin D in terms of stopping SAD symptoms, said Wallace, and cautioned that people should be careful not to take too much of either vitamin D or K. Instead, Wallace recommended most people stick with a daily multivitamin.

What Are Other Treatments for SAD?

If you’re looking for proven treatments for SAD, the good news is there are several that work. You can try light therapy, where you sit in front of a special light box that filters out harmful UV. Most people only need about 20 minutes a day to see results.

You can also speak with a mental health professional or consider selective serotonin reuptake inhibitors (SSRIs), a type of antidepressant medication that helps with SAD symptoms.

Also, eating a nutrient-dense diet and making an effort to go outside more to soak up sunlight can make a big difference in your overall mood.