Does fermented food like kimchi boost your immune system?
Kimchi and other fermented products can improve your gut microbiome and lower inflammatory markers, but whether that actually means you get sick less often has not yet been conclusively proven. Feel free to eat them as part of a varied diet, but do not count on them as a medicine.
One randomised study lasting 17 weeks in 36 healthy adults showed that a diet rich in fermented products gradually increased gut microbiome diversity and lowered several inflammatory markers. A high-fibre diet in the same study did not produce those effects. This is currently the strongest direct evidence for an immune effect in humans.
Kimchi specifically has also been studied in cell and animal research. Lactic acid bacteria from kimchi were found in those experiments to activate an immune receptor in gut cells that plays a role in the defence against bacteria such as Salmonella. However, this is laboratory and mouse research, not clinical evidence in humans, and the question remains whether this effect also occurs when you simply eat kimchi.
A critical analysis of 19 intervention studies on fermented food and the gut microbiome paints a more mixed picture. The studies are too short and too varied in design to draw firm conclusions. Furthermore, the micro-organisms in fermented food have to win the competition in your gut in order to 'establish themselves', which does not always succeed.
There are indications that fermented products may shorten or reduce the frequency of respiratory infections, but that evidence is not yet strong enough to be certain. With synbiotics (combined probiotic and fibre supplements), clinical studies do observe changes in the gut microbiome, but these do not consistently lead to measurable health gains: a proportion of people do not respond.
In practical terms: kimchi and other fermented products as part of a varied diet are promising for your gut health and may favourably influence inflammatory markers. However, you cannot yet attach a guarantee of stronger immunity to them. The science has not settled the matter, and one study with 36 people calls for confirmation.
Basis: one randomised study (n=36, 17 weeks), multiple reviews and narrative analyses, plus laboratory and animal research. No meta-analysis available. Consistently positive signals, but limited in scale and partly indirect evidence.
Does stress really lower your immune system?
Prolonged stress demonstrably lowers your immune system: fewer active immune cells, a weaker response to vaccines and a greater risk of infections. Short-term stress has precisely the opposite effect and makes your immune system briefly more alert.
What does alcohol do to your immune system?
Chronic excessive alcohol use weakens your immune system on multiple fronts simultaneously and increases the risk of serious infections. Light to moderate drinking appears less harmful, but offers no demonstrable benefit for your immune system.
Does cold showering boost your immune system?
Cold showering produces measurable stimulation of the immune system, but whether it actually makes you less likely to fall ill has not been proven. Until better research is available, there is no harm in doing it if you enjoy it, but do not count on it as protection against infections.
Does eating enough protein help my immune system as I get older?
Eating enough protein helps your immune system in later life. Aim for at least 1.0-1.2 grams per kilogram of body weight per day, spread across your meals, and preferably obtain this from ordinary food rather than supplements.
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 creatine do anything to your immune system?
Creatine affects immune cells, but whether that turns out well or badly depends strongly on the situation. For healthy older adults who also do strength training there is a cautiously positive signal; if you have endometriosis or a certain type of cancer, the context is more complex and consulting your doctor is advisable.