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Are potatoes good or bad?
Potatoes have long been considered the most basic of basic foods, a no-frills staple for the everyman or everywoman. One reason potatoes have earned this distinction is, no doubt, their low cost, but another may be their basic nutritional qualities: They are fat, sodium, and cholesterol-free, and a medium-size potato contains just 110 calories.
Nevertheless, the reputation of potatoes has taken a hit lately due to their relatively high glycemic index, which means that the carbohydrate in them is quickly converted to glucose when digested. Many people with diabetes take glycemic index into account when deciding what foods to incorporate into their diet.
Insights into whether potatoes may be good or bad
So how good or bad are potatoes when it comes to weight control and glucose tolerance? A study examining these topics was published a while ago by the Journal of the American College of Nutrition. According to an article on the study in the Daily Mail, the effect of potatoes on weight control may be modestly positive.
Researchers assigned 90 overweight participants to one of three groups. Two of these groups were taught how to reduce their daily caloric intake by 500 calories, but one group was taught how to do this by eating mostly high-glycemic-index foods, and the other by eating mostly low-glycemic-index foods. The third group was not told to change anything about the caloric or glycemic-index composition of their diet. All three groups were told, however, to consume 5–7 servings of potatoes per week.
After 12 weeks of following their prescribed diets, there were no significant differences between the groups in terms of weight loss or body composition changes. All three groups, however, experienced modest weight loss and improvements in body composition. Since the only dietary change that all three groups had in common was consuming potatoes regularly, it’s plausible that the potatoes were responsible for this weight loss.
But since the study had no control group that changed nothing at all in their diet, it’s impossible to say for sure. After 12 weeks, there were no significant changes seen in participants’ triglycerides, glucose tolerance, insulin levels, or insulin sensitivity.
Since the only dietary change that all three groups had in common was consuming potatoes regularly, it’s plausible that the potatoes were responsible for this weight loss. But since the study had no control group that changed nothing at all in their diet, it’s impossible to say for sure. After 12 weeks, there were no significant changes seen in participants’ triglycerides, glucose tolerance, insulin levels, or insulin sensitivity.
One reason why it’s difficult to come to any conclusions on the role potatoes play in glucose control is that they may have very different effects depending on how they’re prepared. It has also been shown that different varieties of potatoes have different glycemic indexes. They are also affected by how they’re cooked.
The numbers range from 58 (low-medium glycemic index) for a boiled Nicola potato to 111 (extremely high) for a baked Russet Burbank potato. This range in numbers doesn’t even take into account the reality that potatoes are often combined in dishes with other ingredients, which can have an enormous effect on their glycemic impact.
Adding ingredients containing fat, protein, and fibre can greatly lower the glycemic index of a food, leading to a more moderate and consistent release of glucose into the bloodstream.
You need to know which potato
Potato variety, boiled GI
- Carisma 55
- Desiree 101
- Nicola 58
- Sebago 87
- Pontiac 89
So are potatoes dangerous?
A prospective study followed 84,555 women in the famed Nurses’ Health Study. At the start, the women, aged 34–59 years, had no history of chronic disease, and completed a validated food frequency questionnaire.
These women were then followed for 20 years with repeated assessments of their diet. The study concluded, “Our findings suggest a modest positive association between the consumption of potatoes and the risk of type 2 diabetes in women. This association was more pronounced when potatoes were substituted for whole grains.”
So, let’s take a closer look at the study and see how accurate these claims are, and where the truth really lies. Specifically, we will look at five key points.
In the study, participants were asked how often, on average, in the previous year, they had consumed potatoes. The options they were given to choose from were either:
a) One baked or one cup mashed potato
b) 4 ounces of french-fried potatoes
These were the only two choices the subjects could pick from. So, while these may represent how potatoes are often consumed in America, they do not account for any differences in how the potatoes were prepared and served.
Mashed potatoes were also counted in with baked potatoes, which are two completely different forms of preparing potatoes.
