A Brief History of
Protein: Passion, Social Bigotry, Rats, and Enlightenment
is an emotional subject and nothing arouses people’s passions more than
the subject of protein in their diet. Widely divergent opinions on
whether more protein or less is best, and on the merits of animal vs.
vegetable sources, have been debated for more than 150 years. And for all
that time solid scientific research has clearly supported the
wisdom of a diet low in protein – favoring vegetable sources. So far,
however, the scientific facts have fought a losing battle against
popular opinion – which values high-protein diets based on animal
foods. Mark Twain once said, “Truth is mighty and will prevail. There is
nothing wrong with this, except that it ain't so.” Even though the facts
may never become popular knowledge, I will always believe it is your
fundamental right to know the truth about your nutritional requirements –
this vital information should be taught from childhood as basic education,
along with reading, writing, and mathematics – and along with health facts
such as cigarettes cause lung damage, drunk driving kills, and automobile
safety belts save lives.
Standard Set by Social Bigotry
One of the earliest
proponents of high protein diets was the distinguished German physiologist
Dr. Carl Voit (1831-1908).1,2 After studying laborers who
consumed approximately 3100 Calories daily, he concluded that protein
intake for people should be 118 grams (g) per day – this value became
known as the “Voit standard.” How did he reach this conclusion? He
believed that people with sufficient income to afford almost any choice of
foods – from meat to vegetables – would instinctively select a diet
containing the right amount of protein to maintain health and
productivity. Other European and American authorities made similar
observations about the eating habits of working men with sufficient
incomes to afford meat and came to similar conclusions – ultimately
recommending diets high in protein (100 and 189 grams of protein a day).
No experiments were performed on the human body to reach these
conclusions. Information on the diets of vigorous individuals living
during these times and following low-protein vegetarian diets was largely
ignored.2,3 The healthy active lives of hundreds of millions
of less affluent people laboring in Asia, Africa, and Central and South
America on diets with less than half the amount of protein recommended by
Dr. Voit (and almost no meat), were overlooked when experts established
protein requirements that still affect us today.3,4
What arrogance! To
conclude that the superior intellect of moderately affluent people of
European descent would cause them to naturally come to correct conclusions
about their personal nutritional needs. What foolishness! You can see the
effects of self-selection when unrestricted food choices are available.
What do more than one billion people living in the 21st century
choose? McDonald’s, Burger King, Pizza Hut – need more be said about
people’s innate wisdom to make food selections in their best interests?
Unfortunately, these flawed recommendations based upon such social
bigotry have not yet been silenced by over 100 years of scientific
Chittenden Tells the Truth a Century Ago
thinking should have been stopped by 1905 when Russell Henry Chittenden,
Professor of Physiological Chemistry, published his
scientific findings on human protein needs in his classic book,
Physiological Economy in Nutrition.2 Professor
Chittenden believed Dr. Voit had cause and effect reversed: people did not
become prosperous because they ate high protein diets, but rather they ate
meat and other expensive high protein foods because they could afford
them. One hundred years ago he wrote, “We are all creatures of habit,
and our palates are pleasantly excited by the rich animal foods with their
high content of proteid (protein), and we may well question whether our
dietetic habits are not based more upon the dictates of our palates than
upon scientific reasoning or true physiological needs.”
He reasoned that we
should know the minimal protein requirement for the healthy man (and
woman), and believed that any protein intake beyond our requirements could
cause injury to our body, especially to the liver and kidneys. As he
explained it, “Fats and carbohydrates when oxidized in the body are
ultimately burned to simple gaseous products…easily and quickly
eliminated...” “With proteid (protein) foods…when oxidized, (they) yield
a row of crystalline nitrogenous products which ultimately pass out of the
body through the kidneys. (These nitrogen-based protein byproducts) –
frequently spoken of as toxins – float about through the body and may
exercise more or less of a deleterious influence upon the system, or,
being temporarily deposited, may exert some specific or local influence
that calls for their speedy removal.” With these few words Professor
Chittenden explained the deleterious effects of diets high in protein and
meat – consequences too few practicing doctors know about today.
Scientific Experiments on Our Protein Needs
first experiment was on himself. For nine months, he recorded his own
body weight, which decreased from 143 pounds (65 Kg) to 128 pounds (58 kg)
on his new diet of one-third the protein that Dr. Voit recommended.
Chittenden's health remained excellent and he described his condition as
being with “greater freedom from fatigue and muscular soreness than in
previous years of a fuller dietary.” He had suffered from arthritis of
his knee and discovered that by reducing his intake of meat his condition
disappeared and his “sick headaches” and bilious attacks (abdominal pains)
no longer appeared periodically as before; plus he fully maintained his
mental and physical activity, with a protein intake of about 40 grams a
valid scientific studies by collecting data on the daily dietary and urine
histories of his subjects (including himself) to determine protein
utilization. Because he was contradicting the known “truths” of his time,
he proceeded with extreme caution with his further investigations. He
organized three controlled trials with increasing demands for testing the
adequacy of diets lower in protein than commonly recommended.
