Purple Power: 7 Benefits of Purple Potatoes
By Anne Danahy, MS, RDN
Purple potatoes are the eye-catching gems of the potato aisle.
Like other members of the potato family (Solanum tuberosum), they come from a tuber plant native to the Andes mountain region in South America.
They have a blue-purple to almost black outer skin and an inner flesh that's brilliant purple, even after cooking.
Some common varieties include Purple Peruvian, Purple Majesty, All Blue, Congo, Adirondack Blue, Purple Fiesta, and Vitelotte.
They have a denser texture and slightly nuttier, earthier flavor than white potatoes.
Purple potatoes are a tasty way to add a pop of color to your plate while enjoying a serving of health benefits.
Here are 7 surprising benefits of purple potatoes.
1. Highly Nutritious
Potatoes often get a bad rap because of their high starch content, but they contain many other important nutrients and can be a very healthy addition to your diet.
Purple potatoes have a nutrient content similar to that of other varieties of potatoes in the Solanum tuberosum family, though their mineral content can vary depending on the soil in which they were grown.
- Calories: 87
- Protein: 2 grams
- Carbs: 20 grams
- Fiber: 3.3 grams
- Fat: less than 1 gram
- Manganese: 6% of the Daily Value (DV)
- Copper: 21% of the DV
- Iron: 2% of the DV
- Potassium: 8% of the DV
- Vitamin B6: 18% of the DV
- Vitamin C:14% of the DV
Interestingly, potatoes have more potassium than bananas. In addition, a serving of potatoes provides 3 grams of fiber, from both the flesh and skin, and they're naturally low in sodium.
All potatoes, including purple potatoes, are quite nutritious and provide a range of nutrients in both their skin and flesh. They're especially rich in minerals and boast more potassium than a banana.
2. Better for Blood Sugar
The glycemic index (GI) is a measure of the extent to which a food raises your blood sugar. It ranges from 0 to 100, and a GI greater than 70 is considered high.
A comparison study in humans found that purple potatoes have a GI of 77, yellow potatoes have a GI of 81, and white potatoes have a GI of 93.
While all potato varieties impact blood sugar levels because of their carbohydrate content, purple potatoes may exert less of an effect than other types due to their high concentration of polyphenol plant compounds.
These compounds may decrease the absorption of starches in the intestines, therefore minimizing purple potato's impact on blood sugar levels.
An animal study observed similar results, finding that feeding purple potato extract to rats resulted in better glucose tolerance and improved short and long-term blood sugar levels.
Eating purple potatoes instead of white potatoes is a good move when watching your blood sugar. While the starch in purple potatoes increases blood sugar, it does so to less of an extent than the starch in yellow or white varieties.
3. Packed With Antioxidants
Like other colorful fruits and vegetables, purple potatoes' bright color is a telltale sign that they're high in antioxidants. In fact, they have two to three times more antioxidant activity than white or yellow potatoes.
Antioxidants are plant compounds that can protect your cells from the damaging effects of oxidative stress.
Purple potatoes are especially rich in polyphenol antioxidants called anthocyanins. They're the same type of antioxidant found in blueberries and blackberries.
A higher anthocyanin intake is linked to several benefits, including healthier cholesterol levels, improved vision and eye health, and a reduced risk of heart disease, certain cancers, and diabetes.
In addition to their high anthocyanin content, purple potatoes pack other antioxidants common to all types of potatoes, including.
- vitamin C
- carotenoid compounds
- polyphenolic compounds like caffeic acid, scopolin, chlorogenic acid, and ferulic acid
A small study in eight people found that loading up on one meal of whole purple potatoes increased their blood and urine antioxidant levels. In contrast, eating a similar amount of refined potato starch in the form of biscuits caused a decrease.
Another study in men who ate 5.3 ounces (150 grams) of different colored potatoes each day for 6 weeks observed that the purple potato group had lower levels of inflammatory markers and markers of DNA damage, compared with the white potato group.
Eating purple potatoes can boost your antioxidant intake and reduce inflammation. They're especially rich in anthocyanins, which are antioxidant compounds linked to improved eye and heart health, as well as a lower risk of chronic disease.
4. May Improve Your Blood Pressure
Eating purple potatoes may promote blood vessel and blood pressure health. This may partly be due to their higher potassium content, as this nutrient helps reduce blood pressure, but their antioxidant content likely plays a role, too.
A small 4-week study in people with high blood pressure found that eating six to eight purple potatoes twice daily reduced systolic and diastolic blood pressure (the top and bottom numbers of a reading) by 3.5% and 4.3%, respectively.
