Vitamin D is a fat-soluble vitamin essential for maintaining healthy bones and teeth, supporting the immune system, and aiding muscle function. Unlike most vitamins, the body can produce vitamin D when the skin is exposed to sunlight, making it unique in how it’s obtained and utilized.
People who would benefit from testing their vitamin D levels include those with limited sun exposure, older adults, individuals with darker skin, those with conditions affecting nutrient absorption like celiac or Crohn’s disease, obese individuals, and people taking medications that impact vitamin D metabolism.
The best dietary sources of vitamin D include fatty fish like salmon, trout, and mackerel, which are among the richest natural sources. Fish liver oils, like cod liver oil, are also high in vitamin D. Small amounts are found in beef liver, cheese, and egg yolks. For those who prefer plant-based options, fortified foods are a good alternative; these include dairy and plant milk, orange juice, and certain cereals.
Vitamin D3 (cholecalciferol) is generally considered more effective than vitamin D2 (ergocalciferol) because it is more potent, stays longer in the body, and is more efficiently utilized. However, the choice between D3 and D2 may depend on dietary preferences, as D3 is usually derived from animal sources and may not be suitable for vegans, while D2 is plant-based.