Until recently nobody knew the answer to that question. However, a recent study (Zamora-Ros et al, J. Nutr. 143: 1445-1450, 2013) suggests that polyphenols may just help us live a bit longer. Of course, the news headlines make it sound like a sure thing, and many of the manufacturers of polyphenol-containing supplements are already citing the study as “proof” that their products will make you live forever.
Polyphenols Are Everywhere:
So, let me give you some background information before I start diving into the study.
- The term polyphenols includes some names you may recognize, such as flavonoids, isoflavones, anthrocyanidins and resveratrol, and many more that might look like the kind of names you might expect to find on a processed food label.
- Polyphenols don’t just come from red wine. There are several hundred polyphenols in edible foods. Many fruits, vegetables (including beans like soybeans) and whole grains - the kinds of foods that every expert recommends for a healthy diet - are also great sources of polyphenols.
- Most polyphenols are excellent antioxidants. Studies suggest that they may also exert antiinflammatory effects and may reduce the risk of heart disease, neurodegenerative disease and cancer. So it is not unreasonable to assume that they might enhance longevity.
An In-Depth Analysis Of The Study:
The study enrolled 807 men and women over the age of 65 (average age = 74, range = 67-81) from the Chianti region of Italy and followed them for 12 years. At the beginning of the study polyphenol intake of the participants was analyzed from a dietary recall form (polyphenol intake based on what they remembered eating) and from a 24 hour urine specimen (actual polyphenol intake).
During the 12 year follow-up, 34% of the participants died. Based on the dietary recall, there was no association between dietary polyphenol intake and mortality. However, based on urinary polyphenol content there was a 30% decrease in mortality for those with the highest dietary polyphenol intake (>650 mg/day) compared to those with the lowest polyphenol intake (<500 mg/day).
Strengths of the Study:
- This is the very first study to actually investigate the relationship between dietary polyphenols and longevity in a meaningful way. The study was well designed and well executed.
- The measurement of urinary polyphenol content is a strength of this study. Dietary recalls are often inaccurate. In fact, this study suggests that dietary recalls should probably not be used to estimate dietary polyphenol intake in future studies.
Weaknesses of the Study:
- This was a first study of its kind, and like any other first study it needs to be confirmed by additional studies.
- The study only measured associations, not cause and effect. Of course, it would be almost impossible to conduct a double blind, placebo controlled study of this duration – especially if one is using urinary excretion as a measure of polyphenol intake.
- The study did not report the dietary sources of the polyphenols, although this information was presumably available from the dietary recalls. Because the study was conducted in the Chianti region of Italy it is probably pretty safe to assume that red wine contributed to the polyphenol intake. However, people in that region of Italy also tend to consume diets rich in fruits and vegetables. Hopefully, future studies will help determine whether some polyphenols are more important for longevity than others.
The Bottom Line:
1) Eat lots of fresh fruits and vegetables. They’ll make you healthier, and you just may live longer.
2) If you like red wine, drink it in moderation. Just don’t assume that it can substitute for a healthy diet. This study measured total polyphenols, not just red wine polyphenols.
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease