 The only potential downside of eating sweet potatoes is if you eat too much, you could get a yellow nose. It's called keratinemia. It's a common, harmless condition due to elevated levels of beta-keratin in the blood. First noticed a century ago when kerats were introduced into infant diets, it's treated mostly by just reassuring parents that it's harmless, but if you don't want your child's nose to be yellow, you can decrease the beta-keratin intake, and in a few months it'll be gone. But color is what we're looking for when picking out varieties at the supermarket. The intensity of the yellow or orange flesh color of the sweet potato is directly correlated to its nutritional content, so the more intense the better. Though if you really want intensity, sweet potato varieties range not only from white to yellow and orange, but to pink and very to deep purple. The natural pigments of which may have special anti-cancer effects of their own. What's the best way to cook sweet potatoes? Boiling may actually best retain the antioxidant power of sweet potatoes compared to roasting and steaming. If you compare baking to boiling microscopically, boiling helps thin out the cell walls and gelatinize the starch, which may enhance the bioavailability of nutrients. While at the same time the glycemic index of boiled sweet potatoes was found to be only about half that of baking or roasting, so boiled gives one less of a blood sugar spike. Make sure to keep the skin on, though. The peel of a sweet potato has nearly 10 times the antioxidant power as the flesh, an antioxidant capacity comparable to that of blueberries. Though it really takes a hit when baked, wiping out over two-thirds, whereas microwaving or boiling was comparatively much gentler. The same with the rest of the sweet potato baking can cause an 80% drop in vitamin A levels, twice as much as boiling. So from a nutritional standpoint, boiling rather than baking can be recommended for sweet potato cooking. Boiling may be best, but sweet potatoes are so incredibly healthy. The best way to prepare them is whichever way will get you to eat the most of them, with the exception of deep frying, which can lead to the formation of acrylamide, a potential human carcinogen.