Hot summer weather and strong sun require extra precaution when spending time outdoors. That said, we do require natural sun light each day to support the synthesis of Vitamin D. Depending upon the geographical location in which you reside, your skin color, and time of year are factors that determine how much sun exposure is required.
Vitamin D: Vitamin D receptors in the skin are activated through natural sunlight exposure. When UVB rays interact with the cholesterol in skin cells, they provide the energy for vitamin D synthesis.. According to research, Vitamin D produced in the skin from natural sunlight may last at least twice as long in the blood when compared to ingested vitamin D.  The biological pathway for vitamin D synthesis in the body is quite complex. It requires a greater understanding that one can study in the research. Moreover, there are numerous factors including diet, lifestyle, chronic disease, drugs, and lack of exposure that may interfere with the manufacturing of natural vitamin D in the body.
It is reported that about 40% of American adults have a vitamin D deficiency. . The combination of consuming foods rich in vitamin D and natural outdoor sunlight exposure is essential for catalyzing sufficient Vitamin D synthesis. Certain foods such as salmon, cod liver oil, swordfish, canned tuna, beef liver, egg yolks and sardines contain vitamin D. Check with a medical professional to verify that you have adequate vitamin D levels in your body and follow their guidelines. Osteoporosis, cancer, depression, muscle weakness are linked to low vitamin D levels.
Too Much Sun
Over exposure to ultraviolet B rays are harmful to the skin (burning effect). Ultraviolet A rays penetrate the skin more deeply than UVB and play an extensive role in aging and wrinkling (photo aging) to the skin. Excessive UV radiation can produce genetic mutations to cell DNA that continue to accumulate with continuous exposure.  UV is a proven carcinogen. Tanning is the skin’s attempt to prevent further DNA damage to cells.
There is no such thing as a “safe” tan. Tanning booths actually emit doses of UVA as much as 12 times that of the sun. It is reported that first exposure to tanning beds in youth increases melanoma risk by 75%. Squamous cell carcinoma and basal cell carcinoma are also results of over-exposure.
HOW MUCH SUN EXPOSURE IS REQUIRED FOR VITAMIN D SYNTHESIS?
Tanning ability is dependent upon the origins of one’s race (ancestors) where the body adapted over thousands of years in order to stay healthy. Melanocytes found in the epidermis are the cells responsible for skin color. They serve as UV-B filters that regulate a precise amount of nanometers of wavelength to stimulate cell receptors.
The closer to the equator our ancestors originated, the darker the skin type. Very fair skin types are found at the top of the globe (Ireland, Great Britain, and Northern European regions) and are more susceptible to sun burn and cancer, especially when living in areas closer to the equator. Modern day humans have migrated all over the globe requiring the skin to adapt as best as possible to a new location.
It is recommended that skin is exposed to outdoor sunlight around midday, (noon) when the sun is at its highest point and when UVB rays are the strongest. Less exposure time is required to efficiently manufacture vitamin D. To maintain healthy blood levels, 10-30 minutes of sunlight several times a week is recommended. Darker skin types may require more time. Exact exposure time may vary depending upon skin sensitivity, time of year, and geographical location. Be aware that UVB rays cannot penetrate through windows.
 Nair and Maseeh (Apr-Jun 2012). Vitamin D: The “sunshine” vitamin”. Journal of Pharmacology & Pharmacotherapeutics. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3356951/
 UVA & UVB – Skin Cancer Foundation. Retrieved from https://www.skincancer.org/prevention/uva-and-uvb
. How to Safely Get Vitamin D from Sunlight. Retrieved from https://www.healthline.com/nutrition/vitamin-d-from-sun
Copyright 2019, A.J. Zani