The use of dietary supplements—particularly multivitamins—continues to stir debate. A common and valid concern is that these supplements are not studied with the same rigor as pharmaceuticals. While the evidence base for vitamins, minerals, and botanicals is growing, many studies still fall short in terms of randomization, sample size, or long-term follow-up.

That said, recent well-designed trials are beginning to show tangible benefits from multivitamin use, including modest reductions in cancer and cataract risk (Christen et al., 2014). These findings invite a thoughtful reexamination of the role multivitamins may play in preventive health strategies for aging populations.

Multivitamins and Biological Aging: A Growing Body of Evidence

In a recent Medscape presentation, Dr. JoAnn Manson, Professor of Medicine at Harvard Medical School and Brigham and Women’s Hospital, shared new findings from a randomized trial investigating the effect of multivitamins on biological aging.

Study Overview:

• Population: ~950 older adults (≥60 years; mean age 70.2)
• Design: Daily multivitamin vs. placebo
• Follow-Up: Blood samples at baseline, 1 year, and 2 years
• Biological aging measured using five epigenetic clocks:
  • Two first-generation clocks
  • Two second-generation clocks: PCGrimAge and PCPhenoAge
  • One pace-of-aging clock: DunedinPACE

Key Findings:

• All five clocks showed slower biological aging in the multivitamin group.
• PCGrimAge and PCPhenoAge demonstrated 10–20% slower aging, equivalent to ~4 months of aging averted over 2 years.
• Stronger effects were observed in participants with accelerated aging at baseline.

While some degree of user bias is inevitable—health-conscious individuals are more likely to take supplements—these findings raise a more important issue: Are we overestimating the nutrient density of modern food?

Why Even a “Healthy Diet” May Fall Short

Defining a “healthy diet” is complex—and achieving it may be harder today than ever. A growing body of evidence suggests that modern agricultural practices have led to a notable decline in the nutrient content of fruits and vegetables.

Contributing Factors to Nutrient Decline:

1. Soil Depletion
   Intensive monoculture farming depletes minerals from soil, reducing plant uptake of nutrients.
   Davis et al. (2004):

• Calcium ↓16%, Iron ↓15%, Phosphorus ↓9%
• Vitamin C ↓20%, Riboflavin ↓38%, Protein ↓6%
  J Am Coll Nutr. 2004;23(6):669–682

2. Selective Breeding for Yield & Shelf Life
   Modern crops are bred for productivity, not nutrient density.
   White & Broadley. J Hort Sci Biotechnol. 2005;80(6):660–667
3. The “Dilution Effect”
   As yields increase, nutrient concentration is diluted in plant tissues.
   Jarrell & Beverly. Adv Agron. 1981;34:197–224
4. Storage and Transport Losses
   Long supply chains degrade vitamins—especially vitamin C and B-complex.
   Rickman et al. J Sci Food Agric. 2007;87(6):930–944

Supporting Data: Nutrient Decline Over Time

US Crops (1950–1999)

• Calcium ↓16%, Iron ↓15%, Vitamin C ↓20%, Riboflavin ↓38%
  Davis et al., 2004

UK Crops (1930s–1980s)

• Calcium ↓19% (vegetables), Copper ↓76%, Magnesium ↓35%
  Thomas, D. Nutr Health. 2003;17(2):85–115

Dilution Effect in High-Yield Farming

• Nutrient concentration can decline 20–30% with doubled yield
  Jarrell & Beverly, 1981

Clinical Takeaway

Even with the best dietary intentions, modern food may no longer provide the full spectrum of essential nutrients, especially for older adults. When combined with age-related changes in absorption and metabolism, this reality supports the judicious use of daily multivitamins as part of a broader preventive care strategy.

Evidence is mounting—not only for modest reductions in cancer and cataract risk, but now for slowing biological aging. As always, individual patient context and nutritional status should guide our recommendations.

References 

Christen, W. G., Glynn, R. J., Manson, J. E., MacFadyen, J., Bubes, V., Schvartz, M., Buring, J. E., Sesso, H. D., & Gaziano, J. M. (2014). Effects of multivitamin supplement on cataract and age-related macular degeneration in a randomized trial of male physicians. Ophthalmology, 121(2), 525–534. 

Davis, D. R., Epp, M. D., & Riordan, H. D. (2004). Changes in USDA food composition data for 43 garden crops, 1950 to 1999. Journal of the American College of Nutrition, 23(6), 669–682. https://doi.org/10.1080/07315724.2004.10719409

Jarrell, W. M., & Beverly, R. B. (1981). The dilution effect in plant nutrition studies. Advances in Agronomy, 34, 197–224. 

Rickman, J. C., Barrett, D. M., & Bruhn, C. M. (2007). Nutritional comparison of fresh, frozen and canned fruits and vegetables. Part 1. Vitamins C and B and phenolic compounds. Journal of the Science of Food and Agriculture, 87(6), 930–944. 

Thomas, D. (2003). A study on the mineral depletion of the foods available to us as a nation over the period 1940 to 1991. Nutrition and Health, 17(2), 85–115. https://doi.org/10.1177/026010600301700201

White, P. J., & Broadley, M. R. (2005). Historical variation in the mineral composition of edible horticultural products. Journal of Horticultural Science & Biotechnology, 80(6), 660–667.