Vitamin D may be the single most important organic nutrient for your overall health. In fact, if this were a drug, it would be considered the discovery of the century.
– Al Sears, M.D., Your Best Health under the Sun
Vitamin D, commonly mistaken for a vitamin is actually a prohormone (the precursor of a biologically active hormone). Vitamin D has no requirement to be eaten, as humans can meet all their requirements by getting enough sunlight exposure. It is critically important for the development, growth, and maintenance of a healthy body throughout its entire lifespan.
Vitamin D has been shown to be critical in (but not limited to):
- Reduce inflammation;
- Help with fat metabolism;
- Help with cancer prevention, including skin cancers;
- Help prevent autoimmune diseases;
- Help prevent cardiovascular disease;
- Help prevent types 1 and 2 diabetes;
- Help the absorption and use of calcium and phosphorus;
- Help promote bone and muscle heath.
How much do we need?
The vitamin D council has the current recommendations (these are only estimated amounts):
- Healthy children over the age of 1 years – 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, MS, cancer, heart disease, or obesity may need higher amounts.
There is difference among some organisations with regards to recommended daily intakes. This is due to researchers For example, the Food and Nutrition Board has the current recommendations:
- Healthy children over the age of 1 years – 600 IU;
- Healthy adults and adolescents – 600 IU;
- Pregnant and lactating mothers – 600 to 800 IU.
The Food and Nutrition Board recommended daily intakes are the official recommendations by the United States government.
The Australian recommended daily intakes are as follows:
- For those who get some sun exposure and are under 70 years – 600 IU / over 70 years – 800 IU;
- For those who get very little or zero sunlight of all ages – 1000 IU to 2000 IU.
Where do we get it?
The best source is obviously the sun. Scientifically speaking, Vitamin D is obtained via a process where UVB radiation from sunlight converts cholesterol into D3. Certain animal foods and products, such as cod liver oil, salmon, makerel, sardines, beef liver and pasture raised eggs also contain Vitamin D.
Vitamin D and sun exposure
The human body was designed to receive vitamin D by producing it in response to sunlight exposure. Since this is the way Nature intended, it should be considered the method of choice. Conservative estimates place ancestral levels around 10,000 – 20,000 IU per day from direct sun exposure.
The human body can produce this amount in a very short time so over exposure isn’t necessary. Basically, the requirement to produce enough Vitamin D in a single day is to be in direct sunlight (as much skin exposure as possible) for about half the amount of time it takes for your skin to burn (turn pink).
The below map of Australia give an estimate of how much sun exposure is required to meet daily requirements. As you can see it doesn’t take too long in the summer months, with more time required during the cooler months.
Even if you decide to stay out in the sun for an extended period of time, you body has a way of shutting down its production of Vitamin D. You will just stop producing it when you don’t need it.
What about sunscreen?
Ingredients in the majority of sunscreens block both UVA and UVB radiation. As mentioned earlier, UVB is responsible for producing Vitamin D. Only recently, have scientific bodies began to agree that it is UVA radiation that causes the deadly melanoma.
Sunlight exposure has a paradoxical effect that is both good and bad. Chronic, long term exposure to the sun, such as lifeguards and other outdoor workers experience, is protective from melanomas and other cancers, where as intermittent, infrequent intense burning, followed by little sun exposure, may promote this deadly form of skin cancer and many other cancers.
– Dr Loren Cordain, Ph. D., The Paleo Answer
Sunscreen with a SPF factor of 15 blocks 93% of UVB radiation, the type that is actually required by the human body to produce Vitamin D. SPF 30 and SPF 50 sunscreens block out 97% and 98% respectively. To be effective, all sunscreen, regardless of strength, should be reapplied every two hours. Also, the “reddening” of the skin is a reaction to UVB radiation alone and does not give any indication to the amount of UVA radiation damage.
So, blocking UVB radiation isn’t the smartest idea going around as this is the spectrum of light that stimulates Vitamin D production within the body. How does one stay sun smart and still benefit from sufficient Vitamin D production?
One method could be to apply sunscreens liberally at the beginning of the summer and as your base level tan is produced you could lower the SFP of your sunscreen until your using very little, if at all (remember, the best protection against unwanted UV radiation is a good tan, some shade or a hat).
Finally, the human species has evolved in the great outdoors and with direct sun exposure, thus having an actual nutrient requirement for it. Don’t deprive yourself of your day in the sun.