The Huffington Post recently ran an article titled “5 Reasons Potatoes Don’t Deserve Their Bad Reputation“. Although I agree with the message the author is trying to convey, the article doesn’t exactly come across as very convincing. I know many of these newspaper articles need to be kept short, but simply claiming that a specific food is healthy because it’s a good source of fiber and a couple of vitamins and minerals doesn’t cut it. So, I decided to write my own piece on potatoes.
The increased popularity of Paleo and low-carb diets has many upsides, chief of which is that more people buy “real”, whole food. However, the trend towards eating diets higher in fat and protein has also led to the unfounded vilification of certain foods simply because they are fairly high in carbohydrates.
While a large part of the ancestral health community has embraced starch as a beneficial nutrient (in moderation), there are still many (both within the Paleo movement and in our society at large) who believe that “all” carbohydrate-rich foods shold be avoided. Sadly, potatoes and other tubers are often included in the same category as pasta, bread, and breakfast cereals.
I like to use the nutritional pattern of our Paleolithic ancestors as a guide for determining how to eat in the 21st century. In my opinion, there’s just no getting around the fact (yes, I consider it a fact) that the food groups we’ve been eating from throughout most of our evolutionary history should form the foundation of a healthy diet.
However, eating exactly like our ancient ancestors is clearly not possible, as there’s a big difference between the wild plants and animals hunter-gatherers ate and the foods we find at the typical grocery store today. Not just in terms of food quality and nutrient composition, but also in terms of the actual species of plants and animals we have access to.
What we want is to use the paleo diet as a starting point for designing a healthy diet in the 21st century and base our diet on modern foods that “mimic” the food groups of our pre-agricultural, hunter-gatherer ancestors. Potatoes certainly fit the bill…
There are many different species of potatoes out there, and they often have markedly different characteristics. However, most commercial potato varieties tend to have a relatively similar nutrient composition. What most people refer to as white potatoes (and the like) will be the main emphasis of this article.
1. Starchy tubers have been an important part of the human diet for a long time
While sweet potatoes are generally included under the Paleo umbrella, strict paleo dieters avoid white potatoes. However, the fact is that humans have been eating starchy tubers – with a fairly similar nutrient composition to that of white potatoes – for hundreds of thousands of years.
Evidence suggests that starchy root vegetables were an important staple food for many Paleolithic tribes, and for contemporary hunter-gatherers like the Hadza, underground storage organs are an essential part of the diet (1, 2).
While some low-carb proponents will claim that starch should be avoided to the extent possible, this notion has little support in the literature. Hunter-gatherer diets generally contain less carbohydrate (22-40%) than the Western diet (45-60%), but there are also many examples of non-westernized populations that have maintained excellent health on starch-heavy diets.
Three well-known examples are the Kitavans on the Island of Kitava, the New Guinea highland tribe at Tukisenta (which has one of the highest documented carbohydrate intakes ever), and the Okinawans in Japan (3, 4, 5). The traditional diets of these populations are rich in root vegetables and contain a respective carbohydrate content of 69%, 94,5%, and 85% (of daily total calories). Also, as Stephan Guyenet points out in his excellent series of posts on potatoes and human health, cultures such as the Quechua, the Aymara, and the Irish have maintained good health on potato-based diets (6).
However, I want to emphasise that this doesn’t mean that a carb-heavy diet is necessarily optimal; it simply shows that starch isn’t the “evil” nutrient some people make it out to be. Also, the fact that starch has been an important component of the human diet throughout our evolution doesn’t mean that everyone should eat a starch-heavy diet. A large subset of the population in the world today are insulin resistant, and for these folks, consuming a high-carbohydrate diet is definitely not the optimal way to go.
Bottom line: Starchy roots and tubers are definitely Paleo!
2. Potatoes have a very high satiety index score
One thing that is often overlooked in the discussion of optimal nutrition is the satiety index. Basically, the satiety index score reflects how full you feel after eating a specific food.
In 1995, researchers investigated the satiety index of common foods by feeding subjects 240 kcal servings of 38 foods separated into six food categories (fruits, bakery products, snack foods, carbohydrate-rich foods, protein-rich foods, breakfast cereals) (7). What they found was that isoenergetic servings of different foods differ greatly in their satiating capacities.
The results from this study are in line with other reports which show that foods with a high protein, water, and/or fiber content are more satiating than foods with a high calorie density. Also, somewhat surprisingly, the study shows that the highest SI score was produced by boiled potatoes, a score that was seven-fold higher than the lowest SI score of the croissant.
Bottom line: Potatoes fill you up.
3. Potatoes are a good source of resistant starch (especially cold ones)
If you’ve been following what goes on in the nutritional community lately, you’ve undoubtedly encountered the term resistant starch. Basically, just like the name implies, resistant starch is starch that’s resistant.
While most of the starch we get through our diet is absorbed in the small intestine, resistant starch can’t be broken down by the human host, and it instead passes into the colon where it becomes energy for our gut bacteria. Why is this important? Well, because these gut microbes repay us by strengthening our immune system, producing short-chain fatty acids, and lowering the pH in the colon.
