One of the best and most available sources of vitamin D is the sun, this is true. Vitamin D is also available in many fortified foods, such as milk and dairy products, and it occurs naturally in foods like egg yolks, salmon, tuna, tofu, and oats, just to name a few.
Being careful of sun exposure is a smart way to reduce the risk of skin cancer. However, some sunshine, in moderation, can be helpful. Studies have shown that a baby who goes into the sun wearing just a diaper only needs 30 minutes of sun exposure per week to get enough of the vitamin, while a fully clothed child, without a hat, only needs 2 hours in the whole week.
Children under 1 year old should have 400 IU (international units) of vitamin D per day. Children older than 1 and adults under 50 should have 200 IU per day, adults over 50 should have 400 IU per day, and those over 70 years should have 600 IU per day. A 75 g serving of cooked or canned salmon provides 608 IU of vitamin D, while 3/4 cup of yogurt with fruit provides 233 IU.