How do I keep my kidneys healthy as I age?
The two best-supported steps to limit kidney damage as you age are keeping your blood pressure under control and exercising regularly. Moderate salt intake and a healthy weight demonstrably contribute to both.
Your kidneys change quietly over the years. They gradually lose filtering cells, receive less blood flow, and recover more slowly from damage. This makes them more vulnerable to everything that puts extra strain on them: high blood pressure, excess weight, or a high salt intake. This has been demonstrated in multiple studies in humans.
High blood pressure is by far the greatest threat to your kidneys as you age. Large studies and randomised trials show that chronically elevated blood pressure is a direct cause of kidney damage, and that you genuinely reduce that risk by keeping your blood pressure under control. Excess weight makes things worse: it causes your body to retain more sodium when you consume salt, which drives blood pressure up.
Salt also plays a larger role as you get older. Your kidneys process sodium less efficiently with age. As a result, your blood pressure rises more after a salty meal than it used to. Moderate salt intake therefore has a greater effect on blood pressure in older people than in younger people.
Regular exercise helps your kidneys in several ways. A study in healthy men showed that repeated training reduces inflammation and cellular ageing processes. There is also evidence that exercise stimulates the production of betaine, a substance that slows ageing in mice. Whether this works in exactly the same way in humans has not yet been proven. However, the beneficial effect of regular exercise on inflammation and cellular ageing has already been demonstrated in humans.
At the cellular level, some aged cells stop dividing but do not die off either. They keep secreting inflammatory substances, damage the blood vessels in the kidney, and inhibit repair. This is called cellular senescence. It is a likely contributing cause of kidney damage during ageing, not merely a by-product. Targeted treatments for it are being investigated, but do not yet exist. The same applies to proteins such as klotho, which decline with age and are associated with faster deterioration of kidney function. Interesting, but not yet an actionable tool for you.
The claims are based on multiple studies in humans, including cohort studies, randomised trials, and a multi-omics study, supplemented by animal research. The evidence for blood pressure is strong. The evidence for cellular ageing and exercise is moderate: demonstrated in humans, but causality and clinical benefit have not yet been fully established. The evidence for betaine in humans and for klotho as a treatment target is preliminary and largely based on mouse studies or associations without a proven causal relationship.
Do your kidneys age at a different rate than your liver?
The kidneys age measurably faster than the liver, but for most healthy people that decline only has major consequences when dosing medications at an advanced age. If you also have high blood pressure or diabetes, it is wise to have your kidney function checked regularly.
Do you need to restrict protein intake to protect your kidneys?
If your kidneys are healthy, you do not need to restrict your protein intake. If you have chronic kidney disease, discuss with your doctor and dietitian whether a protein-restricted diet (0.6-0.8 g/kg/day) is appropriate, because without supervision you risk malnutrition.
How do I keep my eyes healthy and prevent cataracts or macular degeneration?
Protect your eyes with UV-filtering glasses, a diet rich in vegetables and fruit, good diabetes management and regular eye check-ups. If cataracts have advanced significantly, surgery is the only proven solution.
How do I keep my joints supple and prevent osteoarthritis?
Exercise and maintaining a healthy weight are the best-supported ways to prevent osteoarthritis and manage symptoms; however, no treatment stops the disease once it has begun.
What really keeps your mouth and gums healthy?
Daily brushing supplemented with interdental brushes is the best foundation for a healthy mouth; if you have diabetes, regular gum care pays extra dividends for your blood sugar.
How do I know whether my fatigue is caused by my thyroid?
Thyroid blood tests can rule out or confirm whether your thyroid is the cause, but a mildly abnormal TSH alone does not explain fatigue and treating it often does not help. In Hashimoto's, symptoms can persist even when your values are normal.