A patient with a deep tan recently stated that she felt safe going out in the sun without any protection because sun exposure was such a wonderful source of vitamin D. Could this possibly be true? No…and yes. This is a classic example of the debate over vitamin D – diet vs. sun exposure. It is still deemed unsafe by all major health organizations to spend time outside without protection. However, vitamin D is a wonderful vitamin you need for good health. Luckily, you can add it through your diet and avoid long periods of sun exposure.
Why Vitamin D
Vitamin D is making big waves in the medical world. In the past decade research has discovered numerous benefits linked to this vitamin. Several of these studies have focused on vitamin D – diet vs. sun exposure.
The potential benefits of vitamin D are exciting the medical community. It is already known to aid in calcium absorption that can lead to healthy bone growth. The latest research shows vitamin D can help in the prevention of some types of cancer, heart disease, diabetes, and osteoarthritis.1 Vitamin D is beneficial for high blood pressure, high cholesterol, obesity, muscle weakness, multiple sclerosis, arthritis, asthma, premenstrual, syndrome, and tooth and gum disease. It aids in the treatment of vitiligo, scleroderma, psoriasis, actinic keratosis, and lupus.2
A Unique Vitamin 
When considering vitamin D – diet vs. sun exposure it is important to note the uniqueness of vitamin D. It is the only vitamin that responds like a hormone in your body. It relays chemical messages by sending messages to the intestines to absorb calcium from foods. Plus, these signals help the body regulate its uptake via the bone cells.
Vitamin C and other nutrients begin their job in the body in the form they are consumed but vitamin D must go through ‘processing’.3 This is where the vitamin D – diet vs. sun exposure debate begins according to many scientists. The body derives vitamin D from two sources. The process begins with dehydrocholesterol molecules that are stored in your skin. These molecules are activated by previtamin D3 – sunlight absorption – or previtamin D2 – derived from diet. The vitamin D is further processed by the liver and kidneys before reaching out to the cells that need help.4
A Dose of Vitamin D
Vitamin D can now be accurately measured. This means that scientists and doctors know the healthy amount a person should have in their diet. The Institute of Medicine follows the standard guidelines when recommending the adequate intake, not a daily amount, which is needed in a person’s diet.
- 50 and under: 200 international units
- 51-71: 400 international units
- 71 and older: 600 international units
It appears that these dosages will increase as the benefits of vitamin D become clearer.5 With the increased focus on vitamin D – diet vs. sun exposure an increased number of studies are focusing on obtaining vitamin D from the diet.
Sunlight
Sun exposure produces vitamin D. Whenever a person is in the sun, exposed areas of the skin allow vitamin D production. While this method was previously felt to be the best way to add vitamin D to the diet, it has now been determined to have many drawbacks.
First of all, there are no standards of measurement for a dose of vitamin D from the sun. The amount of vitamin D you receive from the sun depends on where you live – how far you are from the sun, the angle of the sun or the hour of the day you are outside, skin pigmentation, age, and the use of skin protection factor products.
A bigger risk than inaccurate dosing exists with sunlight as a source of vitamin D. Sunlight is a known cause of skin cancer. In addition to benign tumors, sun exposure can cause pre cancerous ore actinic keratosis and cancerous or basal cell carcinoma, squamous cell carcinoma, and melanoma.
Skin cancer is one of the most preventable type of cancers, but the numbers of people with skin cancer continue to grow. UV radiation is the number one cause of skin cancer, with UV light from tanning beds as harmful as actual sunlight.
- Basal cell and squamous cell cancers are less serious and make up 95 percent of all skin cancers
- Melanoma is the most serious form of skin cancer and leads to 75 percent of skin cancer deaths
- Cumulative sun exposure usually leads to basal cell and squamous cell skin cancer
- Severe sunburns before the age of 18 can result in melanoma
Vitamin D and Diet
Fatty fish is one of the best sources of vitamin D. The flesh of salmon, tuna, and mackerel are high in vitamin D. This healthy vitamin is also found in beef liver, cheese, and egg yolks.
Fortified foods are available that are high in vitamin D. Most milk in the United States is fortified with vitamin D. Milk was originally fortified with vitamin D in the 1930s to combat rickets, a major health problem at the time.6
Foods high in vitamin D include:
- Cod liver oil
- Salmon
- Mackerel
- Tuna fish
- Orange juice fortified with vitamin D
- Milk fortified with vitamin D
- Margarine fortified with vitamin D
- Beef liver
- Egg
- Sardines
- Swiss cheese
The Great Debate: Diet vs. Sun Exposure
So where does this leave us – do we slather our bodies with SPF 60 sunscreen and race to our cars to avoid any exposure to sunlight? Do we overdose on beef liver?
The great debate over vitamin D – diet vs. sun exposure gives us excellent information to make good, healthy decisions that we can live with. Since it is impossible to avoid sun exposure the major health organizations agree that it is healthy to get a very limited amount of vitamin D through sun exposure.7 However, it is imperative to limit sun exposure and UV light exposure and the use of SPF protection is essential even for limited times in the sun.
A portion of your needed vitamin D should also come from your diet. A happy medium will result in a healthy body. You will be getting vitamin D from natural sources.
References
1 Rhodes, Phillips. Vitamin D is Hot! Here’s How to Get It. CNN.com. Retrieved from:
2 Vitamin D. (July 13, 2011) Retrieved from MedlinePlus:
www.nlm.nih.gov/medlineplus/druginfo/natural/929.html
3 Ibid
4 Dietary Guidelines. (2011) United States Department of Agriculture. Retrieved from: www.usda.gov
5 Vitamin D (2011) Medline Plus. Retrieved from:
6 What Science Says About Dietary Supplements. (2011) Office of Dietary Supplements. Retrieved from ods.od.nih.gov
7 Dieatary Supplement Fact Sheet: Vitamin D. (2011) Office of Dietary Supplements. Retrieved from ods.od.nih.gov/factsheets/vitamind/
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