Is it bad to eat boiled cactus everyday.. and only that?

Answer 1

It isn't good to eat any single food and nothing else, every single day, for an extended period.

Provided you are in good health and have a sensible reason (scientific research?) for eating only one particular food for a short period of time - not more than a few days - you won't come to much harm, unless you turn out to be particularly sensitive, or develop sensitivity, to the food in question.

If your health isn't good, or you're planning to limit your diet to one food only for more than a week, think again.

It doesn't matter what the food is, boiled cactus, baked potatoes, boned fish, broiled bananas, it doesn't matter, nor does whether you also take handfuls of vitamin pills or other supplements: you will damage your health if you don't eat a varied diet on a regular, daily basis.

If you're considering a boiled cactus diet, don't do it. If you know someone who is trying it, or intends to do so, try to gently dissuade them. That possibly won't work, so do some online research into malnutrition, which is what you or your friend will end up suffering from. Malnutrition is not the same as starvation, but its effects are pretty drastic over time. Show your research to your friend.

If they still want to keep on with the cactus, you'll need to enlist help from family or other friends before your friend is cactus.