I know potatoes and sweet potatoes are in different families.
However, tubers are tubers.
Both are root veggies and grow in the ground.
From what I understand, it's the anti-predation chemicals, particularly in the skin which can be toxic, or at least gut irritating to humans.
Maybe sweet potatoes don't have the same chemical defenses as regular potatoes, but it seems reasonable to think they have some mechanism not to be consumed by mold, fungi, etc. Otherwise, they would be extinct.
Am I missing something here?
Are yams / sweet potatoes REALLY free of all chemical defenses ???
asked byCaveMan_Mike (3275)
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on May 03, 2012
at 07:22 PM
The difference lies in the specific antinutrients. There are a few in nightshades, and a few in sweet potatoes, but the nightshade ones have more obvious effects (at least regarding pain). See tab two in this article I wrote a couple months ago:
As you can see, the interaction of nightshades with acetylcholine degredation and possibly production is a major culprit. The vitamin D angle...interesting but not entirely convincing to me. When they find evidence of soft tissue calcification with nightshade consumption, I'll be more convinced.
I have never, anecdotally, heard of someone having acute rheumatological distress from sweet potatoes. But tummy upset? Oh yes! I don't react well to having too many sweet potatoes or weird Asian/African tubers. Maybe it's partly psychosomatic. Who knows.
on May 03, 2012
at 05:08 PM
Sweet potatoes are not nightshades. All nightshades are in the solanaceae family and sweet potatoes are in the convolvulaceae family.
Tubers are tubers, sure. But all plants have evolved with various chemical defenses; we don't always attempt to eat the portions that contain these chemicals, so that works out usually. There are some plants, like peppers, whose chemical defenses we actually seek out (i.e. the capsacin in hot peppers only mammals can taste, but birds cannot -- encouraged the pepper seeds to be distributed widely, and not crowdedly).
So, no plant is completely free from chemical defenses. If you find that you tolerate sweet potatoes well, like many can, then rest assured that eating one is likely more healthy than harmful.
on May 03, 2012
at 07:03 PM
Wonder if sweet potatoes aren't safe because of the large quantities of beta carotene?
Are Carotenes Safe? Are carotenes safe in large doses, as claimed? Dependence on carotenes for vitamin A calls on large reserves of enzymes to make the conversion. In their fascinating book Nutrition and Evolution, Michael Crawford and David Marsh note that in animals, "if any function can be delegated to another organism it leaves the disk space free to perform some new function or to perform an old one better." The cat species does not synthesize vitamin A from carotenes. "If they had to synthesize their own vitamin A . . . it would take up a significant amount of their disk space." Cats get vitamin A from their prey, whose ability to synthesize vitamin A from carotenes compromises other functions, such as night vision and quickness of movement. While medical orthodoxy claims that consumption of large amounts of carotenes has no downside, it is possible that dependence on carotenes for vitamin A, even in those who are good converters, compromises other biochemical functions in subtle ways.
The so-called nontoxic betacarotene supplements contain a synthetic form of carotene, just one of 50 or 60 carotenes found in the typical diet. The biological activity of synthetic betacarotene is much lower than that of the natural complexes of carotenes and, in fact, may put stress on the immune system Studies with humans and rats given synthetic betacarotene found an increase in white blood cells. In cancer trials, synthetic betacarotenes were not found to be protective. In fact, in one study, patients given synthetic betacarotene had worse results than controls (NEJM April 1994 330:(15);891-895).
on May 03, 2012
at 06:58 PM
This awesome article by Mark Sisson answers most of my questions about yams and sweet potatoes, it's pretty comprehensive. Though this part is disappointing, i mean can't we find this out for sure!?:
"Traditionally, sweet potato and yam skins are removed before consumption, so I err on the side of caution and do the same. I doubt a bit of skin is going to hurt you, though, if you decide to eat it. Most of the anti-nutrients in potatoes can be found in the skin, and it seems logical to assume the same is true for yams and sweet potatoes."
Boo, we all know what assuming does regarding assess, u and me.
on June 27, 2012
at 03:08 PM
From what I have heard on various Robb Wolf podcasts sweet potatoes are okay but should be pealed if you have an autoimmune disease or serious gut sensitivity. Nearly everything has some degree of antinutrients but it's all about quantity and type.