The Science of Longevity: Why Some People Live Healthily to 100

September 27, 2026

Obvious though it may be, if you don’t get ill – you live longer! And the most effective way to prevent illness is to slow your rate of ageing.

In the last decade or so research has proven that you can slow the pace at which you age, so your biological age becomes younger than your chronological age1.

That’s the secret of extending your health span and living to 100 – in good health. Because age is the biggest risk factor for almost every disease we fear – including and especially dementia, cardiovascular disease and cancer.

Prevent – rather than treat!

Rather than waiting for age-related diseases to develop and treat them separately, it is far better for you – (and far cheaper for our health services) – to slow ageing and thus help prevent or postpone them.

The aim is NOT, like some billionaires – to pursue an over-optimistic ‘fountain of youth fantasy’ of living to 150. That would be planet destructive. The aim IS to extend the years when you live fit, happy and well with your family – getting older and enjoying it! Longevity without quality of life is pointless.

Health span rather than just life span.

I dislike the term ‘anti-ageing’. It’s negative – whereas growing older but taking action to stay active and healthy is life affirming and positive.

I am 86 at the time of writing and still working. Not because I need to, but because I thoroughly enjoy researching and writing about health.

In December 2025 – chronological age 85 – I had a full body health check including scans, blood and urine readings. My metabolic age was assessed at 70. (A lower metabolic age indicates a more efficient metabolism, an indicator of good health).

As the nurse said wryly: “You must be doing something right!”.

I follow the advice below.

But I don’t obsessively monitor my biomarkers. Life is for enjoying and, for me, that includes the occasional glass of wine and cake. My dad had a great phrase “Moderation in all things – including virtue!”.

Keeping it (comparatively) simple

Ageing is complicated – but we know it is driven by five key factors. (There are several others as explored in this seminal 2023 paper Hallmarks of aging: An expanding universe - PubMed, but these five are arguably the most critical.)

1. The accumulative damage to your cells

Including damage to DNA. Which in turn means your DNA is less efficient in instructing your RNA to make the millions of proteins that run your body. These essential proteins then accumulate errors. Some of these errors manifest as the tau tangles and beta amyloid in the brain of Alzheimer’s patients or the protein build-up in cataracts.

2. Damage and mutations to your mitochondria

Those tiny ‘energy factories’ are in almost every one of your approximately 37 trillion cells. When these are damaged, cellular energy declines, which means less energy to power every function, including your immune system and cell repair.

Mitochondrial health is central to metabolic health: the ability to converts food into energy efficiently, use insulin effectively, and regulate blood sugar levels.

3. Inflammation from senescent cells increases

Billions of your cells die each day – the highest turnover being in your gut and red blood cells. And most are cleared away efficiently. But senescent cells are cells that have died but have not been removed by a decreasingly effective immune system. These senescent cells secrete inflammatory chemicals that cause free radical (oxidative) damage to the tissues around them.

4. Your ability for cellular and DNA repair declines

You have very sophisticated cellular and DNA repair mechanisms – but over time they decline in effectiveness. Which is why cancer is mainly a disease of the over 55s.

It’s partly because the nutrients in fruits and vegetables have a role in helping repair DNA, that increasing intake of plant nutrients is linked to lower rates of cancer. (6, 7)

5. Your microbiome becomes unbalanced

With fewer beneficial gut microbes and bacteria and more pathogenetic ones. Your absorption and metabolism of food become poorer and your immune system weakens – because about 70% of immune function is controlled in your gut.

You may be surprised that an unbalanced gut – called dysbiosis – is not just linked to IBS, constipation and bloating, but also to depression, anxiety, Type 2 diabetes, auto-immune disease, low energy and even dementia.

The result of these 5 factors? Cellular wear begins to win over repair, and we age.

An illustrated infographic comparing cellular repair and cellular wear, showing a healthy blue-green cellular state on the left and a damaged purple-orange cellular state on the right, with explanatory text between the two panels.

Are genetics a factor?

Yes, there are possibly several hundred genes that affect ageing – like the APOE gene, which affects cardiovascular health and the risk of neurodegenerative disease.

But most research indicates that diet and lifestyle account for some 70%-80% of your chance of longevity. So, you have a lot of influence on how long and how well you live.

How to combat these 5 main drivers of ageing

The number one way to slow the rate of ageing is to follow the Mediterranean diet. A healthy ageing diet It helps to lower the risk of heart disease, lower LDL cholesterol, reduce inflammation, lower blood pressure, maintain supple blood vessels, reduce the risk of several cancers, reduce the risk of Alzheimer’s and improve blood sugar control (29).

