Potatoes Are Pillars of Worldwide Nutrition
John McDougall, M.D.
Potatoes are so tied into human life and nutrition
that one of the first toys to be advertised on TV and still popular
after 50 years is “Mr. Potato Head.” With its “eyes” and round body
shape the potato has been used to imitate the human form. But all fun
aside, the potato has improved human health and nutrition, influenced
wars, patterns of human migration, and the economy of many nations for
hundreds of years.
The potato is indigenous to various parts of South
America; plants in a wild state have been found on the Peruvian coast,
as well as on the mountainous lands of Central Chile and Argentina. The
Spaniards are believed to have first brought potatoes from Quito,
Ecuador to Europe in the early part of the sixteenth century. European
immigrants introduced potatoes to North America throughout the 1600s,
but they were not widely grown until 1719 in America.
According to the USDA, potatoes are the most important
vegetable in the United States. Over the past several decades, frozen
potato consumption rose and fresh potato consumption declined.
African-Americans eat more potato chips and French fries per capita than
do other Americans. Seniors favor fresh and canned potatoes, while
teenagers eat more chips and French fries than do other age groups.
The Much Maligned Potato
A recent Time magazine article put potatoes on the
level of bacon grease as far as your heart and health are concerned.1
“According to Meir Stampfer, a nutrition professor at the Harvard School
of Public Health, the problem is potato starch. When you eat a potato
and that starch hits the saliva in your mouth, its tightly bundled
molecules immediately get turned into sugars, which make a beeline for
the blood. ‘You ate a potato,’ says Stampfer, ‘but your body is getting
pure glucose.’ The flood of blood sugar sets off a chain reaction.
Insulin pours out of the pancreas. Triglycerides shoot up. HDL
cholesterol takes a dive. ‘It's a perfect setup for heart disease and
diabetes.’” “Experts” who make these statements show telescopic vision
by latching onto one small quality of a food and blowing it into
national headlines – ignoring the big picture and the truth. The focus
for such statements made by Stampfer and others is a concept called the
glycemic index (GI).
Glycemic Index – of Questionable Importance
The concept of glycemic index was introduced by David
Jenkins in the early 1980s (He was a recent guest on my TV Show,
“McDougall, MD”). The glycemic index is a ranking based on the food’s
immediate effect on blood glucose (blood sugar) levels. Carbohydrate
foods that break down quickly during digestion have the highest glycemic
indexes. The value is expressed as a percent comparison with the rise
that occurs with white sugar or white bread. GI is influenced by starch
structure (amylose versus amylopectin), fiber content, food processing,
physical structure of the food, and other macronutrients in the meal.
Low-GI foods lower glucose and insulin responses, improve lipid
profiles, and increase insulin sensitivity. Thus, some researchers
believe GI has an overwhelming influence on the risk of cardiovascular
disease, diabetes, and obesity.
However, the use of GI as the sole criterion to pass
judgment on a food as “good or bad” for you is wrong. There are many
other qualities of a food that contribute to its nutritional value that
must be taken into consideration before recommending or condemning a
particular food. Based on GI, for example, whole wheat bread (GI=129) is
worse for you than ice cream (GI = 51) and carrots (GI=131) are worse
for you than sugar sweetened chocolate (GI=49). 2 A baked potato with a
GI of 134 would be an unhealthier choice than a Mars candy bar at a GI
of 97. Obviously, those who condemn unprocessed high glycemic index
plant foods are overlooking some serious issues.
One of the lowest glycemic index foods is the simple
sugar fructose. The GI value is 29. Yet this food is simply empty
calories with no protein, essential fat, vitamins, minerals, or dietary
fiber. Of all the sugars, fructose is the one that raises cholesterol
and triglycerides the most, and therefore would be considered one of the
worst foods for people trying to prevent heart and other blood vessel
diseases.3 Because of the contradictions and limitations surrounding the
GI, the most recent position statement of the American Diabetic
Association does not recommend using this concept in the treatment and
prevention of diabetes and related complications.4 They state, “In
subjects with type 2 diabetes, studies of 2–12 weeks duration comparing
low glycemic index and high glycemic index diets report no consistent
improvements in HbA1c, fructosamine, or insulin levels. The effects on
lipids from low glycemic index diets compared with high glycemic index
diets are mixed.”
Another problem with following a low GI diet is the
difficulty in finding the foods and preparing the meals so they continue
to be low GI foods. Food preparation, cooking, and storage will change
the GI of foods. Furthermore, it is virtually impossible to determine
the GI of foods prepared outside the home. The data is conflicting and
reports from different investigators reveal a sometimes-wide range of
glycemic index values for certain foods. You could spend your whole day
chasing after low GI foods that in the end will not make you a speck
healthier and will make you a whole lot more confused, especially when
you see the negative results from all your efforts.