In most western countries, whether it is at home or in restaurants, most all mashed potatoes are made with milk and butter and/or margarine.
In addition, most all baked potatoes are served with butter, sour cream and/or cheese.
The following analysis represents these important differences.
They are of a serving of mashed potatoes, a loaded baked potato and a plain baked potato as served in a popular national restaurant chain.
They are typical for how mashed potatoes and baked potatoes are often served and consumed in American.
In addition, we have included the analysis of a plain medium baked potato for comparison.
Are all potatoes equal? Or “When is a potato not a potato?”
They are typical for how mashed potatoes and baked potatoes are often served and consumed in American. In addition, we have included the analysis of a plain medium baked potato for comparison.
Mashed Potatoes (Restaurant):
367 calories- 24 grams of fat
- 59% calories from fat
- 11.4 grams of saturated fat
- 28% calories from saturated fat
- 9 milligrams of cholesterol
Loaded Baked Potato (Restaurant):
505 calories- 22 grams of fat
- 39% calories from fat
- 10 grams of saturated fat
- 18% calories from saturated fat
- 30 milligrams of cholesterol
Regular Baked Potato (Restaurant):
329 calories- 4.5 grams of fat
- 12% calories from fat
- 0.4 grams of saturated fat
- 1% calories from saturated fat
- 22 milligrams of cholesterol
Baked Potato (Home):
60 calories- 0.2 grams of fat
- 1% calories from fat
- 0.1 grams of saturated fat
- 0.05% calories from saturated fat
- 0 milligrams of cholesterol
Where are the calories coming from?
The mashed potato gets more than ½ its calories, plus nearly all its fat (about 24 grams) and cholesterol (9 mg) from “non-potato” ingredients.
The loaded potato gets more than 2/3 of its calories, plus nearly all of its fat (about 22 grams) from “non-potato” ingredients.
Even the regular baked potato from the restaurant gets ½ its calories, plus nearly all its fat (about 4 grams) and cholesterol from “non-potato” ingredients (most likely oil and/or butter used on the outside and/or as a regular topping).
So, compared to an at-home, plain baked potato:
As we can see, the potato is contributing only a small percentage to what is most likely being counted as “potatoes”. The association applied to potatoes may be more accurately applied to how potatoes are prepared and consumed and the toppings they are served with, more so than just the potato itself.
The study admitted that “cooking methods” were not assessed but because the study was done in America it is safe to assume that they were prepared in ways that Americans consume potatoes.
Other factors:
In addition, other studies on the Nurses database show the majority of their diets are not low fat, low saturated fat, low cholesterol or high fibre which confirms that they are not choosing or consuming the healthier versions.
The big question:
In this study, was the potato the problem itself, or was the potato acting as a marker and pointing to something else that was associated with potato consumption?
“White potatoes and French fries are large components of a “Western 
pattern” diet. This dietary pattern is characterised by a high consumption of red meat, refined grains, processed meat, high-fat dairy products, desserts, high-sugar drinks, and eggs, as well as French fries and potatoes.
Quoting the researchers:
A Western pattern diet previously predicted a risk of type 2 diabetes. Thus, we cannot completely separate the effects of potatoes and French fries from the effects of the overall Western dietary pattern.”
Additional Information:
The researchers found that the study subjects who ate more potatoes also ate more red meat, more refined grains and consumed more total calories (in fact more than 500 additional calories per day). In addition, potato intake was also associated with higher intakes of saturated and trans fat, and less physical activity.
Total US Potato Consumption per person per year:
- 1970: 122 pounds
- 1996: 145 pounds
- 2008: 117 pounds
US Prevalence of Diabetes (% of population):
- 1970: 2.00%
- 1996: 2.89%
- 2008: 6.29%
Consumption Trends:
We can see that consumption of potatoes is trending down since 1996 yet the prevalence of diabetes is rising faster than ever. In fact from 1996 to 2008, potato consumption fell 19% while the percentage of people with diabetes increased by more than 200%. Most importantly, the prevalence of diabetes really began to increase in 1996-1998, which is the same time that potato consumption began to fall sharply.
