What does vitamin D do for the body?

What does vitamin D do for the body?

 

This essential nutrient is called a vitamin, but dietary vitamin D is actually a precursor hormone — the building block of a powerful steroid hormone in your body called calcitriol. It’s been known for many years that vitamin D is critical to the health of our bones and teeth, but deeper insight into D’s wider role in our health is quite new.
Vitamin D works in concert with other nutrients and hormones in your body to support healthy bone renewal — an ongoing process of mineralization and demineralization which, when awry, shows up as rickets in children and osteomalacia (“soft bones”) or osteoporosis (“porous bones”) in adults.
Researchers are discovering that D also promotes normal cell growth and differentiation throughout the body, working as a key factor in maintaining hormonal balance and a healthy immune system. It appears that calcitriol actually becomes part of the physical composition of cells, assisting in the buildup and breakdown of healthy tissue — in other words, regulating the processes that keep you well.
 
What’s more, evidence from studies tracking the prevalence of disease by geography and nationality shows clear links between vitamin D deficiency and obesity, insulin resistance, heart disease, certain cancers, and depression. Since most of these problems take many years to manifest, vitamin D deficiency has been overlooked by many providers for a very long time. I test all of my patients, and have been surprised to find that more than 85% come up with a vitamin D deficiency.
Your body can’t create vitamin D on its own. Instead, it’s designed to make it through sun exposure. In theory, you can make an ample supply of vitamin D with as little as a couple of hours per week in the sun — provided the UVB rays are strong enough. You can also ingest D through food, especially fatty fish like wild–harvested salmon. Plus, lots of foods are fortified nowadays, so vitamin D deficiency should be an easy problem to solve, right? But the truth is, we’re just not getting enough, and so many of us aren’t even close.

Summary

Vitamin D deficiency is a common condition that affects a significant number of Australians. Vitamin D is important in the maintenance of bone health, and deficiency leads to osteomalacia and contributes to fragility fractures. Deficiency has also been implicated in a wide variety of extra-skeletal conditions. Vitamin D can be easily assessed in patients by measuring serum 25-hydroxyvitamin D. Replacement of vitamin D needs to be tailored for each patient and depends on the severity of the deficiency. Toxicity is unlikely with vitamin D when it is administered as cholecalciferol as it has a wide safety window.The adequacy of replacement should be monitored and in cases of persistently low concentrations, malabsorptive conditions (especially coeliac disease) should be excluded.