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.

Many people associate allergies with outdoor pollution, dust, or seasonal changes. However, doctors are increasingly seeing another factor contributing to allergic reactions: the indoor environment.

Allergies Worsening Even When You Stay Indoors?

Over the last two years, there has been a definite increase in patients coming in with respiratory issues. Many people who develop asthma-like symptoms later in life often ask, “Doctor, we hardly go out. How can we develop these problems?” The answer often lies in the indoor pollutants and allergens that go unnoticed in everyday life.

Most people spend nearly 90% of their time indoors — at home, in offices, malls, cars, and other climate-controlled spaces. While staying indoors may feel safer than being exposed to outdoor pollution, it can sometimes mean longer exposure to allergens trapped inside. These may trigger a runny nose, itchy eyes, cough, sinus congestion, asthma, rashes, or hives.

Many indoor irritants are invisible. Common sources include dust mites, pet dander, fungi, chemical vapours from cleaning products, air fresheners, mosquito repellents, and cooking smoke. Poor ventilation or inadequate air exchange allows these allergens to remain trapped for long periods. In many urban homes, indoor air quality can sometimes be worse than outdoor air.

Primary Indoor Irritants That Trigger Allergies

Smoke is one of the most overlooked indoor triggers. Incense sticks, dhoop, and agarbattis, which are part of daily routines in many homes, generate smoke and fine particulate matter that can irritate the airways. Cooking smoke can also be harmful, especially when food is fried, roasted, or cooked with heavy spices. Mosquito coils are another common source. In short, any form of indoor smoke can affect respiratory health, particularly in people who already have allergies or asthma.

Dust is another major concern. Many households practise dry dusting every day, but this can push dust particles back into the air and worsen symptoms in those with dust allergy or asthma. Wet mopping, wet wiping, or vacuum cleaning are safer alternatives.

Air conditioning is another factor. AC filters that are not cleaned regularly can become clogged with dust, pollen, and fungal spores, which keep circulating indoors. Closed rooms with little fresh air make this worse. If anyone in the family smokes or uses vaping products, these are well-established indoor pollutants that can significantly impact respiratory health.

Modern interiors can add to the problem. Fabric sofas, heavy curtains, carpets, and excess furniture increase the surface area where dust collects, and dust mites thrive. Plug-in mosquito repellents, strong floor cleaners, aerosol sprays, room fresheners, smoking, and vaping indoors are also important for indoor pollutants.

How To Tackle It?

Lifestyle changes after the pandemic have worsened exposure. Work-from-home routines, online classes, longer screen time, and reduced outdoor activity mean people spend more hours in closed spaces with limited fresh air.

Small steps help - open windows when outdoor air quality allows, let sunlight in, wash bed linen and curtains regularly, clean AC filters, avoid dry dusting, check damp areas for mold, reduce incense smoke, mosquito coils, and strong fragrances, and air out stored clothes before use.

Pollution remains a concern, but it is no longer the only culprit. The way we live indoors today is quietly shaping our respiratory and immune health. Recognizing these hidden triggers early can prevent allergies from becoming a long-term lifestyle problem.

By Dr Sameer Bansal, Pulmonology Respiratory Medicine Specialist, Apollo Hospitals, Bangalore

The monsoon season brings a respite from scorching heat, but it also increases the risk of contracting various diseases and infections. Apart from common illnesses like dengue, malaria, and typhoid fever, states and cities in India also face the risk of specific infections based on climate, geography, infrastructure, parasites, and sanitation.

Prevention Of Gut Infections During Monsoon

In a conversation with Health and Me, Dr Aabha Nagral, Director of Gastroenterology, Chief Hepatologist and Liver Transplant Physician at Jaslok Hospital and Research Centre, explained how rains can lead to contamination of water sources, increasing the spread of fecal-oral infections.

As the monsoon has set in, several states in India, including Maharashtra, Kerala, Karnataka, and Tamil Nadu are facing an alarming rise of gastrointestinal infections. Heavy rains are one of the reasons behind contamination of drinking water and food supplies.

Bacteria, viruses, and parasites in food and drinking water often result in a spike in diarrhea, vomiting, food poisoning, and gastroenteritis. Increased bacterial growth in warm and humid conditions, combined with poor food hygiene and subpar sanitation facilities, contributes to the rise of gut infections in urban areas like Mumbai.

