The days are getting shorter now, and many of us who go to work early and come home late will feel like we never see the light of day. And besides zapping our energy, lack of sunlight in the winter months can leave us lacking in essential vitamin D—which may add up to poor health and weak bones, in everyone from infants and children to the elderly.

Studies suggest that about half of us (and 40% of young kids) have insufficient levels of vitamin D, otherwise known as the sunshine vitamin. Low vitamin D stems from less sun exposure, use of sunscreens, and low dietary intake of the vitamin. Not only does low vitamin D put children at risk for bone disease like rickets, but it increases our risk for heart disease; breast, colon, and prostate cancers; metabolic syndrome; osteoporosis; depression; fractures; and falls, just to name a few.

But the solution isn't to bake ourselves in the sun—which, even if possible in the wintertime, has dangerous risks of its own. Vitamin D is also available through food and supplements; in fact, new guidelines released by the American Academy of Pediatrics this week suggest that infants and children should get double the current recommended dietary intake for vitamin D.

What the numbers mean
The recommendations suggest that from birth, children need 400 IU vitamin D daily, which is equivalent to four 8-ounce glasses of milk or one teaspoon of cod liver oil. For adults, national guidelines still say that anyone ages 31 to 50 should get 200 IU a day, those 51 to 70 should get 400, and those older than 70 should get 600—but as the benefits of vitamin D keep multiplying, many experts have called for these numbers to increase, as well.

I'm lucky enough to live in California, where I can get 15 minutes a day of sunshine on my arms and legs pretty much year-round (that's enough to make sufficient vitamin D for a light-skinned person like me). But I grew up in Michigan—which I'm convinced is the grayest state in the U.S. during the winter—and spent most of my life in the northeast, where sunshine will be lacking during the long, cold months ahead. This is where the problem starts for many D-deficient Americans.

Next page: Dining for D? Where to get the most

Since not everyone can live in the Sunbelt, focus on getting more vitamin D in your diet during the dark months. If you live where the sun doesn't shine, use the food chart below to help guide your D options. If you still don't think you get enough D in your diet, choose a vitamin mineral supplement that contains calcium plus vitamin D.

Dining for D? Here's where to get the most
Fish and fish oils are the richest sources of vitamin D, but milk is also fortified with vitamin D, as are breakfast cereals, 100% juices with calcium, and a few other foods. The chart below lists the vitamin D in several common foods and beverages.

Food
Amount vitamin D

Cod liver oil, 1 tbs. 1,360 IU
Pacific oysters, 3.5 oz. 640 IU
Most fish, 3.5 oz. 88 IU
Vitamin D fortified milk, 1 cup 100 IU
Tropicana Calcium + Vitamin D, 1 cup 100 IU
Total Cereal, 1-1/4 cup 40 IU
1 egg, cooked 26 IU
Beef, 3.5 oz. 7 IU
Yogurt, 1 cup 4 IU
Cheddar cheese, 1 oz. 4 IU

Source: Nutrients in Food by Elizabeth S. Hand

(PHOTO: ISTOCKPHOTO)