Although potatoes themselves are extremely low in fat and calories, mashed potatoes can be a significant source of fat, saturated fat, calories and sodium. If you're interested in reducing the amount of fat, saturated fat and calories in your mashed potatoes, consider using skim milk instead of whole and vegetable oil instead of butter.
A 1-cup serving of homemade mashed potatoes made with whole milk and butter contains roughly 237 calories, 35.3 grams of carbohydrates, 8.9 grams of fat, 5.5 grams of saturated fat, 3.9 grams of protein, 3.1 grams of fiber, 666 mg of sodium and 23 mg of cholesterol, according to U.S. Department of Agriculture. The calorie composition is approximately 59 percent carbohydrates, 34 percent fat and 7 percent protein.
The same serving of mashed potatoes provides 27 percent of the Institute of Medicine's recommended daily adult amount of Vitamin B-6, 20 percent of pantothenic acid, 15 percent of thiamine, 14 percent of Vitamin C and niacin, 9 percent of Vitamin A, 7 percent of riboflavin and 6 percent of Vitamin B-12. Vitamins B-6 and B-12, pantothenic acid, thiamine, niacin and riboflavin are water-soluble B-complex vitamins that play vital roles in metabolism, central nervous system function, vision and skin health, and hormone, red blood cell and DNA formation. Vitamin C, another water-soluble vitamin, is essential to protein metabolism, wound healing, immune function and iron absorption, according to the National Institutes of Health Office of Dietary Supplements. Vitamin A is a fat-soluble vitamin integral to healthy vision, bone growth, cell division and differentiation, and immune function. Mashed potatoes also contain trace amounts of other vitamins.
A 1-cup serving of mashed potatoes supplies 13 percent of the phosphorus and potassium, 9 percent of the magnesium and 5 percent of the zinc that adults should consume daily. These minerals aid bone health, immune function, wound healing, nerve function, muscle control, cell division, protein and DNA synthesis, and cardiac rhythm and blood pressure regulation. Mashed potatoes contain smaller amounts of other minerals.
Although potatoes are a significant source of many vitamins and minerals, a serving of mashed potatoes only offers 4 percent of the calcium; 3 percent of the vitamin D, iron, and selenium; and 2 percent of the vitamin E that adults should consume each day. A serving also contains 37 percent of the saturated fat, 29 percent of the sodium, 11 percent of the total fat and 8 percent of the cholesterol that the Mayo Clinic website recommends for adults per day, but only has between 8 percent and 15 percent of the fiber adults should consume daily.
Although potatoes can be a healthy addition to any well-balanced diet and even buttery mashed potatoes have their place, no diet that emphasizes one food or type of food to the exclusion of others can be considered healthy or safe. Consult your physician before beginning any weight-loss diet.