Does your immune system really weaken as you get older?
Your immune system does indeed weaken as you get older, but how quickly that happens varies considerably from person to person. Lifestyle factors play a role in this, although little has yet been proven specifically for humans.
Yes, the immune system really does weaken as you get older. This phenomenon is called immunosenescence. Both T cells and B cells (the two types of white blood cells that fight infections) become less effective. The innate immune system, the body's first line of defence, also deteriorates. The practical consequence: older people get infections more often, become more seriously ill from them, and respond less well to vaccines.
An additional mechanism is at play in T cells. The thymus, the organ where T cells mature, shrinks considerably with age. As a result, fewer new, fresh T cells are produced. The T cells that remain also lose diversity: they can recognise fewer different invaders. At the same time, the energy-producing structures inside the cells (the mitochondria) become damaged. This contributes to a higher risk of infections and cancer, as well as autoimmune reactions in which the body attacks itself.
There is a paradox in immune ageing. The immune defence weakens against infections, yet at the same time a chronic, smouldering inflammation develops that never fully subsides. Researchers call this 'inflammaging'. This persistent low-grade inflammation is associated with age-related conditions such as dementia, joint complaints, and type 2 diabetes. An inflammatory substance that plays a role in this also disrupts energy metabolism in certain brain cells of mice; in mice, blocking this substance restored both immune function and memory. Whether the same holds true in humans is unknown.
Not everyone ages immunologically at the same rate. In a study that followed 135 healthy adults for nine years, biological immune age turned out to be a better predictor of death than ordinary chronological age. Two people of the same age can therefore have very different immune conditions. What causes these individual differences has not yet been fully clarified, but lifestyle plays a role. For example, eating less (caloric restriction) slowed immune ageing in rats and reduced chronic inflammation. Whether this works equally strongly in humans has not yet been demonstrated.
Findings are based on multiple large review studies and mechanistic research. The decline in T cell and B cell function and inflammaging are broadly documented. Individual variation in immune ageing is based on one study with 135 participants (associational). Caloric restriction and the PGE2 mechanism are animal research and have not yet been translated to humans.
Does your immune system really weaken as you get older, and can you do anything about it?
Your immune system demonstrably weakens with age, but eating healthily and exercising can reduce the smouldering inflammation that accompanies it. It is still too early to rely on drugs targeting senescent cells.
How do I strengthen my weakening immune system?
You can partly support your immune system by correcting measured deficiencies in vitamins and minerals and by making use of vaccines specifically tailored for older adults. More far-reaching options such as experimental inhibitors are not yet safe enough for daily use outside of studies.
Does eating enough protein help my immune system as I get older?
Eating enough protein helps your immune system in later life. Aim sustainably for at least 1.0 to 1.2 grams per kilogram of body weight per day, spread across your meals, and preferably obtain this from regular food.
Can air pollution weaken your immune system?
Air pollution disrupts your immune system in several ways at once: a greater chance of allergic reactions, less resistance to viruses. Limit your exposure as much as possible, especially during pregnancy.
Does too little sleep weaken your immune system?
Yes, too little sleep demonstrably weakens your immune system and increases the risk of infections and chronic inflammatory conditions. Seven to nine hours of sleep is the most commonly cited guideline, and vaccinations also work better when you are well rested.
Does melatonin support your immune system in later life?
Melatonin has clear effects on the immune system in animal and laboratory research, but whether supplements genuinely improve immune function in older people has not been demonstrated. It has long been used for better sleep, which may be indirectly beneficial for immunity.