One of the common recommendations from “diet experts”
who express concerns about the glycemic index of carbohydrate foods is
for you to change to a low-carbohydrate, high-protein diet. In last
month’s issue of the
Newsletter (February 2002) we discussed some of the dangers,
including an increased risk of heart disease, kidney disease, and
osteoporosis, of these kinds of nutritionally unbalanced diets.
Chock Full of Nutrition
Consider that the primary purpose of eating is to
obtain enough energy to function throughout the day, and the body’s
preferred source of this energy is carbohydrate. Therefore, the foods
that deliver the greatest amount of carbohydrate would logically be
nutritionally superior and a high glycemic index food would be
preferred. So why condemn a food for doing what it is supposed to do –
provide efficient fuel for your body?
There is much more to nutritionally packed potatoes
than just calories. They have 2.5 grams of dietary fiber per potato.
That translates into 50 grams for an active man and 37 grams for an
active woman. The average American eats about 10 grams of dietary fiber
daily. Ideally people on a healthy diet would eat 30 to 100 grams of
fiber a day. Potatoes are very high in vitamin C, most B vitamins,
potassium and other minerals. Just as important are the recognized
health hazards you are avoiding with potatoes -- like sodium,
cholesterol, and fat. Of the calories from potatoes, only 1% comes from
fat, and these few fats are mostly the kind that we need, called
One important reason people think of potatoes as
fattening and unhealthy is all the toppings poured over them, like
high-fat gravies, bacon bits, cheese, sour cream, and butter.
Fortunately, there are many healthy (no-cholesterol, low-fat) toppings
that you can choose like chives, salsas, low-fat tofu sour cream,
low-fat soy cheeses, low-fat salad dressings, soups, chilies, marinara,
and bean sauces.
Don’t confuse baked or boiled potatoes with American’s
favorite forms of potatoes: French fries and potato chips. Cooking a
nutritious food like potatoes in oil increases the percentage of fat
from 1% to 36% for French fries, and up to 58% for potato chips. Often
the fats used for cooking the potatoes are the most damaging forms:
saturated and hydrogenated fats – linked closely with heart disease and
There is no cholesterol in a potato and insignificant
amounts of cholesterol-raising saturated fats. People in New Guinea
living on diets consisting almost entirely of sweet potato tubers (with
an even greater percentage of carbohydrate calories than white potatoes)
and leaves have cholesterol levels on the average of 108 mg/dl.5
(Cholesterol levels below 150 mg/dl are associated with immunity from
heart disease.) Heart disease is unknown in these people on their sweet
potato diet. In animal experiments potatoes have been shown to have a
particularly potent cholesterol lowering effect.6 Therefore, any expert
who says potatoes will lead to heart disease ignores the scientific
literature and common sense.
Complete Nutrition and Protein from Potatoes
Potatoes can provide complete nutrition for children
and adults. Many populations, for example people in rural populations of
Poland and Russia at the turn of the 19th century, have lived in very
good health doing extremely hard work with the white potato serving as
their primary source of nutrition.
One landmark experiment carried out in 1925 on two
healthy adults, a man 25 years old and a woman 28 years old, had them
live on a diet primarily of white potatoes for 6 months (A few
additional items of little nutritional value except for empty calories
-- pure fats, a few fruits, coffee, and tea -- were supplemented in
their diet).7 The report stated, “They did not tire of the uniform
potato diet and there was no craving for change.” Even though they were
both physically active (especially the man) they were described as, “…in
good health on a diet in which the nitrogen (protein) was practically
solely derived from the potato.”
The potato is such a great source of nutrition that it
can supply all of the essential protein and amino acids for young
children in times of food shortage. Eleven Peruvian children, ages 8
months to 35 months, recovering from malnutrition, were fed diets where
all of the protein and 75% of the calories came from potatoes.
(Soybean-cottonseed oils and pure simple sugars, neither of which
contain protein, vitamins, or minerals, provided some of the extra
calories).8 Studies during the experimental feeding showed this simple
diet provided all the protein and essential amino acids to meet the
needs of growing and small children.
Eggs have been promoted for their "perfect pattern" of
essential amino acids found in the protein. However, when volunteer
subjects were fed different foods to determine the ability of humans to
utilize various protein mixtures, investigators found that our bodies
can more efficiently utilize the amino acids in a mixture of potatoes
and eggs -- 36% better -- than those from eggs alone.9
Potatoes Are Naturally Slimming
In our society where over-nutrition is the problem,
some experts consider a high glycemic index value for a food a
fundamental health hazard. But they are mistaken – as you noticed above,
the really fattening foods, like sugar, candy bars, and ice cream, are
the ones with a low GI. The potato, with a high GI, does not deserve a
reputation for being fattening, because as I will show, it is virtually
impossible to consume too many calories from potatoes.
