Your body hosts trillions of bacteria, viruses, and fungi, collectively known as the microbiome. While some bacteria are linked to disease, many play essential roles in supporting your immune system, heart health, weight management, and overall well-being. This article delves into the significance of the gut microbiome and its impact on health.

What Is Gut Microbiome?

Interestingly, bacterial cells outnumber human cells in the body, with approximately 40 trillion bacterial cells compared to 30 trillion human cells. With up to 1,000 species of bacteria present in the gut, each plays a distinct role. While most bacteria contribute positively to health, some can be harmful. Together, these microbes weigh around 1–2 kilograms, functioning almost like an additional organ essential for overall well-being.

How Does Gut Microbiome Influence Your Health?

The relationship between humans and microbes has evolved over millions of years, with the gut microbiome playing a crucial role from birth. Initial exposure to microbes occurs during birth, and some evidence suggests that exposure begins in the womb. As the microbiome diversifies, it starts influencing key bodily functions:

Digestion of breast milk: Beneficial bacteria like Bifidobacteria help break down essential sugars in breast milk, supporting infant growth.

Fiber digestion: Some bacteria process fiber into short-chain fatty acids, which contribute to gut health and reduce risks of obesity, diabetes, and heart disease.

Immune system regulation: The gut microbiome interacts with immune cells, influencing how the body responds to infections.

Brain health: Emerging research suggests a link between the gut microbiome and brain function, potentially affecting mental health and neurological processes.

Gut Microbiome And Weight Management

An imbalance between beneficial and harmful microbes, known as gut dysbiosis, may contribute to weight gain. Studies on identical twins—one with obesity and the other without—suggest that microbiome composition plays a role in body weight independent of genetics. Additionally, animal studies indicate that gut bacteria can influence weight gain, even when calorie intake remains constant.

Probiotics, beneficial bacteria found in supplements and certain foods, can help restore gut balance and support weight loss, though their effects may be modest.

Gut Health And Disease Prevention

The gut microbiome plays a vital role in preventing and managing conditions like irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). Imbalances in gut bacteria may lead to bloating, cramps, and digestive issues. On the other hand, beneficial bacteria like Bifidobacteria and Lactobacilli help strengthen the intestinal lining, reducing the risk of gut-related disorders.

Impact On Heart Health

Research suggests that the gut microbiome influences heart health by affecting cholesterol levels and blood pressure. Certain harmful bacteria produce trimethylamine N-oxide (TMAO), a compound linked to blocked arteries and heart disease. However, probiotics, particularly those containing Lactobacilli, may help reduce cholesterol levels and promote cardiovascular health.

Blood Sugar Regulation And Diabetes Risk

The gut microbiome also plays a role in regulating blood sugar levels. Research on infants genetically predisposed to type 1 diabetes indicates that gut microbiome diversity declines before disease onset. Furthermore, individual variations in gut bacteria may explain why people experience different blood sugar responses to the same foods.

Connection Between Gut And Brain

The gut is physically connected to the brain through nerves, and certain bacteria help produce neurotransmitters like serotonin, which influence mood and mental health. Studies indicate that people with mental health disorders often have different gut bacteria compared to those without such conditions. Additionally, some probiotics have shown promise in alleviating symptoms of depression and anxiety.

Tips For Healthier Gut Microbiome

Maintaining a balanced gut microbiome is crucial for overall health. Here are some strategies to support gut health:

• Eat a diverse range of foods: A varied diet rich in fiber, legumes, and fruits promotes microbial diversity.
• Consume fermented foods: Yogurt, kefir, and sauerkraut contain probiotics that enhance gut health.
• Limit artificial sweeteners: Some artificial sweeteners can encourage the growth of harmful bacteria.
• Include prebiotic foods: Bananas, oats, and asparagus contain fibers that nourish beneficial bacteria.
• Breastfeed infants when possible: Breastfeeding promotes a healthier gut microbiome in babies.
• Choose whole grains: Whole grains contain fiber and beneficial compounds that support digestive health.
• Opt for a plant-based diet: Vegetarian diets may reduce inflammation and support a healthier gut microbiome.
• Consume polyphenol-rich foods: Green tea, dark chocolate, and olive oil contain compounds that foster beneficial bacteria.
• Take probiotics if needed: Probiotic supplements can help restore gut balance after disruptions, such as antibiotic use.
• Use antibiotics cautiously: While antibiotics can be life-saving, overuse can harm beneficial gut bacteria.

Doctors in India’s southern state of Tamil Nadu surgically removed a fully developed canine tooth from the upper eyelid region of a 16-year-old boy. They described the case as the first reported instance of an ectopic tooth in the upper part of the eye socket.

The case was reported by specialists at Aravind Eye Hospital in Madurai in the journal Ophthalmology.

What Did The Doctors Find?

