Why You Need More Vitamin D in Winter

The short, dark days of Winter are here, so it's even more important to make sure you are getting enough vitamin D. Dietitian Julie Upton, MS, RD, of Appetite For Health explains why.

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The cold, dark days of Winter may be a real threat on your health, thanks to the precipitous drop of vitamin D, aka the "sunshine vitamin," during this time of year.

Seasonal variations in vitamin D status are well documented: a recent University of California-Irvine and Mayo Clinic study with 3.44 million blood samples of Americans found that serum vitamin D levels are highest in August after several months of exposure to sunshine and lowest in February due to dwindling daylight. In fact, a national survey of US women reported that 42 percent are considered vitamin D deficient.

While vitamin D is essential to absorb calcium for bone health, the sunshine vitamin's benefits extend well beyond your bones. Vitamin D is essential for the immune system and improves insulin sensitivity, mood, and muscular strength. It's also thought to help in reducing belly fat and protects against autoimmune diseases like type 1 diabetes, rheumatoid arthritis, and multiple sclerosis. Some studies even suggest low vitamin D may up risk for several types of cancer (including breast) and dementia.

How Much Vitamin D Is Enough?

The Institute of Medicine recommends 600 IU per day for adults, but many other experts believe that 1,000-2,000 IU is optimal. Try incorporating natural sources of vitamin D and vitamin-D-enriched foods into your diet to get at least 600 IU per day. A supplement of vitamin D2 or D3 can also help ensure that you're getting enough.

Vitamin-D-Rich Foods

Vitamin D is notoriously hard to get because only a few foods naturally contain it. Cod liver oil, fatty fish, egg yolks, liver, and mushrooms are the few foods that naturally contain significant amounts of vitamin D, but you can also find foods and beverages fortified with it, like milk and nondairy beverages. Use the list below to boost vitamin D in your diet.

Other Foods With Vitamin D

  • 1 tablesoon cod liver oil: 1,360 IU
  • 3 ounces wild Alaskan Sockeye (red) salmon (all salmon contains vitamin D, but wild Alaskan is highest and is also sustainable): 930 IU
  • 3 ounces canned Alaska Sockeye (red) salmon: 790 IU
  • 1 large fortified egg: 120 IU
  • 1 cup fortified soymilk, 120 IU
  • 1 cup fortified milk, 100 IU
  • 6 ounces yogurt (varies by brand; many contain no vitamin D): 40-100 IU
  • 1 cup fortified orange juice (varies by brand): 100-130 IU
  • 1 tablespoon Country Crock With Calcium & Vitamin D: 80 IU
  • 1 large egg yolk: 40 IU
  • 1 ounce swiss cheese: 12 IU

Values from USDA Nutrient Database and manufacturers' websites.