Scientists reveal the four ways we age biologically that matter more than how many birthdays we’ve had

• Four age-o-types pertain to liver function, metabolism, kidneys, immune health
• A person may have a biological age of 40 but an immune or kidney age of 55
• READ MORE: Six women reverse aged themselves by 11 years with healthy diet

Aging is an unavoidable part of the human experience, but not all parts of the body age in the same way at the same pace.

Researchers at Stanford University identified four biological aging patterns, or ageotypes, that explain why certain parts of some people’s bodies change with time differently than others.

The four types involve the metabolism, immune system, liver and kidneys.

Someone may have a chronological age of 40 but an immune system age of 45 that puts them at higher risk of getting an autoimmune disease like rheumatoid arthritis, while a hepatic ageotype will likely have a higher risk of liver diseases such as cirrhosis.

The team of genetics experts set out to understand why certain people are more susceptible to different aging-related disorders throughout their lives, information which they say could give people a better chance at preventing those health problems as they get older.

Researchers at Stanford University set out to determine how individuals age on a molecular level over time in one of the only studies of its kind to follow the same subjects and the ways their bodies change over time.

Dr Michael Snyder, chair of genetics at the Stanford University School of Medicine and lead author of the ageotypes report, said: ‘Our study captures a much more comprehensive view of how we age by studying a broad range of molecules and taking multiple samples across years from each participant.

‘We’re able to see clear patterns of how individuals experience aging on a molecular level, and there’s quite a bit of difference.’

They were able to pinpoint four main biological pathways that could explain why some parts of people’s bodies deteriorate faster than others and how they can take preventative action earlier in their lives.

The team followed 43 healthy men and women ranging in age from 34 and 68 for two years. Researchers took samples of feces, blood, genetic material, microbes, proteins, and other byproducts of metabolic processes over the course of at least five well visits and tracked levels of biological molecules over time.

In tracking how samples changed over time, the team identified 608 molecules that could be used to predict what might contribute to age-related health problems.

A person whose ageotype is metabolic has a greater likelihood as they age of experiencing health problems affecting their metabolism, a finely tuned system of chemical reactions in the body that changes food into fuel for the body’s many biological processes.

A metabolic ageotype would be more likely to have trouble managing their blood sugar levels and are more prone to having heart failure, insulin resistance, obesity, and type 2 diabetes later in life. A metabolic ager may have a higher likelihood of becoming obese in their later years, while they may at the same time have the immune system of a much younger, stronger person.

An immune ageotype refers to a person whose immune system is aging more rapidly than the rest of the body. Immune ageotypes accumulate more markers of whole-body inflammation, which is a response to the body’s fight against harmful pathogens and toxic compounds like free radicals invading the body.

These people may also be at higher risk of autoimmune diseases caused by an overzealous immune system response to the body’s cells, such as rheumatoid arthritis, lupus, type 1 diabetes, and multiple sclerosis.

A hepatic ageotype is one in which the liver ages faster than the rest of the body. Aging is already associated with worsening liver function, including reduced blood flow to the liver.

The liver is a vital organ for filtering and detoxifying blood, processing poisonous substances such as alcohol and drugs, and hundreds of other functions crucial to sustain life. But a hepatic ageotype will see their liver function deteriorate as they get older, putting them at higher risk of cirrhosis and non-alcoholic fatty liver disease.

Do YOU look old for your age? You might be more prone to illnesses 

Dutch researchers guessed the ages of 2,700 people 50 to 90, based only on pictures of their face and interviewed them about their health. Results showed those who looked the youngest compared to their actual age had better thinking skills and were up to a quarter less likely to suffer from health woes. 

The nephrotic ageotype pertains to kidney function. Kidneys clean out waste from blood to produce urine and balance the body’s fluids, sending cleaned blood back throughout the body. Healthy kidneys also help manage blood pressure.

The kidney ageotypes are at a greater risk of kidney diseases later in life.

While people may fall into one of these ageotype pathways, that does not mean they don’t also see aging in other parts of their body.

One person in the study, for instance, showed signs of being a kidney ageotype but only showed minor age-related changes in other pathways. Meanwhile, another person showed signs of fast aging in the kidney and metabolic functioning pathways but slower aging in the immune and liver pathways.

The Stanford researchers’ findings, published in the journal Nature Medicine, suggested that as people gain a better understanding of what biological processes are likely to break down first, they will have a far greater chance at improving their health by losing weight, limiting smoking and alcohol use, and managing their high blood pressure and glucose levels.

Dr Snyder said: ‘The ageotype is more than a label; it can help individuals zero in on health-risk factors and find the areas in which they’re most likely to encounter problems down the line.

‘Most importantly, our study shows that it’s possible to change the way you age for the better. We’re starting to understand how that happens with behavior, but we’ll need more participants and more measurements over time to fully flesh it out.’