While most supermarkets carry one or two different types of
sweet potatoes, about 25 varieties are available in the United States. And I
was amazed to discover that this represents only a tiny fraction of the total diversity
of sweet potatoes.
The sweet potato geeks of the world may be fascinated to
know that the International Potato Center in Peru maintains a gene bank consisting
of over 6,500 varieties of sweet potato. I don’t know about you,
but personally, I wish I could try them all!
Sweet potato varieties range in color from dark red
to brown to purple to orange-yellow to white. They also have different tastes,
sizes, shapes, and textures.
Here are Just a Few of the Most Popular Types of Sweet
Garnet, Jewel, and Beauregard sweet potatoes have
reddish-orange skin and deep orange flesh. These are often the ones masquerading as yams at mainstream grocery
stores. Who knew sweet potatoes could be so sneaky?
White sweet potatoes are crumbly, with
white flesh and golden brown skin. They don’tcontain as many antioxidants as orange
Okinawan sweet potatoes are also known
as purple sweet
potatoes because of their high anthocyanin content. Anthocyanins are the pigments
that give red, blue, and violet plant foods their beautiful colors.
Anthocyanins are also what give Okinawan potatoes 150% moreantioxidant power than blueberries.Despite
their name, Okinawan potatoes are actually native to the Americas. They
were brought over to Japan sometime in the 16th
century, where they grow well and have become a staple in Japanese dishes.
In North America, you will most likely find true purple sweet potatoes in
an Asian supermarket.
Japanese or Satsumaimo sweet potatoes are
known for being sweeter than most other types. This is especially
true when they start caramelizing in the oven.
Sweet potatoes are very hardy vegetables.
They’re able to grow at many altitudes, in many climates, and under compromised
soil conditions. Even if you don’t have the greenest of thumbs, sweet potatoes
are pretty forgiving with just a little TLC.
What Makes a Sweet Potato Sweet?
Have you ever smelled a sweet potato caramelize in the oven
or used them to make a pie or a cake?
If so, you know that even though they aren’t related to what
we think of as potatoes, at least the “sweet” part of their name is
When you heat sweet potatoes, an enzyme starts breaking down
their starch into a sugar called maltose. Maltose isn’t as sweet as table
sugar. But it’s enough to satisfy a sweet tooth that hasn’t been entirely
overwhelmed by M&M’s and Hershey’s Kisses.
You can control the sweetness of sweet potatoes somewhat
by how you cook them. Cooking sweet potatoes quickly (for instance, by
steaming them or cutting them into smaller pieces before roasting) can reduce
their ultimate sweetness.
On the other hand, cooking sweet potatoes slowly on low heat
will allow that maltose-making enzyme more time to convert the starch into
sugar — giving you sweeter sweet potatoes.
Looking for even more control over the sweetness? The sweet
potato enzyme is activated once they reach around 135°F and stops
working at around 170°F. (That’s 57° to 77°C). So the more time they spend in
that range, the sweeter they’ll be.
Are Sweet Potatoes Good for You?
The people of Okinawa, Japan have traditionally enjoyed one
of the highest life expectancies in the world. I discovered this when my dad
was researching his book Healthy
at 100: The Scientifically Proven Secrets of the World’s Healthiest and
One of those secrets, it turns out, is lots and lots of
sweet potatoes. The traditional Okinawan diet consists of minimal meat, dairy,
eggs, and processed foods. Instead, they eat mostly whole plant foods.
And they get a remarkable 60% of their calories from
sweet potatoes alone.
It’s partly because of this high-fiber and antioxidant-rich
dietary pattern that Okinawans enjoy such a long lifespan. Living to be one
hundred years or older is not uncommon in Okinawa. Okinawans also experience less
chronic disease than Americans do — with significantly fewerdeaths from heart disease and cancers of the colon,
breast, and prostate.
Traditional Papua New Guinea Highlanders have also been
known to eat a lot of sweet potatoes. In fact, tubers like sweet potatoes
and yams provide 90%
of their calories!
They don’t eat much, if any, meat either. How has a sweet
potato-based diet affected their health?
A study published in
the Journal of Internal Medicine in 1994 found that, when
these native groups still followed this traditional way of eating, they enjoyed
lower blood pressure and weight than Westerners. And they almost never
experienced heart disease, strokes, or other modern chronic diseases.
So are sweet potatoes good for you? Yes, they are!
What makes them so good for you?
