A large study of nearly 9,000 older adults found that taking daily multivitamin supplements didn’t prevent high blood pressure or lower blood pressure readings for most people over 3+ years. However, the vitamins did seem to help people who had poor diets to begin with. This suggests that multivitamins might fill nutritional gaps but aren’t a magic bullet for heart health in people who already eat reasonably well.

The Quick Take

  • What they studied: Whether taking daily multivitamin supplements could prevent high blood pressure in older adults who didn’t have it yet
  • Who participated: Nearly 9,000 healthy older adults (women 65+, men 60+) without high blood pressure at the start
  • Key finding: About 23% of people developed high blood pressure whether they took vitamins or fake pills - no meaningful difference between groups
  • What it means for you: If you already eat a decent diet, multivitamins probably won’t help your blood pressure, but they might help if your diet is poor

The Research Details

This was a gold-standard study where researchers randomly gave half the participants real multivitamins and half got identical-looking fake pills (placebos). Neither the participants nor researchers knew who got what until the end. The study followed people for about 3.4 years on average, checking in regularly to see who developed high blood pressure. Some participants also had their blood pressure measured directly at clinics or at home by trained technicians.

This type of study design is considered the most reliable way to test whether a treatment actually works because it eliminates bias and other factors that might skew results. The large size and long follow-up period make the findings more trustworthy than smaller, shorter studies.

This was a well-designed study with a large sample size, proper randomization, and long follow-up. The fact that it was published in a respected medical journal and registered beforehand adds to its credibility. However, blood pressure diagnosis relied mainly on self-reports rather than direct measurements.

What the Results Show

Out of nearly 9,000 participants who started without high blood pressure, about 23% in both groups developed it during the study period. The multivitamin group had a tiny bit lower risk (22.9% vs 23.6%), but this difference was so small it could easily be due to chance. When researchers looked at actual blood pressure numbers in smaller groups, they found virtually no difference - both groups saw their blood pressure rise by about the same amount over two years (4.4 vs 4.5 mmHg).

The most interesting finding came when researchers looked at people’s diets. Among participants who had poor-quality diets (measured by how closely they followed a Mediterranean-style eating pattern), multivitamins appeared to reduce high blood pressure risk by about 19%. However, for people who already ate well, multivitamins actually seemed to slightly increase the risk. The vitamins also appeared more helpful for people who started with completely normal blood pressure readings.

This study contradicts some smaller previous studies that suggested multivitamins might help lower blood pressure. However, those earlier studies were much smaller and shorter. This large, long-term study provides more reliable evidence that multivitamins don’t have broad blood pressure benefits for most people.

The main limitation is that high blood pressure diagnosis relied mostly on participants reporting what their doctors told them, rather than standardized measurements. The study also only included older adults, so results might not apply to younger people. Additionally, the subgroup analyses looking at diet quality weren’t planned from the beginning, so those findings need confirmation in future studies.

The Bottom Line

Don’t expect multivitamins to prevent high blood pressure if you already eat a reasonably healthy diet. Focus on proven strategies like eating more fruits and vegetables, reducing salt, exercising regularly, and maintaining a healthy weight. If your diet is poor, a multivitamin might provide some benefit, but improving your actual food choices would be more effective.

Older adults hoping multivitamins will protect their heart health should temper expectations. People with poor diets might see some benefit, but those eating well likely won’t. Anyone already taking blood pressure medication should continue as prescribed and not expect vitamins to replace proper treatment.

This study followed people for over 3 years, suggesting that if multivitamins were going to help blood pressure significantly, the effects would have shown up by then. Don’t expect quick results from vitamin supplementation for blood pressure control.

Want to Apply This Research?

  • Track your daily blood pressure readings and note whether you’re taking multivitamins, along with diet quality scores based on fruits, vegetables, and whole grains consumed
  • Focus on improving diet quality through whole foods rather than relying on supplements - log Mediterranean diet components like olive oil, fish, nuts, and vegetables
  • Monitor blood pressure trends over months while tracking both supplement use and dietary patterns to see what actually correlates with improvements in your personal data

This information is for educational purposes only and should not replace medical advice. Always consult your healthcare provider before starting or stopping any supplements, especially if you have high blood pressure or take medications. Do not use multivitamins as a substitute for prescribed blood pressure treatments.