Research is increasingly emphasizing how much we need to get sun, primarily for something vital: the production of vitamin D. But there's a problem here. Many people—we're talking 40 to 80 percent in the U.S. and up to 43 percent in Mexico City—don't get enough of this essential vitamin.
Why? Well, it turns out that almost all of our vitamin D should come from direct sun exposure. But, between many of us being stuck in the office all day and the pandemic keeping us indoors, these deficiency numbers have likely increased.
What is vitamin D and why is it so important?
In short, it is an essential, fat-soluble nutrient that is scarce in foods but that your body can produce when you expose yourself to the sun.
And how does this happen? Simple: UV-B rays from the sun cause your skin to transform 7-dehydrocholesterol into cholecalciferol. This compound then takes a ride to your liver, is transformed into 25-hydroxycholecalciferol (the version of vitamin D that we can measure in blood), and finally, in your kidneys, it is converted into the biologically active form of vitamin D3. This is how your body creates its own sunshine supplement!
What impact does vitamin D have on your health?
Vitamin D, apart from being famous for its role in strengthening our bones , has a lot of other functions. Did you know that it can prevent diseases such as osteomalacia, rickets and osteoporosis, and reduce the risk of fractures and falls in those over 65?
In addition, this vitamin is a hero of the immune system. It helps our white blood cells fight pathogens and reduces the ability of certain viruses to grow. It has also been linked to a better response to the SARS Cov 2 virus and a lower incidence of autoimmune diseases.
But vitamin D doesn't stop there. It helps keep your blood sugar levels in line and prevent diabetes. It can even be an ally in the fight against cancer, by influencing the growth and death of tumor cells.
As for your heart, vitamin D is a friend of good heart rhythm , regulating blood pressure, cholesterol levels and inflammation.
And your mood ? Well, it also improves with vitamin D, as it regulates hormone production and reduces the risk of mood disorders. It even helps with concentration, learning and memory.
Finally, your skin also benefits from vitamin D, as it promotes skin cell repair and metabolism, and helps combat aging and certain skin conditions.
What happens if your vitamin D levels are low?
Well, you may feel more tired than usual, have a higher risk of fractures, infectious diseases, cardiovascular problems, certain types of cancer, autoimmune disorders, and even feel more depressed. You may also experience sleep problems, arthritis, an increased risk of diabetes, asthma, chronic pain such as fibromyalgia, and skin problems such as psoriasis.
And what causes vitamin D deficiency?
Primarily, lack of sun exposure, but also using too much sunscreen, having certain health conditions like obesity, type 2 diabetes, high blood pressure, having dark skin, being over 70 years old, or having diseases that make it difficult to absorb vitamin D like celiac disease or chronic kidney disease. Oh! And breastfed babies should also keep an eye on their vitamin D levels.
How can you prevent vitamin D deficiency?
To increase your vitamin D level, you should eat foods rich in this vitamin such as fish, eggs, dairy products, and spend time in the sun, ideally about 10-15 minutes a day if you have light to medium skin tone, and up to 40 minutes if it is darker. If you feel your skin getting hot, it is time to take shelter from the sun.
Taking vitamin D supplements can be beneficial, especially in the winter or if you can't be outdoors often. Supplements come in two types: D2 (ergocalciferol) and D3 (cholecalciferol). D3, which is found in animal products and is naturally produced by our bodies in sunlight, is more absorbable and beneficial than D2.
Some foods rich in vitamin D include cod liver oil, fish such as carp, mackerel, eel, wild salmon, free-range eggs, raw milk, and maitake and portobello mushrooms exposed to ultraviolet light. Unfortunately, many fortified foods and supplements contain the D2 form of the vitamin, which our bodies do not absorb as efficiently. D3 is estimated to be up to four times more effective in humans.
Risks and side effects
Vitamin D toxicity can occur if more than 300,000 IU are taken in one day or more than 40,000 IU daily for months without medical supervision. This can cause hypercalcemia, with symptoms such as digestive problems, fatigue, excessive thirst, and frequent urination.
People with certain conditions or taking medications such as steroids, epilepsy medications, weight loss medications, corticosteroids, diabetes medications, blood pressure medications, or calcium supplements and antacids should avoid vitamin D supplements unless directed by their doctor.
Additionally, if you have diseases such as intestinal inflammation, liver or kidney disease, or hypercalcemia, you should not supplement with vitamin D without a doctor's supervision.
References:
- Holick MF. Vitamin D: important in the prevention of cancers, type 1 diabetes, heart disease, and osteoporosis. Am J Clin Nutr. 2004;79(3):362-371.
- Bikle DD. Vitamin D metabolism, mechanism of action, and clinical applications. Chem Biol. 2014;21(3):319-329.
- Volmer DA, Mendes LR, Stokes CS. Analysis of vitamin D metabolic markers by mass spectrometry: Current techniques, limitations of the "gold standard" method, and anticipated future directions. Mass Spectrom Rev 2015;34(1):2-23.
- Sutton AL, MacDonald PN. Vitamin D: more than a "bone-a-fide" hormone. Mol Endocrinol. 2003;17(5):777-791.
- Grober U, Spitz J, Reichrath J, Kisters K, Holick MF. Vitamin D: Update 2013: From rickets prophylaxis to general preventive healthcare. Dermatoendocrinol. 2013;5(3):331-347.
- Sutton AL, MacDonald PN. Vitamin D: more than a "bone-a-fide" hormone. Mol Endocrinol. 2003;17(5):777-791.
- Grober U, Spitz J, Reichrath J, Kisters K, Holick MF. Vitamin D: Update 2013: From rickets prophylaxis to general preventive healthcare. Dermatoendocrinol. 2013;5(3):331-347.
