Vitamin D is important not only to bone health, but also possibly to cardiovascular health and prevention of obesity and diabetes. Overweight people, and dark-skinned people living in the North are prone to having low vitamin D levels.
New research shows that losing weight (diet and exercise) boosts women’s level of vitamin D, even if they don’t take a supplement. This may be a virtuous cycle – weight loss increases vitamin D, which may help to reduce fat accumulation…
I take 5000 U a day of vitamin D. I do not recommend taking that dose of vitamin D without checking with your doctor and gettings blood levels measured.
Good food sources of vitamin D? From the Federal government’s Office of Dietary Supplements (ODS):
Table 3: Selected Food Sources of Vitamin D  Food IUs per serving* Percent DV** Cod liver oil, 1 tablespoon 1,360 340 Salmon (sockeye), cooked, 3 ounces 447 112 Mackerel, cooked, 3 ounces 388 97 Tuna fish, canned in water, drained, 3 ounces 154 39 Milk, nonfat, reduced fat, and whole, vitamin D-fortified, 1 cup 115-124 29-31 Orange juice fortified with vitamin D, 1 cup (check product labels, as amount of added vitamin D varies) 100 25 Yogurt, fortified with 20% of the DV for vitamin D, 6 ounces (more heavily fortified yogurts provide more of the DV) 80 20 Margarine, fortified, 1 tablespoon 60 15 Liver, beef, cooked, 3.5 ounces 49 12 Sardines, canned in oil, drained, 2 sardines 46 12 Egg, 1 large (vitamin D is found in yolk) 41 10 Ready-to-eat cereal, fortified with 10% of the DV for vitamin D, 0.75-1 cup (more heavily fortified cereals might provide more of the DV) 40 10 Cheese, Swiss, 1 ounce 6 2
* IUs = International Units.
Note how good fish is in this regard! I take fish oil every day. I also eat a lot of canned tuna, salmon, sardines, and mackerel.
Sun exposure is crucial, too, for making vitamin D (though not too much for light-skinned people).