" "If active ingredients can be identified, they could be synthesized and given to astronauts in tablet form."

I dunno who's brilliant idea this is (I'm guessing an NSU editor) but why not just send the fruit itself? These effects can usually be attributed to a synergistic effect of the whole fruit rather than a few key chemicals. "

I can think of a number of reasons, first these tablets could be sold to non-astronauts, second, you might give more benefit if you took say 2 pints of strawberries instead of 1, third, I like strawberries but eating a pint of them everyday might make me like them less, fourth, just because something is natural doesn't mean it's healthly [yes, I know this is a radical idea] there could be health problems for some people if they eat a pint of strawberries every day for a year or so.
But anyways the main reason seems to me that if you made this stuff in tablet form you could probably sell it and make a buck or two. Or a jaded view might be that some job program somewhere needs to show it's doing something.

Btw, I found something else wrong with this nature article:
"Those who travel beyond Earth's protective magnetic field are bombarded by cosmic rays - energetic particles left over from the Big Bang. Rats exposed to a lab equivalent are less motivated and able to learn. As missions lengthen, astronauts may face similar problems."

The Big Bang as far as I know has nothing to do with cosmic rays, but rather cosmic rays have to do with things like catastrophe events such as stars exploding and "normal" emission of billion of billion of billions of a wide variety of stellar objects that make up our universe.