Organ health

We usually talk about ageing as one process, but your organs age at different speeds. In a 2023 study that estimated the "age" of eleven organs from blood proteins, around one in five adults had at least one organ ageing noticeably faster than the rest of their body, and that organ predicted which disease they were most likely to develop. Someone with an older-looking heart had a higher risk of heart failure; an older-looking brain, a higher risk of cognitive decline.

You can't feel most of this happening. That's why it's worth knowing what each organ needs, and which simple tests can tell you how it's doing.

At a glance

Heart and blood vessels

Cardiovascular disease is the leading cause of death in Europe, and it's largely preventable. The three most important levers are blood pressure, the particles that carry cholesterol into your artery walls (measured as ApoB or LDL cholesterol), and not smoking.

Lp(a) is a genetic variant of cholesterol-carrying particle that raises heart risk and isn't affected much by lifestyle. Around one in five people have raised levels. Test it once; if it's high, controlling everything else matters even more.

For some adults over 40 with borderline risk, a coronary artery calcium (CAC) scan can show whether plaque has already formed. Ask your doctor whether it's worth it for you.

Brain

Dementia is one of the most feared parts of ageing, and more of it is preventable than most people realise. The 2024 Lancet Commission on dementia concluded that addressing 14 modifiable risk factors could prevent or delay nearly half of all cases. They include high blood pressure, high LDL cholesterol, diabetes, physical inactivity, smoking, excess alcohol, obesity, depression, social isolation, air pollution, head injury, less education, and untreated vision and hearing loss.

Two of those surprise people. Hearing loss in midlife is one of the largest single risk factors, and hearing aids appear to reduce the risk. Vision loss was added in 2024. A hearing test and an eye test are among the cheapest brain-health measures there are.

What protects the brain most is what protects the heart: exercise, blood pressure control, good sleep and staying socially and mentally engaged.

Liver

Fatty liver disease, now called metabolic dysfunction-associated steatotic liver disease (MASLD), affects around three in ten adults worldwide, and most don't know it. It's closely linked to excess waist fat, insulin resistance, sugary drinks and alcohol, and it can progress to scarring and cirrhosis.

Check your ALT and GGT on a standard blood panel. Your doctor can use these with a few other results to calculate a FIB-4 score, which estimates the risk of liver scarring. The good news: the liver regenerates well. Losing 5–10% of body weight can substantially reduce liver fat.

Kidneys

Kidney function declines gradually with age, and faster with high blood pressure and high blood sugar. Chronic kidney disease is common and usually silent until advanced.

The standard measure is eGFR, calculated from creatinine. Creatinine depends partly on how much muscle you have, so cystatin C gives a more accurate picture, especially if you're very muscular or very slight. It's also the strongest single marker in the Bortz biological age clock. A urine albumin-to-creatinine ratio can catch kidney damage earlier than eGFR.

To protect your kidneys: control blood pressure and blood sugar, don't smoke, and avoid regular use of anti-inflammatory painkillers such as ibuprofen without medical advice.

Lungs

Lung function peaks in your mid-20s and declines slowly after that. How well your lungs work predicts overall mortality, not just lung disease. Not smoking or vaping is by far the most important step, followed by reducing exposure to polluted air and staying aerobically fit. If you get breathless more easily than people your age, or have a persistent cough, ask about spirometry.

Bones and muscle

Around one in three women and one in five men over 50 will break a bone because of osteoporosis. A hip fracture in older age is life-changing: many people never regain their previous independence. Muscle loss, called sarcopenia, makes falls more likely and recovery harder.

Both respond to the same things: strength training, impact exercise such as jumping or brisk stair-climbing, enough protein, and adequate vitamin D and calcium. Women over 65, and younger people with risk factors, should ask about a DEXA scan to measure bone density.

Gut

Your gut is home to trillions of microbes that influence digestion, immunity and inflammation. Diversity is a sign of health, and the best-supported way to increase it is to eat a wide variety of plants and plenty of fibre. Bowel cancer is one of the most common cancers in Europe, and one of the most preventable through screening: take the test when you're invited, and see a doctor about blood in your stool or a lasting change in bowel habits at any age.

Key numbers
~1 in 5: adults with at least one organ ageing noticeably faster than the rest of the body.
~45%: dementia cases that could be prevented or delayed (Lancet Commission 2024).
~3 in 10: adults with fatty liver disease.

This week

• Book a hearing test if you've never had one, or if it's been more than a few years.
• Check your last blood test for ALT, GGT and eGFR, and ask about cystatin C next time.
• Add one impact exercise to your week: 20 jumps, or running up a flight of stairs.

In the journal

Most of your organs are covered by the same few boxes: blood pressure and waist at Level 1, the blood panel at Level 2. Organ health is what those numbers are protecting.

Sources: Oh et al., Nature 2023 · Livingston et al., Lancet Commission on dementia prevention, The Lancet 2024 · Younossi et al., Hepatology 2023 · International Osteoporosis Foundation · Kronenberg et al., European Heart Journal 2022