The teenager visited the hospital with painless swelling of his left upper eyelid that had lasted a month. He had no history of injury to the area.

During the examination, doctors noticed two firm, whitish projections beneath the swollen area near the inner side of the upper eyelid, the experts shared in the paper.

A computed tomography (CT) scan revealed a dense structure resembling a tooth, with a crown and root, originating from the roof of the left eye socket. It extended towards the tissues in front of the orbital septum, a thin barrier separating the eyelid from the deeper eye socket, and protruded outwards with two tooth-like points on its surface.

The projections' appearance and texture raised the possibility that they were teeth. Dr. Meghana Tanwar, a medical consultant at Aravind Eye Hospital, told Live Science that they had a “fairly smooth surface and were hard on palpation.”

The doctors surgically removed the structure. Examination confirmed that it was a mature canine tooth without teratomatous elements, consistent with an ectopic tooth in the upper part of the eye socket.

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What Is An Ectopic Tooth?

An ectopic tooth develops or emerges in an abnormal location. Some remain within the mouth but appear outside their usual positions in the dental arch, while others develop outside the normal arrangement of teeth.

The latter is particularly unusual. In this teenager's case, the tooth was located in the upper orbital region rather than within the normal dental arch.

Before confirming the diagnosis, doctors considered whether the projections could be associated with a teratoma, a type of tumor that can contain different tissues, including bone and tooth tissue. They also considered whether a foreign object might be lodged in the eyelid.

Imaging and examination of the removed structure helped establish that it was a mature tooth rather than tissue associated with a teratoma.

Why Is This Case Unusual?

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Ectopic teeth have been documented in several locations, including the nasal cavity, chin and maxillary sinus, an air-filled cavity within the cheekbone. Previous reports have also described teeth in the lower part of the eye socket.

However, the doctors said they could not find an earlier report of an ectopic tooth in the superior orbit, the upper region of the eye socket.

“To the best of our knowledge this is the first and only ectopic tooth reported in the superior orbit,” Tanwar told Live Science.

“This was a first not just for us but the world over,” she said of the case. “We were very surprised by it.”

What Causes Ectopic Teeth?

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The doctors could not determine why the tooth developed in this unusual location.

Possible explanations for ectopic tooth development include abnormalities during development, genetic factors, infections and physical trauma. However, the cause in this case remains unknown.

Imaging did not reveal any additional ectopic teeth. Tanwar said the likelihood of the teenager developing another such tooth was low.

Beth Dobbin, who represented Great Britain at the Tokyo Olympics in 2021, now spends more than 22 hours a day in bed.

The 32-year-old retired from athletics in April 2026, describing her illness as “serious” and “life-changing.” She was later diagnosed with myalgic encephalomyelitis (ME), a chronic condition with no known cure or specific treatment.

Dobbin reached the 200m semi-finals at the Tokyo Olympics and won bronze in the 4x200m relay with Scotland at the 2022 Commonwealth Games in Birmingham.

“It's life-decimating like I can't even put into words,” she said. “I feel like I've lost everything.”

Beth Dobbin's Diagnosis with ME

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Dobbin’s health began deteriorating after back-to-back COVID-19 and glandular fever infections in the winter of 2021-22, the BBC

reported.

She experienced worsening fatigue, slower running times and soreness in the glands in her neck and armpits. Initial tests by British Athletics doctors failed to identify the cause.

Despite her symptoms, she continued training in 2022. At the European Championships, she false-started after losing all feeling in her legs while in the starting blocks.

Her condition subsequently worsened. She struggled to stand and spent most of her time in bed. After consulting four or five specialists, she was diagnosed with ME.

Dobbin has been confined to her house and bed since then. She gets out of bed only to eat and use the bathroom. Even conversations, bright lights or loud sounds can trigger a “crash” lasting days or, in severe cases, months. She has left the house just five times this year, the report said.

She now leaves home mainly for medical appointments and blood tests. Even conversations, bright lights and loud sounds can trigger a “crash” that lasts days or, in severe cases, months. She has left home just five times this year, according to the report.

What Is ME?

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ME, also known as chronic fatigue syndrome (CFS), is a complex, chronic illness that can cause severe fatigue, pain, sleep disturbances and problems with thinking and memory. Symptoms do not improve simply with rest, and there is no established cure.

Dobbin rejects the term “chronic fatigue syndrome” because she believes it understates the severity of the condition.

“I wish it was just fatigue, that would be a walk in the park,” she said. “It's so much more than that. If I thought of fatigue in my top 20 symptoms it might just make the cut.”

She described the illness as feeling as though her entire body “is shutting down; it feels like you are a few days from death”.

More than 400,000 people in the UK are thought to have ME, although some estimates put the number above one million. The illness varies in severity, with some people continuing to work or study while others require extensive care.