Recent research and seasonal trends also support the increase in these infections. A 2025 review published in Frontiers in Tropical Diseases found that tropical infections like cholera, giardiasis, and enterotoxigenic E. coli infections disrupt the gut microbiome by reducing beneficial bacteria and increasing harmful microbes.

Faecal-oral diseases and infections like hepatitis A and E mainly cause jaundice, whereas gastroenteritis presents with diarrhea. On the other hand, typhoid can present with high fevers.

Dr Nagral says, “You can have various other diseases during the rains by what we call faecal-oral contamination of water. So, we know that during the rainy season, the water gets contaminated more easily. So, make sure that you are boiling your water for at least 10 minutes, or if you are using RO or any other means of sterilising the water. Also, make sure your systems are well serviced regularly so that the water you drink is well filtered and sterile.”

The water source is among the first to get contaminated during the monsoon. Dr Nagral suggests these tips to prevent gut infections.

• Avoid foods and drinks that contain water in different forms

• Avoid street-side juices during monsoons to prevent gut infections

• Avoid any drink that contains ice or that has been sitting out for a long time

Dr Aabha Nagral also spoke about avoiding consuming street foods as they are more likely to be contaminated during the monsoon.

She explains, “Also, I would say avoid all street food because that’s how diseases spread. They spread through flies which sit on the faeces, which are often unfortunately there on our roadside, and then onto your food or drinks.”

Common Monsoon Diseases

Monsoon diseases can vary across India depending on rainfall, flooding situation, sanitation, and local mosquito populations. Some of the most common ones include dengue, malaria, typhoid, and diarrheal diseases. These infections affect nearly every state during the rainy season.

Specifically, Kerala, Maharashtra, Karnataka, and Tamil Nadu have seen a higher likelihood of leptospirosis following floods.

Odisha, Chhattisgarh, and Jharkhand continue to record high malaria cases, while flood-prone states like Odisha, Assam, and Bihar are vulnerable to water-borne illnesses, including cholera and gastroenteritis.

A recent study has found proof that an autoimmune reaction is triggering certain neurological symptoms seen in some long COVID patients. The study, conducted in healthy mice, found that the mice exhibited symptoms mirroring those of affected patients to some extent.

What is Long COVID?

While it has been a long time since the end of the COVID pandemic, its effects continue to linger even today. Several patients who contracted COVID continue to suffer.

Autoantibodies Behind Long COVID Symptoms?

A US NIH-funded research group, directed by Drs. Akiko Iwasaki and Tamas L. Horvath of the Yale University School of Medicine and Dr. David Putrino of the Icahn School of Medicine at Mount Sinai recently found that autoantibodies could be triggering these neurological symptoms in some long COVID patients.

Antibodies, in a healthy person, help fight infections. In patients with autoimmune diseases, these antibodies target the body’s own tissues. They are called autoantibodies.

The study also discovered that patients who had these autoantibodies are more likely to experience similar symptoms. For example, people with autoantibodies are more likely to face symptoms like loss of taste and smell. They are also more likely to experience nausea and joint pain.

The Mouse Experiment

The researchers conducted the study by transferring purified antibodies from long COVID patients into healthy mice. It was discovered that the mice developed the following changes that resembled the donors' symptoms:

• Antibodies from patients with chronic pain caused increased pain sensitivity

• Antibodies from patients with dizziness caused balance problems

• Antibodies from fatigued patients reduced treadmill endurance

The recent breakthrough in long COVID research has brought the healthcare industry one step closer to personalizing care for those affected.

Dr. Putrino says, “Our study now shows that if you are in a subgroup of Long COVID patients who have autoantibodies circulating in your body, this is a quantifiable sign that you may be a good candidate for these drugs.”

Long COVID Patients More Likely To Develop Heart Diseases

The study finds that cardiovascular diseases were more common among long COVID patients. It concluded that 11.9% of those with long COVID have CVD compared to 6.8% without this condition.

Specifically, it further revealed that long COVID was associated with a higher risk of chest pain and heart attack, but not coronary heart disease and stroke.