Previous research has linked a common vitamin to a slowdown in aging—and now a new Harvard study appears to confirm those findings.
The study, which was published in The American Journal of Clinical Nutrition, found that taking a daily vitamin D pill prevented telomeres from shortening—a hallmark of aging.
What Are Telomeres?
Telomeres, which are often compared to the plastic tips on the ends of shoelaces, act as “protective ends” on chromosome strands, according to a Harvard press release.
| Telomere Fact | Why It Matters |
|---|---|
| Protect chromosomes from damage | Longer telomeres are linked to better health |
| Shorten with age | Shorter telomeres increase the risk of poor health and mortality |
| Can be influenced by lifestyle and nutrition | Higher vitamin D levels are linked to longer telomeres |
As people age, telomeres get shorter, which can increase the likelihood of poor health and mortality, prior studies have shown. Research has also suggested that higher levels of vitamin D in the blood are linked to longer telomeres.
The Harvard Study: What the Research Found
Study Design
| Detail | Information |
|---|---|
| Participants | Approximately 1,000 people aged 50 and older |
| Groups | Divided into two groups |
| Group 1 | Took 2,000 international units (IU) of vitamin D daily |
| Group 2 | Took a placebo |
| Duration | 4 years |
Key Findings
| Finding | Result |
|---|---|
| Telomere shortening | The vitamin D group showed less than half the telomere shortening compared to the placebo group |
| Autoimmune diseases | The vitamin D group had fewer autoimmune diseases |
| Inflammation markers | The vitamin D group had reduced inflammation markers |
| Safety | 2,000 IU per day was “very safe,” without side effects or adverse events |
Lead Researcher’s Comments
Lead study author JoAnn Manson, professor of medicine at Harvard Medical School, said the findings “suggest a promising role for vitamin D in slowing a pathway for biological aging and age-related chronic disease.”
While the researchers were surprised that vitamin D was linked to such substantial protection against telomere shortening, Manson said the findings are consistent with previous evidence.
“Vitamin D tamps down inflammation, a major cause of telomere shortening and chronic diseases of aging.”
— Dr. JoAnn Manson, Harvard Medical School
What This Means for You: Vitamin D Recommendations
The question of what constitutes an “adequate” blood level of vitamin D is a “controversial topic,” according to Manson.
Current Guidelines
| Organization | Recommendation |
|---|---|
| National Academy of Medicine | 600 IU/day for adults up to age 70; 800 IU/day above age 70 |
| Endocrine Society (recent guidelines) | May be helpful for adults aged 75+, infants/children, pregnant women, and those with prediabetes |
| U.S. Preventive Services Task Force | Does not recommend universal screening or routine use of vitamin D supplements |
Dr. Manson’s Practical Advice
For anyone who has concerns about getting adequate vitamin D from their diet and/or time outdoors, Manson said that supplementation with 1000 to 2000 IU/day of vitamin D would be “very reasonable.”
“More is not necessarily better, and very high doses—such as more than 10,000 IU/day—may be associated with high blood or urine calcium levels and toxicity.”
— Dr. JoAnn Manson
