Not Everyone Gets The Same Benefits From Healthy Foods & Science Now Knows Why
You eat the blueberries. Your friend eats the blueberries. You both follow a polyphenol-rich diet, load up on pomegranate, flaxseeds, and walnuts, and yet somehow the benefits don't land the same way.
New research1 published in Nutrients may finally explain why; and the answer lives in your gut.
About the study
Many of the beneficial plant compounds in foods like pomegranates, flaxseeds, and berries aren't absorbed very well on their own. Instead, they travel to the large intestine, where gut bacteria break them down into smaller compounds that your body can use more easily.
But not everyone has the same mix of gut bacteria, so not everyone gets the same benefits from these foods. That's what this recent review explored.
Researchers examined studies published between 2004 and 2026 to better understand how gut bacteria convert these plant compounds into beneficial substances, why this process differs from person to person, and what it could mean for more personalized nutrition in the future.
Your gut microbiome determines whether polyphenols actually work for you
This is where the idea of microbial metabotypes comes in.
A metabotype describes how well your gut bacteria can turn beneficial plant compounds into forms your body can actually use.
In other words, it's a way of measuring what your gut microbiome is capable of doing with the foods you eat.
The review highlights three main metabotypes that have the strongest evidence in humans:
- Urolithin producers: When you eat foods like pomegranates, walnuts, strawberries, and raspberries, your gut bacteria may convert their plant compounds into substances called urolithins, which have been linked to health benefits. Some people produce a lot of these compounds, some produce only certain types, and others don't produce any at all. The difference comes down to which gut bacteria they have.
- Equol producers: Soy contains a plant compound called daidzein that some gut bacteria can convert into equol, a more biologically active compound that interacts with estrogen in the body. Only some people have the gut bacteria needed to make this conversion. While it's more common in people who regularly eat soy, diet alone doesn't determine whether you're an equol producer.
- Lignan converters: Foods like flaxseeds, sesame seeds, whole grains, and legumes contain plant compounds called lignans. Before your body can use them, gut bacteria need to convert them into active forms. Some people's gut microbes do this efficiently, while others get much less benefit from eating the same foods.
What these metabolites actually do
Why does this matter? It could help explain why the same healthy foods don't have the same effects for everyone.
The strongest evidence is for urolithin A. Studies show that urolithin A supplements can improve muscle function and support healthier mitochondria, the structures that produce energy in your cells. Researchers still don't know whether people who naturally produce urolithin A get the same benefits from food alone.
Equol may be especially important for women. Because it interacts more strongly with estrogen, it could help explain why studies on soy and women's health often produce mixed results.
One study found that postmenopausal women who could produce equol benefited more from a polyphenol-rich diet than those who couldn't.
The evidence for lignan converters is less established, but researchers think people who convert lignans efficiently may also get more benefit from lignan-rich foods.
What shapes your metabotype
Metabotypes aren't fixed. The review identifies several factors that influence whether and how efficiently your gut converts polyphenols:
- Diet: What you eat over time helps shape your gut bacteria. But eating more polyphenol-rich foods doesn't guarantee you'll produce their beneficial compounds if you don't have the right microbes.
- Antibiotics: Antibiotics can reduce the gut bacteria responsible for making these beneficial compounds, and they don't always fully recover afterward.
- Age: Your gut microbiome changes as you get older, which may affect how well it processes certain plant compounds.
- Where you live: Regional eating habits and differences in gut bacteria mean some metabotypes are more common in certain populations than others.
- Lifestyle: Exercise, sleep, and stress all influence gut health, though researchers are still learning exactly how they affect these metabotypes.
How to feed a polyphenol-converting gut
The researchers stress that this isn't something doctors can test for yet. There aren't any standard tests to tell you which metabotype you have. Even so, the findings suggest there are practical ways to support the gut bacteria that help your body get more out of polyphenol-rich foods.
- Eat a variety of plant foods: Include foods like berries, pomegranates, walnuts, flaxseeds, soy, whole grains, legumes, tea, and cocoa to give your gut microbes a wider range of beneficial compounds to work with.
- Get enough fiber: Fiber helps feed the beneficial gut bacteria that support a healthy microbiome.
- Be consistent: Eating these foods regularly is more likely to benefit your gut than having them only once in a while.
- Avoid unnecessary antibiotics: Antibiotics can wipe out beneficial gut bacteria, so it's important to use them only when they're truly needed.
- Add fermented foods: Foods like yogurt, kefir, kimchi, and sauerkraut may help support a healthy, diverse gut microbiome.
The takeaway
Healthy foods don't always deliver the same benefits to everyone. As researchers learn more about the gut microbiome, nutrition may become less about what's on your plate and more about how your body responds to it.