Vitamin D: Too Much of a Good Thing?

There is no question that vitamin D is essential—it helps to maintain healthy bones and can protect against a variety of diseases. This vitamin, that we naturally produce from spending time in the sun, helps contribute to a healthy life.

However, researchers are now asking, is there such a thing as too much vitamin D? Daily recommendations for vitamin D supplementation range from 400 to 2,000 international units (IU). However, some adults report daily vitamin D supplementation above 4,000 IU. If vitamin D is healthy and necessary, shouldn’t more be better? Not necessarily, say authors of a recent Harvard study.

The Harvard study, published in the Journal of the American Medical Association, found that increasing the amount of vitamin D past a certain point may not be beneficial. The study even posed a new hypothesis for future study, that high-dose vitamin D may have a negative effect on bone health.

What Is Vitamin D?

Vitamin D is different from other vitamins. It is not readily available in most foods and it is actually technically a hormone. When your skin is exposed to sunlight, your body produces vitamin D through a process involving both your liver and kidneys. If you wear sunscreen, keep in mind that vitamin D is only produced when it is exposed to ultraviolet B (UVB) sun rays.

In addition to absorption from the sun, vitamin D may be available through supplements and in a limited amount of foods (including some fortified foods). Vitamin D is a fat-soluble vitamin and can be stored in your body for a long time.

There are two main types of vitamin D, vitamin D2 and vitamin D3. Fortified foods can contain either type of vitamin D. Vitamin D3 is found in a limited number of animal-sourced foods and is produced by your body when your skin is exposed to sunlight. Vitamin D2 comes from plant sources.

Why Do We Need Vitamin D?

Vitamin D has multiple roles in the body. Your body needs vitamin D to absorb calcium and maintain healthy bones and teeth. Vitamin D helps with regulating insulin levels and diabetes management. Vitamin D supports cardiovascular, immune, brain, and nervous system health. There is also research suggesting that vitamin D and calcium may help with the aging process.

How Do I Get Vitamin D?

If you are not getting enough vitamin D there are several options available, including: sunshine, food, and supplements.

• Sunshine - The number one source of vitamin D is the sun. Your body can produce large quantities of vitamin D when your skin is exposed to the sun’s UVB rays. However, many factors affect this process including age, skin color, and geographic location.
• Food - Vitamin D is available in a few natural food sources. Natural sources of vitamin D include beef liver, cod liver oil, and egg yolks. Fatty fishes with vitamin D include mackerel, salmon, sardines, swordfish, and tuna. Cheeses can also provide you with your daily dose of vitamin D. Mushrooms treated with UV light may also provide high doses of vitamin D. Fortification is the addition of nutrients to food. Food fortification can be used to correct identified nutrient deficiencies in the population. In the United States there are several foods fortified with vitamin D that you can eat to supplement your diet. These fortified foods include orange juice, soy milk, cereals, margarine, yogurt, and milk.
• Supplements - If your lifestyle does not allow for you to consume vitamin D through sunlight or foods, then you may also get vitamin D through supplements. Vitamin D supplements may also be necessary if you have certain conditions such as Crohn’s disease, celiac disease, liver and kidney diseases, or had gastric bypass surgery.

What if I Don’t Get Enough Vitamin D?