Designed to Thrive, Eat to Thrive

Vitamin D & Sunlight

8314202adbcaf057522e3b113bccb6e8Vitamin D is actually not a vitamin at all.  It is a prohormone, a precursor to a hormone, produced in your skin in response to sunlight exposure.  While you can also get vitamin D from some food sources and supplements, the ideal method of accumulating vitamin D in your body should be from the sun.  However, not all sunlight stimulates the production of Vitamin D.  The sun emits ultraviolet radiation in the UVA, UVB, and UVC band wavelengths.

UVA is by far the most abundant type of radiation from the sun.  It can pass through window glass, is not affected by a change in altitude or weather, and is present all day every day of the year.  UVA penetrates deep into our skin layers and is responsible for long-term skin damage.

UVB, on the other hand, cannot pass through window glass, is more intense during the middle of the day, at high altitudes and near the equator.  It is also more intense during the summer months and is responsible for sunburn and tanning.  UVB rays can cause skin cancer and cataracts.  It is the UVB rays that stimulate the body to produce vitamin D.  When exposed to direct sunlight, the body will produce vitamin D at a rate up to 1,000 IUs per minute.  You don’t need to worry about the body making too much vitamin D from sunlight exposure because the body has a built-in mechanism to halt vitamin D production once it has enough.  While you may get a sunburn from too much sunlight, you will NOT develop vitamin D toxicity.

Vitamin D has enormous health-promoting benefits and effects.  It plays a huge role in calcium metabolism, which is vital for the normal functioning of the nervous system, as well as for bone growth and maintenance of bone density.  Vitamin D also plays a major role in immunity, cell proliferation, insulin secretion, and blood pressure.  Current research shows that ALL cells in your body have vitamin D receptors, which means that every cell and tissue in your body needs vitamin D for its optimal functioning and well-being.  Vitamin D is also responsible for the regulation of over 2,000 genes in your body and plays a tremendous role in protecting you from various types of cancer, such as breast cancer, ovarian cancer, colon cancer, and prostate cancer.  Vitamin D prevents osteoporosis, depression, and even effects diabetes and obesity.

How Do I Increase My Vitamin D?7ce04edece826ba1cb05dd3c92a7080c

The body prefers to get its vitamin D through direct exposure to the sun.  As we mentioned before, the body has a self-regulating mechanism that will shut off vitamin D production in the presence of sunlight to keep you from developing vitamin D toxicity from making too much vitamin D.  Ideally, you should expose about 40%-50% of your bare skin to the sun for 15-20 minutes every day to produce the vitamin D you need.

While that sounds simple enough, in reality, it can be quite difficult.  For most of us, our work keeps us indoors during the peak sun hours.  You need a lot more sun exposure at 5:00 pm than you do between the hours of 11:00 am and 2:00 pm.  Cold winter months also make direct sun exposure to bare skin quite cumbersome (unless you’re a member of the polar bear club).  Therefore, most of us will need to supplement with vitamin D.

Before beginning any sort of supplementation with vitamin D it is important to have your current vitamin D levels checked.  Optimally, your blood levels of vitamin D should fall somewhere between 50-80 ng/ml (125-200 nmol/L) for both adults and children.

If you are like 50%-85% of people, you are probably deficient in vitamin D and you’ll want to start supplementing immediately.  How much vitamin D you need is highly individualized.  Factors such as age, obesity (obese and overweight people need more vitamin D), pregnancy (requires more vitamin D), skin tone (dark-skinned people need more vitamin D), amount of sun exposure and overall health will play a role in how much vitamin D you need to take every day.

For proper functioning, a healthy human body uses around 3,000-5,000 IU of vitamin D per day.  Therefore, based on the body’s indicated daily vitamin D usage, the Vitamin D Council recommends the following amounts of supplemental vitamin D3 per day, in the absence of proper sun exposure:

  • Healthy children under the age of 1 year – 1,000 IU
  • Healthy children over the age of 1 year – 1,000 IU per every 25 lbs of body weight.
  • Healthy adults and adolescents – at least 5,000 IU.
  • Pregnant and lactating mothers – at least 6,000 IU.

Additionally, children and adults with chronic health conditions such as autism, Multiple Sclerosis, cancer, heart disease, or obesity may need as much as double these amounts.