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.

Obesity during the 20s and 30s can fuel the risk of many lifestyle disorders like type 2 diabetes, cardiovascular diseases, metabolic syndrome, non-alcoholic fatty liver disease, sleep apnea and many others.

But according to a large study published in Annals of Internal Medicine, obesity could also increase the risk of developing cancer before midlife. The study identified higher chances of thyroid, endometrial and ovarian cancers.

How Was The Study Conducted?

Researchers examined health records of 6,313,338 adults in South Korea, aged between 20 to 39 years, who had no previous history of cancer.

Participants were followed for an average of 11.2 years to study the relationship between body weight and cancer risk.

During the follow-up period, 151,893 cancer cases were recorded. The findings showed that cancer risk increased in people with higher body mass index (BMI).

The researchers found that the 10-year total incidence of cancer was 1.84% among people with normal body weight. This increased to 2.24% among those with class I obesity and 2.62% among those with class II obesity.

In other words, the 10-year cancer incidence was approximately 0.78 percentage points higher among people with class II obesity than among those with normal weight.

The researchers also found that people with abdominal obesity were at higher cancer risk than those who didn’t have.

Among people with class I obesity, the 10-year cancer incidence was 2.45% in those with abdominal obesity, compared with 2.13% in those without it.

“Because abdominal obesity may be an important indicator for distinguishing cancer risk, it is important to manage waist circumference along with weight from a young age,” the authors wrote.

Also read: High-Fibre Diet Outperforms Metformin In Blood Sugar Control And Weight Loss, Study Finds

Three Cancers Linked To Early Adulthood Obesity

The study identified particularly strong associations between obesity and cancers involving the thyroid and female reproductive system.

Thyroid cancer: Excess body weight has previously been linked with changes in metabolic and hormonal changes that may affect thyroid cancer development.

Endometrial cancer: Obesity can increase oestrogen levels because fat tissue produces this hormone. Prolonged exposure to excess oestrogen can stimulate the growth of the uterine lining and increase the risk of endometrial cancer.

Ovarian cancer: The relationship between obesity and ovarian cancer is complex and may involve inflammation, insulin resistance and hormonal changes.

Also read: Warren Buffett Says He Hasn't Drunk Water In 48 Years: What Happens If You Replace It With Coke?

Obesity & Cancer Risk

Obesity causes several biological changes that may contribute to cancer development. One of them is chronic inflammation.

Excess fat tissue can fuel inflammation that may create an favourable environment for abnormal cell growth.

Obesity can also lead to insulin resistance, in which the body’s cells respond less effectively to insulin. This can cause higher insulin levels, which may fuel cell growth and proliferation.

Hormonal changes are also a factor. Fat tissue produces oestrogen, and higher levels of this hormone have been linked with cancers like endometrial and ovarian.

The study authors wrote, "Some cancers have recently become more common even among younger people, and this study confirmed that obesity in young adults is significantly associated with the development of these cancers."

Scientists have discovered a previously unknown mechanism that could explain why high cholesterol diet makes it challenging for the liver to remove bad cholesterol from the bloodstream. Researchers have also identified an experimental drug that blocks this process, offering a new method for treating high cholesterol.

The findings are published in the journal Nature by researchers from the University of California San Diego School of Medicine. Their experiments showed that blocking a specific enzyme called cathepsin A (CTSA) helped retain the liver's ability to clear low-density lipoprotein (LDL), commonly known as bad cholesterol.

In mice, inhibiting this enzyme stabilised LDL receptors in liver cells, reducing LDL cholesterol.

"We've known for a long time that a high-cholesterol diet reduces the liver's ability to clear cholesterol from the blood, but we didn't fully understand why," said senior author Alan Saltiel, professor of medicine at UC San Diego School of Medicine. "This new discovery explains a critical piece of that puzzle."

More About The Experiment

The liver plays a key role in regulating cholesterol levels. It uses LDL receptors located on the surface of liver cells to capture LDL cholesterol from the bloodstream.

When fewer of these receptors are available, the liver becomes less efficient at removing LDL cholesterol, allowing it to increase in the bloodstream. The researchers discovered that consuming high amounts of dietary cholesterol activates a protein called Ral. This increases the activity of CTSA, an enzyme that breaks down LDL receptors.

As these receptors are lost, the liver's ability to clear bad cholesterol declines. When researchers blocked CTSA using a small molecule inhibitor, LDL receptors became more stable and LDL cholesterol levels decreased dramatically in mice.