Conclusions:
During the 20 years that the subjects in the Nurses study were followed, we saw a dramatic shift in the dietary and lifestyle pattern of Americans. Not only has potato consumption and the type of potato changed dramatically, but there have been significant changes in other areas.
Americans have sharply increased their consumption of refined sugars/sweeteners, refined grains/carbohydrates, added oils/fats, hydrogenated fats/trans fat, cheese, calories, etc. Meanwhile the percentage of Americans who are overweight, and even obese, increased, while the percentage who are active fell dramatically.
These factors, and not the potato itself, are what is responsible for the dramatic increase in the incidence of diabetes. Sure, mashed potatoes, loaded baked potatoes and french-fries, which are calorie dense, high in fat, saturated fat, cholesterol, sugar, and salt increase your risk for disease and should be avoided.
However, there is no credible evidence that potatoes, when consumed close to their natural state and cooked conservatively by baking, boiling, and/or steaming, will cause diabetes or are associated with an increased risk. In fact, potatoes have long been part of healthy diets around the world.
It now becomes complicated
We know that different varieties have different GI’s.- We know that preparation makes a huge difference.
- Potatoes are used in more processed foods than ever.
Potatoes are used for a variety of purposes, and not only as a vegetable for cooking at home. In fact, it is likely that less than 50 percent of potatoes grown worldwide are consumed fresh. The rest are processed into potato food products and food ingredients fed to cattle, pigs, and chickens; processed into starch for industry and re-used as seed tubers for growing the next season’s potato crop.
Global Potato Use:
Potatoes are used for a variety of purposes, and not only as a vegetable for cooking at home. In fact, it is likely that less than 50 percent of potatoes grown worldwide are consumed fresh. The rest are processed into potato food products and food ingredients fed to cattle, pigs, and chickens; processed into starch for industry and re-used as seed tubers for growing the next season’s potato crop.
Global consumption of potato as food is shifting from fresh potatoes to added-value, processed food products. One of the main items in that category is frozen potatoes, which includes most of the french fries (“chips” in the UK & Australia) served in restaurants and fast-food chains worldwide.
The world’s appetite for factory-made french fries has been put at more than 7 million tons a year. Another processed product, the potato crisp (“chips” in the US) is the long-standing king of snack foods in many developed countries.
Dehydrated potato flakes are used in retail mashed potato products, as ingredients in snacks, and even as food aid. Potato flour, another dehydrated product, is used by the food industry to bind meat mixtures and thicken gravies and soups.
A fine, tasteless powder with “excellent mouth-feel,” potato starch provides higher viscosity than wheat and maize starches, and delivers a more tasty product. It is used as a thickener for sauces and stews, and as a binding agent in cake mixes, dough, biscuits, and ice-cream.
In eastern Europe and Scandinavia, crushed potatoes are heated to convert their starch to fermentable sugars that are used in the distillation of alcoholic beverages, such as vodka and akvavit.
So what now?
- If you do have a potato make sure you make it, if you don’t, treat it just like any other processed food.
- Go with the safe option sweet potato. The food industry does abuse sweet potato.
A note on Sweet Potatoes:
The way you prepare sweet potatoes makes a difference in their GI. The GI of a 150-g sweet potato, boiled with its skin for 30 minutes, is 46.
That number rises to 94 if the same sweet potato is baked for 45 minutes. These dramatic differences come from the way the starches in sweet potatoes gelatinise during cooking.
Foods that turn viscous, or jelly-like, in your digestive tract have a lower GI because the gelatinous substance slows the release of the nutrients in the food. Baking your sweet potatoes instead of boiling them changes the quality of their starches and transforms this root vegetable from a moderate-GI food to a high GI-food.
With sweet potato the key is not to overcook or over-bake. As a matter of fact cook or bake them for as short as possible.