The ketogenic diet, or keto diet, is a popular dietary approach characterized by high fat and very low carbohydrate consumption. Originally developed in the 1920s as a treatment for epilepsy, it has gained widespread popularity as a weight loss strategy. The diet aims to induce ketosis, a metabolic state where the body primarily burns fat for fuel instead of carbohydrates. While the keto diet has potential benefits, it can also lead to several side effects, including changes in body odor.
Understanding the Keto Diet
The keto diet typically consists of approximately 80% of calories from fat, 15% from protein, and only 5% from carbohydrates. By drastically reducing carbohydrate intake, the body is forced to break down fat stores, producing ketones. These ketones then serve as an alternative energy source.
Keto Crotch: Is It Real?
One peculiar side effect that some individuals report while on the keto diet is what's colloquially termed "keto crotch." This refers to a perceived stronger vaginal odor and increased discharge. While "keto crotch" hasn't been scientifically investigated, it raises questions about the diet's impact on the vaginal microbiome.
Potential Connection to Bacterial Vaginosis (BV)
It's theorized that "keto crotch" might be related to bacterial vaginosis (BV). BV occurs when the balance of bacteria in the vagina is disrupted, with a decrease in beneficial lactobacilli and an overgrowth of other bacteria. Lactobacilli are crucial for maintaining the acidic environment of the vagina, typically around 4.5 pH.
An older study from 2007 suggested that a high-fat diet may lead to a higher vaginal pH. Participants with high-fat diets had an average vaginal pH of 5.1. A vaginal pH above 4.5 can indicate BV. A 2020 review reinforced the link between a high-fat diet and BV, particularly saturated fats. Since the keto diet involves consuming large amounts of fat, it could potentially alter the vaginal pH, creating an environment conducive to BV.
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Symptoms of BV
The symptoms of BV are similar to those reported with "keto crotch" and include:
- Thin vaginal discharge (white or gray)
- Burning, itching, or pain in or around the vagina
- A strong, fishy odor
- A burning sensation when urinating
It's important to note that these symptoms may be attributed to the keto diet itself, but they could also indicate BV.
Causes of BV
Several factors can disrupt the natural vaginal flora and lead to BV, including:
- Semen
- Douching
- Scented vaginal products
- New sexual partners
BV is not a sexually transmitted infection (STI), but new sexual partners can increase the risk.
Complications of BV
If left untreated, BV can lead to health risks, according to the CDC, such as:
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- Increased risk of HIV transmission
- Increased risk of contracting other STIs (chlamydia and gonorrhea)
- Increased risk of premature birth if pregnant
Treatment for BV
BV can sometimes resolve on its own, but treatment is recommended if symptoms are present. Doctors typically prescribe antibiotics like clindamycin or metronidazole, available as creams, vaginal suppositories, or oral tablets.
Other Body Odor Changes on Keto
Beyond "keto crotch," the keto diet can influence other aspects of body odor. This is largely due to the metabolic changes that occur when the body enters ketosis.
Keto Breath
One of the most well-known side effects is "keto breath," often described as fruity or smelling like nail polish remover. This is caused by acetone, a ketone that exits the body through the lungs.
Urine Odor
Changes in diet, including the keto diet, can affect urine composition and odor.
General Body Malodor
Accumulating evidence suggests that microbiota plays a critical role in physiological processes in humans. However, it might also contribute to body malodor by producing numerous odorous molecules such as ammonia, volatile sulfur compounds, or trimethylamine.
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Origins of Body Odor
The body can emit odorous substances (odorants) with breath, saliva, sweat (skin), urine, or reproductive organs fluids. The major odorants are small, volatile compounds that may either be produced in situ (skin, oral cavity) or be carried by blood from the gut, which is a major site of bacterial metabolism. Origins of body odor associated with bacterial metabolites:
- Diet
- Composition and metabolic activity of bacteria in the gut, skin, or mucosa
- Gut function
- Intestinal transit time and gut-blood barrier permeability affect penetration of bacterial metabolites and their precursors from the gut lumen to the bloodstream
- Liver function
- Kidney function
Specific Odorous Compounds and Their Origins
Several compounds contribute to body odor, with bacteria playing a key role in their production.
Volatile Sulfur Compounds (VSCs)
These are predominant substances present in the breath of individuals suffering from halitosis. Several Gram-negative bacteria are associated with the production of volatile sulfur compounds from sulfur-containing substrates that are present in food or saliva.
