Decoding Vitamin D

We’re constantly bombarded with the latest “it” food or supplement promising to revolutionize our health. Vitamin D, “the sunshine vitamin,” has had its time in the spotlight. Here is what you need to know about it.

Defining & Quantifying

Vitamin D is a nutrient that helps the body use calcium and phosphorus to maintain strong bones and teeth.

“If you don’t absorb enough vitamin D, your gut cannot absorb calcium, and that can lead to certain diseases,” says Dr. Rumi Cader, an internal medicine physician at the Torrance office of UCLA Health. “In the 1800s this caused rickets and osteomalacia (softening of the bone), which we generally only find now in poverty-stricken parts of the world. But even in developed countries, we do see mild to medium vitamin D deficiency, and that can lead to osteoporosis later in life.”

The recommended daily amount depends on age: 400 International Units (IU) daily for children younger than one year; 800 IU for adults 71 years and older; and 600 IU for everyone in between.

The body produces vitamin D when the skin is directly exposed to the sun. A 15-minute daily walk in the sun typically provides sufficient amounts. Those of us who live in Southern California generally don’t have to worry about getting enough sun exposure, unlike people in other parts of the country or world where the sun doesn’t shine much.

“We have a lot of sun. But we also have a lot of patients with skin cancers,” says Dr. Cader. He says it is more important to use sunscreen and cover up than to expose your skin to the sun for the sake of getting vitamin D.

A better way to get vitamin D is through food. Three ounces of cooked salmon—among the highest sources—provides 320 IU. Milk, orange juice and cereals fortified with vitamin D offer 40 to 100 IU per serving.

Identifying a Deficiency 

Most people get enough vitamin D from sun exposure and diet. However, some groups tend to have lower levels than the norm. They include people who are dark-skinned, obese and elderly, as well as those who live in institutional settings. Individuals with Crohn’s disease, cystic fibrosis and celiac disease may have trouble absorbing vitamin D.

A blood test can reveal vitamin D levels. Symptoms of low vitamin D levels include muscle aches, muscle weakness and bone pain, but many people do not experience symptoms.

“I screen my patients who are at risk or who request screening,” says Dr. Cader. “I’m surprised to find as many deficiencies as I do.” 

About six months ago, Dr. Cader himself discovered that he suffered a vitamin D deficiency. Since taking a supplement, he noticed the disappearance of some minor body aches he had attributed to age. 

Other Benefits

One study looking at vitamin D levels in close to 50,000 healthy men over a 10-year period found that men deficient in vitamin D were twice as likely to have a heart attack as those with adequate levels. Studies also seem to indicate an association between low vitamin D levels and the risk of colon cancer.

Vitamin D may also play a role in seasonal affective disorder, the tendency to get depressed during the winter when there is less sunshine and lower vitamin D levels in the body.

Too much of the vitamin is not good, however. Taking extremely high doses of vitamin D can spike blood calcium levels, which could cause nausea, constipation, confusion or abnormal heart rhythm.

The bottom line? Your body needs vitamin D, and you probably get enough. If you’re in a high-risk group or notice any bone pain or muscle weakness, see your doctor.