Vitamins are substances that the body needs in order to properly function. But vitamins in general are not made in the body and have to be ingested through food or supplements. And there are quite a few of them — vitamins A, B1 to 12, C, D, E and K. Vitamin D is the exception, because it can be made by the body when your skin is exposed to direct sunlight.

It is a common misconception that exposure to early morning sunlight is enough to make vitamin D in the skin. It’s not just any sunlight that you need, but a particular wavelength of UVB light, the kind that only occurs midday, around 10 a.m. to 12 noon. Not to discourage you from early morning outdoor activities as any activity at any time of day is good for you, but you may not enough to get the Vitamin D you need.

The exposure to sunlight must be directly to bare skin, without protective clothing or sunblock, or the use of tinted windows or umbrellas. You do only need about 10-15 minutes, but this may still be uncomfortable for some in our climate, plus the risks of heat stroke and skin cancer.

If you can’t go out in the sun, some sources of vitamin D are fatty fish like salmon, mackerel and sardines. Mushrooms and egg yolks also have some vitamin D. In some countries some foods are fortified with vitamin D, like milk, orange juice and cereal.

Commonly available preparations in tablet or capsule form are vitamin D3 (also known as cholecalciferol) in doses of 400, 600, and 800 IU, which are the usual recommended doses for healthy adults.

But why do we need Vitamin D?

Vitamin D helps in building and maintaining healthy bones by helping your body absorb calcium, the primary component of bones. A low vitamin D can cause low calcium levels, leading to fatigue and muscle cramps. A lack of calcium and vitamin D during the growing years in childhood can lead to weak, misshapen bones, while a deficiency in adults can contribute to bones that can break easily, such as in osteoporosis.

So does this mean that we should all be taking vitamin D?

Guidelines were recently published in The Journal of Clinical Endocrinology that relate to the use of vitamin D in people without established indications for vitamin D treatment or testing — so guidance for generally healthy people without underlying conditions related to low vitamin D.

The guidelines recommend that generally healthy individuals do not need to be tested for Vitamin D levels and they should not take intermittent, large doses of Vitamin D. It’s ok to take the recommended daily low doses of 400-800 IU.

The guidelines do suggest that these groups of people may benefit from empiric vitamin D supplementation, or higher doses:

1. Children aged one to 18 years: To prevent rickets and to potentially lower the risk for respiratory tract infections.

2. Pregnant people: To lower the risk for maternal and fetal or neonatal complications.

3. Adults older than 75 years: To lower the risk for mortality.

4. Adults with prediabetes: To lower the risk for type 2 diabetes.

It has been found however that three out of five Filipinos are vitamin D deficient. And it must be noted that these recent guidelines reviewed research studies that largely included study participants who were of European ancestry, or identified as non-Hispanic White, so not a lot of Asians or other ethnicities were studied.

If you are concerned about whether you’re getting enough vitamin D, talk to your doctor about your diet and any other health conditions you may have, and if you need to check your vitamin D levels.

When taken in appropriate doses, vitamin D is generally considered safe. Don’t overdo it and take it only as prescribed because too much vitamin D can also cause other health problems.