Actually there’s no need to juice onions, as scientists did it only to force-feed rats.
Twice a day slice, even grossly, a quarter of a regular onion and add it to your food.
I add it in my meal either raw or slightly heated, and it’s painless. To tell the truth, on my personal taste scale, I find it less noticeable than mustard in a hot-dog, and it’s enough to have effects on my “private” scale.
I’m eating more onion but don’t notice any difference.