What Is the Role of Gut Bacteria in Calorie Restriction?

By Dr. Mercola

Lowering your caloric intake has been scientifically proven to slow down aging, reduce age-related chronic diseases and extend lifespan. The effects have been observed in a variety of species from worms and yeast to rats and fish, with some research showing that restricting calories in certain animals can increase their lifespan by as much as 50 percent.

There's evidence that calorie restriction has a similar effect on the human lifespan, as well, and one of the key reasons why is likely related to its ability to lower your insulin levels as well as improve insulin sensitivity.

However, researchers recently studied whether calorie restriction also prompts changes to your gut microbiota, which may also be responsible for some of its beneficial role in health.

Calorie Restriction Prompts Significant Changes to Your Gut Bacteria

Science is increasingly revealing that microorganisms living in your gut are there performing indispensable functions. Known as your microbiome, about 100 trillion of these cells populate your body, particularly your intestines and other parts of your digestive system.

There is also an emerging consensus that most disease originates in your digestive system, and this includes conditions that impact your brain, your heart, your weight and your immune system, among others. There's also evidence that the microorganisms present in your gut can affect how well you age,¹ and this, of course, ties in directly with the latest research on calorie restriction and longevity.

One important thing to remember about the microbes in your gut is that they are not static. They can change profoundly throughout your life, for better or for worse, and one of the biggest influences on this change is your diet.

Indeed, the latest study showed that life-long calorie restriction in mice "significantly changes the overall structure of the gut microbiota" in ways that promote longevity.² So it now appears that one reason why calorie restriction may lengthen lifespan is because it promotes positive changes to the microorganisms in your gut.

The researchers noted:

"Calorie restriction enriches phylotypes positively correlated with lifespan, for example, the genus Lactobacillus on low-fat diet, and reduces phylotypes negatively correlated with lifespan.

These calorie restriction-induced changes in the gut microbiota are concomitant with significantly reduced serum levels of lipopolysaccharide-binding protein, suggesting that animals under calorie restriction can establish a structurally balanced architecture of gut microbiota that may exert a health benefit to the host via reduction of antigen load from the gut."

Intermittent Fasting May Provide Comparable Health Benefits to Calorie Restriction

While the research supporting calorie restriction is compelling, it's not a very popular dietary strategy for most people, for obvious reasons. Many are simply not willing to deprive themselves of calories to the extent needed to prompt the beneficial effects.

An alternative that is much more acceptable is intermittent fasting, which can be as simple as restricting your daily eating to a narrower window of time of say 6-8 hours (this equates to 16-18 hours worth of fasting each and every day).

Recent research suggests that sudden and intermittent calorie restriction appears to provide many of the same health benefits as constant calorie restriction, including extending lifespan and protecting against disease. For instance, intermittent fasting leads to:

1. Increased insulin sensitivity and mitochondrial energy efficiency – Fasting increases your leptin and insulin sensitivity along with mitochondrial energy efficiency, and thereby retards aging and disease, which are typically associated with loss of insulin sensitivity and declined mitochondrial energy.
2. Reduced oxidative stress – Fasting decreases the accumulation of oxidative radicals in the cell, and thereby prevents oxidative damage to cellular proteins, lipids, and nucleic acids associated with aging and disease.
3. Increased capacity to resist stress, disease and aging – Fasting induces a cellular stress response (similar to that induced by exercise) in which cells up-regulate the expression of genes that increase the capacity to cope with stress and resist disease and aging.

Intermittent Fasting Switches Your Body to Fat-Burning Mode… With Radical Improvements to Your Gut

If you want to give intermittent fasting a try, consider starting gradually. You can delay breakfast as long as possible and extend the time every day before you eat breakfast until you are actually skipping breakfast. Make sure you stop eating and drinking anything but water three hours before you go to sleep, and restrict your eating to an 8-hour (or less) time frame every day. In the 6-8 hours that you do eat, have healthy protein, minimize your carbs like pasta, bread, and potatoes and exchange them for healthful fats like butter, eggs, avocado, coconut oil, olive oil and nuts — essentially the very fats the media and "experts" tell you to avoid.

