Flashback Friday: The Best Way to Cook Sweet Potatoes

Flashback Friday: The Best Way to Cook Sweet Potatoes
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How does sweet potato baking compare to boiling and steaming, and should we eat the skin?

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

The only potential downside of eating sweet potatoes is if you eat too much, you could get a yellow nose. It’s called carotenemia. It’s a common, harmless condition due to elevated levels of beta-carotene in the blood, first noticed a century ago, when carrots 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 their beta-carotene intake, and in a few months, it will 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 anticancer 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 ten 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.

Please consider volunteering to help out on the site.

Images thanks to Jim Hickcox and Alpha via flickr

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

The only potential downside of eating sweet potatoes is if you eat too much, you could get a yellow nose. It’s called carotenemia. It’s a common, harmless condition due to elevated levels of beta-carotene in the blood, first noticed a century ago, when carrots 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 their beta-carotene intake, and in a few months, it will 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 anticancer 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 ten 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.

Please consider volunteering to help out on the site.

Images thanks to Jim Hickcox and Alpha via flickr

Doctor's Note

Next up in our Flashback Friday series: Sweet potatoes are cheap, healthy, nutrient powerhouses—check out Anticancer Potential of Sweet Potato Proteins. What if most of what you ate was sweet potatoes? Find out in my video The Okinawa Diet: Living to Be 100.

What about cooking methods for other vegetables? See Best Cooking Method.

Want more information about acrylamide, the potential crispy carb carcinogen? See Cancer Risk from French Fries. And, for why deep frying, in general, might not be good, see Deep-Frying Toxins and Carcinogens in the Smell of Frying Bacon.

Since this video first aired, I’ve got some more cooking method videos:

And how about a bonus recipe? Yum: Stuffed Sweet Potatoes with Balsamic Glaze.

If you haven’t yet, you can subscribe to my videos for free by clicking here.

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