Updated: Aug 13, 2020
When I started this article several weeks ago, I wanted to make sure I had current information about the role vitamin D has in our health. I began my research and was blown away by the amount of information I found. I waded through articles and various studies, which led to more information. I found myself in a sea of information that seemed to go on forever! The information included in this article is just a highlight of what is available. I hope you will find this article as informative as I did.
Vitamin D is more than just a vitamin, it is a prohormone. Prohormones are substances the body converts into a hormone, like a precursor. Vitamin D and steroid hormones, also a prohormone, share many similarities: the same chemical structure, are derived from cholesterol, and resemble adrenal and sex hormones.
However, the manufacturing process differs. To manufacture vitamin D, the body uses a cholesterol compound found in the skin that combines with ultraviolet B rays from the sun to synthesize the precursor of vitamin D. This precursor then goes through a series of conversions by the liver and kidneys into its active form, calcitriol. Once converted to its active form, calcitriol is absorbed in the intestinal tract and circulates in the bloodstream, binds to receptors in the cells, and begins a biological response within the body. This response is involved in the absorption and utilization of calcium and phosphorous and helps balance their blood serum levels. People with liver and kidney disorders or intestinal disorders are at an increased risk for health issues associated with poor vitamin D, calcium, and phosphorous levels.
Vitamin D helps generate adrenaline, noradrenaline, and dopamine within the brain. Plus, it helps protect serotonin from being depleted, helps regulate heartbeats, assists healthy thyroid function, and helps protect against muscle weakness. It is crucial for children to get adequate vitamin D because it is necessary for proper growth and development of strong bones and teeth.
Low vitamin D is a serious issue in this country and is associated with many health conditions such as rickets in children, osteomalacia in adults, high blood pressure, kidney disorders, high blood sugar, increased infections and illness, heart conditions, mental disturbances including mood disorders, obesity, Multiple Sclerosis, and may increase the chance of falling. According to an article in MS Focus Magazine, there have been numerous studies involving calcitriol and lung related diseases and infections. These include upper respiratory infections, asthma, COPD and tuberculosis. Data from these studies suggest vitamin D has a protective role against inflammation.
There are many reasons for inadequate serum levels of vitamin D. Among them are: a diet low in food sources of vitamin D, avoiding sun exposure, excessive use of sunscreen, dark skin color, intestinal disorders, liver and gallbladder malfunctions, poor kidney function, and medications which interfere with vitamin D absorption. The best source of vitamin D comes from the sun, specifically UVB rays which are the most prevalent between 10 am and 3 pm. The increased use of sunscreen also affects the absorption of UVB rays since most sunscreens block these rays.
Skin pigmentation matters greatly when it comes to absorbing UVB rays; the darker the skin the less UVB is absorbed and the less vitamin D is made. These individuals may need to spend more time in the sun without sunscreen than those with lighter skin. People with darker skin color tend to be lower in vitamin D.
According to the value shown on most lab results, vitamin D levels should fall between 30 ng/ml and 100 ng/ml. However, research suggests 40 ng/ml as the minimum for D levels, with an ideal range being 60 ng/ml – 80 ng/ml. This is supported by recent findings from various studies evaluating the optimal levels of vitamin D in relation to various health factors. According to Heike A Bishoff-Ferrari, these conditions include: “bone mineral density (BMD), lower extremity function, dental health, fall risks, nursing home admissions, fractures, cancer prevention and incident hypertension.” Serum vitamin D is measured in ng/ml on labwork while researchers tend to use nmol/L. They are not interchangeable so its important to pay attention to those letters when talking about serum D levels or you could be comparing apples to oranges!
Vitamin D levels are easy to monitor and adjust. It involves a simple conversation with your doctor and an inexpensive blood test. Depending on your serum levels, you may simply need to spend some extra time soaking up the rays, or you may need to supplement your diet.
Bischoff-Ferrari HA. Optimal serum 25-hydroxyvitamin D levels for multiple health outcomes. Adv Exp Med Biol. 2008;624:55-71. doi:10.1007/978-0-387-77574-6_5