One 5-ounce baked potato has 150 calories. An active
man may burn 3000 calories a day and a woman 2300 calories a day. That
means the man would have to eat 20 potatoes and the woman 15 potatoes or
they would lose weight. That’s 5 to 7 large potatoes per meal, three
times a day – a big dent in even the hardiest appetite – especially
considering potatoes are among the most satisfying of all foods (see
When it comes to the national health epidemic of
obesity there are only three food issues to consider:
1) Don’t Be Dense. Potatoes are at the bottom
of the list of calorie dense foods, at one calorie per gram. By
comparison, sugar, cheese, and beef are about 4 calories per gram and
vegetable oils are 9 calories per gram.
2) The Fat You Eat Is the Fat You Wear.
Potatoes are 1% fat – so there are virtually no fat calories to wear. By
comparison beef and cheese can be 70% fat and butter is 100% fat.
3) Carbohydrate Satisfies the Hunger Drive.
Potatoes are at the top of the carbohydrate list with about 90% of the
calories from appetite-satisfying carbohydrates. Beef, fish, chicken,
butter, and olive oil are a few examples of commonly consumed foods with
no carbohydrates. Only 2% of the calories from cheese come from
One of the strongest risk factors for type II diabetes
and heart disease is excess body fat. Therefore, any expert who says
potatoes will lead to diabetes or obesity is ignoring the bulk of the
scientific and nutrition literature. And they are ignoring an
observation anyone can make: People living on diets high in starch (like
Japanese and Chinese) are trim, young, and active people with very low
rates of diabetes.
Simply Satisfying Spuds
The reason I eat is to satisfy my powerful hunger
drive. I can’t ever remember thinking about the glycemic index of my
foods when I sat down to a meal. Just fill me up and get rid of those
unpleasant hunger pangs so I can get on to my next project. In a recent
experiment, 38 separate foods were fed to subjects and a rating of their
level of satisfaction (satiety index) was determined every 15 minutes
for 2 hours after the meal. The highest satiety index was produced by
boiled white potatoes, which was seven times higher than the lowest
index of croissants. 10 Potatoes were almost 5 times more satisfying
than a Mars candy bar and twice as satisfying as beef or cheese. The
main reasons for this high level of satisfaction were the low calorie
density, the high carbohydrate, and low fat contents of the potato.
Carbohydrate satisfies the hunger drive, whereas fat offers almost no
Does It Make Sense?
People in Peru, the potato capital of the world, have
about one-quarter the death rate from heart disease of people in the
USA. Obesity and diabetes are very rare, even today, in Peru. But things
are changing. Fast food restaurants are encroaching on Peru’s major
cities -- serving French fried potatoes, shakes, and burgers. Soon this
potato-eating country will have an epidemic of diseases similar to those
in the US. Why? Because they have abandoned their traditional foods, and
especially the much maligned potato.
When you read a sensational article in newspapers or
magazines, like Time, ask yourself, “Does it make sense – based upon
everything else I know?” The potato is a much loved, inexpensive,
“comfort” food that continues to provide a large part of people’s
nutritional needs worldwide. And the potato should continue to make up a
large part of your diet. Based upon the facts, if famine struck and
times were desperate, and I had to choose only one food to live on --
potatoes would keep me strong and healthy until the stock market’s Dow
Jones Industrial Average hit 11,722.98 again.
1) Horowitz J. 10 Foods that pack a wallop. Time January 21, 2002
2) Foster-Powell K. International tables of glycemic index. Am J Clin
Nutr. 1995 Oct;62(4):871S-890S.
3) Hallfrisch J. Metabolic effects of dietary fructose. FASEB J. 1990
4) Evidence-based nutrition principles and recommendations for the
treatment and prevention of diabetes and related complications. Diabetes
Care. 2002 Jan;25(1):202-12.
5) Luyken R. Nutrition studies in New Guinea. Am J Clin Nutr
6) Morita T. Cholesterol-lowering effects of soybean, potato and rice
proteins depend on their low methionine contents in rats fed a
cholesterol-free purified diet. J Nutr. 1997 Mar;127(3):470-7.
7) Kon S. XXXV. The value of whole potato in human nutrition.
Biochemical J 22:258-260, 1928.
8) Lopez de Romana G. Fasting and postprandial plasma free amino
acids of infants and children consuming exclusively potato protein. J
Nutr. 1981 Oct;111(10):1766-71.
9) Kofranyi E. The minimum protein requirement of humans. Tested with
mixtures of whole eggs plus potato and maize plus beans. Z. Physiol Chem
351 1485-1493, 1970.
10) Holt S. A satiety index of common foods. Eur J Clin Nutr. 1995
2002 John McDougall All Rights Reserved
Fair Use Notice: This document may contain copyrighted material whose
use has not been specifically authorized by the copyright owners.
We believe that this not-for-profit, educational
use on the Web constitutes a fair use of the copyrighted material (as
provided for in section 107 of the US Copyright Law). If you wish to use
this copyrighted material for purposes of your own that go beyond fair
use, you must obtain permission from the copyright owner.