If you enjoy feeling the warm rays of the sun on your skin, you already know that sunlight feels good. But you might not know that it can also be good for you. For decades, people have been told by experts and the media that the sun is harmful and should be avoided. We’ve been told there’s no such thing as a healthy tan, and we’ve been warned to cover our skin, coat ourselves in chemical sunscreens, and avoid exposure to direct sunlight. It turns out that this advice is not only inaccurate it is a contributing factor to a significant amount of the disease and illness in our society.

That’s because exposure to sunlight is the ideal and safest way for your body to obtain vitamin D. It’s nearly impossible to get adequate amounts of this vital nutrient from your diet without supplementation. This is why sensible exposure to natural sunlight is absolutely essential for optimal health. Whether it’s due to misguided warnings about the danger of sunlight, lifestyles that keep people indoors during daytime hours, or even because they live too far north, most people do not get enough sunlight to create the vitamin D their bodies need. And, yes . . . you DO need vitamin D.

Increasing numbers of scientists agree that vitamin D deficiencies are widespread in the North American population, leading to a wide variety of health problems. In fact, vitamin D deficiency is clearly linked to heart disease, high blood pressure, diabetes, obesity, and depression. It’s also associated with autoimmune disorders such as multiple sclerosis and rheumatoid arthritis. In addition, without enough vitamin D, your body is unable to absorb calcium. That’s why sufficient levels of vitamin D are crucial for healthy bones.

Over 25 million adults in the United States have, or are at risk of developing, osteoporosis, a disease characterized by fragile bones. Clinical studies also show that a deficiency of vitamin D increases the risk of a number of different cancers, including four of the most common: breast, prostate, colon, and skin cancer. The risk of all of these conditions, however, can be reduced naturally . . . simply by maintaining adequate levels of vitamin D. Take cancer, for example. Numerous studies have shown that cancer — even skin cancer — is less prevalent in places where people are exposed to sunlight more frequently.

In fact, lifeguards in Australia exhibit their country’s lowest rates of melanoma — while office workers have the highest. One recent study was conducted by William B. Grant, Ph.D., one of the top vitamin D researchers in the world. Grant’s research, which was published in the prestigious journal Cancer, proved a very strong correlation between the incidence of 16 different types of cancer and latitude. In other words, as the distance from the equator increases (and UVB radiation decreases), the rate of cancer in the population rises. This is not to say that too much sun exposure cannot cause skin cancer. It can . . . if you allow your skin to get burned.

To avoid burning, limit the amount of time you spend in strong (afternoon) sunlight, and moderate your exposure with clothing. Sunscreens should generally be avoided. They virtually eliminate your body’s production of vitamin D and also contain a number of potentially harmful chemicals. Fair skinned, thin, and younger individuals need far less exposure to the sun to produce vitamin D. People in this category may be fine with as little as 10 minutes of sunlight on a sunny summer day, while deeply pigmented individuals may require 10 to 20 times as much.

This is one of the major reasons why African Americans have a much higher rate of cancer in North America than other ethnic groups. They simply can’t get enough sun to generate vitamin D, because their skin serves as an effective barrier to beneficial UVB radiation. But they are not alone in this regard. If you fall under any of the following categories, you are likely to be deficient in vitamin D and, therefore, run a greater risk of serious health problems: If you work indoors and rarely spend more than 10 or 15 minutes at a time in direct sunlight. If you do not go out in the sun without sunscreen. If you are overweight.

Excess fat impairs vitamin D utilization in the body, meaning obese people need twice as much vitamin D to maintain health. If you live in a northern geographic region. The further you live from the equator, the longer the exposure you need to the sun in order to generate vitamin D. If you have dark skin. Darker skin pigments require significantly more sun exposure to synthesize vitamin D. If you are over 65. There is an enzyme in the skin that helps produce vitamin D. However, this enzyme decreases with age, putting elderly people at an increased risk of vitamin D deficiency. If any of these factors apply to you, you should look for ways to gradually increase the amount of time you spend in the sun. And you should also strongly consider supplementation.

However, the vitamin D found in milk — as well as that put in most vitamins — is synthetic. It does not function the same way as the natural vitamin D you obtain from sunlight. Next to your body’s own production, the very best source of vitamin D is found in cod liver oil. Supplementing with cod liver oil is the healthiest way to assure you are getting the proper amount of vitamin D and decrease your risk of cancer and other diseases associated with vitamin D deficiency.

For most people, one tablespoon per day should be enough. However, vitamin D supplements, if taken in too large a dose, can cause toxicity. So I would definitely encourage you to have your vitamin D level measured so you’ll know exactly how much you should take. It’s impossible to get vitamin D toxicity from too much sun exposure — your body self-regulates and will only generate what it needs. That’s why receiving your vitamin D from the sun is your best option, if possible. Getting enough sunlight is the simplest, easiest, and yet one of the most important strategies for improving your health.

(Ed. Note: Dr. Joseph Mercola is the Director of The Optimal Wellness Center in Chicago, one of the nation’s leading natural health clinics. He is the author of two best-selling books, and is the founder of Mercola.com, the world’s most visited natural health website. To sign up for Dr. Mercola’s excellent, twice-weekly e-newsletter, please visit www.mercola.com.)