Do you supplement with 2000-5000 International Units (IU) of vitamin D each day? Or, do you use your lunch hour to lie in the sun in just a loincloth? If not, you're likely low in vitamin D.



More than half of the world’s population is deficient in vitamin D, and as many as four out of five in the United States may be below optimal levels.



Low blood levels of vitamin D increase risk factors for diabetes, arthritis, dementia, and bone loss. You could also be increasing your risk of viral infections, like the flu.



Fortunately, the most common micronutrient deficiency in the world is easily preventable. High-quality supplements are inexpensive, and if you live in the right latitude, you can get a healthy dose from moderate mid-day sun exposure.



After reading this article, you’ll understand why vitamin D is one of my Foundational Five, the best supplements for foundational health.




In all my many years of practice of medicine, I've never seen one vitamin, even vitamin C, have such a profound effect on human health.
Dr. Soram Khalsa, board-certified internist and medical director of the East-West Medical Research Institute





What is Vitamin D?



Vitamin D is actually a prohormone, not a vitamin. It influences the expression of more than 200 genes and acts as a precursor to hormones such as DHEA and cortisol.



The active form is called 25-hydroxy vitamin D, or 25(OH)D.



You consume vitamin D in two forms: ergocalciferol (D2) and cholecalciferol (D3). However, even if you consume fortified foods like orange juice or milk, you'll fall woefully short of optimal cholecalciferol intake.



Ergocalciferol comes from plants. Humans cannot convert it to cholecalciferol very well.



Cholecalciferol comes from animals and is superior to ergocalciferol at improving vitamin D status. The best food sources include fatty fish, beef liver, and cod liver oil.



Of course, food and supplementation aren't the only ways to raise 25(OH)D. Since the time of Adam and Eve, humans relied on sun exposure.




In ancient Egypt, Greece, Rome, Babylon, and Persia, sunlight (heliotherapy) prevented and treated various medical conditions.
Juzeniene A, et al.



When the sun reaches your skin, the UVB rays stimulate the production of 25(OH)D. Of course, sunblock prevents this production.



To benefit from the sun's rays, you need to live close to the equator and expose most of your skin to the mid-day sun for 20-30 minutes. That would give you about 10,000 IU, or 200 times the amount in a glass of fortified milk.



Some practitioners believe exposing your private parts to the sun is the best way to get vitamin D to levels to rise. I have no personal experience, but if you have the right place to try nude sunbathing, go for it.



A lack of sun exposure limits the amount of vitamin D in your body, but other factors reduce its production, as well.



For example, melanin blocks UV rays, and UV rays stimulate vitamin D production. As a result, those with darker skin produce less vitamin D than those with lighter skin when exposed to the same amount of UV light.



Liver and kidney dysfunctions compromise the conversion of cholecalciferol to active vitamin D. Also, certain medications like statins and plant compounds interfere with absorption.



Cholesterol and vitamin D are absorbed in similar ways. Medications and plant compounds that interfere with cholesterol uptake also interfere with vitamin D absorption.



Effects of Low Vitamin D



Since vitamin D affects almost every body system, it's no surprise that low levels can lead to catastrophic consequences.



The Flu



The role of vitamin D in supporting your immune system cannot be understated.



A British doctor named R. Edgar Hope-Simpson first connected low 25(OH)D to the flu. He observed that in both hemispheres, cases of the flu rise in late fall and early winter, which is the same time when levels drop from their summertime high. His observations were correct.