Vitamin D: Why It Matters

The human body is miraculously engineered—to cool off, it sweats; when it’s cold, you feel chills; and its built-in mechanisms indicate when something is wrong, like headaches, swelling and pain. However, there are some things that the body needs that it does not maintain itself, like food, water and exercise.

That’s exactly what vitamins are—something the body needs, but does not produce, said Dr. Priscilla Pemu, who specializes in internal medicine and is a full professor and director of clinical trials at Morehouse School of Medicine in Atlanta, Ga., U.S. Vitamin D, in particular, is something your body needs for metabolism—it’s how your body works on the inside—how it lays down calcium in bones, said Pemu. Vitamin D comes in through your diet or as a supplement, she said.

Vitamin D is essential to have strong bones. It is involved in how calcium is absorbed from the intestinal tracts and how it is laid down in the bone. When laid down correctly, the bones become stronger. It’s especially critical for young children to avoid rickets—a disease resulting in soft bones and skeletal deformities, and for older adults to avoid osteomalacia—a disease that softens bones that causes them to break more easily, said Pemu

“Babies that are fully breast-fed need [vitamin D] supplement,” said Pemu, who is from Ebu, Delta State, Nigeria, and completed medical school at University of Benin. While breast milk contains vitamin D, it is often not sufficient to meet the baby’s daily requirement particularly if the mother has low vitamin D levels. Mothers who take vitamin D supplements are likely to have higher levels of the nutrient in their milk. The recommended vitamin D dose for exclusively or partially breastfed infants is 400 IU per day.

Vitamin D deficiency also poses a problem for older adults.

“In higher altitudes, colder climates (less sun), older people began to have vitamin D deficiency,” said Pemu. “Those who are not exposed to the sun a lot tend to have lower levels.  People with less sunlight in different times of the year, and home bound people can have a problem. Sun block also creates a problem.”

People with darker skin have increased levels of melanin in their skin, which reduces the skin’s ability to convert vitamin D in the blood when exposed to sunlight. Older adults who have darker skin can be considered at higher risk of vitamin D deficiency, according to reports

Other at-risk groups for vitamin D deficiency include people who are very obese, gastric bypass patients, those with certain chronic kidney diseases and celiac disease (the inability to digest gluten), said Pemu.

Sources of Vitamin D

Pemu discussed how the synthesis of vitamin D works: Through the action of sunlight, our skin breaks down vitamin D in the blood to active form. The metabolic conversion of vitamin D1 to D2 happens a lot in the skin, and the conversion of vitamin D2 to D3 happens a little bit in the kidneys. The body breaks it down further where it is active in the tissues.

The best time to get some sun is before noon daily, said Pemu. A mid-morning walk will do your body good and supply the best UVB rays.

Another source of vitamin D is your diet.

“Nigerians like sardines; they are good source of vitamin D.” she said. Other food sources rich in vitamin D include, milk, dairy products, eggs, fatty fish, beef and cod liver oil. A lot of ready-to-eat cereals are also fortified with vitamin D. You can also get vitamin D by taking vitamin D supplements.

A blood test performed by a physician can test for vitamin D levels; however, medical communities do not agree on what is considered a normal vitamin D level.

In 2010, the Institute of Medicine, an independent U.S. organization with a 150-year history of advising the U.S. on health and health care issues, recommended 600 IU/day (international units per day) of vitamin D for ages one to 70 and 800 IU/day of vitamin D for those over age 70, by diet or vitamin supplement.

Pemu agrees with the Institute of Medicine’s recommendation for healthy people. “If you are suffering with some other kind of disease, then the recommendation can be different based upon the disease condition,” she said.

However, readers should be wary of consuming too much vitamin D.

“It is a major fad now that everyone is getting measured for vitamin D,” said Pemu. “People need to be aware that there are side effects from having too much vitamin D in their systems. If someone puts you on vitamin D, they should be monitoring your levels. Your levels should be kept in a certain range.”

Side effects from too much vitamin D include high levels of calcium, which can cause confusion, vomiting, abdominal pain, increased thirst, increased urination, and kidney stones, said Pemu.

To be healthy, Pemu recommends that you keep your regime simple. Get a reasonable amount of morning sun—moderate exercise 30-60 minutes outside daily is good. Maintain your weight with a balanced diet, including the foods rich in vitamin D discussed in this story.