Walter Willett, the Chair of the Department of Nutrition at Harvard School of Public Health says “Potatoes and french fries don’t count” as a vegetable. I’ll give him the fries but he’s wrong about dismissing the potato.
If you’re Michele Bachmann and you’re running for President of the United States you don’t get to run your mouth about how a vaccine can cause mental retardation and is VERY dangerous without having a factual basis to do so. If you do then you are practicing irresponsible alarmism.
If you’re Dr. Mehmet Oz and you have a popular daytime television show then you don’t get to run your mouth about the dangers of arsenic in apple juice based on results from one lab measuring total arsenic rather than organic vs. inorganic arsenic. If you do then you are practicing irresponsible alarmism.
And if you’re Dr. Walter Willet M.D. Ph.D., the Fredrick John Stare Professor of Epidemiology and Nutrition, and Chair of the Department of Nutrition at Harvard School of Public Health (almost ran out of characters just saying what he is) then I don’t think it makes good sense to “run your mouth” by redoing the Department of Agriculture’s “My Plate” with a “Healthy Eating Plate” that says “The more veggies–and the greater the variety–the better. Potatoes and french fries don’t count.”
I can agree on the french fries. But potatoes? A categorical dismissal of potatoes as a healthy vegetable from the Chair of the Department of Nutrition at Harvard School of Public Health? What possible rationale would Willett have for such a recommendation?
A quote from the Harvard School of Public Health website goes “The Healthy Eating Plate encourages an abundant variety of vegetables, since Americans are particularly deficient in their vegetable consumption—except for potatoes and French fries. Potatoes are chock full of rapidly digested starch, and they have the same effect on blood sugar as refined grains and sweets, so limited consumption is recommended.”
It’s true that potatoes are a starchy vegetable. What’s misleading and, in my opinion, what makes the categorical dismissal of potatoes as a vegetable that doesn’t count wrong is this part “…and they have the same effect on blood sugar as refined grains and sweets…”
It’s well known among we supposedly in the know within nutrition circles that the Harvard School of Public Health is referring to the glycemic index (GI).
“The glycemic index (GI) is a ranking of carbohydrates on a scale from 0 to 100 according to the extent to which they raise blood sugar levels after eating. Foods with a high GI are those which are rapidly digested and absorbed and result in marked fluctuations in blood sugar levels.” http://www.glycemicindex.com/
The glycemic index, however, is not the best measure of a food’s relative blood-sugar-spiking ability. The glycemic index, first of all, only measures what happens when we consume that food by itself prepared the way the index says it was prepared when it was measured. Huh? Well take a look at this image and you’ll see that the GI is different for not only different varieties of potatoes but also depending on how the potato is prepared (i.e., boiled, baked, microwaved, roasted in soybean oil etc.).
Beyond the wide variation we see with the GI depending on how a potato is prepared and what kind of potato (i.e., white, red, sweet etc.) is eaten I just said that GI is not the best measure of relative blood-sugar-spiking ability for foods. So what is the best measure? It’s called glycemic load (GL) and you see the GL listed above for each food in the far right column.
What is the glycemic load? “The glycemic load (GL) is a ranking system for carbohydrate content in food portions based on their glycemic index (GI) and the portion size. Glycemic load or GL combines both the quality and quantity of carbohydrate in one ‘number’. It’s the best way to predict blood glucose values of different types and amounts of food. The formula is: GL = (GI x the amount of available carbohydrate) divided by 100.” http://en.wikipedia.org/wiki/Glycemic_load
Even when you consider GL there is a reality to how we eat that isn’t taken into consideration. We don’t typically eat foods by themselves. We typically eat foods in combination. So what happens to the glycemic index and glycemic load when we eat a potato (or any other food for that matter) with a healthy serving of fish or poultry? I can tell you what happens. The glycemic index and glycemic load changes. That’s what happens. They may increase or they may decrease. It depends on the foods eaten and the effect of their combination.
Using a bully pulpit to claim that potatoes shouldn’t count as a vegetable because they have a high glycemic index is yet another version of “irresponsible alarmism.”
I could almost shut up about it too if there was any uniformity to the overall message. If foods with a potentially-high glycemic index should not be counted within their respective food-group category then I want brown rice eliminated from what counts as a whole grain.
