Digging for real answers about potatoes

Potatoes don’t get a lot of respect from nutritional scientists. Even the government can’t decide (as if that is any criterion) about the health benefits of potatoes. They go back and forth, taking them out and putting them back again, in school lunch programs and the Women, Infants, Children (WIC) program.

I find — as is often the case with nutrition — the answers are often more complicated than they appear.

For example, as an anthropologist, I tend to look first back at history. Incas first cultivated potatoes in the Andes before the 1400s. Then the Irish famously grew them during the 1800s in times of famine.

Throughout this expanse of time, the potato served as a “staple” food, providing basic nutrition to large numbers of people. Indeed, it was a food for the masses as potatoes produce about 15 million calories per acre, compared to a typical green vegetable, which produces only two million calories per acre.

Second, I tend to look at categories of food. We typically include plants in the category of vegetables whether they are salad greens, green/leafy vegetables, cruciferous vegetables, legumes (beans, garbanzos, peas), or roots and tubers (like carrots, radishes, rutabagas, onions, turnips, and potatoes).

Third, I look at the metabolic and nutritional properties. The legumes have more protein and calories. Carrots have a high glycemic index. And potatoes have a lot of starch.

Molecules of chains of glucose, which is a simple sugar, make up starches. And our cells use glucose from the blood (blood sugar) as fuel to burn for energy and hydration.

When you eat simple sugars like glucose, they go straight into the blood, spiking blood sugar and causing the pancreas to release insulin to drive sugar into the tissues cells, where it can be burned for fuel and water. When we burn those calories rapidly, blood sugar falls again, and we can experience hunger all over again.

Experts come down against potatoes

I also tend to look at what my respected colleagues think. My old friend and colleague Dr. Walter Willett has come down against potatoes. Walt says they don’t behave metabolically like most other vegetables.

And studies seem to back him up. Research links potato consumption with Type II diabetes, high blood pressure and weight gain — which are all risk factors for heart disease.

But here again, I often find answers are more complicated than they first appear.

In these diet studies, researchers ask people about what they eat — specifically whether they eat potatoes. But they need to know more…

They need to know whether the potato is boiled, baked, mashed, roasted, scalloped, or fried. They also need to know if the subject ate the potato prepared with butter, bacon, or cheese, mayonnaise, or some type of low-quality oil. In addition, did the subjects eat the potato with foods like cheeseburgers and hot dogs? Or did they put ketchup (made with a lot of sugar!) on them?

Indeed, the potato is a very versatile food. It reminds me of the scene in Forrest Gump where his Vietnam soldier friend describes all the ways he can prepare shrimp…leading to the formation of the (original) Bubba Gump Shrimp Company.

Poor quality studies continue confusion

As I have said before, this lack of information exemplifies the poor quality of the national data on which all these nutrition and health studies are based.

Better controlled studies have tracked hunger and satiety (feeling full or satisfied after eating) associated with different foods. They looked at 38 different foods and tracked how hungry participants became after eating them.

White bread scored the worst of all with a baseline score of 100. Potatoes had the highest score when it came to feeling full after eating, with a score of 323. Fish came in second with 223, and oatmeal came in third at 209. (As a side note, it’s interesting to see fish come in second on this list. We don’t normally think of fish or seafood as particularly filling. And we tend not to eat large portions — between the cost and inedible parts. But I remember never feeling as full in my life as after eating a meal of large sea bass caught fresh off the coast of New England during the season.)

So, potatoes clearly don’t act like the quick sugar fix when it comes to satiety and hunger — just the opposite.

Potatoes also beat out other starches, carbs and grains by having more vitamins, phosphorus, potassium, and fiber.

Of course, it’s a mistake to rely on potatoes to the exclusion of other vegetables. Around the world, over thousands of years, evidence consistently shows the more diverse your diet, the healthier you are. Mix it up. Eat a wide variety of foods. And avoid diets that focus on eating only one or a few kinds of foods.

The more varied your diet, the more likely you will get all the different nutrients you need. You’re also more likely to avoid excess contaminants present in certain foods.

So, if you dig potatoes, you can keep eating, but not to the exclusion of green vegetables, in a balanced diet. Mix potatoes up with other vegetables, eating them only in moderation. And practice dietary diversity with a full range of different foods.

 


CLOSE
CLOSE