During this dark, dreary winter season, we think there’s no better time to provide you with an important update on the “sunshine vitamin.” If you pay attention to medical news, media stories, infomercials, and advertisements, then you know that vitamin D supplementation is commonly promoted for a variety of health-related issues. Several of these touted claims you may have heard include:
- Cancer prevention (e.g. colon cancer, breast cancer, prostate cancer)
- Improvement of physical performance
- Prevention of heart disease
- Treatment of diabetes
- Boosting of immune response in tuberculosis and influenza
- Prevention of autoimmune diseases (e.g. multiple sclerosis, rheumatoid arthritis)
- Improvement of neuropsychological functioning in disorders from autism to Alzheimer’s
- Decreased risk for preeclampsia and pregnancy-induced hypertension
- Bone health
On November 30, 2010 the Institute of Medicine (IOM) released a report that abruptly put the brakes on the widespread supplementation of this essential vitamin for most of the claimed health benefits.
This 1000-page document concluded that, with the exception of vitamin D’s positive benefits on bone health, the other claims “…could not be causally linked reliably or consistently, with relevant outcomes as a function of calcium and vitamin D intake.” In other words, you may be wasting your money and putting yourself at risk in hopes of curing or preventing the myriad of ailments we have outlined above.
After reading the report, we took special interest due to the warnings about the potential of vitamin D toxicity from chronic over-supplementation. Vitamins A, D, E, and K are the “fat-soluble” vitamins, and are stored for longer periods of time in body tissues as compared to other “water-soluble” vitamins such as the B-complex and C vitamins. If you take excessive amounts of vitamin D, typically in the form of vitamin D3 (cholecalciferol), your blood calcium can possibly rise to dangerous levels. If left unchecked, this rise in calcium can lead to organ damage, especially to the heart and kidneys, causing irregular heartbeats and even death.
If you don’t think that vitamin D is potentially hazardous, take a look at our blog entitled Ways to Deal with Unwelcome Fall House Guests which describes cholecalciferol as a USEPA registered rat and mouse poison. Yikes!
In addition to its negative effects on the heart and kidneys, some signs and symptoms associated with vitamin D poisoning include:
- Nervous system: headache, fatigue, weakness, confusion
- Gastrointestinal: loss of appetite, nausea, constipation or diarrhea
So how much vitamin D is necessary for good health? And how much is too much? Unfortunately, vitamin D is found naturally only in very few foods – fatty fish (e.g. salmon, tuna), mushrooms, egg yolks, and cheese. But if your family is as finicky as some of ours, many of these foods are not regularly served at the kitchen table – so, in some cases dietary supplementation with vitamin D products may make sense for you and your family.
Other good sources of dietary vitamin D are dairy products, such as milk and milk substitutes (e.g. soy formula) that are fortified with vitamin D (400 IU per quart). Another great way to get vitamin D is good ‘ol sunshine, but that can be limiting during the winter season – depending on where you live of course; I hear Hawaii’s beautiful this time of year. One reference states that exposure to UVB rays from sunlight for 5 to 20 minutes per day, without sunscreen, twice weekly allows the body to make adequate amounts of vitamin D. Of course, we’re not recommending that you slip into your summer swimsuit and flip-flops and stroll along one of Chicago’s beaches this time of year, but certainly should be considered when the weather is more appropriate.
The November 30th IOM report also established new Dietary Reference Intakes based on age and pregnancy status and we recommend that you check them out if you are going to be taking any Vitamin D supplements to avoid overdoing it.
Always remember that all vitamins, minerals, herbals, and other nutritional supplements have the potential of helping you or harming you, depending on factors such as dose, pre-existing medical conditions, or interactions with other medications. You should always carefully read a nutritional supplement’s entire label before purchase and use, and discuss any questions you have with your primary care physician or pharmacist. If you suspect overdose, overuse, or adverse reactions to any nutritional supplement product, the specialists at the IPC (1-800-222-1222) are available 24/7/365 to offer immediate assistance.
by Tony Burda and Elizabeth Ospina, PharmD Student