The Mediterranean diet features high intakes of fruits, vegetables, herbs, beans, nuts, and whole grains. These are rich in polyphenols (largely nutrients found in the vibrant colours of fruits and vegetable) and fibre. These reduce oxidative stress (thus reducing free radical damage to cells and DNA) and lower chronic inflammation.

Just as importantly, polyphenols can directly slow aging – as a 2024 paper(3) shows. This finding has been confirmed in a clinical trial, conducted by the University of Exeter on a novel supplement called DailyColours(30). This supplement contains 161 plant nutrients. And the clinical trial showed that the general benefits of polyphenols are significantly enhanced when nutrients from different coloured plant foods, found in the Mediterranean diet, are combined.

You can find an eating plan that delivers all these benefits at the end of this article.

This Mediterranean diet-based plan, plus maintained activity levels, helps you combat all five main threats to health and longevity.

They support the body’s ability to produce its own antioxidants – which is the most powerful way to combat free radical damage. They also increase the level of antioxidants in your diet.
They reduce inflammation and ‘inflamm-ageing’.
They support better gut health and the maintenance of a wide range of beneficial intestinal flora and boost your immune response.
They improve insulin sensitivity and help you maintain a healthy blood sugar level and weight.
They help improve the health of your mitochondria and therefore maintain cellular energy.

It’s not the passing of the years you need to fear, but the accumulated damage to cells. Limiting and repairing this damage is the secret of longevity and healthy ageing.

The cost/benefit of extending health span

We’ve all heard the phrase “You can’t put a price on health”. Maybe not. But you can put a price on ill health in later years.

The Sunday Times in September 2025 revealed that the average price of a care home was now £1,278 – a week! Or £65,000 a year. Many are considerably more, and the average care home stay is 3-4 years.

Unfortunately, quality healthy foods are somewhat more expensive that addictive junk food. Staying fit takes effort. Science-backed healthy ageing supplements cost extra.

But prevention is not just better than cure – it can be far less expensive.

10 more years of healthy life

Several recent studies have confirmed that the simple decisions not to smoke, to ensure 30 minutes average of exercise/activity a day, to follow the type of eating plan below and to maintain a non-obese weight can add 10 years to the average lifespan.

That doesn’t seem so hard, does it? But with the science-based advice below, we can do considerably better.(8)

What NOT to eat

The foods and proportions of foods we recommend are recommendations of what to eat. But knowing what NOT to eat for healthy aging is also important.

Only two dietary elements have been proved to directly cause cancer.

The first element is processed meats like salami, bacon and hot dogs, which contain cancer-causing nitrates.
The second is alcohol. As alcohol is metabolise, byproducts (especially acetaldehyde) are generated and DNA damage may occur. In addition, alcohol depletes NAD+ reserves, which runs your energy down. Which is why you feel tired ‘the morning after’

So, consume these very sparingly, and in the case of alcohol, stick to the guidelines of a maximum of 1 unit per day for women and 2 for men. Less is better.

However, other foods are known to increase the risk of cancer and ageing generally.

Red meats (beef, veal, pork, lamb, venison, goat) especially grilled at high temperature, increase the risk of colorectal cancer and breast cancer. Refined sugar foods are linked to the faster progression of certain cancers as well as cognitive decline.

Since obesity is a cancer risk factor, and refined carbohydrates like sweets and sugary drinks cause weight gain, limit or eliminate these nutritiously empty calorie foods.

One driver of ageing I haven’t mentioned is what scientists call ‘ deregulated nutrient sensing’. Your cells have built-in nutrient sensors that shift between growth mode and repair mode. When growth signalling stays continuously high, from constant eating or excess calories, cells spend less time on maintenance. That’s why snacking is ageing.

When not to eat

One very clear conclusion from longevity research is that calorie restriction increases lifespan. (76) But not many people would trade being hungry for another few years of life.

Fortunately, there is a less extreme way. Research shows that ensuring a 12–14-hour overnight period without food – a version of intermittent fasting – is strongly linked to healthy ageing and to markers of increased longevity. (9)

This fasting period aims to shift from burning carbohydrates to burning fats for fuel. It boosts your body’s natural repair mechanisms, fights oxidative stress (free radical damage), and may slow down your ageing clock.

Fasting also enhances mitochondrial function, because it challenges your mitochondria to make your cells’ powerhouses work more efficiently. It also activates sirtuins, a family of proteins known as “longevity genes”.

