[jobu]

The digestibility of the carbs in sweet potatoes is highly dependent on the way they're cooked. Boiling them leads to a fairly low glycemic index and glycemic load, whereas baking them essentially turns them into candy: http://www.livestrong.com/article/295025-the-glycemic-index-...

[rotwoof]

It is also possible to reduce the glycemic index of food by ingesting acetic acid (apple vinegar).

See: http://www.jbc.org/content/135/1/157.full.pdf

TL;DR Apple cider vinegar will decrease the glycemic index of food by interfering with carbohydrate digestion.

[cbr]

Acetic acid is vinegar, not apple cider vinegar in particular.