Which peptides occur naturally in food?
Almost all protein-rich foods, from legumes to fish and dairy, naturally contain peptides that are released during digestion and can be biologically active. Studies show promising effects, but how much of that actually occurs in people has been only limitedly researched.
Proteins in virtually all foods contain 'sleeping' peptides that only become active once they are broken down. That happens through your digestive enzymes or through fermentation. Animal sources such as dairy, meat and fish provide them, but so do plant-based sources such as legumes and grains.
When plant proteins are digested, peptides are released that have antioxidant, blood-pressure-lowering and blood-sugar-regulating properties. Experiments in the lab that mimic human digestion show this clearly. Whether those effects are equally strong in a real human body has not yet been sufficiently demonstrated.
Whey proteins from dairy have been well studied. They contain peptides with antioxidant and immune-supporting properties, and there are early hints of possible protective effects against cancer. The latter is not yet supported firmly enough to make strong claims about. Fish, shrimp, algae and fishing by-products also yield peptides, with antioxidant and blood-pressure-lowering properties and the ability to bind minerals. Almost all of the evidence for this comes from laboratory and animal studies.
Peptides from meat and milk proteins can help reduce inflammation in cell and animal studies, working through a molecule inside cells that controls the body's inflammation response. Animal studies also show that such peptides strengthen the gut wall, increase protective substances in the gut, and improve the balance of gut bacteria. What that means for people is not yet well understood: too few studies in people have been carried out.
In practical terms, varied protein sources, both plant-based and animal, are worth considering. Fermentation (as in fermented dairy or fermented legumes) can promote the release of active peptides. The science in this area is growing quickly, but most findings have not yet been translated into concrete advice for everyday eating.
This answer draws on several overviews combining existing research. The evidence for the release of active peptides during digestion is reasonably solid. The effects themselves (blood pressure, inflammation, gut health) have been found repeatedly in laboratory and animal studies, but have barely been confirmed in studies in people. The researchers themselves stress that studies in people are largely absent and that too little is still known about what happens to these peptides inside the body after absorption.
Which fermented foods are the healthiest?
Yoghurt has the strongest support: regular consumption is linked to a lower risk of diabetes and heart and vascular disease. Cheese follows at a reasonable distance; for kefir, the evidence from studies in people remains limited.
How many fruits and vegetables do I actually need per day?
Five portions of fruit and vegetables per day (two pieces of fruit, three serving-spoon scoops of vegetables) is the number with the strongest evidence base; eating more does not provide additional benefit, but most people do not even reach this minimum.
Which foods or habits effectively raise NAD+ levels?
Exercise and NAD+ supplements (NR or NMN) demonstrably raise NAD+ levels, but whether higher levels also confer health benefits in humans has not yet been proven. Regular physical activity is the only approach for which broader health benefits have also been demonstrated.
How many vegetables do you really need per day?
Five servings of vegetables and fruit per day offers the best protection, with non-starchy vegetables counting and juice and potatoes not. More than five servings adds nothing.
Is eating organic food really healthier?
Eating organic demonstrably leads to lower pesticide exposure and less contact with antibiotic-resistant bacteria through meat. Whether this translates into less disease in the long run remains unclear.
Are there dietary patterns that have been proven to reduce your risk of cancer?
The Mediterranean diet and sufficient vegetables and fruit are consistently associated with a lower cancer risk, although the effects are modest and the findings are associations. The evidence is strongest for colorectal cancer; ideally combine diet with other healthy habits for the greatest effect.