Vitamin D’s role in bone health and overall immunity is well established, but now scientists are finding that it’s also potentially effective in slowing the aging process, lowering the risk of colorectal cancer, and protecting against a second heart attack in people who have experienced cardiac arrest.
In the Vitamin D and Colorectal Cancer Prevention: Immunological Mechanisms, Inflammatory Pathways, and Nutritional Implications study, researchers found that the hormone enhances immune organ functions such as the spleen and lymph nodes, and boosts T-cell activity, which can defend against tumors in the body.
“Vitamin D mitigates inflammatory responses closely linked to cancer development, reducing the inflammation that contributes to CRC,” the research report states. “Vitamin D also activates mechanisms that suppress cancer cell survival, proliferation, migration, and metastasis.”
A second study called “Vitamin D3 and Marine ω-3 Fatty Acids Supplementation and Leukocyte Telomere Length” found that Vitamin D supplement intake could slow down biological aging by preserving the length of telomeres in white blood cells.The U.S. Centers for Disease Control and Prevention (CDC) describes telomeres as structures that prevent chromosomes from unraveling or sticking together.
“This study signals a major shift in how we understand vitamin D,” surgeon and cancer survivor Dr. Pete Sulack told NTD. “It’s no longer just about bones. The new information here, especially around telomeres and aging, supports the idea that simple deficiencies can have big consequences over time.”
The Cleveland Clinic includes fatigue, bone pain, muscle weakness, and mood changes like depression as symptoms of Vitamin D deficiency.Healthline found that 42 percent of U.S. adults have vitamin D deficiency.
For a natural boost in Vitamin D, physician and University of Connecticut research fellow Ali Cadili recommends eating sardines, cod, liver, oil, red meat, liver, tuna, egg yolks, and mushrooms, but adds that the fat-soluble compound is far from being a panacea.
“Vitamin D’s role in both health and immunity is well established,” Cadili told NTD. “It has also shown promise in mood and weight management. Larger trials are needed.”
Family physician Dr. Joseph Mercola warns that food rarely supplies enough vitamin D.
“Sensible sun exposure remains your best strategy,” Mercola told NTD. “Sunlight allows your skin to produce large amounts of vitamin D, and your body controls this process with far more precision than you can achieve with food alone.”
A third Vitamin D study was conducted by Intermountain Health researchers and presented at the American Heart Association Scientific Sessions 2025 last week.
The data show the rate of follow-up heart attacks was 3.8 percent in the vitamin D3 treatment group compared to 7.9 percent in the control group.
The study results were gleaned from a randomized clinical trial in which patients’ blood levels of vitamin D were monitored and vitamin D3 dosing adjusted to achieve optimal levels.
“Previous studies just gave patients supplementation without regularly checking blood levels of vitamin D to determine what supplementation achieved,” Intermountain Health cardiovascular epidemiologist and study author Heidi May said. “With more targeted treatment, when we checked exactly how supplementation was working and made adjustments, we found that patients had their risk of another heart attack cut in half.”
