Mediterranean. DASH. MIND. Nordic. Plant-based. There is no shortage of diets promoted as the healthiest way to eat, which can make nutrition advice feel more confusing than helpful.
New research suggests there may not be one perfect formula. In a study of more than 6,000 adults in Germany, people whose diets scored higher across several different measures of healthy eating tended to show more favorable signs of biological aging. Researchers found broadly similar results in a separate group of about 1,000 adults. The study was observational, however, so it does not prove that any of these eating patterns actually slowed aging.
The findings, published in Nature Communications, may be reassuring for people who feel pressured to choose the “right” diet. Researchers compared 10 different approaches to healthy eating, including Mediterranean, DASH, MIND, Nordic and plant-based patterns.
“There is probably no single ‘correct’ diet,” said Monique Breteler, director of Population Health Sciences at the German Center for Neurodegenerative Diseases and head of the Rhineland Study. “According to our data, various dietary patterns are associated with slower aging, some more, some less.”
Researchers first looked at 6,470 adults in the Rhineland Study, whose average age was 56. Participants reported what they typically ate over the previous year, and researchers scored their diets according to how closely they matched each of the 10 eating patterns.
One of the most striking findings was how little overlap there was between the people considered the healthiest eaters under each system.
Only 18 participants ranked in the healthiest quarter for all 10 diet scores. Just 77 did so for at least nine of them. In other words, someone could eat very well by one standard without necessarily scoring highly under another.
That is partly because the diets emphasize different things. Many favor fruits, vegetables and whole grains while limiting foods such as processed meat and added sugars. But they differ in how they treat individual foods, nutrients and eating habits.
The researchers then compared diet quality with three blood-based measures designed to estimate biological aging.
These measures look at age-related changes in DNA. They are not the same as measuring how long someone will live or whether they will develop disease. Instead, they give researchers one way to estimate how the body may be aging beneath the surface.
Across most of the healthier eating patterns, better diet scores were associated with more favorable aging markers. DASH and the Nordic diet showed particularly consistent associations across all three measures. Diet scores that reflected less healthy eating generally pointed in the opposite direction.
The differences were measurable but relatively small, which is important context. This was not a case of one diet dramatically changing biological age.
Researchers also found that different diets were linked to different DNA changes, but many of those changes were tied to the same broad biological processes. That suggests several styles of healthy eating may affect the body in overlapping ways, even if the diets themselves are not identical.
The team then tested the main findings in a separate group of 1,034 adults from the EPIC-Potsdam study. The overall pattern was similar, which gives the findings more weight. Still, some of the more detailed DNA findings were less consistent between the two groups.
One unexpected result was that the association between healthier eating and aging markers appeared stronger among current smokers. The researchers saw a similar pattern in the second group, but they do not know why.
That does not mean healthy eating can undo the effects of smoking. The study was not designed to test that question, and smoking remains strongly harmful to health.
There are other limitations to keep in mind. This was an observational study, so it cannot show that diet caused the differences in aging markers. Participants reported their own diets, which is not always perfectly accurate, and other lifestyle or health factors could have influenced the results.
The study populations were also predominantly German and of European ancestry, which means the findings may not translate equally to people with different backgrounds or eating traditions. Some dietary information in the second study was collected in the 1990s, when eating habits may have differed from today.
Most importantly, the researchers did not measure whether people lived longer, stayed healthy longer or developed fewer age-related diseases. They measured biological aging markers, which can help researchers study aging but are not the same as clinical outcomes.
Still, the broader message is useful: Healthy eating may not require following one specific diet or matching someone else’s definition of the ideal plate.
As lead author Juliana Tavares put it, “You don't need a perfect diet.”
The Rhineland Study is funded by the German Center for Neurodegenerative Diseases. The research also received support from German and European public research agencies, the Alzheimer’s Association and other nonprofit sources. The EPIC-Potsdam portion received support from the German Federal Ministry of Education and Research and the State of Brandenburg through the German Center for Diabetes Research.