Finally, a 12-14 hour fasting period better regulates your circadian rhythm, which improves cellular health.

You can achieve all these proven benefits by regularly finishing dinner at say 6.30 pm and only starting breakfast at around 8pm. So, no raiding the fridge at night!

Movement is medicine

Just why is activity SO critical to increasing your health span?

It’s partly because exercise causes very mild damage to body tissues and stimulates the natural recovery processes in your body. Making you stronger.

This challenge/response mechanism is also true of some healthy foods. For example, kale, an especially healthy food, contains a very mild toxin – and your immune system rises to that challenge to perform at a slightly higher level.

As we have just seen, intermittent fasting also challenges the body – the response is improved repair mechanisms.

So, staying active is non-negotiable. And both cardio and strength exercise are critical in staying healthy as you get older.

You don’t necessarily have to do intense workouts — consistent, moderate exercise or activity makes a major difference. Staying active also supports mental health by releasing mood-boosting endorphins.

The optimum number of steps?

A huge 2025 analysis in the Lancet confirms that the ‘sweet spot’ average number of steps per day is 7,000. At this point the risks of cardio-vascular disease, Type 2 diabetes, and depression all drop significantly – and the risk of all-cause mortality drops by 47%!! 10

This number of average steps reduces cancer risk, too. 11

Interestingly, a 2025 study shows that a slight increase in walking pace – by about 10-15% extra – made a substantial difference to long term outcomes for older people. So, speed matters12

Keeping up your strength – at any age

Include some resistance exercises that keep your core strong. Maintaining muscle is important because studies show that low muscle strength doubles mortality risk.

A study covering almost 2 million men and women clearly shows that those with more muscle mass lived longer than those who allowed their muscles to decrease. 13

So, build a short simple sequence that includes wall squats, planks and push ups. A study in the Journal of the American Medical Association showed that a group of 90-year-olds were able to significantly improve their strength and independence with just 8 weeks of strength training2.

Even standing on one leg as you brush your teeth helps 😊.

A plank is one of the most effective strength exercises – it lowers blood pressure, too.

The British Heart Foundation has an exercise sequence suitable for any age. And we surveyed the literature to calculate the least amount of time you need to spend on strength activities to keep fit. (It’s 21 minutes a week!!).

While walking increases the flow of oxygen and nutrients to the brain, strength training stimulates actual brain cell growth. The combination is ideal.(14)

So, for example, while walking is best for cardio-vascular health, strength training is best to prevent bone and muscle loss – and reduce blood pressure.

How exercise cuts cancer risk

Your immune system includes two aptly named elements – Natural Killer (NK) cells and killer T-cells. Their role is to seek out cancer (and viral) cells and kill them. Recent research shows that exercise increases both the number and effectiveness of these immune cells.

Importantly, when NK cells and killer T-cells arrive at an early-stage tumour, they also signal to other types of immune cell to join in the effort to kill the tumour. 15

This doesn’t mean that exercise will prevent you getting cancer, but it does mean that it significantly cuts the risk. Surely a very convincing reason to commit to regular exercise?

Particular benefits for women

For women, exercise helps balance oestrogen and testosterone levels, which in turn reduces the risk of hormone-sensitive cancers like breast and prostate cancer from progressing.

A recently completed trial followed almost 900 patients over 8 years, 90% of whom had stage 3 colon cancer.

Half followed the sort of simple exercise plan as above for 3 years and aimed for 3–4 moderate walks a week.

The other half received general health education materials with no specific exercise plan.

After 8 years, those in the exercise group had a 28% lower risk of cancer recurrence or new cancers. AND had a 37% lower risk of death. Combined, that’s an almost 60% reduction in risk.(16)

Take an activity break from sitting

Finally, sitting for long periods is serious for everyone’s health – contributing not just to obesity, but heart disease and diabetes. Standing up for a couple of minutes every 45 minutes while working at a desk or watching TV is a simple way to break up prolonged sitting.

I undoubtedly look very silly, but if I have been watching TV for an hour or more, I often get up and run on the spot vigorously for 30 seconds. I feel much better afterwards.

In passing, maybe a cup of cocoa while watching TV isn’t just for grandma and grandpa! A 2025 study from the University of Birmingham shows that flavanols, found in cocoa and other polyphenols found in apples, berries, nuts and tea – can help counteract the impact of inactivity.

