Just eat your veggies
This highlights a serious problem with all the attempts to put good food in pill form: the dose has been far in excess of what is in the actual foods. For example, wheat germ has the highest concentration of vitamin E tested, yet the tablets used in the trials of vitamin E had more than 10 times this amount. The Western medicine paradigm of “if a little is good, more must be better” is almost never true; for example, water is a good thing, right? But drink too much water in a short time, and you’ll drop dead.
The vegetables that are linked to lower risk of disease contain many nutrients in addition to antioxidants such as beta-carotene. The combination of all these nutrients in a natural source may be the key to their effectiveness and thereby not amenable to a reductionist splitting into one “active ingredient” that can be put into a pill.
I prefer to eat the foods, but if you must take a pill, make it a low dose multivitamin and hold the iron.