Which food crops should I grow?

Phytochemicals

Your first priority should be to grow plants that are rich in phytochemicals, e.g. antioxidants and flavonoids.

Herbs are rich in phytochemicals. Growing them takes very little of your time. Even if you have only a window box, grow some herbs.

Reasons for doing this are as follows.

Much of the food in the shops has been irradiated. Irradiation destroys phytochemicals.

It also generates radiolytic (not radioactive) compounds; they are harmful. Phytochemicals help to protect from that harm.
In many countries, much of the food in the shops has been genetically modified. Such food can be very harmful.

Phytochemicals help to protect from that harm.

We are fortunate here in Europe that there are many suppliers of non-gm foods and seeds.
Phytochemicals help to prevent cardiovascular and many other diseases.