Purple Sweet Potatoes Contain Anthocyanins
Unlike regular sweet potatoes, purple sweet potatoes contain high levels of anthocyanins.
Anthocyanins are purple-colored pigments found within certain plant foods, such as blueberries and raspberries. They are a type of polyphenol sometimes referred to as “antioxidants,” and evidence suggests they may have protective benefits for human health (1).
On this note, a large 2021 meta-analysis of large observational trials found that regular consumption of anthocyanin-rich foods was associated with a 9% lower risk of coronary heart disease (2).
Interestingly, a 2006 study published in the Journal of Agricultural and Food Chemistry investigated the estimated intake of anthocyanins from everyday foods. Based on the results of this study, the average daily intake of anthocyanins was 12.5 mg per day per person in the United States (3).
Meanwhile, it has been demonstrated that fresh purple sweet potatoes can contain 519 mg of anthocyanins per 100 grams (4).
For an idea of how this compares to other foods, studies have shown that blueberries contained 25-495 mg and red cabbage had 250-322 mg of anthocyanins per 100 grams (5).
An Excellent Source of Vitamin A
Purple sweet potatoes are one of the best sources of vitamin A.
Vitamin A is an essential micronutrient that, among other functions, plays a critical role in the immune system and visual health (6).
Good Source of Vitamin C
Purple sweet potatoes also provide moderate amounts of vitamin C, another essential micronutrient.
With 34 mg of vitamin C per medium-sized cooked purple sweet potato, this represents 38% of the recommended daily value.
Vitamin C is essential for the immune system and its antioxidant activity (7).
May Lower Blood Pressure
Research has shown that purple sweet potato intake may help lower blood pressure.
In this regard, a 2016 trial that enrolled 20 participants with elevated blood pressure examined the effect of a purple-fleshed sweet potato beverage on blood pressure (8).
Each participant consumed two purple sweet potato beverages per day for 28 days. This intake level was equivalent to 234 mg of anthocyanin per day.
Additionally, cell and animal studies support the ability of anthocyanins to lower blood pressure. However, this has yet to be confirmed in humans, and the existing research provides mixed outcomes (11).
Longer, high-quality randomized controlled trials in this area are necessary to provide more clarity.
May Have Benefits for the Liver
There has been some research into the potential benefits of purple sweet potato for liver health.
Firstly, a 2007 Japanese randomized, double-blind, placebo-controlled study examined the effect of two purple sweet potato beverages per day on markers of liver health. Forty-eight participants consumed two of these drinks daily (200.3 mg anthocyanins per drink) for eight weeks (12).
Notably, compared to placebo, the intervention group consuming the drinks had statistically significant lower levels of several liver enzymes associated with liver damage.
However, a 2016 double-blind, placebo-controlled pilot trial had a less certain outcome. This study also examined the effect of an anthocyanin-rich purple sweet potato beverage on markers of liver health (12).
The study recruited 40 Caucasian participants aged 40 and 70 who were otherwise healthy aside from having ‘borderline hepatitis.’ Each participant was asked to consume a purple sweet potato beverage (177 mg anthocyanins) three times per day for eight weeks.