What is the best natural source apart from sunshine to help keep the vitamin d levels up?

Fortified foods. The flesh of fatty fish (such as salmon, tuna, and mackerel) and fish liver oils are among the best sources. Small amounts of vitamin d are found in beef liver, cheese, and egg yolks. Some mushrooms provide vitamin d2 in variable amounts. Ready-to-eat breakfast cereals often contain added vitamin d, as do some brands of orange juice, yogurt, margarine and other food products.
Fish. Fatty fishes (tuna, mackerel, catfish, salmon) are one source. Eggs have some; beef liver has a little. Cod liver oil has a lot. After that, you're looking at fortified dairy products or cereals that have vitamin d added to them, or vitamin d supplements or multi-vitamins.

Related Questions

What is the best natural source apart from sunshine to help keep vitamin d levels up?

Meat protein. Vitamin d is really a hormone and as you say, we were designed to live under the sun. It is poorly absorbed by mouth but the best way to keep it up is with a supplement of vitamin d3. Ask your doc re dose.

What's the best type of dr to see for a vitamin d deficiency, my pcp is an internal medicine doc & wont really do much about my blood level of 11?

Endocrinologist. Of the sub specialists, endocrinologists are the experts for vit d, however, there is much new literature re vit d deficiency and the importance of aggressive treatment. You may consider a 2 md opinion with a board certified internist, who can also help you with this problem.
Vitamin d deficiency. Most internists will treat vitamin d deficiency. Maybe it's time for a change?

Apart lack of sunlight, what causes low vitamin d levels?

Insufficient intake. There are two ways to get vitamin d. Your body makes it when you are exposed to the sun, or you can take it in your diet. Vitamin d tends to be found in fish (usually cold water) and eggs. There's some in fortified milk, but not enough. Over all, it's pretty hard to get enough from your diet unless you eat huge amounts of certain fish or take a supplement, so I recommend supplements.
Hypovitaminosis D. Vitamin d deficiency can be caused by inadequate intake, inadequate sunlight, impaired absorption, and impaired conversion to the active form by the body. Within each of these categories there can be many causes.

What causes low vitamin d levels apart from a lack of sunlight?

Vitamin D. Usually this is genetically related. Theoretically sunshine will increase vitamin d levels but a study in hawaii showed that 50% of people with 20 hours of sunshine a week still had low vitamin d levels. You can supplement with over-the-counter vitamin d safely.