Claim 1: The majority of Americans are deficient in vitamin D.
Since the 1980s the incidence of vitamin D deficiency has increased. This is generally attributed to the increased use of sunscreen. However, the CDC recently reported that the majority of Americans has appropriate levels of vitamin D. Certain groups do have a higher incidence of vitamin D deficiency, with women, African Americans of both genders, and the elderly at greater risk.
Claim 2: Vitamin D can help prevent certain forms of cancer.
The National Cancer Institute notes that epidemiological studies have shown a decreased incidence of prostate, breast, and colorectal cancer in populations with higher levels of vitamin D. One function of vitamin D is to decrease cell division, which may help stop or slow the growth of rapidly dividing cancer cells. Although many studies are being conducted to see what role vitamin D may play in cancer prevention, the National Cancer Institute does not make any specific recommendations regarding vitamin D at this time.
Claim 3: Vitamin D helps prevent heart disease.
Vitamin D is active in the vascular system and acts as an anti-inflammatory. Scientists know that populations with higher levels of vitamin D have lower incidence of cardiovascular disease. What's not yet known is the exact mechanism in this relationship. It is likely that there are so many things happening in this pathway that vitamin D is just one of the important nutrients that help control heart disease.
Claim 4: Vitamin D boosts insulin activity and helps prevent type-2 diabetes.
Vitamin D works in the pancreas to help produce insulin. Outside the pancreas, vitamin D effects how cells use insulin. In type-2 diabetes cells become resistant to insulin, so helping cells use insulin will certainly help with type-2 diabetes. Let's be clear, though, when it comes to diabetes prevention, getting lots of vitamin D is no replacement for skipping the simple sugars and maintaining an appropriate weight.
The Bottom Line
The Institute of Medicine recommends 600 International Units (IU) of vitamin D a day for people ages 1 to 79 and 800 IU a day for people age 70 and up. A balanced diet containing fish, eggs, and fortified dairy products can provide enough vitamin D to prevent deficiency. If you don't regularly consume foods high in vitamin D, you may want to consider a supplement that provides 50 to 100 percent of the recommended daily allowance. This will ensure that you don't become deficient and you get all the healthy benefits of this little power nutrient.
Jennifer Webb, MS, RD, CNSC is a practicing dietitian and freelance writer based out of Southern California. She has been practicing medical nutrition therapy for the past five years. Prior to her career in nutrition, she received a degree in early childhood development. She has combined her two passions, nutrition and family, into a career educating people about the impact food can have on health across the lifespan. She is currently a dietitian at a top children's hospital and runs a private practice. Her private practice specializes in family nutrition therapy, a technique that focuses on changing family habits to lead them to lifelong healthy lifestyles. Contact Jennifer at firstname.lastname@example.org.