Every ingredient in this category came from something edible first. It is worth knowing which, and how far ordinary eating gets you.
Where they are: cooked kale and spinach by a distance, then collard greens, turnip greens and Swiss chard. Egg yolk holds less per gram but gives it up unusually well, because the fat it travels in is already there. Broccoli, peas, sweetcorn and pistachios contribute across a week.
The gap: most people in the West are thought to get somewhere between one and two milligrams in a day. The study that recorded a cognitive benefit in older adults was handing out twelve.
Making up that difference from the plate alone means cooked greens on most days of the week. A minority of households manage it. Of every nutritional case in this category this is the tidiest, because all four pieces are present: a compound you can measure, a tissue level you can measure, a shortfall nobody disputes, and a trial run at a stated dose.
Where it is: turmeric root, fresh or dried. Curry powder contains it, usually at modest concentration.
The catch: by weight, turmeric is somewhere between two and five percent curcuminoids, and curcumin arriving by itself is absorbed poorly. However much curry you eat, you will not reach the amounts the trials used.
What helps: fat and black pepper — which is precisely how turmeric has been eaten for several thousand years. The piperine in pepper slows how quickly the liver clears curcumin, and the fat carries it across.
Where they are: green tea, straightforwardly. Brewed tea delivers the catechins, the theanine and the caffeine together.
This is the one ingredient where ordinary consumption gets you genuinely close. Several cups a day is not an unusual habit and supplies a meaningful amount. If you already drink it, you are already getting this.
And a word in the opposite direction. There are rare reports of liver damage tied to concentrated extract, taken in large amounts with nothing in the stomach. No such reports attach to drinking tea. Stronger is not the same as better.
Silicon is in oats, barley, root vegetables, beer and the drinking water in some regions. Most people get a reasonable amount without thinking about it. Glucosamine is made by the body and is not meaningfully available from ordinary food.
Neither has cognitive research behind it, so neither is a reason to change what you eat.
Put a plate of cooked kale in front of someone and the lutein is the least of it: there is folate in there, vitamin K, a decent amount of fibre and several hundred compounds nobody has finished cataloguing. A capsule gives you the lutein. The word “supplement” is doing real work — it fills a gap you can measure, and it was never a replacement for dinner.
Six named ingredients, each printed with its own amount, taken with a meal.
See package optionsCooked greens lead comfortably — kale and spinach first, then chard, collards and turnip greens. Egg yolk carries less of it but hands it over more readily, because the fat that carries it is already in the yolk. Set a typical intake of one or two milligrams a day against the twelve used in the trial.
Not at the quantities used in the research. Turmeric is only two to five percent curcuminoids by weight and curcumin absorbs poorly on its own. Fat and black pepper both improve it, which is how turmeric has traditionally been eaten.