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Purple potatoes may give us another good reason to "eat the rainbow". Aside from their vibrant colour, these special spuds pack more reasons to add extra colourful produce to our plates!
Though potatoes have been extensively researched at Agriculture and Agri-Food Canada (AAFC), recent research findings at AAFC’s Guelph Research and Development Centre show a series of beneficial health effects associated with consuming purple potatoes.
The research team, including Research Scientist Dr. Rong Cao, Hua Zhang (former postdoctoral fellow), Ronghua Liu, Lili Mats, Dion Lepp, Honghui Zhu, as well as former students Yuhuan Chen and Shilian Zheng, studied the antioxidant and anti-inflammatory effects of purple potato extracts in collaboration with Yoshinori Mine from the Food Science Department at the University of Guelph. They found that purple potatoes can play an important role in managing systemic inflammation throughout the body, which is oftentimes the root cause of disease – particularly metabolic disorders – including heart disease, stroke, and type 2 diabetes. Talk about purple power!
Purple potatoes: a polyphenol powerhouse
Vibrantly-coloured fruits and vegetables contain polyphenols which are not only responsible for their intense pigmentation, but also contain potent antioxidants with anti-inflammatory properties.
These polyphenols, called anthocyanins, are naturally-occurring purple pigments found in several fruits and vegetables. Anthocyanins can help reduce the occurrence of some chronic diseases linked to gut health, particularly the composition of beneficial bacteria versus harmful bacteria in the gut microenvironment.
"Purple potatoes show tremendous potential to become a functional food because of the strong connection between reduced inflammation and prevention of gut-borne diseases and the purple pigment found naturally in these potatoes."
- Dr. Rong Cao, Research Scientist, Agriculture and Agri-Food Canada
Putting purple to the test
The research team studied the effectiveness of the purple potato’s antioxidant and anti-inflammatory properties on mice in a lab environment. The study included live trials of purple potato extracts on obese mice who were fed a high-fat diet that mimicked similar diets in humans. High-fat human diets can be linked to a weaker bacterial environment in the gut, which can decrease a person’s defense against inflammation-related diseases.
The trials provided new insights into how highly-coloured vegetables, including purple potatoes, can be instrumental in maintaining optimal gut health and help reduce the risk of diseases associated with chronic inflammation.
The team found a direct link between the polyphenols in purple potatoes and its effects on gut microbiota. This is because coloured vegetables can significantly suppress inflammation caused by endotoxins, which are toxins that exist in the cell wall of harmful (pathogenic) bacteria and are released when a cell breaks down – for example, through digestion.
The studies also determined a minimum dosage requirement to have an effect on the gut. Purple potato extract fed to mice at a minimum dose equivalent of 75 grams for humans, 3 times a week (equal to 3 potatoes) was instrumental in preventing leaky gut syndrome (weakened intestinal walls) and enhancing immunity as a result of improved gut microbiota composition.
Potatoes as prebiotics
The purple potato extract trials have shown that anthocyanins can be categorized as a prebiotic. Prebiotics help promote the growth of beneficial bacteria in the gut microenvironment.
This is a key finding because a healthy human intestine is an important player in the defense against the harmful, pathogenic bacteria behind gut-borne diseases. When the intestinal lining is intact, it enables nutrient absorption and prevents the entry of bacteria, which can help maintain good health. However, when the lining is not intact, the gut microenvironment is impaired, which can lead to inflammation and a weakened immune system.
In addition to improving gut health, the purple potato extract-fed mice also demonstrated significantly lowered blood glucose and cholesterol levels, reduced body weight gains, as well as reduced inflammation in the blood plasma and tissues.
Purple power
These results position purple potatoes as a great addition to Canadian diets to help promote a healthier lifestyle. It’s a "purple power" that can play a part in counteracting the effects of unhealthy diets by helping to improve gut health, and to reduce bodily inflammation and associated obesity.
Key discoveries/benefits
- Purple potatoes, and other colourful fruits and vegetables, owe their intense, naturally occurring colour to polyphenols, an antioxidant with anti-inflammatory properties.
- Results show that there is a strong connection between consuming purple potatoes and the prevention of leaky gut syndrome (weakened intestinal walls) and enhanced immunity as a result of improved gut microbiota composition, which can help in the management of bodily inflammation linked to metabolic diseases.
- The beneficial health effects of the potatoes were tested in a lab environment, where it was determined that the minimum dosage required to have an effect on the gut microbiota is the equivalent of 75 grams of purple potato extracts (3 potatoes) per week.
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