(NewsDakota.com/NDSU) – The other day the sun was shining brightly as I peered out the window before choosing my outerwear. I grabbed my lighter winter coat. I was expecting the temperature to be slightly warmer than the previous day.

The temperature was not warm by any stretch of the imagination. It was colder.

I went back inside and changed into my full-length coat, added a hat and scarf, and I changed from gloves to warm mittens.

In warmer weather, when our skin is exposed to sunlight, our bodies can generate vitamin D.

Vitamin D is called the “sunshine vitamin” for this reason.

However, in cold climates, we cover ourselves. Only our eyes may be peeking out. Sunglasses on sunny days are a good addition to protect our eyes too.

Like many, I do the “penguin hustle” as I waddle quickly over icy paths to my vehicle or indoor destination. I am barely exposed to sun at all, much less getting 10 to 30 minutes of midday sun on my skin to make vitamin D.

Unfortunately, some medical experts believe that as many as half of us are deficient in vitamin D. People with darker skin may have more difficulty making vitamin D because the natural pigment, melanin, can block the action of sun.

Older adults, infants who are exclusively breastfed, obese individuals and those who have undergone gastric bypass surgery also are at greater risk for low vitamin D levels.

You probably have noticed Vitamin D on cartons of milk. Vitamin D was first added to milk as a public health measure in the 1930s. Vitamin D acts with calcium (found naturally in milk) and other nutrients to help build and maintain strong bones and teeth.

If we lack sufficient vitamin D and calcium throughout our lives, we can face debilitating conditions. Children may face rickets leading to bowed legs and other malformations. Adults can face osteomalacia (softening of bones) or osteoporosis (“porous bones” that break easily).

The functions of vitamin D extend far beyond bones and teeth, though. It plays a role reducing inflammation and helping with our immune function. During the COVID pandemic, many people with the most severe outcomes were deficient in vitamin D according to some research.

Having adequate vitamin D may be protective against heart disease, certain types of cancer and diabetes according to some studies. However, the results are not always conclusive.

Many medical experts recommend that we take a vitamin D supplement, especially during the winter. Visit with your medical care provider for their recommendations for you.

Laboratory tests can determine the quantity of vitamin D in your blood.

The Recommended Dietary Allowance for vitamin D is 600 International Units (IU) for people from ages 1 to 70, but healthcare providers may prescribe a higher dose.

Vitamin D is found in some foods, including fortified milk and cereal. “Fortification” means the nutrient is added to the food because it was not present in the first place.

You may have heard stories of children getting a spoonful of cod liver oil in earlier generations. One tablespoon of cod liver oil provides 1,360 IU. Having a spoonful of fish oil, however, may have been perceived as a punishment.

The latest version of Nutrition Facts labels now provides an up-to-date “percent daily value” for vitamin D. You may notice that many foods contain no vitamin D.

Fatty fish is a notable vitamin D source. Salmon has 570 IU per 3 ounces. Milk has about 120 IU per cup, and eggs provide 44 IU per egg.

Although it is not my role to “prescribe” vitamins, I will say that my family members and I take a vitamin D-3 supplement throughout the cold, gray months. Some one-tablet-a-day supplements include 100% of the daily recommendation for vitamin D. Staying within 100% of the daily recommendation is considered safe for dietary supplements, even when consuming food sources.

If you choose to take a supplement, visit with your healthcare provider because vitamin D may interact with some medication. Read the information on the medication information provided by pharmacies.

More isn’t “better” with vitamin D supplements, or supplements in general. The “Upper Tolerable Intake Level” is set at 4,000 IU for vitamin D.