One of the more amazing bits of science uncovered in the past few years is that the bacteria living with us in our gut (our microbiome) may determine if we’re fat or skinny. Think about that for a second: no more counting calories or worrying about food, because if you have the right bacteria, you’ll get skinny. This morning I’d like to review recent research that’s adding a bit of reality to that future.
What We’ve Already Learned About Gut Bacteria and Our Health
Before we dig into our feature study, let’s review what we know about gut bacteria and health. We know the cells that make up most of our immune system live in the walls of our intestines, so our gut bacteria literally live next door and can impact our immune system in a big way. Hence, the microbiome has been thought of as a second immune system. We also know that these bacteria eat some of our food, which can reduce the number of calories we absorb. Finally, we know that the wrong bacteria can produce bad chemicals that can lead to leaky gut syndrome, which can cause excessive and dangerous whole body inflammation.
Now, lets’ review some of what I’ve covered so far on the blog:
- Earlier this summer, a study found a link between type-2 diabetes and gut bacteria
- One study found evidence that Parkinson’s disease may be generated from alterations in the gut bacteria and then move to the brain.
- Gut bacteria may help or hurt stem cells, depending on the bacteria.
- Bad gut bacteria can cause leaky gut, which can lead to metabolic syndrome (obesity, high blood pressure, and blood sugar, and increased risk for diabetes).
- Your gut bacteria can have an impact on your emotional health (interestingly, the overgrowth of Prevotella bacteria was associated with a more negative effect when compared to the Bacteroides bacteria—in today’s feature study Prevotella was more beneficial for weight loss).
- Artificial sweeteners can wreak havoc on your gut bacteria, while walnuts can enhance your healthy gut bacteria.
Bacteria Ratio Found in Stool Determines Success with New Nordic Diet
The new study, published in the International Journal of Obesity, investigated the ratio of Prevotella to Bacteroides bacteria in fecal samples and the effect on weight loss in overweight individuals. Sixty-two participants were randomized into either a New Nordic Diet group or an Average Danish Diet group. Note that the focus is on the ratio of these two bacteria, which is likely to be a delicate dance of one not taking over too much versus the other.
The “Nordic Diet” included vegetables (particularly dark-green, root, and cruciferous), fruits and berries, whole grains, fatty fish, and wild game meats. The Average Danish Diet, on the other hand, focuses on richer, heavier foods, including white breads; dairy (cheese, milk, and butter); seafood, pork (ham, bacon, chops, etc.), and beef; potatoes; and eggs.
Researchers found that the subjects on the Nordic Diet lost an average of 1.8 kg more than those on the Average Danish Diet. Subjects were then divided into two groups by their bacteria levels and another interesting finding emerged: Those with a higher Prevotella to Bacteroides ratio lost 3.5 kg more body fat on the Nordic Diet than those on the Average Danish diet. While those with a lower Prevotella to Bacteroides ratio did not lose any additional body fat on the Nordic Diet.
In other words, while the Nordic Diet was beneficial for some (about half the subjects), it didn’t benefit others, and the contributing factor was the Prevotella to Bacteroides ratio found in the subjects’ stool. So if your Prevotella to Bacteroides ratio is high, the Nordic Diet could help you lose weight; if it’s low, the diet is unlikely to help you lose weight. Let’s think about that for a second. Losing weight was a combination of eating the right foods and having the right gut bacteria!
The Connection Between Weight and Gut Bacteria Isn’t New
This isn’t the first time we’ve seen a connection between weight and gut bacteria. A couple of years ago, we covered a huge study that researched weight by looking at sewage samples from over 70 US cities. The study found distinct bacterial patterns in the sewage, and researchers were able to predict, with 80% accuracy, the average weight of the population in the cities. Interestingly, in this study, the cities with higher amounts of Bacteroides had more obesity in their populations. However, we need to be cautious about this study because there’s no telling what happens to these ratios when the sewage sits for a while versus a “fresh” sample technique used in this study.
The upshot? While science needs to learn more about the optimal bacterial compositions to lose weight, what’s clear is that diets of the future will likely be focused on food and gut bacteria. Think about that for a second: instead of telling a friend to “mix in some salads,” it may be “mix in some Prevotella“!