Vitamin D is a hormone essential for multiple bodily functions, including immune response, inflammation regulation, and bone health. It is naturally present in some foods, added to others, and available as a dietary supplement. The skin also produces vitamin D when exposed to sunlight.
Despite its critical role, vitamin D deficiency is widespread, affecting nearly 42% of adults in the United States. The recommended daily intake for most adults is around 15 micrograms (mcg) or 2,000 international units (IU), though excessive intake may be harmful. Maintaining adequate levels is increasingly recognized as an important factor for long-term health and longevity.
Vitamin D may help lower colorectal cancer risk
A comprehensive review published in Nutrients in April 2025 examined 50 studies with over one million participants. The findings suggested that higher vitamin D levels could lower the risk of colorectal cancer and improve survival for those diagnosed with the condition.
Researchers noted that vitamin D supports immune function and may reduce inflammation. It may also have direct anticancer properties, including promoting programmed cell death and controlling abnormal cell growth. While promising, experts stress that larger, randomized clinical trials are needed to confirm these effects.
Dr. Wael Harb, MD, hematologist and medical oncologist at MemorialCare Cancer Institute, explained that maintaining optimal vitamin D levels may enhance immune surveillance and support standard colorectal cancer treatments. Personalized approaches are essential, as vitamin D requirements vary based on genetics, baseline levels, and overall health.
Could vitamin D help slow biological aging?
Telomeres are repetitive DNA sequences that protect the ends of chromosomes from damage. They naturally shorten with age, and shorter telomeres are linked to age-related diseases. A study in The American Journal of Clinical Nutrition in July 2025 suggested that vitamin D supplementation could preserve telomere length in white blood cells, potentially slowing biological aging.
The study analyzed data from the VITAL trial, which included adults taking 2,000 IU (50 mcg) of vitamin D daily. Participants receiving vitamin D experienced significantly less telomere shortening compared with those taking a placebo—an effect equivalent to roughly three years of reduced biological aging.
The benefits were more pronounced in participants without obesity and across different ethnic groups. Dr. Yoshua Quinones, MD, noted that vitamin D may do more than support bones—it could slow cellular aging and help prevent age-related diseases, highlighting its broad health potential.
Vitamin D3 supplements may reduce the risk of a second heart attack
Low vitamin D levels have long been linked to cardiovascular risks. Recent findings from Intermountain Health, presented at the American Heart Association Scientific Sessions 2025, indicate that tailored vitamin D3 supplementation may lower the risk of recurrent heart attacks.
The TARGET-D trial enrolled 630 participants, mostly males averaging 63 years old, within a month of experiencing a heart attack. Vitamin D3 doses were adjusted to reach a target serum level of 40 ng/ml. While overall cardiac events were not significantly reduced, the rate of follow-up heart attacks dropped by more than half in the vitamin D3 group compared with controls.
Dr. Cheng-Han Chen, MD, interventional cardiologist, noted that vitamin D3 may also help reduce inflammation and support blood pressure regulation. He emphasized that while more research is required, the findings highlight vitamin D’s potential as a supportive cardiovascular strategy.
Conclusion
Emerging research underscores vitamin D’s role beyond bone health, suggesting potential benefits in cancer prevention, slowing biological aging, and supporting heart health. Maintaining optimal vitamin D levels may be a simple, safe, and impactful step toward long-term wellness and longevity.
