How harmful are microplastics in your body to your health?
Microplastics demonstrably accumulate in your organs and are associated with signs of inflammation and reduced sperm quality. How harmful that actually is, we do not yet know.
Microplastics and their even smaller cousins (nanoplastics) have by now been found in virtually every organ examined: the heart and blood vessels, the gut, the lungs, the eyes and the reproductive organs. That they are there is beyond doubt. What exactly they are doing is a great deal less certain.
The clearest signal comes from research into the heart and blood vessels. People with higher concentrations of microplastics in their blood clots and blood more often showed signs of inflammation and more heart problems. That sounds alarming, but it involved only a few hundred people, and it is an association, not proof that microplastics are the cause.
For fertility the picture is similar. Seven studies in people linked microplastics in semen and tissue to poorer sperm quality. Animal studies suggest how that might work, but here too cause and effect in people has not been proven. The same applies to the gut and lungs: small studies found raised liver values, a disrupted gut balance and signs of airway inflammation, supported by findings from animal studies.
Microplastics can also carry chemicals such as phthalates and bisphenol A, which can interfere with hormones. That has so far been shown mainly in cell and animal studies. Direct evidence in people is largely lacking. For cancer, a combined analysis of more than 43 studies involving over a million patients found a slightly raised risk in certain types of research, but in studies that followed people for years that link was absent. No firm conclusions can be drawn here.
The problem is that the studies are small, the ways of measuring are not comparable across studies, and confounding factors are rarely accounted for. Experiments in which people are deliberately exposed are not possible. That does not mean nothing is going on, but it does mean we genuinely do not yet know how serious the effects are.
This answer draws on several combined overviews of the evidence and one large combined analysis. The researchers themselves rate the evidence as moderately to seriously limited: studies are small, measurement methods are not comparable, and the risk of bias is high in most analyses. An association has been shown; cause and effect has not. The combined cancer analysis covered more than a million patients but found only a weak link in certain types of studies, not in research that followed people for years.
How harmful is air pollution to your health?
Air pollution is seriously harmful: it increases your risk of lung and heart disease and costs millions of lives worldwide each year. Cleaner air, both through policy and through personal choices such as avoiding busy roads, demonstrably reduces that risk.
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.
Is eating a lot of protein bad for your kidneys?
For healthy people, kidney damage from eating a lot of protein has not been demonstrated. If you already have kidney disease, the amount and type of protein matter: discuss this with your doctor or dietitian.
Does collagen help your joints and your skin?
For joint pain due to knee osteoarthritis and for active athletes, collagen is worth trying: 10 grams of collagen peptides per day for 6 months, preferably in combination with exercise. For the skin, 2.5 to 5 grams per day is recommended, but some of the research comes from manufacturers.
Is ashwagandha safe for your liver?
For healthy people the risk of liver injury appears small, but it is not negligible. If you have a liver condition, do not use ashwagandha without consulting your doctor.
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.