Also read: Recreational Drugs, Steroids & Birth Control: Expert Explains Why Strokes Are Arriving Decades Earlier

Experimental Drug That Can Help Lower Cholesterol

The discovery has sparked interest as researchers have identified an experimental drug that targets CTSA. The drug was originally developed as a possible treatment option for heart failure. Although its development for that purpose was discontinued for other reasons, it had already completed a Phase 1 clinical trial, which evaluated its safety in humans.

This previous test could help researchers move towards studying its ability as a cholesterol treatment. However, the drug has not yet been shown to lower LDL cholesterol in humans.

"There's still a real need for new cholesterol-lowering options, since some people can't get to safe levels even with the drugs we have now," Saltiel said.

He added, "This new pathway we discovered is completely separate from anything that existing drugs target, so it gives us a new opportunity to fill that gap."

The researchers hope to test the experimental CTSA inhibitor in a Phase 2 clinical trial to determine whether it can safely and effectively lower cholesterol in people. If successful, the approach could offer another option for people who struggle to control LDL cholesterol despite using existing treatments.

Saltiel said, "Luckily, there's an experimental drug sitting on the shelf that's already been shown to be safe in humans."

"We hope to test whether this might be effective by conducting a clinical trial -- which could potentially bring a new treatment option to patients much sooner than would have been expected."

Irritable bowel syndrome (IBS) is often characterised by digestive symptoms like abdominal pain, bloating, constipation and diarrhoea. However, the condition involves more than the digestive system.

A new review published in The Lancet explains how interactions between the gut and brain, changes in the gut microbiome, immune activity and the body's response to pain can contribute to the development of symptoms.

The review, titled Irritable bowel syndrome and related disorders of gut-brain interaction, brings focuses on biological and psychological evidence behind IBS. Researchers describe it as a disorder of gut-brain interaction, in which signals between the digestive system and the central nervous system affect gut function.

The authors also discuss chronic constipation and functional diarrhoea, which belong to the bigger group of disorders related to gut-brain interaction. These conditions may affect an estimated 20% of the global population.

What Is The Gut-Brain Connection In IBS?

Also read: Olympian Ciara Mageean Dies At 34 After Bowel Cancer Battle: Warning Signs In Young Adults

The gut and brain communicate continuously through a complex network that involves the central nervous system, autonomic nervous system, enteric nervous system and hypothalamic-pituitary-adrenal (HPA) axis.

The brain can influence intestinal movement, secretion and sensitivity, while signals from the gut can affect how the brain processes pain and other sensations.

In people with IBS, this communication may become disrupted. The result can be changes in bowel movements, more sensitivity to normal digestive processes and abdominal discomfort.

The authors said, “These central and peripheral mechanisms can act in an integrated way to cause IBS symptoms, via the gut-brain axis.”

For instance, a person with IBS may experience pain or bloating even when the amount of gas or intestinal movement would not cause discomfort in someone without the condition. This is due to a condition called visceral hypersensitivity, in which the nerves supplying the digestive organs become unusually sensitive to internal sensations.

The review explains that changes in both peripheral mechanisms within the gut and central mechanisms involving the brain can contribute to symptoms.

Gut Bacteria And Inflammation May Contribute To IBS

Also read: Can Coffee Trigger Irritable Bowel Syndrome?

The gut microbiome, which consists of microorganisms living in the digestive tract, is another important part of the gut-brain connection.

Changes in the composition and activity of gut bacteria may impact intestinal function, immune responses and communication with the nervous system. The review identifies the following:

• Gut infections: Gastrointestinal infections can trigger IBS symptoms in some people, even after the initial infection has subsided.
• Altered gut microbiome: Changes in intestinal bacteria may affect digestion, immune activity and gut function.
• Increased intestinal permeability: Changes in the intestinal barrier may allow substances to pass through more easily, potentially contributing to immune activation.
• Low-grade inflammation: Mild inflammation in the intestinal lining and changes in immune function may contribute to symptoms.
• Abnormal gut movement: Changes in gastrointestinal motility can cause food and waste to move through the digestive tract too quickly or too slowly.
• Visceral hypersensitivity: Increased sensitivity in the gut can make normal digestive processes feel painful.

Mental Health And IBS

Psychological health is another component of the gut-brain axis. Stress, anxiety and other psychological difficulties can influence how the brain processes pain and communicates with the digestive system.

The HPA axis, which helps regulate the body's response to stress, plays a role in this process . Changes in stress levels can affect gut movement, secretion and sensitivity.

Currently, there is no single biomarker that can diagnose IBS. Doctors assess symptoms, medical history and clinical findings, while using tests to rule out other conditions.

The review highlights that some underlying mechanisms can already be measured through approved tests and questionnaires. These include abnormal bile acid metabolism, accelerated movement of contents through the colon and psychological conditions.