Dobbin’s illness has also taken an emotional toll on her family.

“I'm just so desperate to help her but I can't because there is nothing. I'd take her anywhere, I'd take her to America if I had to, but there's nothing,” her father, Jim, said.

Beth Dobbin Aims To Raise ME Awareness

Dobbin describes her future as “very bleak” but hopes that greater awareness will lead to better treatment options.

The emergence of long COVID, which shares some symptoms with ME, has brought renewed attention to the illness and increased research funding.

She also wants to highlight the experiences of patients who are dismissed or disbelieved.

“A lot of people that have this illness that I've spoken to have said to me 'I don't get believed, people think I'm lazy'. I've never experienced one person that doesn't believe me and that's because, why would an athlete just suddenly stop after 20 years?”

Infections accounted for an estimated 2.3 million new cancer cases worldwide in 2024, or about 12% of all cancers diagnosed that year, according to a September 2026 study published in The Lancet Oncology. Among these, Helicobacter pylori (H. pylori), a bacterium that infects the stomach, was associated with an estimated 760,000 cancer cases.

A 2025 study by the International Agency for Research on Cancer (IARC), part of the World Health Organization (WHO), estimated that 76% of the 15.6 million stomach cancer cases expected over the lifetimes of people born between 2008 and 2017 could be attributable to H. pylori infection if prevention efforts do not improve.

Although infections can contribute to cancer development, they are not the only cause. Genetics, age and non-infectious factors also play a role, Dr. Vivek Kaul, Professor of Medicine in the Gastroenterology & Hepatology Division at the University of Rochester Medical Center, told HealthandMe in an exclusive interview.

“I think, generally speaking, I think H. pylori is a well-known carcinogen, mostly responsible for the development of gastric cancer,” Kaul said.

Is Cancer Increasingly Linked To Infections?

The findings highlight the contribution of infectious agents to the global cancer burden. However, Kaul cautioned against concluding that cancer is increasingly being driven by infections.

“But I don't think it's fair to say that, you know, we are moving towards a more infectious etiology for cancer,” he said.

“Cancer is a multifactorial disease state that develops, most commonly develops from genetic and from non-infectious causes,” Kaul added.

He explained that cancer development also depends on the ability of cells to defend themselves against external threats and genetic mutations.

“In many cases, cancer development comes primarily from genetic and age-related issues and boils down to the individual cell's ability, you know, to fight external attacks, such as from H. pylori type of agents or from genetic mutations,” he said.

Kaul also noted that other infectious agents have been implicated in cancer development.

How Does H. pylori Raise Stomach Cancer Risk?

H. pylori is a bacterium that infects the stomach lining and can persist for years. The infection can cause chronic inflammation and damage to stomach tissue, increasing the risk of gastric cancer.

According to scientists at the International Agency for Research on Cancer (IARC), part of the World Health Organization (WHO), H. pylori infection is responsible for an estimated 76% of stomach cancer cases worldwide. The infection often causes no noticeable symptoms, although some people may experience digestive complaints.

The bacterium can spread through contaminated food or water and close contact with infected individuals. In some cases, the infection can cause stomach ulcers. Because many infected people have no symptoms, testing may be needed to identify it.

Can H. pylori Infection Be Prevented From Progressing To Cancer?

The World Gastroenterology Organisation's global guidelines state that eradicating H. pylori before precancerous changes develop can help prevent gastric cancer. This evidence supports test-and-treat screening programmes for young adults in countries with a high disease burden and sufficient resources.

Testing can involve blood, breath or stool tests, depending on the clinical context. People diagnosed with the infection can receive treatment to eradicate the bacterium. Follow-up testing can then confirm whether treatment has worked.

Nobel laureate and gastroenterologist Dr Barry Marshall has also highlighted the potential for early treatment to reduce cancer risk.

“H. pylori is much more than an ulcer organism. If the infection persists for many years, it can cause chronic inflammation in the stomach and increase the risk of gastric cancer. That gives us an opportunity because this is a potentially preventable cause of cancer,” Marshall told PTI.

He stressed the need for wider testing, appropriate treatment and follow-up to ensure the infection has been cleared.

Other Digestive Cancers Are Also A Growing Concern

Beyond infection-associated cancers, Kaul highlighted the rising incidence of several digestive cancers.

“We know that esophageal squamous cancer is another example where we will be close to a million cases by 2035,” he said, pointing to the burden in East Asia, sub-Saharan Africa and South America, including India.

Kaul also identified liver cancer as a growing concern and noted the rise in colorectal cancer among younger people in Western countries. The increase in colorectal cancer among younger adults in the US contributed to recommendations to begin average-risk screening at age 45 rather than 50.

These trends underline the need to address infectious causes of cancer alongside other risk factors, while improving access to prevention, early detection and appropriate care.