Look at the variety of GI and GL values for brown rice (an acceptable whole grain) and compare those values to the potato values in the image above it. I’m not saying one is better or worse than another. What I’m saying is if potatoes don’t count as a vegetable because of their blood-sugar-raising potential (i.e., glycemic index) then brown rice can’t count as a whole grain for the same reason.
Willett and the Harvard School of Public Health aren’t the only influential bodies saying potatoes don’t count. The National Health Service (NHS) based in the United Kingdom has this to say about potatoes and whether they count toward their “5-a-day” campaign.
“While potatoes don’t count towards your 5 a Day, they do play an important role in your diet. They are a great choice of starchy food, particularly if they are not cooked in too much salt or fat. They are a good source of energy, fibre, B vitamins and potassium. Although potaoes don’t contain much vitamin C compared to other vegetables, in Britain we get a lot of our daily vitamin C from them because we eat so many.” http://www.nhs.uk/Livewell/5ADAY/Pages/Whatcounts.aspx
The NHS doesn’t like potatoes as a vegetable because they are a starchy vegetable. And here we go again. So even though they say potatoes play an important role in your diet they should not count as a vegetable. Hey NHS…make up your mind but be consistent for God’s sake!
The NHS gives kudos to the potato for energy, fibre, B vitamins and potassium but says the potato doesn’t contain much vitamin C. Is this true? Let’s take a quick look and see.
The Food and Agriculture Organization of the United Nations (FAO) has this to say about sources of vitamin C (ascorbate). “Ascorbate is found in many fruits and vegetables. Citrus fruits and juices are particularly rich sources of vitamin C but other fruits including cantaloupe, honeydew melon, cherries, kiwi fruits, mangoes, papaya, strawberries, tangelo, watermelon, and tomatoes also contain variable amounts of vitamin C. Vegetables such as cabbage, broccoli, Brussels sprouts, bean sprouts, cauliflower, kale, mustard greens, red and green peppers, peas, tomatoes, and potatoes may be more important sources of vitamin C than fruits. This is particularly true because the vegetable supply often extends for longer periods during the year than does the fruit supply.” http://www.fao.org/docrep/004/Y2809E/y2809e0c.htm
According to a document prepared by Colorado State University about potatoes “Potatoes are an important source of several nutrients, especially Vitamin C. A single medium sized potato of 150 g provides nearly half the daily adult requirement (100 mg) of Vitamin C. The potato is a good source of iron and its high Vitamin C content promotes iron absorption. It’s also a good source of Vitamin B6, niacin, and potassium.” http://farmtotable.colostate.edu/files/potatofactsheet1.pdf
A recent headline over at Science Daily said this “Potatoes Reduce Blood Pressure in People With Obesity and High Blood Pressure.” The Science Daily writers said “The potato’s stereotype as a fattening food for health-conscious folks to avoid is getting another revision as scientists report that just a couple servings of spuds a day reduces blood pressure almost as much as oatmeal without causing weight gain.”
Regarding the issue of nutrient density the article states “…when prepared without frying and served without butter, margarine or sour cream, one potato has only 110 calories and dozens of healthful phytochemicals and vitamins.”
With respect to why potatoes might have exerted their blood-pressure lowering effect the articles states “Other phytochemicals in potatoes occur in amounts that rival broccoli, spinach and Brussels sprouts, and also may be involved.”
So what are my take-home points with all of this?
- If whole-grain rice, breads, cereals and pastas are okay in the grain category then potatoes should be okay in the vegetable category. Authoritative nutrition heads and those with a bully pulpit that can reach hundreds of millions of people need to put out a consistent message. Excluding potatoes categorically but retaining rice, breads, cereals and pastas is not consistent.
- Potatoes shouldn’t be lumped into the same cautionary sentence as french fries. If you want to say “French fries don’t count.” I’m perfectly okay with that. It makes sense.
- Instead of saying “Potatoes don’t count” why not use language consistent within the same Healthy Eating Plate that says “Limit refined grains like white rice and white bread.” Perhaps the language could read “Limit potatoes …” This would be more consistent overall than saying they don’t count.
- As a weight-loss educator and Wellness Coach I am not a big fan of the potato if it’s overeaten and prepared with oils, butters and creams.
- People of power and authority and with massive influence over millions of people have a great responsibility to get it right. I believe Willett and Harvard got this wrong.
Feel free to sound off and let me know what you think about any of this. Agree? Disagree? I welcome your thoughts and feedback.