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.

Even a mild case of COVID-19 may trigger long-lasting eye problems, with new research revealing that persistent inflammation and nerve damage could be responsible for symptoms that standard eye tests often fail to detect.

The study, led by researchers at Linköping University in Sweden and published in Nature Communications, sheds light on why some COVID-19 survivors continue to experience debilitating vision issues months or even years after infection.

The research began after people who had recovered from mild COVID-19 sought medical help for persistent eye complaints. Many reported:

• Severe eye pain
• Light sensitivity (photophobia)
• Difficulty reading and focusing
• Extreme eye fatigue

Many participants said the condition significantly disrupted their daily lives, preventing them from working or continuing their education.

What the Study Found

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Researchers evaluated 100 people who developed eye problems after mild COVID-19 but had never been hospitalized. Their symptoms had persisted anywhere from three months to three years.

The findings were compared with those of 32 people who had recovered from mild COVID-19 without developing eye symptoms.

Using advanced imaging and laboratory techniques, researchers identified several abnormalities that conventional eye exams failed to detect.

Persistent Inflammation and Nerve Damage

The study found evidence of:

• Long-term inflammation in the eyes
• Damage to nerves controlling multiple eye functions
• Abnormal immune activity involving T cells
• Changes in proteins found in tear fluid

Lead author Petros Moustardas, senior research associate at Linköping University, said the findings indicate that COVID-19 may trigger a severe immune reaction in the eyes, resulting in chronic inflammation and nerve dysfunction.

Why Light Sensitivity Happens

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One of the most common complaints among participants was extreme sensitivity to light. Researchers found that their pupils were allowing too much light into the eyes because of impaired nerve control.

This abnormal pupil function was also associated with:

• Headaches
• Difficulty reading
• Trouble maintaining focus

An Unusual Eye Movement Disorder

The study also identified impaired coordination between the two eyes.

Some participants developed adult-onset strabismus—commonly known as crossed eyes—a condition that is rare in adults.

Researchers believe this occurred because COVID-19 affected the nerves responsible for controlling eye muscles.

A New Way to Diagnose COVID-Related Eye Problems

Because routine eye tests often miss these abnormalities, the research team developed two diagnostic models.

The first relies on specialized ophthalmic tests available at advanced eye clinics, while the second combines these examinations with tear fluid protein analysis to improve diagnostic accuracy.

Researchers hope these models will help doctors recognize COVID-related eye syndrome earlier and pave the way for future treatments.

"We found that the problems experienced by those affected were not detectable by standard tests. We had to perform specialised examinations to detect deviations. The puzzle pieces then fell into place, and we found explanations for the symptoms," said Neil Lagali, professor of experimental ophthalmology at Linköping University.

He added that while the findings provide important clues about how COVID-19 affects the eyes, more research is needed to develop effective treatments for those living with persistent vision problems.

Plant-based Vitamin D3 is often marketed as a healthier or superior alternative to traditional supplements, but doctors say that's not necessarily the case.

According to Dr. Murtaza S. Bagwala, Head of Emergency Medical Services at Saifee Hospital in Mumbai, existing research shows that plant-based Vitamin D3 is just as effective as conventional Vitamin D3 in increasing the body's vitamin D levels.

"Current evidence suggests that plant-based Vitamin D3 performs similarly to conventional Vitamin D3 supplements. For people who prefer vegan or plant-based products, it is a suitable alternative," he told HealthandMe.

Echoing this view, Dr. Sudhir Kumar, Neurologist at Apollo Hospitals in Hyderabad, said that plant-derived Vitamin D3—usually obtained from lichen, algae, or modern fermentation methods—provides an animal-free option without sacrificing effectiveness.

In a post on X, he noted that while plant-based Vitamin D3 is welcome news for vegans and those seeking cruelty-free supplements, both forms work equally well. He added that there is no medical need for people to switch if they are already taking conventional Vitamin D3 supplements.

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India has approved its first plant-based Vitamin D3 (cholecalciferol) ingredient, a move that could expand options for food fortification and dietary supplements while addressing the country's widespread Vitamin D deficiency.

