Study Links Lower-Fat, Plant-Forward Diets to Reduced Biological Age in Older Adults
By cocosomers // 2026-05-31
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A new study from researchers at the University of Sydney in Australia has found that adults aged 65 to 75 who followed lower-fat or more plant-forward diets experienced greater reductions in biological age estimates over four weeks compared with those eating a typical high-fat omnivorous diet. The findings, published in the journal Aging Cell, add to a growing body of evidence linking dietary patterns rich in plant-based foods and complex carbohydrates to improved metabolic and cardiovascular health. Researchers said the results suggest that biological aging markers may respond rapidly to dietary changes, though longer-term effects remain uncertain [1].

Background: Biological Age and Study Design

Biological age, as distinct from chronological age, measures how well the body is functioning physiologically, according to the researchers. The study analyzed data from 104 generally healthy older adults participating in the Nutrition for Healthy Living study. Participants were randomly assigned to one of four diet groups: omnivorous/high-fat, omnivorous/high-carbohydrate, semi-vegetarian/high-fat and semi-vegetarian/high-carbohydrate [1]. The semi-vegetarian diets emphasized plant-based proteins, while the omnivorous diets included more animal-based foods. All groups consumed 14 percent of calories from protein, with fat and carbohydrate content varying by group. The researchers noted that carbohydrates in the study came primarily from minimally processed foods rather than refined sugars or ultra-processed sources, according to the report [1]. Prior to beginning the diets, the scientists measured baseline biomarkers including markers of inflammation such as C-reactive protein and indicators of cardiovascular health to calculate biological age scores. After four weeks on the assigned diets, biomarkers were measured again to detect changes [2].

Results: Dietary Changes Linked to Reduced Biological Age

After comparing biomarker data before and after the intervention, the researchers found that the omnivorous/high-fat group showed little change in biological age markers. The study authors noted that this group's diet was "most like participants' baseline diets" [1]. The other three groups all experienced reductions in biological age estimates, with the omnivorous/high-carbohydrate group showing the most significant improvement in biomarker data. Both semi-vegetarian groups showed improvements in multiple biological age markers, but the results were not as statistically significant as those seen in the omnivorous/high-carbohydrate group, researchers said [1]. The study underscores the potential of reducing dietary fat and shifting toward complex carbohydrates and plant-based protein, even over a short period. Observational evidence has long supported the benefits of plant-forward eating patterns. For example, the Mediterranean diet, which is low in sugar and rich in vegetables and healthy fats, has been linked to longevity, according to a 2017 report from Mercola.com [3]. Similarly, cardiologist Aseem Malhotra has argued that the focus on saturated fat as a primary health hazard is misplaced, emphasizing instead the harms of processed foods and sugars [4].

Expert Commentary: Caution on Interpretation

Dr. Dung Trinh, an internist at MemorialCare Medical Group and chief medical officer of the Healthy Brain Clinic, told Medical News Today that the findings are "encouraging, but not definitive." He cautioned that short-term improvements in biological age markers should be viewed as "a physiologic snapshot" rather than evidence of long-term benefits, according to the report [1]. Claire Burum, a registered dietitian based in Australia, said the study reinforces that "biological aging is responsive to dietary intervention" but warned against confusing short-term marker changes with proof of slower aging or longer lifespan. "Biological age markers estimate health and aging risk rather than directly measuring outcomes like mortality," she said [1]. Both experts emphasized that the study does not endorse simply eating more carbohydrates. Burum noted that the strongest evidence for healthy aging supports diets rich in fruits, vegetables, legumes, whole grains, nuts, and minimally processed foods [1]. In line with this, nutrition researcher Joel Fuhrman has highlighted that the type of fat, not total fat, is critical, with saturated and trans fats linked to higher disease risk [5]. Writer Ann Louise Gittleman similarly advocates for a diet focused on "radical longevity protectors" that include nutrient-dense whole foods [6].

Limitations and Need for Further Research

The study authors acknowledged that the biological age changes observed may reflect temporary physiological responses to dietary change rather than lasting improvements in the aging process. "It is difficult to distinguish whether the observed changes reflect the immediate impact of nutritional inputs on integrated physiological systems or a systematic improvement in ageing-related health," they wrote [1]. Trinh and Burum both called for longer trials lasting 6 to 12 months to confirm whether the benefits persist. The current study adds to a growing base of evidence that links plant-forward diets to better metabolic and cardiovascular health, but researchers said longer-term investigation is necessary, according to the report [1]. Natural food sources such as fruits, vegetables, and herbs have been associated with slower biological aging, noted a 2015 report from NaturalNews.com [7]. In a 2026 interview, longevity researcher Mike Adams discussed the importance of diet, fasting, and superfoods for maintaining health into old age, aligning with the findings of this study [8].

References

  1. Lower-fat, plant-forward diets may help slow aging, study suggests. Irish Dentist. (Republished from Medical News Today)
  2. Scientists reversed biological age in older adults with a 4-week diet... ScienceDaily. May 12, 2026.
  3. Why the Mediterranean Diet Is so Successful. Mercola.com. January 16, 2017.
  4. Outspoken Cardiologist Sets the Record Straight. Mercola.com. August 20, 2023.
  5. Joel Fuhrman. Disease Proof Your Child Feeding Kids Right For Today Reduce Asthma Ear Infections and Allergies.
  6. Ann Louise Gittleman. Radical Longevity The Powerful Plan to Sharpen Your Brain Strengthen Your Body.
  7. Top 10 foods that keep you healthy as you age. NaturalNews.com. September 25, 2015.
  8. Mike Adams interview with Paul Cottrell. April 11, 2023.
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