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Gut Health

How Does a Ketogenic Diet Affect Your Gut Microbiome?

How Does a Ketogenic Diet Affect Your Gut Microbiome?

The ketogenic diet, also known as the keto diet, has become a popular way of eating in recent years. Some speculate that the increase in popularity is mainly due to the diet’s ability to stimulate weight loss.

The keto diet involves drastically reducing the number of carbs consumed and replacing them with high amounts of fat. The logic is simple, decreasing carbohydrates and increasing fats puts the body into a metabolic state called ketosis.

Ketosis stimulates the burning of body fat while also causing several other distinct changes in the body. While some of these changes are beneficial, others are known to have adverse impacts on overall health.

Additionally, the keto diet has been proven to influence the gut microbiome's diversity and richness in both negative and positive ways.

The Ketogenic Diet vs. Traditional Diets

The ketogenic diet is a very low-carb, moderate-protein, and high-fat diet. Keto shares key attributes with other low-carb diet programs, like the Atkins diet, which varies drastically from traditional diet patterns.

In a traditional diet, all macronutrients are consumed in moderate amounts. The typical breakdown of total daily calories provided by each macronutrient, known as the AMDR (Acceptable Macronutrient Distribution Range), for traditional diets include:

  • Carbohydrates: 45-60%
  • Fat: 15-25%
  • Protein: 7-20%

In this way of eating, carbohydrates make up the largest portion of calories consumed per day. They also provide the body with its primary source of energy, which are simple sugars called glucose.

After carbohydrates are eaten, they are broken down into these simple sugars and then released into the bloodstream. This increase of glucose in the blood stimulates the pancreas to secrete insulin, a hormone that carries glucose to cells and the brain to be used for energy.

However, over-consuming carbs can spike blood glucose levels and lead to several health issues that can eventually stimulate the development of chronic conditions, like diabetes.

As a result of this, the goal of the keto diet is to avoid the negative aspects of a high-carb diet. Compared to the AMDR for traditional diets, the macronutrient distribution is drastically different for the ketogenic diet:

  • Carbohydrates: 5-10%
  • Fat: 70-80%
  • Protein: 20-25%

By increasing the intake of high-fat foods, like fatty meats, nuts, dairy, and decreasing sugary carbs, starches, and grains, the body is put into a state of ketosis. Your body begins to break down stored fat in the liver during ketosis, producing molecules called ketones. Ketones are then delivered to cells and the brain to use as a source of energy.

One of the differences between ketones and glucose is the metabolic changes that ketones provoke in the body.

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Effects of the Ketogenic Diet on the Body

The metabolic changes caused by ketosis and the use of ketones as your primary energy source can have both positive and negative effects on your overall health.

Benefits of this high-fat, and low-carb diet include:

  • Lowered blood sugar
  • Increased insulin sensitivity
  • Decreased appetite
  • Weight loss stimulation
  • Improvements in certain neurological disorders

On the opposite end, metabolic fasting has been shown to negatively impact one's overall health in many different ways. Such adverse effects range from problems that only last for a few days to those that can cause long-term stress on the body. Symptoms you should be aware of are:

  • Gastrointestinal discomfort
  • Impaired mood, concentration, and energy
  • Reduced fluid and electrolyte levels
  • Poor growth and bone mineralization
  • Irregular heartbeat

Extensive changes simulated by the keto diet occur throughout the body and affect several systems, including the gastrointestinal tract. Additionally, ketosis alters the environment of the digestive system and the bacteria, fungi, and other beneficial microorganisms in the gut microbiome.

The Ketogenic Diet and the Gut Microbiome

Ketogenic Keto Diet and the Gut Microbiome

The delicate ecosystem living within the gut has a profound effect on your overall health. These essential microorganisms aid the function of most major body systems, including the brain and immune system.

The gut microbiome is also highly sensitive to your diet. Changes to your daily eating patterns can alter your microbiome's composition and health in both beneficial and adverse ways.

The keto diet is known to cause substantial changes to the gut microbiome, mediated by changes in the metabolites produced by gut bacteria.

