We all must have come across the phase: this is why women live longer than men. These are all over the social media, where men are performing more often than not, some experiments, without gears, just for fun, "in the name of science". The caption reads: this is why women live longer. However, is there really a science to it, other than the fact that women choose to do things more safely?

In the United States, women have a life expectancy of about 80, whereas men have 75. Women outlive men and this holds true regardless of the country women live, the money they make, and other factors. In fact, it is true for most other mammals too.

Dr Dena Dubal, a professor of neurology at the University of California, San Francisco told the New York Times, "It is a very robust phenomenon all over the world, totally conserved in sickness, during famines, during epidemics, even during the times of starvation."

But what are the reasons? These reasons are often more complicated and less established. It is important to note that only because women are outliving men does not mean they are living a better life. In fact, women tend to have shorter health spans, which means the number of healthy years in a person's life is less in women than men, confirmed Bérénice Benayoun, an associate professor at the U.S.C. Leonard Davis School of Gerontology.

As per a 2021 study titled, Sex differences in frailty: Comparisons between humans and preclinical models, found that women are more physically grail than men in old age. They are also more vulnerable, especially after menopause and are at more risk of developing cardiovascular issues and Alzheimer's disease because of age.

The key is in figuring out what makes one sex more resilient or vulnerable.

Genetics

For things which do not find easy explanations, scientists look for their answers in genes. Many research, including a 2020 study titled, The sex with the reduced sex chromosome dies earlier: a comparison across the tree of life, suggests that the XX set of female sex chromosomes may impact longevity. However, there has not been any clarity on how it affects longevity.

Another 2018 study titled, Female XX sex chromosomes increase survival and extend lifespan in aging mice, which was conducted by Dr Dubal's lab, looked at genetically manipulated mice with different combinations of sex chromosomes and reproductive organs. It was found that those with two X chromosomes and ovaries lived longest, followed by mice with two X chromosomes and testes. Mice with XY chromosomes had shorter life spans.

"There was something about the second X chromosome that was protecting the mice from dying earlier in life, even if they had testes. What if there was something on that second X chromosome that was in some ways a sprinkle of the fountain of youth," says Dr Dubal. While scientists have not yet looked at this factor in humans, Dr Dubal suggests that humans have the same hormones and sex chromosomes, and similar reproductive system that could corroborate the similar findings in people.

Hormones

Plenty research has shown that estrogen is responsible for longevity also effect on the immune system. The data also shows that before menopause, the female immune system tends to do better. In fact Dr Benayoun said that males tend to do much worse in response to infection.

Another 2017 study titled, Ages at Menarche and Menopause and Reproductive Lifespan As Predictors of Exceptional Longevity in Women: The Women's Health Initiative, found that women who experienced menopause later in life over the age 50 lived longer than those who experienced it earlier.

Lifestyle and Behavior

There are also disparity in behavioral patterns between men and women. This includes smoking, drinking heavily, which can contribute significantly to mortality. Women also have more "health promoting behavior", believe experts. Women are also more likely to socialize than men and thus it protects them from detrimental effects of social isolation and loneliness. In fact, a 2023 analysis published in Jama Network, titled, Widening Gender Gap in Life Expectancy in the US, 2010-2021, found that women are less likely to die by drug overdose or suicide.

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.