Protein-rich or high-fiber: which breakfast is best for our gut microbiota?
Are you more of an eggs person or an oatmeal person in the morning? Researchers have tested two approaches in overweight adults. Weight loss, appetite, gut microbiota... the findings reveal some unexpected differences.
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About this article
Breakfast is an essential meal for anyone seeking to lose weight or stay in shape.
But should we prioritize protein (dairy, eggs, ham, etc.), known for its satiating effect, or dietary fiber (oatmeal, whole-grain bread, fruit, etc.) which is beneficial for gut health?
50% Diet accounts for more than 50% of the variability of the microbiota. ¹
Hearty, balanced, but distinct
To try to find some answers, British researchers 2 put 19 overweight or obese adults on a balanced but low-calorie diet for 28 days. This diet was based on hearty breakfasts (45% of daily calories) and light dinners (a mere 20%).
For 28 days, each participant followed:
- a high-fiber diet (30 g per day, with 15% of calories from protein)
- then a high-protein diet (30% of calories from protein, with less than 15 g of fiber per day)
- or vice versa, with a washout period in between.
The scientists measured changes in weight, satiety, blood markers, and more, and collected stool samples from the participants to analyze their microbiota. The results?
The Mediterranean diet: good for the body, good for the heart
Weight loss achieved
In both groups, weight loss was significant: nearly 5 kg in the fiber group and nearly 4 kg in the protein group. Blood pressure, fasting blood sugar, blood lipid levels, and other markers also decreased significantly, reflecting a marked improvement in the participants’ health.2
However, satiety was more pronounced in the protein group, suggesting that protein may be useful for regulating appetite outside of a diet or for sustaining energy levels during periods of restriction.
And the gut microbiota? That’s a different story...
Sugar added to foods/beverages (by the manufacturer, the cook, or you) plus sugar naturally present in honey, syrups, fruit juices, and juice concentrates.
Fats found mainly in animal products (butter, cream, cheese, fatty meats) and also in certain vegetable fats (e.g., coconut/palm oil). Limit their intake.
Industrially-modified fats (often through “hydrogenation”) found mainly in certain ultra-processed foods. The WHO recommends a very low intake.
Fats found primarily in vegetable oils (olive, rapeseed, sunflower, etc.), nuts/seeds, and fatty fish. These are the fats that should replace saturated or trans fats.
Fiber, the microbiota’s ally
An analysis of bacterial strains showed that, compared to the fiber diet, the protein diet led to a significant loss of diversity and a decrease in the abundance of bacteria known for their beneficial effects: bifidobacteria and butyrate-producing bacteria, such as Faecalibacterium, Roseburia, and Anaerostipes.
According to previous studies, this type of microbiota profile—which results from the fact that high-protein, low-fiber diets lead to a marked reduction in these bacteria and their beneficial metabolic products—is associated with an increased risk of several diseases.
Key role of butyrate
Butyrate is a short-chain fatty acid (
(sidenote:
Short chain fatty acids (SCFA)
Short chain fatty acids (SCFA) are a source of energy (fuel) for an individual’s cells. They interact with the immune system and are involved in communication between the intestine and the brain.
Silva YP, Bernardi A, Frozza RL. The Role of Short-Chain Fatty Acids From Gut Microbiota in Gut-Brain Communication. Front Endocrinol (Lausanne). 2020;11:25.
)
) that is important for maintaining good gut health. It serves as an energy source for gut cells, strengthens the gut barrier, and is believed to possess anti-inflammatory and anti-carcinogenic properties.
In practice, the high-protein breakfast was more effective at curbing appetite. However, the high-fiber breakfast was associated with a more “beneficial” microbiota, containing more bifidobacteria and butyrate-producing bacteria. So, which of the two is right for you?
3. WHO