This will help shift you from carb-burning to fat-burning mode. Once your body has made this shift, it is nothing short of magical as your cravings for sweets, and food in general, rapidly normalizes and your desire for sweets and junk food radically decreases -- if not disappears entirely.

Remember, it typically takes a few weeks for most to shift from burning carbs to fat-burning mode. Once you succeed and switch to fat-burning mode, you'll be easily able to fast for 18 hours and not feel hungry. The "hunger" most people feel is actually cravings for sugar, and these will disappear once you successfully shift over to burning fat instead.

Another phenomenal benefit that occurs is that you will radically improve the beneficial bacteria in your gut, as occurs with calorie restriction. Along with improving your immune system, you will sleep better, have more energy, have increased mental clarity and concentrate better. Essentially, every aspect of your health will improve as your gut flora becomes balanced.

Certain Gut Bacteria are 'Major Contributors' to Cancer

As if you needed even more reason to optimize the bacteria in your gut, recent research has revealed an association between different gut bacteria and the development of lymphoma, a cancer of the white blood cells. The study involved mice with ataxia-telangiectasia (A-T), a genetic disease linked to a high rate of B-cell lymphoma in both mice and humans. Those with certain microbial species in their gut lived significantly longer before developing lymphoma, and had less of the gene damage that causes the disease. The researchers also created a catalog detailing which types of bacteria had either promoting or protective effects on genotoxicity and lymphoma.

This is not the first time gut bacteria has been linked to cancer. Findings published in the journal Nature,³ for instance, reported the discovery of microbial-dependent mechanisms through which some cancers mount an inflammatory response that fuels their development and growth. Another study, published in the journal Science,⁴ suggested cancer may be due to a chain reaction that starts with inflammation that disrupts your gut ecosystem, allowing pathogens, such as E. coli, to invade your gut and cause cellular damage.

Healthy Gut 101: How to Optimize Your Microflora for Better Health

With it now becoming increasingly clear that your microflora influence the expression of your genes, your immune system, weight, mental health, memory, and your risk of numerous chronic and acute diseases, from diabetes to cancer, destroying your gut flora with antibiotics and poor diet is a primary factor in rising disease rates.

As discussed, your diet is crucial in this equation, and it appears likely that calorie restriction, or intermittent fasting, may have a beneficial effect on the makeup of your microflora. But there are other factors, too. Remember, an estimated 80 percent of your immune system is also located in your gut, so reseeding your gut with healthy bacteria is important for the prevention of virtually ALL disease, from colds to cancer. In light of this, here are my recommendations for optimizing your gut bacteria.

• Fermented foods are the best route to optimal digestive health, as long as you eat the traditionally made, unpasteurized versions. Healthy choices include fermented grass-fed organic milk such as kefir, various fermentations of vegetables like cabbage, turnips, eggplant, cucumbers, onions, squash and carrots, and natto (fermented soy).

Fermented vegetables, which are one of my new passions, are an excellent way to supply beneficial bacteria back into your gut. And, unlike some other fermented foods, they tend to be palatable, if not downright delicious, to most people. Most high-quality probiotic supplements will only supply you with a fraction of the beneficial bacteria found in such homemade fermented vegetables, so it's your most economical route to optimal gut health as well.

• Probiotic supplement. Although I'm not a major proponent of taking many supplements (as I believe the majority of your nutrients need to come from food), probiotics are an exception if you don't eat plenty of raw organic and fermented foods on a regular basis.

In addition to knowing what to add to your diet and lifestyle, it's equally important to know what to avoid, for optimal microflora balance, and this includes:

Antibiotics, unless absolutely necessary (and when you do use them, make sure to reseed your gut with fermented foods and/or a probiotics supplement)	Conventionally raised meats and other animal products, as CAFO animals are routinely fed low-dose antibiotics, plus genetically engineered grains, which have also been implicated in the destruction of gut flora	Processed foods (as the excessive grains and sugars, along with otherwise "dead" nutrients, feed pathogenic bacteria)
Chlorinated and/or fluoridated water	Antibacterial soap	Agricultural chemicals