My lower middle class family of 4 kids was raised on $1 McChicken sandwiches through my teen years. I don't know if there is an equivalent today.
But meat is more expensive than beans and rice.
If no: check for MTHFR gene mutation.
American rice is often washed in folic acid - don’t ask me why - and that’s toxic to MTHFR mutated individuals.
In that case, all of the "enriched" bread, folic acid, certain forms of vitamin B, will be difficult to process (often causing problems).
https://www.mygenefood.com/blog/mthfr-and-folic-acid-build-u...
Folate, folinic acid: those are safe to take, and pass through, for the entire population.