Researchers gave 99 older adults either berry supplements or a placebo for 24 weeks to see if the supplements would change their gut bacteria and help their memory. They found that the berry supplements did change the types of bacteria in people’s guts, but the changes were different depending on each person’s weight and their starting gut bacteria makeup. Interestingly, while the supplements changed the bacteria, they didn’t improve memory or thinking skills. This suggests that one-size-fits-all supplements might not work the same way for everyone, and doctors may need to personalize recommendations based on individual differences.

The Quick Take

  • What they studied: Whether taking anthocyanin supplements (natural compounds from berries) would change the bacteria in people’s stomachs and improve their memory in older adults with early thinking problems.
  • Who participated: 99 people aged 60-80 years old who had mild memory problems or heart/metabolism health concerns. Half got real berry supplements, half got fake pills (placebo) for 24 weeks.
  • Key finding: The berry supplements did change which bacteria lived in people’s guts, but the changes were different for different people. People with healthy weight had different bacteria changes than people with obesity. However, the supplements did not improve memory or thinking abilities.
  • What it means for you: Berry supplements may affect your gut bacteria, but the effect depends on your weight and your current gut bacteria makeup. These supplements alone may not boost memory, and a personalized approach based on your individual health profile might be more effective than taking the same supplement as everyone else.

The Research Details

This was a randomized controlled trial, which is considered one of the strongest types of research. Researchers randomly assigned 99 older adults to receive either anthocyanin capsules (made from berry compounds) or identical-looking placebo pills for 24 weeks. Neither the participants nor the researchers knew who was getting the real supplement or the fake one, which helps prevent bias. The researchers collected stool samples to analyze the bacteria using advanced genetic testing that identifies different bacterial species. They also tested participants’ memory and thinking abilities at the start and end of the study.

The researchers divided participants into groups based on their starting gut bacteria patterns (called enterotypes), their body weight (BMI), and their age. This allowed them to see if the supplement worked differently for different types of people. This approach is important because it recognizes that people’s bodies are different and may respond differently to the same treatment.

Understanding how supplements affect different people is crucial because it shows that nutrition isn’t one-size-fits-all. By studying how factors like weight and existing gut bacteria influence supplement effectiveness, researchers can eventually help doctors recommend the right supplements for the right people. This personalized approach could make health interventions much more effective.

This study has several strengths: it was randomized (reducing bias), double-blind (neither participants nor researchers knew who got the real supplement), and included a placebo control group (allowing fair comparison). The sample size of 99 is reasonable for this type of research. The researchers used advanced genetic sequencing to identify bacteria, which is more accurate than older methods. However, the study only lasted 24 weeks, so we don’t know about long-term effects. The study focused on older adults with specific health concerns, so results may not apply to younger, healthier people.

What the Results Show

The anthocyanin supplements changed the composition of gut bacteria in measurable ways. However, these changes were not the same for everyone—they depended heavily on each person’s starting gut bacteria pattern and body weight. People with healthier, more diverse gut bacteria at the start showed modest but consistent changes when taking the supplements. People with less healthy gut bacteria patterns showed bigger changes, but these changes were less organized and predictable.

When researchers looked at body weight, they found different bacteria responded in healthy-weight people versus people with obesity. In healthy-weight individuals, bacteria called Oscillibacter and Ezakiella increased. In people with obesity, different types of bacteria (Bacteroidota) increased instead. Both groups showed a decrease in Firmicutes bacteria. These findings suggest the supplement’s effect depends on your starting point.

Age also mattered. Different age groups within the study showed different bacterial changes, suggesting that older versus younger participants (within the 60-80 age range) responded somewhat differently to the supplement.

The study measured overall bacterial diversity (alpha diversity) and found no significant changes from the supplements. The researchers also tested participants’ memory and thinking abilities, which is important because many people take supplements hoping to improve brain function. However, the supplements did not improve episodic memory (remembering specific events) or other cognitive measures. Additionally, the changes in gut bacteria did not appear to be connected to any cognitive improvements, suggesting the bacteria changes alone weren’t responsible for brain benefits.

Previous research has shown that anthocyanins (berry compounds) can influence gut bacteria in laboratory and animal studies. This human study confirms that anthocyanins do affect real human gut bacteria, which is important validation. However, while some earlier research suggested gut bacteria changes might improve thinking and memory, this study found no such connection. This suggests that changing bacteria alone may not be enough to improve brain function, or that the specific bacteria changes from anthocyanins don’t target the bacteria most important for brain health.

The study lasted only 24 weeks, so we don’t know if effects continue, increase, or decrease over longer periods. The study included only older adults (60-80 years) with specific health concerns, so results may not apply to younger people or those without memory problems. The supplement didn’t improve memory in this study, which limits its practical value. The study was relatively small (99 people), so some findings might not hold up in larger groups. The researchers didn’t measure whether participants actually followed the supplement schedule perfectly, which could affect results.

The Bottom Line

Based on this research, anthocyanin supplements may change your gut bacteria composition, but the effect is highly individual and depends on your weight and current gut bacteria makeup. The supplements did not improve memory in this study, so don’t expect them to boost brain function. If you’re interested in gut health, focus on proven approaches like eating whole berries, increasing fiber intake, and maintaining a healthy weight. Confidence level: Moderate (the study was well-designed but showed no cognitive benefits).

This research is most relevant to older adults (60+) concerned about memory and thinking, people interested in personalized nutrition, and healthcare providers looking to understand how supplements affect different populations. People should NOT use this as a reason to expect memory improvement from anthocyanin supplements. This research is less relevant to younger, healthy individuals without cognitive concerns.

The study lasted 24 weeks to see bacterial changes, which occurred relatively quickly. However, since the supplements didn’t improve memory or thinking in this timeframe, don’t expect cognitive benefits even with longer use. If you’re taking anthocyanin supplements for gut health reasons, you might see bacterial changes within weeks, but meaningful health improvements may take months or may not occur at all.

Want to Apply This Research?

  • Track daily anthocyanin intake (berries, supplements) and monitor digestive symptoms (bloating, regularity, energy levels) weekly. Note your weight and any changes in digestion patterns to see if you notice individual responses similar to what the study found.
  • Instead of relying on supplements alone, increase whole berry consumption (blueberries, blackberries, raspberries) 3-5 times per week. Log these in your nutrition app alongside other fiber sources and digestive notes to track your personal response, since the study shows responses are highly individual.
  • Create a monthly check-in tracking: (1) digestive comfort and regularity, (2) energy levels, (3) weight stability, and (4) any cognitive changes you notice. This personalized tracking helps you determine if anthocyanins are working for YOUR body specifically, since the research shows effects vary greatly by individual.

This research shows that anthocyanin supplements change gut bacteria in individual ways but did not improve memory or thinking in this study. Do not use anthocyanin supplements as a treatment for memory problems or cognitive decline without consulting your doctor. This study involved older adults with specific health concerns; results may not apply to other populations. Always speak with a healthcare provider before starting any supplement, especially if you take medications or have existing health conditions. This summary is for educational purposes and should not replace professional medical advice.