In addition, some studies suggest that compared with eating white potatoes, eating purple potatoes may reduce arterial stiffness. Having stiff arteries increases your risk of heart attack or stroke, as your vessels can't dilate as easily in response to changes in blood pressure.
In general, eating more polyphenol-rich foods, including those that contain anthocyanins like purple potatoes, may help relax and strengthen your blood vessels.
In fact, the polyphenol compounds in purple potatoes and many other foods work to reduce blood pressure in a way similar to that of some types of blood-pressure-lowering medications known as angiotensin-converting-enzyme (ACE) inhibitors.
Purple potatoes have been found to improve blood pressure. This effect might be related to their polyphenolic antioxidant compounds, which work in a way similar to that of some blood-pressure-lowering medications.
5. May Reduce Your Risk of Cancer
A few lab studies have indicated that some of the compounds in purple potatoes, including their antioxidants, may help prevent or fight cancer, including colon and breast cancer.
In one study, cancer cells that were treated with purple potato extract grew more slowly. In some cases, the extract even caused cancer cell death.
It's important to note that the research thus far has been limited to cancer cells treated in a lab and cancers in lab rats. Therefore, it's unknown whether eating purple potatoes would have similar effects in humans.
Some of the compounds in purple potatoes may slow the growth of — or even kill — certain cancer cells. The current research is limited to lab studies, so it's unknown whether adding purple potatoes to your diet affects cancer risk.
6. Can Help Fill Your Fiber Gap
Most people don't meet the Dietary Guidelines for Americans' recommendation to consume 14 grams of fiber per 1,000 calories, but adding a few servings of purple potatoes to your diet each week can help fill the gap.
Dietary fiber helps keep you feeling full, prevents constipation, stabilizes blood sugar, and helps maintain healthy cholesterol levels.
The fiber content of potatoes varies slightly depending on the cooking method, but mostly depending on whether you eat the skin.
For example, a 3.5-ounce (100-gram) potato with the skin cooked in the microwave contains 3.3 grams of fiber, while a potato of the same size boiled without the skin has 1.8 grams.
Part of the starch in purple (and all) potatoes is a type of fiber called resistant starch. Resistant starch resists digestion in your gastrointestinal tract, but the bacteria in your large intestine ferment it.
During this fermentation process, compounds known as short-chain fatty acids are produced. These compounds contribute to improved gut health.
The resistant starch content of potatoes also varies depending on the cooking method, though it doesn't seem to vary much between the color of potatoes. Resistant starch is highest when potatoes are cooked and then chilled, but not reheated.
Adding purple potatoes to your diet can help increase your fiber intake and add some gut-healthy resistant starch to your diet. To reap the greatest fiber benefits, eat them with the skin on and cook them ahead of time, eating them chilled, such as in a salad.
7. Brighten Up Your Plate
You can use purple potatoes similarly to how you'd use white, yellow, or red varieties.
Substituting them for a lighter flesh potato is a great way to add more color and interest to your meals — after all, you really do eat with your eyes.
Use them to make mashed or baked potatoes and add your favorite toppings for a side dish that everyone will want to try.
If you like them crispy like fries, slice them into wedges, toss them with olive oil, minced garlic, and rosemary, and roast them at 400°F (204°C) for about 20 minutes or until they're tender.
To reap the benefit of their resistant starch, use purple potatoes to make potato salad.
Leave the skins on, cut them into chunks, and boil them until they're tender. Then drain and toss them with thinly sliced onions, a handful of fresh minced herbs, and some Dijon-vinaigrette dressing. Chill them in the refrigerator and serve them cold.
Boil, mash, or roast purple potatoes just like you would any other light-fleshed variety. They don't take any additional time to cook and add interest and a bright pop of color to your meals.
The Bottom Line
Purple potatoes are a healthy and colorful member of the potato family that's worth getting to know.
You can prepare them similarly to how you would prepare white or yellow flesh potatoes, but if you swap them in, you'll enjoy quite a few health benefits.
Compared with regular potatoes, they have a lower glycemic index and may be better for your blood sugar.
Many of their health benefits, including those related to blood pressure and cancer protection, stem from their content of anthocyanins — important antioxidants that are abundant in these colorful potatoes.
Next time you head to the supermarket, see if you can find this unique potato variety and give it a go.
Reposted with permission from Healthline.
By Melissa Gaskill
Two decades ago scientists and volunteers along the Virginia coast started tossing seagrass seeds into barren seaside lagoons. Disease and an intense hurricane had wiped out the plants in the 1930s, and no nearby meadows could serve as a naturally dispersing source of seeds to bring them back.
