What is spermidine and where is it found?
Spermidine is a molecule that occurs naturally in your body, declines with age, and is obtained through fermented foods and gut bacteria. As a supplement it is too poorly studied in humans to recommend a dose or duration.
Spermidine is a small nitrogen molecule that occurs naturally in virtually all living organisms, from yeast to humans. Your body produces it on its own, you take it in through food, and your gut bacteria generate it when breaking down proteins. Fermented and aged products generally contain the highest amounts of spermidine.
Levels in your body decline as you age. Whether that falling level actually contributes to ageing has not been firmly established in humans. Researchers do describe that spermidine activates the same cellular clean-up system as fasting, hence its nickname 'fasting mimetic'.
A population study of 829 people (aged 45 to 84, followed for 20 years) shows that people who consume more spermidine through their diet die less often, but whether spermidine is the cause has not been proven. For any goal, such as living longer, cardiovascular protection, cognition or metabolic health, the amount you would need to take as a supplement has not been established in human research. As a supplement, spermidine is available as a capsule or powder, often derived from wheat germ; the label then reads 'spermidine' or 'wheat germ extract'. Which brand or form of administration works better does not matter on the basis of available research, as this has not been compared.
Because an effective dose in humans has not been established for any goal, a supplement is currently too poorly studied to recommend. If you still want to try it, bear in mind that the evidence so far comes from population studies and animal experiments, not from comparative studies in humans using spermidine as a direct supplement.
All claims are based on reviews and studies not further indexed (PMID 29371440, 42235230, 30306826, 29955838, 31940783, 32009110, 27841876). There are no randomised trials or meta-analyses in the source set. Statements about declining levels with age and mortality risk are associative in nature.
How much taurine do you need per day?
There is no established daily figure for taurine alone. Anyone who regularly eats fish, meat or dairy is probably getting enough. A supplement is unnecessary for healthy people and is not recommended.
What does quercetin do in your body?
Quercetin has interesting properties in the lab and in small human studies, but whether supplements actually make a difference in practice remains unclear. Through ordinary foods such as onions and berries, you obtain the most bioavailable form without safety risks.
How much magnesium do you need per day?
Research suggests that your body reaches balance at around 165 mg per day, but official recommendations are higher and there is considerable individual variation. In any case, make sure you get enough magnesium-rich foods, as a large part of the population falls short.
How healthy are yoghurt and dairy for your heart and bones?
Yoghurt and dairy are a perfectly good choice for bone health for most people, and are likely neutral to mildly beneficial for the heart. Opt preferably for fermented products such as yoghurt, and keep an eye on your total saturated fat intake if you have an elevated cardiac risk.
Which fermented foods are the healthiest?
Yoghurt and kefir have the most human evidence, so if you want to make one choice, start there. For kimchi, kombucha and miso, human evidence is not yet available, although they show promise in the laboratory.
Am I consuming too much protein, and is that bad for my kidneys?
For people with healthy kidneys there is little reason to worry about a generous protein intake, but those who have kidney disease or were born with a single kidney do face a genuine risk and should discuss their protein intake with a doctor or dietitian.