An estimated 42% of American adults are vitamin D deficient. And a 2025 NIH and Harvard-backed study of 25,871 people just found that may be costing them something they can't get back — time.
Researchers in the VITAL trial measured telomeres: the protective caps on your DNA that shorten every year as you age. When telomeres get too short, cells stop functioning properly. It's one of the most reliable markers of biological aging that scientists have.
The people taking vitamin D daily lost their telomeres significantly more slowly.
The difference was equivalent to nearly three years of biological aging — prevented.
That's a major finding and this wasn't a small study. It was one of the largest and most rigorously designed nutrition trials ever conducted, and the results held up across age groups, genders, and ethnicities.
Here's what makes it personal:
Vitamin D deficiency rarely causes obvious symptoms. Most people have no idea they're low until the effects have been quietly accumulating for years. The body produces vitamin D through sun exposure, but indoor lifestyles, sunscreen use, and aging skin all reduce that production significantly. And synthetic vitamin D found in many supplements isn't absorbed equally well by everyone.
Longevity sources its vitamin D alongside 21 other essential vitamins and minerals from real food ingredients — broccoli, kale, spinach, kelp, and chlorella — as part of a nutritional foundation designed to support healthy aging from the inside out.
Because aging is inevitable. But how fast it happens may be more within your control than you think.
References
Buring JE, et al. (2025). "Vitamin D supplementation and telomere length: findings from the VITAL randomized trial." American Journal of Clinical Nutrition. Available via NIH.