Keeping your brain sharp

We know the Mediterranean Diet and its cousin the MIND Diet are brain protective – and that’s reflected in the foods in our eating plan. Research indicates that this way of eating cuts the risk of Alzheimer’s by 53%.(17)

You’ll notice that whole grains, colourful vegetables and legumes (beans and pulses) and nuts and seeds are featured strongly. That’s partly because they contain trace amounts of the mineral lithium which recent research has indicated can significantly cut the risk of cognitive impairment and dementia.(18)

In addition, nuts and seeds contain a type of Omega 3 called alpha-linolenic acid (ALA). Numerous studies have linked eating enough Omega 3 with slower rates of cognitive decline and a lower risk of dementia. Of course, there are also good levels of Omega 3 in oily fish such as salmon, herring, mackerel and sardines.

You need more Omega 3 as you get older, to support brain repair. And each cell needs quality fatty acids like Omega 3 to ensure its outer membrane is well built. Which is why I recommend at least 2 portions of oily fish a week.

There is a recent intriguing indication that the live herpes zoster shingles vaccine may help protect against dementia(19) – and researchers are investigating how. Worth mentioning to your doctor.

Activity levels directly improve brain health too

Numerous studies have shown that the parts of the brain that control thinking and memory are larger in volume in people who exercise than in people who don't. And maintaining brain volume is directly correlated with brain health.(20)

The importance of a plant-rich diet, and of walking, was underscored at a presentation at the Alzheimer’s Association International Conference (AAIC) 2025. Intake of Mediterranean fruits and vegetables was shown to increase the formation of new brain cells as well as increased synaptic connections.

This is the same conference where the findings on the polyphenol rich supplement called DailyColours were presented. It too demonstrated ‘significant improvements in cognitive and physical measures consistent with what is known about the effects of the Mediterranean Diet.”

There is merit in playing word games, Sudoku, and solving puzzles. But recent research confirms that the secret of long-term brain health is ‘neural plasticity’. That is, creating new pathways in the brain and even new brain cells.

Playing the same word games, every day, doesn’t create new pathways. Doing something entirely different does. So, take up a new hobby, or learn a new skill as well as playing those word games. People who avoid cognitive decline stay curious and eager to learn.

Control your weight

It’s long been known that obesity and dementia are linked. But is that a correlation or causation? In other words, is a higher BMI a cause of dementia?

Thanks to a study published in 2026 involving over 504,400 participants, we know the answer. Carrying excess weight directly increases dementia risk – largely via increased blood pressure. 21

Long-term untreated high blood pressure causes damage to the delicate blood vessels in the brain. This eventually leads to reduced blood flow, micro-infarcts (tiny strokes), and white matter damage.

Neurons no longer get the level of oxygen and nutrients they need – and this leads to cognitive decline and ultimately vascular dementia.

A sense of purpose

One vital aspect of health span and quality of life is illustrated by David Attenborough, Jane Goodall and Pablo Picasso. It’s having a sense of purpose – as the Japanese saying ikigai goes – “a reason to get up in the morning”. Such people have an astonishing 46% lower risk of mortality over the following 4 years than others. 22

So what skills can you bring to your community?

What else extends health span?

Cold therapy

Research shows that exposure to cold may offer multiple health advantages beyond controlling inflammation.

According to UCLA Health, cold therapy can enhance immunity against common infections, alleviate pain, address depressive symptoms, boost metabolic rate and enhance blood circulation.

So that occasional cold shower or sea bathe may sound intimidating – but it has research to support it.

Keep hydrated

Speaking of water, far too many older people are under-hydrated.

The NHS recommends that we drink 6–8 glasses of water per day, and the key is to start drinking in the morning and continue to do so regularly throughout the day. Tea and coffee count in that total.

Keeping hydrated is vital for keeping you blood pressure under control – indeed the majority of people with high blood pressure are found to drink less water than they should (23). Drinks that are extra helpful in curbing high blood pressure include beetroot juice(4), unsweetened apple juice and pomegranate juice(5).

Get checked

Although our concentration is on prevention, you are wise to have regular check-ups. Early diagnosis of disease saves lives – especially for cancer.

For women, cervical screening from your late 20s and breast and bowel screenings from 50 can flag up any issues that can be dealt with quickly before anything becomes serious.

Blood pressure is a clear risk factor for dementia. So, both men and women over 50 should know their blood pressure, blood sugar and cholesterol readings, and have a bi-annual kidney, liver, heart and lung function test.