Hydrogen Sulfide (H2S)
At higher concentrations, H2S is mostly known for its toxic effects and specific foul smell, often compared to the odor of rotten eggs. Anaerobic bacteria present in the oral cavity might degrade sulfur-containing amino acids such as l-cysteine to odorous volatile sulfur compounds with H2S being an important contributor to offensive breath odor. Certain food products contain sulfides and sulfites that can be substrates for the production of H2S by bacterial reductases, such as onion, garlic, wine, cabbage, broccoli, mushrooms, nuts, potatoes, and dried fruits.
Methyl Mercaptan (CH3SH)
Studies show that CH3SH is a predominant causative factor of intra-oral halitosis. The smell of MT is often described as putrid and musty and can be compared to barnyard odor. The researchers reported high prevalence of Prevotella, Veillonella, Atopobium, Megasphaera, and Selenomonas in saliva of these individuals and suspect that these species are involved in the production of CH3SH.
Dimethyl Sulfide (DMS, CH3SCH3)
This is the main contributor to blood-borne (extra-oral) malodor. Possible reasons for the presence of DMS in the blood are some metabolic disorders that need to be further investigated. Other causes reported in the literature include hepatic failure, hypermethioninemia, and therapeutic intake of dimethyl sulfoxide or cysteamine.
Trimethylamine (TMA)
Trimethylamine is a volatile, aliphatic tertiary amine known for its characteristic odor of rotten fish and toxic effects at high concentrations. It is formed from excess choline and other TMA-containing dietary nutrients by gut bacteria. After being absorbed from the intestines, TMA is oxidized by the liver to almost odorless trimethylamine oxide (TMAO). TMAu should always be considered as a possible reason for bad breath smell.
Indole and Skatole
Their smell can be equated to that of fecal matter, and of these two compounds, skatole has a stronger odor.
Putrescine and Cadaverine
These diamines have been suspected to contribute to the foul smell of breath for a few decades and are both associated with the putrefaction of food by bacteria present in the dental plaque.
Acetone
Acetone is a three-carbon, volatile ketone that is derived from acetoacetate. Its fruity smell has been associated with uncontrolled diabetes mellitus. High concentrations of breath acetone have been linked with diabetic ketoacidosis. It also increases with fasting, high-fat, or ketogenic diets.
Pyridine
Pyridine is an aromatic nitrogen-containing, volatile compound that has a fishy, sweaty odor and might contribute to halitosis.
Ammonia (NH3)
With its urine-like, fetid smell, ammonia plays an important role as a biomarker in liver and kidney diseases as well as in halitosis. Gut bacteria are important contributors to the formation of ammonia in mammals.
Managing Body Odor on the Keto Diet
If you experience unpleasant body odor changes while on the keto diet, several strategies can help.
Addressing "Keto Crotch"
- Consult a doctor: It's crucial to rule out BV or other infections.
- Consider diet adjustments: If the keto diet is causing recurring issues, a dietician can help explore alternative dietary approaches.
General Strategies for Managing Body Odor
- Maintain excellent hygiene: Pay close attention to personal hygiene.
- Stay hydrated: Drink plenty of water to dilute urine and reduce odor.
- Adjust macronutrient ratios: Ensure you're not consuming too much protein, as it can worsen urine odor.
- Consider gut health: A healthy gut microbiome is essential.
Other Side Effects of the Keto Diet
Besides body odor changes, the keto diet can cause other short-term and long-term side effects.
Short-Term Side Effects
- Keto flu: Nausea, headaches, insomnia, fatigue, and constipation.
- Keto breath: Fruity or acetone-like breath odor.
Long-Term Side Effects
- Hepatic steatosis (fatty liver)
- Hypoproteinemia (low protein levels in the blood)
- Kidney stones
- Vitamin and mineral deficiencies
Signs and Symptoms of Ketosis
It can be helpful to know the signs and symptoms of ketosis, both positive and negative:
- Bad breath: Elevated ketone levels cause bad breath.
- Weight loss: Keto diets are highly effective for weight loss.
- Increased ketones in the blood: The most reliable method of measuring ketosis.
- Increased ketones in the breath: Another way to measure blood ketone levels is a breath analyzer.
- Appetite suppression: Many people report decreased hunger while following a keto diet.
- Increased focus and energy: Long-term keto dieters often report increased focus and energy.
- Short-term fatigue: The initial switch to a keto diet can be one of the biggest issues for new dieters.
- Short-term decreases in performance: Removing carbs can lead to general tiredness at first.
- Digestive issues: Digestive issues such as constipation and diarrhea are common side effects in the beginning.
- Insomnia: A lot of people report insomnia or waking up at night when they first reduce their carbs drastically.