The Food Safety and Standards Authority of India (FSSAI) has cleared VITADEE Green, developed by Fermenta Biotech, for use in health supplements, nutraceuticals and food products.

The company stated that the ingredient is produced using an India-patented process and offers a sustainable, scalable and vegetarian-friendly source of Vitamin D3.

The approval allows Indian manufacturers to incorporate the ingredient into fortified foods, beverages and dietary supplements.

It is particularly significant for vegetarians and vegans, who have traditionally had limited access to Vitamin D3 because most supplements are derived from lanolin, a by-product of sheep's wool.

The approval also supports India's broader efforts to improve nutrition through food fortification, an area where experts say Vitamin D remains a major gap.

What Is Vitamin D3?

Vitamin D3, often called the "sunshine vitamin," is produced by the body when the skin is exposed to sunlight.

It helps the body absorb calcium, maintain healthy bones and teeth, and lowers the risk of fractures. In children, severe deficiency can lead to rickets, while in adults it increases the risk of osteoporosis, muscle weakness, and falls.

Beyond bone health, Vitamin D3 also supports immune function. Research suggests low Vitamin D levels may be associated with increased susceptibility to infections and higher levels of inflammation.

Who Should Take Vitamin D3 Supplements?

The experts said the key question is whether supplementation is needed, not whether the source is plant- or animal-derived.

"The source matters mainly for ethical, dietary or personal preference—not for efficacy," Dr. Sudhir said.

Dr. Bagwala cautioned against taking high-dose Vitamin D without medical advice, as excessive intake can raise calcium levels and increase the risk of kidney stones and other complications.

Yawning has a certain fact attached to it, which is without a doubt a reason for curiosity and amazement among people. Many of you must have noticed that when someone nearby yawns, you often end up yawning too. Even in some cases, a person yawns just after hearing the word yawn or watching someone yawn on screen.

Yawning itself is a natural physical process that involves taking a deep breath and stretching the muscles used for breathing. Some experts suggest that it may help increase alertness and leave us feeling refreshed. However, while scientists have proposed several theories about the purpose of yawning, one question continues to intrigue researchers: why are yawns so contagious?

Dr. Debanjan Pan, Consultant Psychiatrist at Saltlake Mindset, told Health and Me, "Contagious yawning may be linked to mirror neurons, which help us understand and imitate the behavior of others. Humans have survived by living in groups, and our brains are naturally wired to synchronize with the people around us. When we see someone yawn, the same neural networks in our brains may become activated, prompting us to yawn as well."

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Yawning involves taking a very deep breath, which increases oxygen intake and stimulates several parts of the respiratory system. This deep inhalation can temporarily raise the heart rate and boost blood circulation to the spinal cord and the brain, making a person feel calmer and more relaxed afterward.

According to Dr. Pan, this sense of relaxation may also explain why yawning is contagious. When we see someone else yawn, the brain's empathy circuits, particularly those linked to mirror neurons, become active. As humans are highly social beings, we often unconsciously mimic the behaviour and emotions of people around us, causing a yawn to spread from one person to another.

But there might be a question: if yawning is contagious because humans are social animals and human brains are naturally wired to synchronize with the people around them, then why doesn't coughing and sneezing have the same effect?

Dr. Vikas Mittal, Director - Pulmonologist, CK Birla Hospital, Delhi, addressed this very issue and explained, "Yawning is different than coughing and sneezing. Coughing and sneezing are protective reflexes that protect you from irritants. They can be contagious, but that contagion comes after one or two days, not immediately as is with yawning. Yawning occurs because of the brain's automatic self-mirroring networks."

Dr. Mittal further added, "What it means is when somebody yawns, then your brain starts imitating that unintentionally. Not only yawning, but other emotions like a smile, laugh, and fear can trigger the same emotion in the people around you. This is because of the same brain's automatic self-mirroring networks."

Contagious yawning appears to be more than a simple reflex, offering insights into empathy, social bonding, and the human brain.