The marketing folks at Doric Foods made a smart business decision in the 1960s by naming their product “Sunny D.” Sun exposure was seen as healthy at the time, and vitamin D was being added to “enriched” foods like milk and cereals. While these days it is common to see food packaging that emphasizes specific nutrients such as fiber or protein, vitamin D was among the first to be actively promoted.
Vitamin D has received renewed attention recently, as it has been estimated that up to 75 percent of Americans are vitamin D deficient. What do we need vitamin D for, and what happens when we do not have enough of it?
Best known for building strong bones in combination with adequate calcium, this essential nutrient regulates calcium and phosphate concentrations in the blood, promoting proper bone mineralization and growth.
According to Don Mankie, a registered dietitian and nutritionist with Carilion Clinic’s Dining and Nutrition Services, vitamin D may also provide significant additional health benefits.
“Beyond its proven necessity for healthy bones, vitamin D is critical for immunity,” he said. “It prompts the production of antimicrobial substances that seem to act like natural antibiotics and antiviral agents.”
The risks associated with a chronic vitamin D shortage can include rickets and osteomalacia, osteoporosis, muscle pain, weight gain, depression, decreased immune function, heart disease, hypertension and even certain types of cancer.
“Emerging research points to a role for vitamin D in cancer prevention, particularly against breast, colon, prostate and lung tumors,” said Mankie. “Another possible benefit of vitamin D is prevention of Type 2 diabetes, which affects an estimated 17 million Americans.”
Are You Getting Enough?
A simple blood test can determine whether you are getting enough vitamin D in your diet. In general, younger people have higher levels than older people and males have more than females. According to Mankie, the following other groups may not get enough vitamin D:
- Breastfed infants
- Elderly people
- People with dark skin
- People with chronic conditions such as Crohn’s or celiac disease
- Obese people
Sources of Vitamin D
Vitamin D is called the “sunshine vitamin” because the human body can obtain adequate amounts entirely from exposure to sunlight. Ultraviolet–B (UVB) radiation on the skin converts certain cholesterol-containing components in our blood into vitamin D3, the form of vitamin D that allows the body the greatest benefit.
So grab a few rays early in the day. Note that the emphasis is on "few," since the American Academy of Dermatology advises that prolonged sun exposure significantly increases the risk of skin cancer. According to Mankie, just 20 minutes of sun exposure two to three times per week enables the skin to produce about 20,000 IUs (international units) of vitamin D, more than enough to satisfy the current recommendations of 1,000 to 2,000 IUs per day.
"You'd have to drink about 400 glasses of milk to get that same amount," he said.
While vitamin D is not found in many natural foods, some are good sources. They include:
- Fatty fish such as salmon, tuna and mackerel
- Beef liver
- Egg yolks
Dietary supplements are also available and certain processed foods are still fortified with vitamin D. These include almost all of the U.S. milk supply and many breakfast cereals, in addition to some brands of orange juice, yogurt and soy beverages. Oh, and about that Sunny D drink? Clever marketing aside, the sugary concoction actually contains less than two percent fruit juice—and no vitamin D.