How Sweet Potato Proteins May Help Prevent Cancer

Sweet potatoes can be considered a superfood. They are one of the healthiest and cheapest vegetables on the planet. (And one day, perhaps, even off the planet, as NASA has chosen the sweet potato for space missions.) A study out of the University of Washington aimed to identify which vegetables provided the most nutrients per dollar. If you click on the above video, you can see a graph of affordability versus nutrition for different foods. The healthiest foods, like dark green leafy vegetables, may also be the cheapest, and the highest nutrient-rich food scores per dollar were obtained for sweet potatoes.

Sweet potatoes are not just packed with nutrition but may also have special cancer-fighting properties. In 1931, a unique protein was discovered in sweet potatoes. It turns out that 80 percent of the protein in sweet potatoes is a type of protease inhibitor with potential anticancer effects. These proteins were originally tested against leukemia and appeared to suppress the growth of leukemia cells in a petri dish.

But how would a sweet potato protein ever get into our bloodstream? As soon as most proteins hit our stomach, they start getting digested. To get around the digestion issue, researchers tried sweet potato protein against tongue cancer (sweet potato constituents certainly come in contact with our mouth!). Tongue cancer is often treated with chemotherapy, and most of the chemo drugs for tongue cancer have great adverse effects, so it is indispensable for us to find other therapeutic strategies. Sweet potato protein rapidly diminished viability of the cancer within a matter of days, leading the researchers to propose that sweet potatoes may be useful for human tongue cancer. But could they possibly help with other cancers as well?

Remarkably, this special class of proteins doesn’t just survive digestion but may also be absorbed into the bloodstream intact (in at least two of the nine women with advanced cervical cancer researchers tried giving them to). Most recently, sweet potato proteins were tried on colorectal cancer cells, one of our most common and deadly cancers. Normally we just surgically remove the colon, but that only works in the early stages since there are often “micrometastases” outside the colon that can subsequently lead to cancer recurrence and death, so we’ve been searching for anti-metastatic agents. Not only does sweet potato protein slow down the growth of colon cancer cells, but it may also decreases cancer cell migration and invasion.

Sweet potato consumption has also been associated with lower gallbladder cancer rates, but it has never been directly put to the test. But what’s the downside?

Sweet potatoes are one of my favorite snacks. During the harsh Boston winters, I used to put two freshly microwaved sweet potatoes in my coat pockets as natural hand-warmers. When they cooled down, my hand-warmers became instant healthy snacks!

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mac C
mac C2 years ago

My favorite way to enjoy sweet potatoes is bake them and cut them into rounds, then sprinkle nutritional yeast on them. I like your hand warmer story, Dr. Greger. Thanks for the post.

Sarah Hill
Sarah Hill3 years ago

I love sweet potatoes! I enjoy them baked with butter, cinnamon and nutmeg on them! YUM!

Siyus Copetallus
Siyus Copetallus3 years ago

Thank you for sharing.

Sandra Haddock
Sandra Haddock3 years ago

I love sweet potatoes! I've tried them everyway, but did you know that you can make sweet potato salad as well. It's even better as a left-over when the flavors meld.

Julianna D.
Juliana D3 years ago


Angela K.
Angela K3 years ago

Thanks for sharing

Elena Poensgen
Elena Poensgen3 years ago

Thank you

Joemar Karvelis
Joemar Karvelis3 years ago


Corey Brideau
Corey Brideau3 years ago

I could live off sweet potatoes

Leanne B.
Leanne B3 years ago

Thanks good stuff.