As you know if you’ve been reading my articles on the human microbiome, the gut microbiome plays an essential role in human health, and many researchers now refer to the ecosystem in our gut as the forgotten organ, because we’ve essentially forgotten – or more correctly, not been fully aware of – this second genome in our body. However, this is now changing, at least in the ancestral health community, where the critters that live in and on our bodies are given massive attention.
Estimates from hunter-gatherer tribes show that the average intake of fermentable substrates – food ingredients that are fermented by gut bacteria – is many times higher than the recommended intake of dietary fiber (~35 g/day) in industrialized nations.
So, do you want to make a change and be a more gracious host? Eating more potatoes and other starchy tubers is definitely high up there on the list of things you can do to feed your guests. Cold potatoes that have been refrigerated for 24+ hours are especially great, as they contain a retrograded form of resistant starch.
Well-known benefits of resistant starch include better satiety, improved digestion, and increased insulin sensitivity.
Bottom line: The resistant starch and fiber found in potatoes help promote a healthy gut microbiota.
4. Potatoes don’t contain as much carbohydrate as people have been led to believe
Is carbohydrate inherently fattening? No. That’s not to say that low-carb diets aren’t effective for a variety of purposes (I eat a “low-carb” diet myself), but it’s clear that if we look at the data as a whole, the insulin hypothesis of obesity doesn’t hold up.
However, it’s important to note that the average carbohydrate intake in contemporary affluent nations is absurdly high, and there’s no doubt that one of the primary reasons the Paleo Diet is so effective is because it removes some of the most dense sources of carbohydrate – such as cereal grains – from the diet.
But what about potatoes? They are often included in the list of high-carbohydrate foods and blacklisted from most low-carb diets. However, the fact is that potatoes aren’t especially high in carbs, at least if we compare them to cereal grains. While the carbohydrate content of wheat (hard, red winter) is 71 g/100 g, raw potatoes with skin only contain 17 g/100g.
Bottom line: Potatoes are higher in carbohydrate than most fruits and vegetables, but low-carb compared to cereal grains.
5. Glycemic index isn’t necessarily a good indicator of the healthfulness of a food
Glycemic index (GI) is often touted as an important measure of how healthy a food is, and the general recommendation was/is to choose foods with a low GI. While this general advice is certainly helpful in the sense that it gets all the pastries, refined grains, and sugar-laden drinks out of the diet and brings in unprocessed carb sources, I don’t believe in using glycemic index as a primary tool for determining which types of foods to eat.
First of all, although a food has a relatively low GI, that doesn’t mean that it’s necessarily healthy. Whole grain products often have a fairly low GI, but as my regular blog readers know, basing your diet on cereal grains isn’t a good idea.
Second, most foods are not eaten in isolation. Boiled white potatoes have a high glycemic index, no doubt about it. Eating a massive serving of cooked white potatoes will promote a surge in insulin. But how often do you really sit down and stuff yourself with white potatoes? Probably not very often. Most of the time, potatoes are eaten alongside other foods such as meat, fish, and vegetables, and the glycemic load of the entire meal is therefore more important than looking at each food in isolation.
Third, people respond differently to a carbohydrate-rich meal. While metabolically healthy people (think the Kitavan islanders, endurance athletes, and just normal folks with no weight issues) will do just fine with a lot of carbohydrate in their diet, people with impaired glucose tolerance or insulin resistance tend not to do well on a starch-heavy diet.
Fourth, the glycemic load is generally a better measure than the GI, as it accounts for how much carbohydrate is in the food and how much each gram of carbohydrate in the food raises blood glucose levels. White potatoes actually have a GL that is fairly similar to sweet potatoes (11).
As S. Guyenet concluded in his mini-review on potatoes and human health: “Overall, these studies do not support the idea that lowering the glycemic index of carbohydrate foods is useful for weight loss, insulin or glucose control, or anything else besides complicating your life. I’ll keep my finger on the pulse of this research as it expands, but for the time being I don’t see the glycemic index per se as a significant way to combat fat gain or metabolic disease” (9).
Despite these limitations, I want to highlight that the GI of food does hold some importance. Many people (myself included) feel “drowsy” and fatigued after eating a meal that contains a lot of high GI carbohydrates, and I wouldn’t recommend anyone to eat a large meal that is exclusively composed of boiled potatoes. However, for metabolically healthy people, I see no problem with eating a steak with 1 or 2 potatoes on the side.
Preparation method has a significant impact on GI, and cold potatoes (refrigerated for at least 24-36 hours) are superior also here, as they have a lower GI.
Bottom line: For metabolically healthy people, the high GI of potatoes is usually not a problem.
6. Potato antinutrients are probably not problematic in the concentrations most people get through their diet
Pretty much all plants produce toxic substances designed to protect them from marauding creatures. Some plant foods, such as grains, white potatoes, and legumes, are especially rich in antinutrients, and the high concentration of these secondary metabolites is one of the main reasons these foods are excluded from a strict Paleo Diet.
