Nutrition

Why potatoes are good for you

The healthy option
According to the 11 Food Based Dietary Guidelines (FBDG) of South Africa, we are advised to make starchy foods the basis of most meals, and as an one-stop supply of starch, it is hard to beat the potato. Approximately 100 grams of boiled, fresh potato with its skin provides as much as 354 kilojoules of energy. The starch in potatoes is digested to glucose in the gut and is absorbed as such. The glucose travels to the liver and from there to all body cells where it is metabolised so that the energy is extracted from it. This glucose is metabolised for use by our muscles as well as our nervous system, thus contributing to both physical and mental performance.

Nutritional value

Some foods have higher nutritional values than other. Potatoes are so nutritious that one serving will meet a person's daily nutrition requirements. They are very nourishing, appetising and a good source of energy, proteins, minerals and vitamins. Today's lifestyle related diseases are best prevented through nutrition therapy.

What's in it for you?

Carbohydrates are the body's source of energy. The carbohydrates in potatoes are complex, meaning they provide the body with a steady flow of energy for an extended period. In any balanced meal the carbohydrates should be 60% of the daily kilojoules, therefore potatoes should be an important part of the menu.

Proteins

Protein provides the body's main source of growth and tissue repair. Like most proteins of plant origin, potato protein is lacking in essential amino acids. If consumed in combination with animal protein foods like milk it becomes a complete protein food. The body only needs small amounts of protein per day (60 - 100 g)

Vitamins and minerals

Potatoes make a useful contribution to our daily mineral and vitamin intake. One portion of potatoes contains many of the B-complex vitamins and up to a third of our daily vitamin C requirement. Potatoes are also a rich source of potassium, phosphorous and fluoride and contain small amounts of iron and zinc which are readily absorbed.

Dietary fibre

Dietary fibre is such an important part of a healthy diet yet most of us still seem to lack sufficient amounts of it in our daily intake. There are two types of fibre : soluble and insoluble fibre. Soluble fibre dissolves in water to form a gel in the intestines which softens the stools, whereas insoluble fibre retains water, therefore increasing the stool volume. Fibre is important in preventing diseases like cancer, obesity, diabetes and in maintaining health. The recommended intake of fibre for adults is 20 - 30 g daily. Potatoes are a good source of fibre, particularly the skin.

Fat

Potatoes contain very small amounts of fat, only 0.1 % per
100 g, which makes them ideal for slimming. Remember the fat is added to potatoes via dressing or sauces.

Nutritional values

Nutrients in 100/g of potatoes Unit Baked Potato Potato boiled with skin

Water % 71.2 77
Energy kj 456 365
Carbohydrate g 23.3 18.6
Protein g 2.3 1.9
Fat g 0.1 0.1
Fibre g 1.09 1.5
Potassium mg 418 379
Phosphorous mg 57 44
Magnesium mg 27 22
Vitamin C mg 13 13
Calcium mg 10 4
Sodium mg 8 1.04
Niacin (Vit B3) mg 1.6 1.4
Iron mg 1.4 0.3
Thiamine (Vit B1) mg 0.11 0.11
Riboflavin (Vit B2) mg 0.03 0.03

Source
MRC Food Composition Tables (1991)

Potatoes and Glycaemic Index (GI)
In the eternal quest to determine what makes it difficult to lose fat, experts are linking insulin levels with our body’s ability to burn fat. The carbohydrates that we consume determine the height of our insulin levels: the higher the glycaemic index (GI) of these carbohydrates, the higher our levels of insulin. When insulin levels are low, we mainly burn fat, but when they are high, we mainly burn carbohydrates.

Potatoes don’t always have a high GI. The table below indicates how GI levels vary according to type of potato and how it is prepared. This relates to potatoes as a meal on their own. As soon as a protein or fat is added, the GI of the meal changes (is reduced), so it is debatable how useful a GI-determined diet for health and weight-loss. Ideally, we should strive for nutrition, balance and variety in our diets.

GI values of potatoes

Classification

Old potatoes Medium to high GI
New potatoes High GI
Hot potatoes High GI
Cold potatoes Low to Medium GI

GI determination is not an exact science

But the explanation of GI provided above is perhaps an oversimplification of a very complex matter. Numerous studies into GI as the basis of diet plans, such as The Glycemic Index: Research Meets Reality by Katherine A. Beals, PhD, RD, FACSM, question the validity of the methods used to compile the GI and its use in determining what we eat. In her study, she suggests that the way in which a food is prepared, where it originates, how it is eaten and even the time of day it is eaten can influence our body’s blood glucose responses to the food, and thus the GI level. The conclusion of her extensive study (quoting more than 70 references) is that: “Like the low-carbohydrate craze that preceded it, the GI has enjoyed increasing popularity despite the lack of research to support its efficacy as a dietary tool for weight loss, disease prevention, and/or health promotion. However, unlike the low-carbohydrate diets whose popularity could be attributed in a large part to their simplicity (i.e., just eliminate carbohydrates from the diet), there is nothing simple about the GI. It is a complex measure that is made even more complex by the multitude of factors that can impact it (e.g., processing, preparation, maturation, the addition of other macronutrients, time of day, etc.).”

Potatoes and weight management

Potatoes, on their own, contain a negligible amount of fat, no more than 0.1 gram per medium-sized potato, and potatoes are completely free of cholesterol. Like most pure foods, it is not the potato itself but the way in which it is prepared and the things you add to them that increase the fat content of the dish.
Potatoes, on their own, contain a negligible amount of fat, no more than 0.1 gram per medium-sized potato, and potatoes are completely free of cholesterol. Like most pure foods, it is not the potato itself but the way in which it is prepared and the things you add to them that increase the fat content of the dish.

In fact, says Professor Esté Vorster, Director: Africa Unit for Transdisciplinary Health Research at the Faculty of Health Sciences of North-West University, “Potatoes, when boiled in their skin, have low energy values and are ideal for slimming diets and diets to maintain a healthy body weight.”

Potatoes are good for your heart

Besides being cholesterol free, a recent study has shown that potatoes may contribute to the healthy status of your heart in other ways. In the European Journal of Nutrition, Volume 45 Issue 5 of 2006, researchers reported on their study of the effects of a potato-rich diet on rats. They concluded that the consumption of cooked potatoes may enhance antioxidant defense and improve lipid metabolism, results which could be interesting for the prevention of cardiovascular disease. Of course one cannot always extrapolate from rats to humans, but in this instance, the esearch has provided evidence on how potatoes may protect us against cardiovascular disease.
Besides being cholesterol free, a recent study has shown that potatoes may contribute to the healthy status of your heart in other ways. In the European Journal of Nutrition, Volume 45 Issue 5 of 2006, researchers reported on their study of the effects of a potato-rich diet on rats. They concluded that the consumption of cooked potatoes may enhance antioxidant defense and improve lipid metabolism, results which could be interesting for the prevention of cardiovascular disease. Of course one cannot always extrapolate from rats to humans, but in this instance, the esearch has provided evidence on how potatoes may protect us against cardiovascular disease.