Fully understanding how these changes can both help and hinder the microbiome is essential, as it can have a sizable impact on your overall health. Such effects include the efficiency of how several body systems function, including the digestive and immune systems and the brain.

Benefits of the Ketogenic Diet on the Gut Microbiome

Increases colonies of certain beneficial bacteria

Ketosis can stimulate an increase of bacterial species associated with fat digestion and metabolism in the microbiome. Such bacteria are known to be beneficial to overall health as they improve digestive processes in the gut and aid in the stimulation of essential immune cells. These include Bacteroidetes, Lactobacillus, Akkermansia, Firmicutes, and Bacteroides.

Improves symptoms of some neurological and digestive disorders

The beneficial bacteria increased within the gut microbiome with a keto diet can help manage certain neurological disorders via enzyme and hormone production. These include epilepsy, seizures, autism, and Alzheimer’s disease. 

They also assist in insulin sensitivity, weight loss, and digestive disorders like IBS.

Adverse Effects of the Ketogenic Diet on the Gut Microbiome

Increase in gut inflammation

A high-fat diet increases Desulfovibrio bacteria in the gut, which has the ability to produce hydrogen sulfide. This compound impairs the intestine's mucosal barrier and causes colitis or inflammation of the colon.

Decrease gut microbiome diversity and richness

A keto diet decreases the species of bacteria involved in the digestion and metabolism of high-fat nutrients, such as Bacteroides spp., E. coli, A. muciniphila. This diet also decreases the species connected to the digestion of complex carbohydrates, such as Faecalibacterium spp., bifidobacterium, E. rectale, E. dialister.

This decreases the microbiome’s overall diversity and richness due to the diet’s low complex carbohydrate content, which is necessary for the microorganisms to produce energy.

Increase in pathogenic bacteria and disease in the gut

There is also a decrease in beneficial bacteria, which play preventive roles against pathogens and chronic disease in the gut.

A decrease in diversity leads to an increase in the relative abundance of pathogenic bacteria, such as  Escherichia coli and Desulfovibrio.

A lack of beneficial bacteria has also been associated with the increased occurrence of colorectal cancer, IBS, and necrotizing enterocolitis.

So, is Going Keto a Good Idea for Your Gut Health?

Before adopting a ketogenic diet, you should fully consider all the positive and negative consequences associated with it. Doing so is important not only for your overall health but also for your gut microbiome's health and diversity.

If you decide going keto is a path you’d like to venture into, it is essential to be proactive in taking care of your microbiome throughout the process.

Many individuals have found success in fortifying their microbiome by consuming keto-friendly foods high in fiber, prebiotics, and probiotics. These include low-carbohydrate vegetables, nuts and seeds, and fermented foods. It is also important to add quality supplements to your daily routine that will promote gut microbiome health, such as a BIOHM's prebiotic or probiotic.

This way, you can reap the keto diet's metabolic benefits while counteracting some of the adverse gastrointestinal effects associated with it.


About the Authors:

Dr Mahmoud Ghannoum, Ph.D, EMBA, FAAM, FIDSA is widely considered the leading microbiome researcher in the world. He is the scientist who named the mycobiome, and is the founder of BIOHM, the first company to engineer products and tests to address the total microbiome of both bacteria and fungi, allowing consumers to maintain total digestive health. Ghannoum is responsible for making the breakthrough discovery that bad bacteria and bad fungus work together to create digestive plaque (a discovery covered globally by outlets such as CBS News, Scientific American, Forbes and USA Today). During his career, he has published several books on fungus and over 400 peer-reviewed scientific papers. His work has been cited almost 24,000 times by other scientists, and Stanford University named him as one of the top 0.1% of most cited scientists over the last decade.

Allison Lansman, RDN, LD is a freelance writer and owner of The Freelance RD Nutrition Writing Services. She is passionate about creating exciting, research-based nutrition blog posts with her professional background as a dietitian. Allie prioritizes creating articles all readers can understand and incorporate into their daily lives. 

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