One in five Americans regularly reaches for vitamin D supplements, yet most are unaware that they’re taking not just a vitamin – but a hormone.
While renowned for bolstering bone strength and immune health, vitamin D’s story is not straightforward. A blend of myth and established science invites a closer look into its true nature and impact.
Vitamin D: Understanding Its Dual Role
Vitamin D stands apart in the world of nutrients. It’s a sun-sourced substance acting as both a nutrient and a hormone. This dual role is significant, as hormones, which orchestrate many bodily functions, aren’t typically taken as supplements like vitamins.
Endocrinologist Dr. Michael Holick, a leading vitamin D expert, tells sources, “The body more effectively utilises vitamin D when it’s naturally synthesised from sunlight, compared to standard supplement doses.”
This difference is key to understanding vitamin D’s health role and the complexities of supplementing a hormone.
Unlike most nutrients, the hormonal nature of vitamin D means it has a broader systemic impact, influencing not just bone health but also immune function, cell growth, and inflammation control. This understanding is crucial in guiding medical approaches to its use, including the potential risks and benefits of supplementation.
Beyond Bone Health
Vitamin D is more than just a bone health and immune system booster. Its multifaceted role in the body impacts everything from mood regulation to cardiovascular health.
At its core, vitamin D is vital for calcium absorption in the gut, and essential for bone strength and health. “Without enough Vitamin D, the body can only absorb 10–15 percent of calcium,” Dr. Alex Foxman, a leading internist and preventive care specialist, told sources. Insufficient calcium can result in weaker bones and heightened fracture risks.
Moreover, vitamin D is pivotal for immune health. Dr. Holick observes, “Vitamin D receptors are in almost every cell, including immune cells.” Proper levels are vital for a balanced immune response and preventing autoimmune disorders.
Dr. Nathan Goodyear, an integrative cancer physician and director of Brio Medical, an integrative cancer treatment center in Scottsdale, Arizona, stresses vitamin D’s essential role in immune functionality and its influence on chronic diseases, like cancer. He explains, “The immune system does not work well if vitamin D is not optimal,” emphasizing its role in cancer, where immune strength is crucial.
Recent research, including melanoma studies, indicates that vitamin D supplementation can enhance treatment responses and prolong survival in cancer patients, even with currently insufficient daily dosage recommendations.
Vitamin D also plays a significant role in heart health.
Studies have linked low vitamin D levels to an elevated risk of heart disease. Those deficient in vitamin D are more likely to experience hypertension, heart failure, and strokes.
Mental health is another arena where vitamin D plays a significant role.
Kimberly Parker, a licensed psychotherapist, told sources, “There’s a clear link between low levels of vitamin D and higher incidences of depression and mood disorders.”
It also affects seasonal affective disorder, a depression variant tied to seasonal changes. “I have seen my patients have a reduction of symptoms once they started to become consistent with their vitamin D intake,” she reports.
Vitamin D’s Journey From Sunlight to Cellular Powerhouse
Vitamin D is vital for health, existing in different forms, each taking a unique path within our body. Grasping these forms is key to understanding how vitamin D functions in our system.
Once vitamin D enters our body through sun, diet, or supplements, it transforms to become active.
First, it changes into calcidiol in the liver, then into calcitriol, its active form, in the kidneys. Dr. Holick clarifies, “Calcitriol is the form that our body can use to perform various functions.”
Interestingly, each form of vitamin D undergoes a similar conversion process in the body. The source of vitamin D might differ, but the pathway it takes in our bodies converges.
The conversion efficiency of vitamin D can differ. The skin’s capacity to produce vitamin D3 diminishes with age and is influenced by skin pigmentation, geographical location, and lifestyle.
