Vitamin D: Are you getting enough of this key nutrient?
Known as the sunshine vitamin, vitamin D is actually a hormone produced by the body in response to sunlight. It is also occurs naturally in a few foods-including some fish, fish liver oils, and egg yolks-and in fortified dairy and grain products.
It’s hard, though, to get enough vitamin D through food alone-unless you want to take a tablespoon of cod liver oil every day (it has 1,360 IU of D per tablespoon)! Ummm…no thanks!
But, according to The Mayo Clinic, the major biologic function of vitamin D is to maintain normal blood levels of calcium and phosphorus. Vitamin D aids in the absorption of calcium, helping to form and maintain strong bones-why getting enough calcium is only half of the strong bones equation. But preliminary research also indicates the importance of vitamin D for overall health and wellbeing:
1) It contributes to a healthy heart A recent analysis of research, published in the journal Osteoporosis International, found that there’s a link between low vitamin D levels and “stroke, myocardial infarction, diabetes mellitus, hypertension, and heart failure.” Enough reason for me to supplement with D…but if you need more proof, read on.
2) It may lower your risk of cancer Research suggests that vitamin D has an anti-cancer benefit. It may stop the growth and progression of cancer cells and may be beneficial during cancer treatment, too. One study, from the University of San Diego School of Medicine, has also found that higher blood levels of vitamin D are associated with an overall reduced risk of cancer.
3) It plays a critical role in youthful skin One study in the journal Dermo-Endocrinology found that vitamin D seems to help regulate aging in many tissues, including the skin. Plus, researchers determined that “laboratory investigations have now convincingly shown that vitamin D compounds protect the skin against the hazardous effects of … ultraviolet (UV) radiation.”
4) It may help with hormonal problems Vitamin D influences the functions of hormones in body, including insulin, serotonin, and estrogen-hormones involved with health conditions such as diabetes, blood pressure, heart disease, stroke, depression, and premenstrual syndrome.
5) It’s key for healthy iron levels in the blood One study-conducted by Gangnam Severance Hospital and Yonsei University College of Medicine, both in Seoul, Korea-found that vitamin-D-deficient Korean women had a higher risk of anemia.
6) A deficiency of D may contribute to obesity Some research shows that a vitamin D deficiency can interfere with the “fullness” hormone leptin, which signals the brain that you’re full and should stop eating.
7) It may help control inflammation Vitamin D may help control the inflammation involved with periodontal disease, rheumatoid arthritis, and osteoarthritis.
Also, some research suggests that vitamin D may help strengthen the immune system-why I’m sure to take vitamin D during the cold and flu season or when I feel that I might be coming down with something. It’s also critical for breastfeeding moms: A recent review of studies, published in the Journal of Human Lactation, found that “Maternal vitamin D insufficiency during lactation, related to lack of sun exposure and minimal intake of vitamin D from the diet, contributes to low breast milk vitamin D content and, therefore, infant vitamin D deficiency.”
How do you get enough vitamin D?
Well, being in sunlight is the best way to get enough vitamin D. The sun’s energy turns a chemical in your skin into vitamin D3, which is carried to your liver and then to your kidneys to transform it to active vitamin D. But no one should sit unprotected in the sun because doing so speeds up premature aging of the skin and can cause skin cancer.
The next best option is to eat plenty of foods with vitamin D, including mushrooms, salmon, eggs, and fortified milk. But most experts agree that it’s hard to get enough D from food alone. (For adults under age 50, the U.S. National Osteoporosis Foundation [NOF] recommends 400 to 800 IU of vitamin D and 800 to 1,000 IU for adults age 50 and older. And for children, it’s generally recommended that infants and children get 400 to 600 IU daily.)
So the next step is usually to take a supplement. Most multivitamins contain vitamin D-but you can also take a separate D supplement particularly if you’re deficient, as I am (in which case, your doctor may recommend you take a much higher dosage of D than what’s recommended by the NOF to bring up your levels). But this is key: Opt for vitamin D3 over D2, because research shows that D3 is 87 percent more potent in raising and maintaining vitamin D concentrations. (If you’re vegan, though, know that most vitamin D3 or cholecalciferol comes from animal sources, but vitamin D2 or ergocalciferol comes from plant sources.)
An important note: you can take vitamin D supplements with or without food. While your body needs vitamin D to absorb calcium, you do not need to take vitamin D at the same time as a calcium supplement.