Sweet potato (Ipomoea batatas) is among the most nutritious subtropical and tropical vegetables. It is also used in traditional medicine practices for type 2 diabetes mellitus. Research in animal and human models suggests a possible role of sweet potato in glycaemic control.
Three RCTs met our inclusion criteria: these investigated a total of 140 participants and ranged from six weeks to five months in duration. All three studies were performed by the same trialist. Overall, the risk of bias of these trials was unclear or high. All RCTs compared the effect of sweet potato preparations with placebo on glycaemic control in type 2 diabetes mellitus. There was a statistically significant improvement in glycosylated haemoglobin A1c (HbA1c) at three to five months with 4 g/day sweet potato preparation compared to placebo (mean difference -0.3% (95% confidence interval -0.6 to -0.04); P = 0.02; 122 participants; 2 trials). No serious adverse effects were reported. Diabetic complications and morbidity, death from any cause, health-related quality of life, well-being, functional outcomes and costs were not investigated.
Sweet potatoes should not be confused with yams, another starchy root widely grown in Western Africa. Yams are indeed larger in size and can weigh upto 120 pounds in weight and 2 meters in length. Yams are tropical crops and indeed never grow where the temperature dips below 68 degrees F. Important differentiating features that distinguish sweet potatoes from yams are:
- Sweet potatoes (Ipomoea batatas) are dicotyledonous, relatively smaller and possess very thin peel.
- Whereas, yams are monocotyledons, larger, feature thick, rough, dark brown to pink skin depending upon the cultivar type.
Internally, sweet potato has starchy, sweet flesh which, depending upon the pigment concentration, ranges from white through yellow, orange, and purple.
Health benefits of Sweet potato
- Sweet potato is one of the high calorie starch foods (provide 90 calories/100 g vis a vis to 70 calories/100 g in potato). The tuber, however, contains no saturated fats or cholesterol, and is rich source of dietary fiber, anti-oxidants, vitamins, and minerals than potatoes.
- Its calorie content mainly comes from starch, a complex carbohydrate. Sweet potato has higher amylose to the amylopectin ratio than that in potato. Amylose raises the blood sugar levels rather slowly on comparison to simple fruit sugars (fructose, glucose etc) and therefore, recommended as a healthy food item even in diabetes.
- The tuber is an excellent source of flavonoid phenolic compounds such as beta-carotene and vitamin-A. 100 g tuber provides 14,187 IU of vitamin A and 8,509 µg of ß-carotene, a value which is the highest for any root-vegetables categories. These compounds are powerful natural antioxidants. Vitamin A is also required for the human body to maintain integrity of mucus membranes and skin. It is a vital nutrient for healthy vision. Consumption of natural vegetables and fruits rich in flavonoids helps protect from lung and oral cavity cancers.
- The total antioxidant strength of raw sweet potato measured in terms of oxygen radical absorbance capacity (ORAC) is 902 µmol TE/100 g.
- The tubers are packed with many essential vitamins such as pantothenic acid (vitamin B-5), pyridoxine(vitamin B-6), and thiamin (vitamin B-1), niacin, and riboflavin. These vitamins are essential in the sense that the human body requires them from external sources to replenish. These vitamins function as co-factors for various enzymes during metabolism.
- Sweet potato provides good amount of vital minerals such as iron, calcium, magnesium, manganese, and potassium that are very essential for enzyme, protein, and carbohydrate metabolism.
- Sweet potato top greens are indeed more nutritious than the tuber itself. Weight per weight, 100 g of fresh leaves carry more iron, vitamin C, folates, vitamin K, and potassium but less sodium than its tuber.