Restored seagrass beds in Virginia now provide habitat for hundreds of thousands of scallops. Bob Orth, Virginia Institute of Marine Science / CC BY 2.0<p>The paper is part of a growing trend of evidence suggesting seagrass meadows can be easier to restore than other coastal habitats.</p><p>Successful seagrass-restoration methods include <a href="https://www.sciencedirect.com/science/article/abs/pii/S0304377099000078?via%3Dihub" target="_blank">transplanting shoots</a>, <a href="https://onlinelibrary.wiley.com/doi/10.1111/j.1061-2971.2004.00314.x" target="_blank" rel="noopener noreferrer">mechanized planting</a> and, more recently, <a href="https://www.nature.com/articles/s41467-020-17438-4" target="_blank" rel="noopener noreferrer">biodegradable mats</a>. Removing threats, proximity to donor seagrass beds, planting techniques, project size and site selection all play roles in a restoration effort's success.</p><p>Human assistance isn't always necessary, though. In areas where some beds remain, seagrass can even recover on its own when stressors are reduced or removed. For example, seagrass began to recover when Tampa Bay improved its water quality by reducing nitrogen loads from runoff by roughly 90%.</p><p>But more and more, seagrass meadows struggle to hang on.</p><p>The marine flowering plants have declined globally since the 1930s and currently disappear at a rate equivalent to a football field every 30 minutes, according to the <a href="https://www.unep.org/resources/report/out-blue-value-seagrasses-environment-and-people" target="_blank" rel="noopener noreferrer">United Nations Environment Programme</a>. And research published in 2018 found the rate of decline is <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2018GB005941" target="_blank" rel="noopener noreferrer">accelerating</a> in many regions.</p><p>The causes of decline vary and overlap, depending on the region. They include thermal stress from climate change; human activities such as dredging, anchoring and coastal infrastructure; and intentional removal in tourist areas. In addition, increased runoff from land carries sediment that clouds the water, blocking sunlight the plants need for photosynthesis. Runoff can also carry contaminants and nutrients from fertilizer that disrupt habitats and cause algal blooms.</p><p>All that damage comes with a cost.</p>
The Value of Seagrass<p>As with ecosystems like rainforests and <a href="https://therevelator.org/mangroves-climate-change/" target="_blank">mangroves</a>, loss of seagrass increases carbon dioxide emissions. And that spells trouble not just for certain habitats but for the whole planet.</p><p>Although seagrass covers at most 0.2% of the seabed, it <a href="https://www.unenvironment.org/news-and-stories/story/seagrass-secret-weapon-fight-against-global-heating" target="_blank">accounts for 10%</a> of the ocean's capacity to store carbon and soils, and these meadows store carbon dioxide an estimated 30 times faster than most terrestrial forests. Slow decomposition rates in seagrass sediments contribute to their <a href="https://www.researchgate.net/publication/238506081_Assessing_the_capacity_of_seagrass_meadows_for_carbon_burial_Current_limitations_and_future_strategies" target="_blank" rel="noopener noreferrer">high carbon burial rates</a>. In Australia, according to <a href="https://onlinelibrary.wiley.com/doi/10.1111/gcb.15204" target="_blank" rel="noopener noreferrer">research</a> by scientists at Edith Cowan University, loss of seagrass meadows since the 1950s has increased carbon dioxide emissions by an amount equivalent to 5 million cars a year. The United Nations Environment Programme reports that a 29% decline in seagrass in Chesapeake Bay between 1991 and 2006 resulted in an estimated loss of up to 1.8 million tons of carbon.</p>
Eelgrass in the river delta at Prince William Sound, Alaska. Alaska ShoreZone Program NOAA / NMFS / AKFSC; Courtesy of Mandy Lindeberg / NOAA / NMFS / AKFSC<p>Seagrasses also protect costal habitats. A healthy meadow slows wave energy, reduces erosion and lowers the risk of flooding. In Morro Bay, California, a 90% decline in the seagrass species known as eelgrass caused extensive erosion, according to a <a href="https://www.sciencedirect.com/science/article/abs/pii/S0272771420303528?via%3Dihub" target="_blank" rel="noopener noreferrer">paper</a> from researchers at California Polytechnic State University.</p><p>"Right away, we noticed big patterns in sediment loss or erosion," said lead author Ryan Walter. "Many studies have shown this on individual eelgrass beds, but very few studies looked at it on a systemwide scale."</p><p>In the tropics, seagrass's natural protection can reduce the need for expensive and often-environmentally unfriendly <a href="https://www.nioz.nl/en/news/zeegras-spaart-stranden-en-geld" target="_blank" rel="noopener noreferrer">beach nourishments</a> regularly conducted in tourism areas.