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. In my video, Anti-Cancer Potential of Sweet Potato Proteins, 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% 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 cells (sweet potato proteins certainly come in contact with our mouth!). Tongue cancer is often treated with chemotherapy, and most of the chemo drugs for tongue cancer have adverse effects; so, it is indispensable for us to find other therapeutic strategies. Sweet potato protein rapidly diminished viability of the cancer in vitro 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 decrease 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 during my medical training, 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!
More videos on getting the most nutrition for one’s dollar:
What other vegetables might contain cancer fighting properties? See #1 AntiCancer Vegetable.
Are sweet potatoes best steamed? Should we eat the skin? Find out in my video: Best Way to Cook Sweet Potatoes.
-Michael Greger, M.D.