Metabolism & drugs

A tea compound was linked to slower aging in a US survey and helped worms live longer

In about 11,000 American adults, people whose diet included EGCG, a compound found mainly in tea, had blood tests that looked slightly younger and a lower risk of dying over eight years. In worms and mouse liver cells, EGCG worked through peroxisomes, small fat-burning compartments of the cell. The human part is observational, and the mechanism was shown only in worms and cells.

Tea contains a family of plant compounds called catechins. The most abundant one in green tea is epigallocatechin gallate, or EGCG. Lab studies have suggested it might slow some signs of aging, but it has been unclear whether people who eat and drink more of it actually age more slowly, and how it would work.

This study combined both questions. It looked for a link in a large US health survey, then tested EGCG in worms and in liver cells to find a mechanism. The answer pointed to peroxisomes: small bubbles inside cells that break down very long fatty acids, the building blocks of fats, which are too long for the cell's main power plants, the mitochondria, to handle directly. Peroxisomes are known to work less well with age.

What they did

In people. The team used the National Health and Nutrition Examination Survey (NHANES), a nationally representative US survey. 10,977 adults had reported everything they ate and drank on two separate days, and gave blood. From the diet records, the researchers estimated each person's intake of six catechins; EGCG stood out as the one most tied to biological age, so they focused on it. Almost all of it (over 99%) came from tea; black tea was the largest single source.

People were split into three groups of similar size: no EGCG at all (35.1%), low intake and high intake. Biological age was measured with PhenoAge, a score built from age and nine routine blood tests, such as blood sugar, kidney function and markers of inflammation. "PhenoAge acceleration" means being biologically older or younger than expected for your age. The team also checked who died by the end of 2019.

In worms and cells. They gave EGCG to the tiny roundworm C. elegans, which lives only a few weeks, and to mouse liver cells that had been pushed into an aged, non-dividing state with a cancer drug. Then they switched off peroxisome genes to see whether the effects disappeared.

What they found

  • Slightly younger blood tests. Compared with people who took in no EGCG, the low and high groups had PhenoAge acceleration lower by about half a year (0.53 and 0.62 years).
  • Lower risk of dying. Over a mean follow-up of 7.9 years, 1,276 people died. Both EGCG groups had a 17–18% lower death rate than non-consumers, after accounting for lifestyle and health. That translated into an estimated 1.2 to 1.3 extra years of remaining life from age 45.
  • Longer-lived worms. EGCG extended worm lifespan by up to about 11%, and older treated worms moved and fed better.
  • Peroxisomes were needed. EGCG raised the number of peroxisomes and the activity of the enzymes inside them that shorten long fatty acids, and lowered levels of very long fatty acids. When the team blocked key peroxisome genes, the lifespan gain vanished.
  • Fewer aged cells. In the mouse liver cells, EGCG reduced the markers of cell aging, and this effect weakened when peroxisome genes were switched off.

What to keep in mind

  • A link in people, not proof. The survey part is observational: tea drinkers differed from others in many ways (age, income, physical activity, smoking), and the authors say residual confounding remains possible.
  • Very small amounts. Typical intake was tiny: the median daily intake was 0.16 milligrams, and the low and high groups were split at just 1.42 milligrams. The low and high groups looked almost the same, so the data don't show a clear "more is better" pattern.
  • Diet recalls are rough. Two days of reported eating may not reflect normal habits, and the EGCG content of foods is itself an estimate.
  • Worms and cells are not people. The authors stress that the lab results should not be directly applied to human aging, and that the doses used there can't be translated into human intakes.
  • Not a supplement study. No one was given EGCG in this study, and it says nothing about EGCG pills.

Why it matters

The study links an everyday dietary compound to slightly slower biological aging and longer survival in a large, nationally representative group, and it offers a concrete mechanism for testing: keeping the cell's peroxisomes working, so long fatty acids don't pile up. Peroxisomes get less attention than mitochondria in aging research, and this work suggests they deserve more. Whether tea or EGCG actually slows aging in people would need trials and long-term studies with better measures of intake, as the authors note.

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