</p><p>Seagrass ecosystems improve water quality and clarity, filtering particles out of the water column and preventing resuspension of sediment. This role could be even more important in the future. By producing oxygen through photosynthesis, meadows could help offset decreased oxygen levels caused by warmer water temperatures (oxygen is less soluble in warm than in cold water).</p><p>The meadows also provide vital habitat for a wide variety of marine life, including fish, sea turtles, birds, marine mammals such as manatees, invertebrates and algae. They provide nursery habitat for <a href="https://wedocs.unep.org/bitstream/handle/20.500.11822/32636/seagrass.pdf?sequence=1&isAllowed=y" target="_blank" rel="noopener noreferrer">roughly 20%</a> of the world's largest fisheries — an <a href="https://www.floridamuseum.ufl.edu/science/seagrass-meadows-harbor-wildlife-for-centuries/" target="_blank" rel="noopener noreferrer">estimated 70%</a> of fish habitats in Florida alone.</p><p>Conversely, their disappearance can contribute to die-offs of marine life. The loss of more than 20 square miles of seagrass in Florida's Biscayne Bay may have helped set the stage for a widespread <a href="https://www.wlrn.org/2020-08-14/the-seagrass-died-that-may-have-triggered-a-widespread-fish-kill-in-biscayne-bay" target="_blank">fish kill</a> in summer 2020. Lack of grasses to produce oxygen left the basin more vulnerable when temperatures rose and oxygen levels dropped as a result, says Florida International University professor Piero Gardinali.</p>
Damaged Systems, a Changing Climate<p>Governments and conservationists around the world have already put a lot of effort into coastal restoration efforts. And that's helped some seagrass populations.</p><p>Where stressors remain, though, restoration grows more complicated. <a href="https://www.rug.nl/research/portal/en/publications/the-future-of-seagrass-ecosystem-services-in-a-changing-world(3a8c56db-7bed-4c9e-ac7f-c72453e2a102).html" target="_blank">Research</a> published this September found that only 37% of seagrass restorations have survived. Newly restored meadows remain vulnerable to the original stressors that depleted them, as well as to storms — and <a href="https://www.ecowatch.com/tag/climate-crisis">climate change</a>.</p>
Seagrass in Dry Tortugas National Park, Florida. Alicia Wellman / Florida Fish and Wildlife / CC BY-NC-ND 2.0<p>In Chesapeake Bay a cold-water species of seagrass is currently hitting its heat limit, especially in summer, according to Alexander Challen Hyman of University of Florida's School of Natural Resources and Environment. As waters continue to warm due to climate change, the species likely will disappear there.</p><p>Climate-driven sea-level rise complicates the problem as well. Seagrasses thrive at specific depths — too shallow and they dry out or are eaten, too deep and there isn't enough light for photosynthesis.</p>
But There’s Good News, Too<p>Luckily, left to its own devices, a seagrass meadow can flourish for hundreds of years, according to a <a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2019.1861" target="_blank" rel="noopener noreferrer">paper</a> published last year by Hyman and other researchers from the University of Florida. The researchers arrived at their conclusion by looking at shells of living mollusks and fossil shells to estimate the ages of meadows in Florida's Big Bend region on the Gulf Coast.</p><p>That area has extensive, relatively pristine seagrass meadows. "Our motivation was to understand the past history of these systems, and shells store a lot of history," said co-author Michal Kowalewski.</p><p>A high degree of similarity between living and dead shells indicates a stable area, while a mismatch suggests an area shifted from seagrass to barren sand. The researchers found that long-term accumulations of shells resembled living ones, suggesting that the seagrass habitats have been stable over time.</p><p>That stability allows biodiversity to thrive, creating conditions where specialist species can survive and flourish, according to Hyman.</p><p>Discovering the long-term stability of seagrass meadows has implications for choosing restoration sites, Kowalewski notes.</p><p>"There must be reasons they thrive in one place, while a mile away they don't and fossil data says they probably never did," he said. "If we remove a seagrass patch, we cannot hope to plant it somewhere else. It's not just the seagrass that is special. The location at which it's found is special, too."</p><p>A better approach is conserving these habitats in the first place, but we're not doing enough of that right now. The UN reports that marine protected areas safeguard just 26% of recorded seagrass meadows, compared with 40% of coral reefs and 43% of mangroves.</p>
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