Carambola are more commonly referred to as star fruit, a term that refers to the distinctive five-point shape created by a cross section of the tropical fruit. Star fruit offer an unusual flavor profile that ranges from lemony tartness to ripe-plum sweetness, depending on the variety and age of the fruit. The low-calorie, low-fat fruit is a rich source of vitamins and nutrients, and its antioxidant properties show promise for significant health benefits.
An average, medium-sized star fruit measuring just under 4 inches long contains approximately 28 calories, according to the USDA nutrient database. None of the caloric energy is attributed to fat. Protein accounts for a small percentage of the caloric energy, with just 1 gram of protein per serving. A majority of the caloric energy from star fruit is attributed to carbohydrates and sugar. Star fruit have 6 grams of carbohydrates per serving and almost 4 grams of total sugar. The proportionally high carbohydrate content also contributes to star fruit's 3.5 grams of fiber for serving.
The Centers for Disease Control and Prevention prize star fruit for its high concentration of vitamin C, a vitamin essential for supporting cell production and a healthy immune system. A single medium star fruit provides you with 52 percent of your daily recommended value of vitamin C, or approximately 31 milligrams. Though star fruit are not a significant source of other minerals or vitamins, they do provide 8 percent of your daily value of vitamin B-5 with approximately 0.36 milligrams, as well as 12 milligrams of phosphorus and 133 of potassium.
Antioxidants inhibit the activity of oxidized molecules in your body that are responsible for a range of health conditions, including neurodegenerative diseases. A 2003 study published in the "Journal of Chromatography" identified star fruit's high content of ascorbic acid, epicatechin and gallic acid as the main sources for the fruit's antioxidant properties. A subsequent 2007 study conducted by researchers at Khulna University confirmed that star fruit extracts were capable of isolating and inhibiting free radicals. Additional research exploring the precise role of star fruit antioxidants in terms of health benefits is required before significant claims can be made, though the antioxidant capacity of star fruit is promising.
Healthy individuals are unlikely to experience any health complications related to the nutrition makeup of star fruit, but people with kidney-related disorders should limit their intake to prevent complications. Star fruit contain considerable concentrations of oxalic acid, an organic compound that can cause toxicity in high doses and presents significant complications for patients with decreased kidney functionality. Though normal consumption of star fruit may only produce some digestive discomfort for people with decreased kidney function, high doses of the aggravating acid can be fatal.