Before reading on I encourage you to watch the video from UCSan Diego Medical School:
and then visit this great resource:
First, I should let you know about the “nerdy” science information:
Vitamin D is a fat-soluble vitamin that is naturally present in very few foods, added to others, and available as a dietary supplement. It is also produced endogenously when ultraviolet rays from sunlight strike the skin and trigger vitamin D synthesis. Vitamin D obtained from sun exposure, food, and supplements is biologically inert and must undergo two hydroxylations in the body for activation. The first occurs in the liver and converts vitamin D to 25-hydroxyvitamin D [25(OH)D], also known as calcidiol. The second occurs primarily in the kidney and forms the physiologically active 1,25-dihydroxyvitamin D [1,25(OH)2D], also known as calcitriol .
So, with all the heavy science out of the way the important thing to know is vitamin D is essential to ensure calcium absorption in the gut to maintain adequate blood calcium levels and enable normal mineralization of bone. In addition to bone health current research has implicated vitamin D deficiency as a major factor in the pathology of at least 17 varieties of cancer as well as heart disease, stroke, hypertension, autoimmune diseases, diabetes, depression, chronic pain, osteoarthritis, osteoporosis, muscle weakness, muscle wasting, birth defects, periodontal disease, and more . Lastly with the flu season upon us, R Edgar Hope Simpson, who became famous in the late 1960s after he discovered the cause of shingles, proposed that a principal cause of seasonal influenza is linked with the deficiency of solar radiation which triggers the production of vitamin D in the skin . The vitamin D promotes the immune response to fight of the flu.
Now you know the importance of vitamin D the next phase is where to get it and how much to take. Adequate Intake levels have been established by the U.S. Institute of Medicine of the National Academy of Sciences. Recommendations are: 5 micrograms (200 IU or International Units) daily for all individuals (males, female, pregnant/lactating women) under the age of 50 years-old. For all individuals from 50-70 years-old, 10 micrograms daily (400 IU) is recommended. For those who are over 70 years-old, 15 micrograms daily (600 IU) is suggested. Some authors have questioned whether the current recommended adequate levels are sufficient to meet physiological needs, particularly for individuals deprived of regular sun exposure. The upper limit for vitamin D has been recommended as 2,000 IU daily due to toxicities that can occur when taken in higher doses . However the skin produces approximately 10,000 IU vitamin D in response 20–30 minutes summer sun exposure—50 times more than the US government’s recommendation of 200 IU per day!
Below I have a list of the most Vitamin D rich foods provided by the National Institute for Health (NIH). The most important thing I want to point out is where milk lands in the list. In a future blog I will be detailing the many misconceptions about Milk and why it is not as healthy as you may have been taught. As with calcium, though high in Vit. D, it is not the best source for Vit. D and calcium. Look for that in future posts and feel free to call or email with any questions. Thanks again for reading and take care.
Food IUs per serving* Percent Daily Value**
Cod liver oil, 1 tablespoon
Mushrooms, enriched with vitamin D, 3 ounces
Salmon, cooked, 3.5 ounces
Mackerel, cooked, 3.5 ounces
Sardines, canned in oil, drained, 1.75 ounces
Tuna fish, canned in oil, 3 ounces
Orange juice fortified with vitamin D, 1 cup (check product labels, as amount of added vitamin D varies)
Milk, nonfat, reduced fat, and whole, vitamin D-fortified, 1 cup
Yogurt, fortified with 20% of the DV for vitamin D, 6 ounces (more heavily fortified yogurts provide more of the DV)
Margarine, fortified, 1 tablespoon
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)
Egg, 1 whole (vitamin D is found in yolk)
Liver, beef, cooked, 3.5 ounces