Maybe you, too, saw this article that turned up recently in a lot of Facebook feeds –
– which aims to clear the “bad rap” potatoes have gotten via an industry-funded study.
For the study, Gibson analyzed the food intake records of 876 children and 948 adults who were participating in the UK’s National Diet and Nutrition Survey program. She found that because they are so widely consumed, potatoes contribute more significant amounts of folate, iron, magnesium, and potassium to most people’s diets than traditional “superfoods” like broccoli. Most children in the study also got more selenium from potatoes than from all nuts and seeds combined.
A study published in January of this year also found that potatoes lower blood pressure in people with hypertension and obesity without increasing weight.
Like the author of this short post, we’ve no reason to doubt the findings, despite the appearance of conflict-of-interest. But do they actually support the notion that potatoes are a “superfood”?
In a word, no.
All natural foods we eat provide some nutrients, potatoes included. Which nutrients and how much we get depend on the specific food and how it’s prepared. Boil peas, for instance, and you cook out much of their antioxidant content; boil carrots, and their antioxidant levels actually increase.
More, to state the obvious, we don’t get any nutrients at all from foods we don’t eat.
And that gets to what the paper actually looked at: not the nutritional value of potatoes versus other vegetables but nutritional intake from vegetables actually eaten. According to Sigrid Gibson, the “independent nutritionist and data analyst” who worked on the report:
We looked in detail at all the food intake records of 876 children and 948 adults. Some superfoods are not very popular and the nutritional value is obviously zero if they are not eaten.
Broccoli is a good source of folate [Vitamin B9] but the data shows potatoes provide more of this vitamin to the diet overall and also the important minerals iron and magnesium some children lack.
Similarly we think of bananas as being a good source of potassium, and they are, but potatoes make a more significant contribution in the diet.
They don’t do this because they’re nutritionally superior. They do so because people eat more of them than any other vegetable. To put it another, if slightly cruder way, if you were to eat lots of Hostess Cherry Pies – each of which contains 10% of the RDA for iron – and little spinach, you could logically say that the pies were a more important source of iron in your diet. But this wouldn’t make the pies healthier or more inherently nutritious.
Then there’s the matter of how we eat potatoes – often fried or baked and dolled up with fats (e.g., butter, sour cream, cheese). Considering that combined fat and carbohydrate increase body fat most efficiently, this is a major nutritional offset. Additionally, most of us tend to eat a limited range of potato varieties, seldom the really colorful ones. Yet the supplemental study cited in reports on the potato research singles out pigmented potatoes, which “contain high concentrations of antioxidants, including phenolic acids, anthocyanins, and carotenoids.” (And just how many varieties of potato are there? Here’s a sample.)
Potatoes aren’t evil. But it takes more than that to make something a “superfood.” They’re one option – a good source of potassium, magnesium, vitamin C and folic acid, but not the only source. And they lack many nutrients – and phytochemicals and enzymes – just like any other food. No single food is nutritionally perfect. Hence, the usual advice to eat a varied and balanced diet.