Sweet Potato Nutrition
Sweet potatoes are high in fiber, vitamin C, potassium, pantothenic acid
(vitamin B5), niacin (vitamin B3), vitamin B6, manganese, magnesium, and
They get their orange color from beta-carotene, which is a
pigment and antioxidant. Sweet potatoes also contain a modest but helpful amount of protein —
around four grams per cup when cooked.
When compared to white potatoes, sweet potatoes offer
more vitamins and antioxidants. Surprisingly, considering their sweeter
taste, they also have a mildly lower glycemic index score. This
makes them slower to digest.
But the greatest sweet potato nutritional glory of
all may be its rich supply of vitamin A. A single sweet potato offers over
double the daily value for vitamin A.
Sweet Potatoes Are Remarkably High in Vitamin A
Worldwide, vitamin A deficiency is the leading cause of
preventable blindness in children. An estimated 250,000 to 500,000 children become blind
every year due to a lack of this critical nutrient. Half of these children die
within a year of losing their sight.
Hoping to solve this problem (and with perhaps a few other
less noble motives in the mix), over the last several decades, biotechnology
companies, governments, foundations, and scientists have spent hundreds of millions of dollars attempting to
develop and popularize “golden rice.”
This is a form of rice that’s been genetically engineered to
provide beta-carotene (a precursor to vitamin A). Despite decades of
effort, the product still hasn’t reached the market.
How ironic that this same effort could have gotten sweet
potatoes and the means to grow them into the hands of most of the impoverished
families now suffering from vitamin A deficiency. Of course, that wouldn’t
have made biotech company, Syngenta, any money. But it would have helped a
whole lot more people than golden rice ever has, and most likely, ever will.
News flash: The biotech industry and its supporters have
long promoted GMO golden rice as an urgently needed solution to vitamin A
deficiency. But in late 2018, in a surprising twist, the US Food and Drug
Administration (FDA) concluded its consultation process on golden rice by
informing the current developers, the International Rice Research Institute
(IRRI), that golden rice does not meet the nutritional requirements to
make a health claim.
In effect, the FDA was saying that GMO golden rice
offers no meaningful nutritional benefits.
Which again raises the question: How much better off would
people be if the hundreds of millions of dollars spent on developing golden
rice had instead been used to support the growth of sweet potatoes, carrots,
and other vitamin A-rich vegetables in parts of the world where vitamin A
deficiencies are a problem?
10 Incredible Sweet Potato Health Benefits
The unique nutritional profile of sweet potatoes makes
them powerful allies in preventing disease and supporting overall
Here are some health benefits of adding sweet potatoes to
Sweet Potato Health Benefit #1: They Support Digestive Health
Sweet potatoes are an excellent source of fiber,
especially when you eat the skin. Fiber is important for your digestive health, preventing constipation and serious diseases, such as
One medium sweet potato has six grams of dietary fiber. They also contain
resistant starch, a type of starch that plays a role in feeding your
body’s “good” bacteria.
Sweet Potato Health Benefit #2: They Keep Your Heart
The high fiber content of sweet potatoes
can lower LDL (bad) cholesterol levels, helping to preventcardiovascular
Sweet potatoes are also high in potassium, which
works in balance with sodium in your body to maintain healthy blood pressure.
They’re also high in copper, an essential metal
for making red blood cells and keeping your heart healthy. Low levels of copper
have been linked to dangerously high homocysteine, blood
pressure, and LDL cholesterol levels.
Sweet Potato Health Benefit #3: They Help Stabilize Blood
The fiber and complex carbohydrates in sweet potatoes can help
keep your blood sugar stable. And it can help you feel full longer. Sweet potato
varieties also contain other substances that benefit stable blood sugar.
A 2004 study published in Diabetes
Care successfully used Caiapo, an extract from white sweet potatoes,
to naturally reduce and manage blood glucose in people with type 2 diabetes.
The 30 participants who were given 4 grams of Caiapo every
day for 12 weeks saw a decrease in their HbA(1c) (going from 7.21 to 6.68),
fasting blood glucose (143.7 vs. 128.5), and two-hour blood glucose (193.3
vs.162.8). The 31 participants who were given a placebo instead saw no such
Sweet Potato Health Benefit #4: They Can Boost Your
Sweet potatoes are rich in antioxidants that prevent
free radical damage in your body.
One cup of baked sweet potato contains 52% of your daily value for vitamin C,
which is important for wound healing and tissue repair.
And the vitamin A in sweet potatoes helps your body
make immune cells
that stave off infections and disease and have anti-tumor effects.
Purple sweet potatoes contain especially potent antioxidants.
