Winter can be taxing on our mental and physical strength: it’s a season that persistently tests our limits of surviving darkness and cold, biting winds. But one way to assist in boosting your immune system as well as fighting your seasonal affective disorder during the months of flu, darkness, and general down-trodden spirits, is to make sure your Vitamin D levels are up to par.

Vitamin D, known as the “sunshine vitamin,” is essential to maintaining our health and immune systems, and our main source is from the sun. Studies have shown that vitamin D deficiencies can lead to a slew of health problems and contribute to chronic disorders, including osteoporosis, depression, obesity, diabetes, and hypertension. So if you want to maintain your Vitamin D levels, especially if you’re living in the Northeast during the winter months, read about the various ways you can do so below.

A Tiny Bit Of Sunlight

In the winter time, people typically hibernate indoors; not to mention there’s barely enough sunshine during the day, and by the time you leave work it’s already dark out. So how is it possible to snatch some of those important rays in the winter, especially when the sun isn’t as strong and it’s freezing outside?

The fact is, you won’t be able to get as much Vitamin D from the sun between the months of November and March. But spending even small snippets of time outside when the sky does clear up and the sun shines through is better than nothing. In addition, planning vacations or short trips to Southern states or warmer areas can provide you with much-needed Vitamin D boosts, at least temporarily. If you can’t swing that, then it might be time to turn to artificial lighting, tanning booths (in moderation), or most importantly, diet.

Vitamin D-Fortified Diet

Certain foods are fortified with Vitamin D, including milk, cereal, yogurt, and orange juice. Vitamin D doesn’t often occur naturally in many foods, but it does in eggs and oily fish like salmon, tuna, and mackerel — so pack your diet with these fatty fish. A 3-ounce fillet of sockeye salmon contains about 450 international units (IUs) of vitamin D, which is a large chunk of the daily recommended 600 IUs (the maximum is 4,000 IUs, since overdosing on Vitamin D can actually be bad for you). Other foods with Vitamin D include soy milk, beef liver, cheese, certain mushrooms, and egg yolks. Of course, it’s not essential to eat these same foods every day; but if you can find ways to incorporate them into your diet more often during the winter months, you’ll be naturally boosting your Vitamin D levels without having to buy expensive (and sometimes useless) supplements.

Basking Under Vitamin D Lamps

You should avoid tanning beds if you can, since they are associated with a higher risk for skin cancer and exposure to dangerous UV rays. But tanning beds are one way to provide you with some extra vitamin D during winter months.

For the artificial light without the melanoma risk, turn instead to special Vitamin D lamps. The only FDA-approved Vitamin D lamp is known as the Sperti, which reportedly boosts your vitamin D levels within 1-5 minute sessions several times per week. The Sperti is quite expensive ($425), but it certainly eliminates the need to go out of your way to find sunshine in a far-off place.

Supplements

If all else fails, you can complement your Vitamin D routine with some supplements — especially if you’re older, living in the Northern hemisphere, or have had a history of being Vitamin D-deficient. But since the efficacy of many types of Vitamin D supplements is still debated — and several studies have claimed they don’t do anything — it’s better to trust the sources of sun and food instead. And soon enough, summer will arrive and you can go back to your 15 minutes of daily sun-tanning to get your needed Vitamin D fix.