If you’ve been reading up on the potential adverse effects of potato consumption, you’ve undoubtedly encountered the terms alpha-solanine and alpha-chaconine. These two glycoalkaloid saponins are toxic at high doses. However, there are scant good data showing adverse effects of normal potato feeding in humans – meaning that most studies have used green or blemished potatoes, isolated potato skins, or isolated glycoalkaloids (9, 10).
The amount of glycoalkaloids you ingest from eating a couple of potatoes for dinner is probably unproblematic. Also, as peeling the potatoes reduces the glycoalkoid concentration significantly, most people remove most of these toxic substances before consumption.
It’s also important to note that common commercial potato varieties such as russet and white potatoes are low in glycoalkaloids (9).
Bottom line: Little is known about the concentrations of potato antinutrients required to elicit adverse health effects. However, it’s unlikely that potato antinutrients pose a risk, as long as you don’t eat potatoes that are sprouted or blemished and make sure to store them in a cool place. However, people with gut dysbiosis and leaky gut are probably more susceptible to the toxins found in potatoes.
7. Potatoes have a low-moderate palatability/reward value
If you’ve ever eaten a dinner that’s primarily composed of potatoes, then you know that these starchy root tubers are very hard to eat “a lot of”. First of all, as mentioned earlier, potatoes have a very high satiety index score: they fill you up. Second, potatoes aren’t that palatable. You can definitely increase the palatability and reward value of potatoes by covering them in melted butter and spices, but even then it’s hard to “overindulge” on potatoes. Compared to the hyper-palatable and hyper-rewarding processed food you find at the Deli market, potatoes have a palatability and reward value that the human body is well adapted to handle.
Bottom line: It’s difficult to overeat on potatoes.
8. Potatoes are a complete source of protein
While most plant foods lack some of the essential amino acids humans need, potatoes are a complete source of protein. This high protein quality can help explain why several cultures around the world have maintained excellent health when eating potatoes as a staple food, and it can also explain why studies show that humans are able to maintain good health even on a strict potato diet (6).
The potato diet was a very popular hack in the paleo community a while back and basically involved eating nothing but potatoes (or at least mostly potatoes). Many people reported significant reductions in body fat and improved metabolic health on this potato-only diet, which likely stems from a combination of the following factors:
- Potatoes have a potent effect on satiety (point 2)
- Potatoes contain food for our gut microbes (point 3)
- Potatoes have a low-moderate palatability/reward (point 7)
- Potatoes are a complete source of protein (point 8)
While I clearly don’t recommend subsiding exclusively on potatoes, there’s no doubt that potatoes are one of the best foods to choose if you are only allowed to eat one type of food for a long period of time.
Bottom line: Potatoes contain a relatively low percentage of protein, but they do contain all of the essential amino acids.
9. Potatoes are a decent source of vitamins, minerals, and phytochemicals
Bottom line: While not as nutrient-dense (on a calorie by calorie basis) as fruits and non-starchy vegetables, potatoes are a decent source of micronutrients, especially vitamin C, vitamin B6, and potassium. It’s often believed that sweet potatoes have a much better micronutrient profile than white potatoes, but the fact is that they contain fairly similar concentrations of the different vitamins and minerals (with the exception of beta-carotene) (11).
10. Potatoes are a good carb source for fueling your workouts
Since you’re reading a blog that focuses on health, medicine, and fitness, chances are pretty high that you work out on a regular basis, whether it’s weight lifting, running, sprinting, or any other type of physical activity. One of the things I’ve learned from my own training career and my years as a personal trainer is that it can be difficult to achieve peak athletic performance on a very low carbohydrate diet, particularly if you do a lot of anerobic training. I’ve read many of the papers on ketogenic diets and athletic performance, and I’m open to the idea that you can become a keto-adapted athlete as long as you put in the required amount of time and effort. However, this is usually not a viable option for the average fitness enthusiast.
While the typical western diet contains far too much carbohydrate, the opposite can sometimes be true for a contemporary Paleo Diet. Basically, when you ditch the grains and remove highly processed food, you’ve eliminated the major sources of starch in your diet. Many paleo dieters replace these dense sources of carbohydrate with fats such as coconut oil, avocados, and eggs and sometimes end up with a very low carbohydrate intake.
While I’m a big proponent of a reduced carbohydrate intake (compared to “modern” standards), I’ve found that eating some starchy foods on a regular basis is often a good idea, particularly for those who do a lot of anaerobic training. Potatoes are a great choice in that regard.
Bottom line: While some athletes do well on a low-carbohydrate diet, a lot of people (particularly those who perform a lot of anaerobic training) perform better if they include some starchy foods in their diet.
Potatoes aren’t for everyone, and I don’t recommend eating massive amounts of boiled root vegetables even if you are metabolically healthy. However, including a couple of potatoes with lunch and/or dinner is no problem for the majority of people. To avoid getting bored of potatoes and to get optimum benefits, mix things up by using different species and preparation methods.