Sweet Potato Health Benefit #5: They Are Good for Your
Sweet potatoes contain several nutrients that have been
linked to improved eye health and vision. Some of the most powerful are the
carotenoids. They include alpha-carotene, beta-carotene, lutein, and
Beta-carotene, when taken as a supplement in isolation from
the other carotenoids, can cause imbalances. But when eaten in foods, where it
is always accompanied by, and in balance with, an entire suite of
carotenoids, it’s been shown to have powerful anti-cancer and
Orange sweet potatoes (as well as other orange plants,
including carrots) have particularly high concentrations of carotenoids.
It’s not just the orange sweet potatoes that are good for
your vision, though. A class of anthocyanins called PSPA, derived
from purple sweet potato roots, might also benefit your eyes.
A study published in Food
& Nutrition Research in 2015 looked at whether PSPA could
influence the health and growth of human retinal pigment epithelial (RPE)
Why does this matter? The RPE is responsible for helping
your eyes absorb light. It also directs immune response when faced with a
threat to eye health. The researchers found that PSPA promoted DNA synthesis
and healthy RPE cell growth and survival. They concluded that PSPA
could potentially find use as a supplement for maintaining healthy vision.
Sweet Potato Health Benefit #6: They Fuel Your Brain
Sweet potatoes also contain compounds that help your brain
function at its best, including choline and manganese.
Choline is an essential nutrient for brain growth and
development, as well as the synthesis of the neurotransmitter acetylcholine
that sends messages between cells.
Manganese is also important for brain health. It binds to
neurotransmitters and helps moveelectrical
impulses through your body faster. You can find 43% of your daily value of manganese in one cup of baked sweet potato.
The anthocyanins unique
to purple sweet potatoes may also have memory-enhancing
Sweet Potato Health Benefit #7: They Can Help Ease Stress
Sweet potatoes may help you relax. They’re high
in magnesium, which has been shown to play a role in calming the brain. Magnesium deficiency has
been linked to depression, mood disturbances, and headaches.
Other good sources of magnesium include avocados, legumes,
tofu, nuts, seeds, and leafy greens.
(I’m dreaming right now of a loaded baked sweet potato piled
high with a soft nut cheeze, avocado, a drizzle of flax oil, and a sprinkle of
seasoning. It’s also accompanied by some freshly steamed and piping hot leafy
greens for a delicious, magnesium-rich meal.)
Sweet Potato Health Benefit #8: They Can Help Boost
Vitamin A is an essential nutrient for healthy reproduction. And
as we know, sweet potatoes are a fantastic source.
Sweet potatoes also offer a rich supply of iron, which
has also been shown to be important in supporting fertility.
Sweet Potato Health Benefit #9: They Can Help Fight
Sweet potatoes are a rich source of cancer-fighting
antioxidants, especially in their skin. They have other anti-cancer
Up to 80% of the protein in sweet potatoes is a type of storage protein
known as sporamin. This unique protein has been studied for anti-cancer ability and
found to be effective in several disease types.
Research has been promising in the use of sporamin to
inhibit tongue, gallbladder,
It has also been shown capable of slowing cancer
cell growth and reducing cell
migration and invasion in metastatic cancers.
Sweet potato peels, particularly those of the purple
varieties, may be especially powerful when it comes to cancer
A study published in Nutrition and Cancer in
2016 looked at the antioxidant and anti-cancer effects of an extract from sweet
potato peels. They found promising anti-cancer activity for cancers of
the breast, colon, ovary, lung, and head/neck.
Sweet Potato Health Benefit #10: They Have
Eating sweet potatoes may also help reduce inflammation.
This is chiefly due to their high levels of
beta-carotene, vitamin C, and magnesium. Their abundance of antioxidants
doesn’t hurt here, either.
One of the particular antioxidants that’s found most
abundantly in purple sweet potato flesh is cyanidin. Cyanidin
has been linked to reducing inflammation,
especially in the digestive tract.
How to Choose and Store Sweet Potatoes
Next time you shop for sweet potatoes, here are a few things
to keep in mind.
When you pick one up, take a close look at its skin (no, you
don’t have to pack your magnifying glass). It should all be mostly the
same color without visible signs of decay or cracking.
Give it a little squeeze. You don’t want your sweet
potato to be squishy anywhere, as this could indicate rotting.
When you get your sweet potatoes home, make them a nice
place to rest in a basket on your countertop or pantry. You should keep
them dry and cool (room temperature, not refrigerated).
Typically, you should use sweet potatoes within a
few weeks of purchase.
The Best Way to Prepare Sweet Potatoes