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.
Yes, and the difference is measurable: kidney function declines by approximately 0.97% per year from the age of forty, while liver function (measured as the rate at which the liver breaks down drugs) declines by approximately 0.80% per year. By the age of eighty, the liver's drug-metabolising capacity is roughly 32% lower than it was at forty. The kidneys decline somewhat further over the same period.
The kidneys also lose more at a structural level than the liver does. The number of functioning filtration units decreases, kidney tissue stiffens, and kidney volume shrinks. This has been found in otherwise healthy individuals, so independently of disease. Nevertheless, a lower kidney filtration value at advanced age, in the absence of protein loss in the urine, carries only a modest to no increased risk of death. Whether that normal age-related decline should be regarded as a disease remains an open question in scientific circles.
The liver ages more quietly in turn: liver volume and blood flow decrease, and recovery after damage proceeds more slowly. But routine blood tests for liver function often remain entirely normal in healthy older adults. The decline is real, yet it shows up most clearly in how the liver processes medications, rather than in standard laboratory values.
Two caveats are important. First, conditions such as high blood pressure, diabetes, and heart disease accelerate kidney damage on top of ordinary ageing, making it difficult to separate what is 'normal ageing' from what is disease. Second, organs also age differently from person to person: research into so-called biological organ clocks shows that the kidneys and liver within the same body can age asynchronously. Firm clinical recommendations based on those organ clocks do not yet exist.
All claims are based on reviews; no randomised trials or meta-analyses are available. The figures on clearance come from pharmacological research across multiple drugs and direct kidney filtration tests. The structural kidney changes are consistently described across multiple reviews. The ageotyping concept is still exploratory.
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.
Do your eyes age faster than the rest of your body?
The lens of the eye ages noticeably early and quickly, but whether your eyes as a whole age faster than the rest of your body has not been demonstrated. The retina actually reveals a great deal about your overall health, so the two track more closely together than you might think.
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.
Which supplements are risky in the presence of kidney damage?
Yes, multiple supplements are demonstrably risky in the presence of kidney damage. Herbal preparations (particularly those containing aristolochic acid), germanium supplements, and high doses of vitamin D or C stand out the most; if you already have kidney problems, discuss every supplement with your doctor.
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.
Is ashwagandha safe for your liver?
Ashwagandha can cause liver damage, including in people without known liver disease, and regulators see wider risks. The RIVM advises against it, Denmark has banned it and an EU procedure is under way. If you have a liver condition, avoid it; if you use it anyway, watch for jaundice or unusual fatigue and stop immediately if these occur.