Take those vaccines

The efficiency of your immune system declines over time – partly linked to inflammation which causes senescence in immune cells too. So, take up those offers of flu vaccines – because bouts of flu can lead to faster ageing. 24

Hearing checks

Finally, cognitive decline appears 2-3 times more common in people who have hearing impairment and who lack social contact. So have your hearing checked and make every effort to stay regularly in touch with family, friends and neighbours.(25)

Four simple ways to check your likely health span

There are now epigenetic tests to help assess your biological age and glimpse your likely health trajectory. These and other biomarkers of ageing are explained in detail in this article.

Although your DNA is a constant, the way that your DNA is ‘expressed’ is directly affected by your diet and lifestyle. ‘Expressed’ means that genes can be switched on or off by your diet and nutrient intake and activity.

So, epigenetic testing measures chemical modifications to DNA that regulate gene activity without changing the DNA sequence itself. Such tests produce ‘epigenetic clocks’ that calculate your biological age as opposed to your chronological age. They can also show the seperate biological age of your heart, memory, brain, kidneys, etc. Expect to pay about £350 for such a test.

But four simple free or low-cost tests are also predictive. Walking speed, grip strength, the ability to stand on one leg and a simple sit-to-stand test.

Research shows that walking speed correlates with life expectancy. People who walk faster tend to have greater cardiovascular fitness, stronger muscles and joints, improved balance, and better cognitive function.(26)

Adults under 30 typically walk around 3 mph, while those over 65 average about 2.1 mph. So, it’s not just those 7,000 steps that are important – it’s their speed.

The sit-to-stand test costs nothing. You sit in a kitchen type chair without arms. Then with your arms folded across your chest, stand up fully five times in a row as quickly as you can. Do not use your arms to push yourself up or lean on anything for support.

Measure how many times you can sit and stand in 30 seconds. For people aged 60 to 64, the average is between 14 and 19 repetitions for men and 12 and 17 repetitions for women.

In the 70 to 74 age bracket, the average range shifts to 12 to 17 repetitions for men and 10 to 15 for women.(27)

The alternative is to time 5 sit and stands. Researchers timed how long it took participants to complete all five. For every six seconds faster that participants completed the five stands, mortality risk dropped by 4%.

So the difference between someone who took 20 seconds and someone who took 14 seconds translated into a measurable difference in survival over the next eight years.

The single-leg stance (SLS) test – AKA standing on one leg - measures how long a person can stand unassisted on one foot, typically with hands on hips and eyes open. It measures balance, lower-body strength, coordination, inner ear, vision and neurological function.

Typical averages(97) are:

Ages 40–59: ~37–40 seconds
Ages 60–69: ~27–29 seconds
Ages 70+: ~11–18 seconds

Grip strength does require a grip strength tester – which costs under £20. This measure does, clinically, correlate with bone density, fracture risk, cognitive function, sarcopenia, and mortality risk. If you want to check your performance against norms reference link 28 takes you there.

A visual of what is possible

This is a typical health timeline for most people. Too many later years spent in sub-optimum or actual ill-health.

But this is what we are aiming for. Health extension with just a year or two of decline at the very end.

A Longevity Food Plan – from most intake to least

Notice that the foundation of this longevity food plan consists of vegetables, because veggies contain some of the most protective nutrients and fibre.

But there is another reason. When University College London published their study confirming 9-10 portions of fruit and veg a day as optimal, they also showed that consuming vegetables had an even greater protective effect than eating fruit.

Part of a Series

This article is part of series on staying healthy as you get older and improving your quality of life.

It’s not only a goal almost everyone shares, but has huge implications on national healthcare spending, productivity and economic resilience.

It strongly recommends the Mediterranean diet as the best way of eating but recognises that maintaining strength and aerobic fitness is also a critical part of a healthy ageing lifestyle.

It also suggests a supplement to help reach the increased plant nutrient levels that you need as you get older.

DailyColours® contains 161 plant nutrients – nutrients that are missing from an ordinary vitamin and mineral pill. Clinical trials show that it offers Mediterranean diet benefits in a daily supplement. You can see it here.

Note: The content on this site is intended for general wellness and informational purposes only. It is not personalized medical advice. Consult a healthcare professional before making any changes to your diet, exercise, or lifestyle routines.

Author: Colin Rose
Colin Rose BSc is a health and longevity researcher and author with more than 30 years of experience researching healthy ageing, nutrition, and longevity. He is a Fellow of the Royal Society of Arts and a Senior Associate of the Royal Society of Medicine.

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