The first trial
involved a group of five men connected with Yale University, leading
active lives but not engaged in very muscular work. On a low-protein diet
(62 grams daily) for 6 months, they all remained healthy and in positive
nitrogen balance (more protein went into, than out of, their bodies). The
second trial used 13 male volunteers from the Hospital Corps of the U.S.
army. They were described as doing moderate work with one day of vigorous
activity at the gymnasium. They remained in good health on 61 grams of
protein daily. His final trial was with 8 Yale student athletes, some of
them with exceptional records of athletic events. They ate an average of
64 grams of protein daily while maintaining their athletic endeavors, and
improving their performance by a striking 35 percent. Following these
studies, Chittenden in 1904 concluded that 35–50 g of protein a day was
adequate for adults, and individuals could maintain their health and
fitness on this amount. Studies over the past century have consistently
confirmed Professor Chittenden’s findings, yet you would hardly know it
with the present day popularity of high protein diets.
Many people have the
idea that animal foods contain protein which is superior in quality to the
protein found in plants. This misconception dates back to l9l4, when
Lafayette B. Mendel and Thomas B. Osborne studied the protein requirements
of laboratory rats and demonstrated nutritional requirements
for the individual amino acids.5 They found that rats grew
better on animal sources of protein than on vegetable sources. So,
investigators at that time suspected that the vegetable foods had
insufficient amounts of some of the amino acids essential for the normal
growth of rats. Because of these and other animal-based experiments,
flesh, eggs, and dairy foods were classified as superior, or "Class
A" protein sources. Vegetable proteins were designated inferior,
or "Class B" proteins.
Studies completed in
the early 1940's by Dr. William Rose of the University of Illinois found
that l0 amino acids were
essential for a rat’s diet.6 The
removal of any one of these essential amino acids from the food of growing
rats led to profound nutritive failure, accompanied by a rapid decline in
weight, loss of appetite, and eventually death. Animal products, such as
meat, poultry, milk, and eggs prevented this decline in the rats’ health,
and were found to contain the l0 essential amino acids in just the right
proportions for needs of growing rats. Based on these early rat
experiments the amino acid pattern found in animal products was declared
to be the “gold standard” by which to compare the amino acid pattern of
vegetable foods. According to this concept, wheat and rice were declared
deficient in lysine and corn was deficient in tryptophan.
has shown the obvious: the initial premise, that animal products supply
the most ideal protein pattern for humans, as they do for rats, is
incorrect.7 The dietary needs of rats are considerably
different from those of humans, mainly because rats grow very rapidly into
adult size as compared to people. Rats are fully adult after 6 months;
whereas a person takes 17 years to fully mature. This difference in need
is especially clear when the breast milk of both species is examined and
compared. The protein content of rat breast milk is 10 times greater than
the milk intended for human babies.8,9 Baby rats double in
size in 4.5 days; an infant doubles in size in 6 months. The obvious
reason for the different needs is because rats grow very rapidly into
adult size as compared to humans; therefore requirements for protein to
support that growth are very much higher.
Dr. William Rose
Discovers Human Needs
In 1942, Dr. William
Rose turned his attention from rats to people and began studying the amino
acid requirements for humans using basically the same methodology
he had used with rats. Healthy, male graduate students, grateful in
those days for the free food, the dollar a day they were paid
and the prospect of getting their initials in print in Rose's
widely read publications, served as his experimental
animals. They were fed a diet consisting of corn starch,
sucrose, butter fat without protein, corn oil, inorganic salts,
the known vitamins, and mixtures of highly purified amino
acids. Their diet also included a large brown "candy," which
contained a concentrated liver extract to supply unknown vitamins,
sugar, and peppermint oil to provide a "never-to-be-forgotten
The study used a
chemical measurement called nitrogen balance to determine whether
the subjects were getting enough usable protein from the mixture. From
his experiments, Dr. Rose found that only eight of the ten amino acids
essential to rats were also essential to men – we were better at making
two amino acids than rats. When an essential amino acid was given in
insufficient amounts for approximately two days, all subjects complained
bitterly of similar symptoms: a clear increase in nervous irritability,
extreme fatigue, and a profound failure of appetite. The subjects were
unable to continue the amino acid deficient diets for more than a few days
at a time.
Through his studies,
Dr. Rose also determined a minimum level of intake for each of the eight
essential amino acids.10 He found small amounts of variation in
individual needs among his subjects. Because of these unexplained
differences among people, he included a large margin of safety in his
final conclusion on minimum amino acid requirements. For each amino acid,
he took the highest recorded level of need in any subject, and then
doubled that amount for a "recommended requirement" – described as a
definitely safe intake. It is important to realize that his higher
requirement is easily met by a diet centered around any single starchy
vegetable. Even in children, as long as energy needs are satisfied by
starch, protein needs are automatically satisfied in almost every
situation because of the basic and complete design of the food. These
investigations were completed by the spring of 1952, resulting in sixteen
papers in The Journal of Biological Chemistry that are considered
classic contributions in the history of nutrition for the benefit of human
The results of Dr.
Rose`s studies are summarized in the following chart, under "minimum
requirements". From the chart, it is clear that vegetable foods contain
more than enough of all the amino acids essential for humans.11
have measured the capacity of plant foods to meet our protein needs.
Their findings show that children and adults thrive on diets based on a
single starch; and they grow healthy and strong.11,12
Furthermore, no improvement is obtained by mixing plant foods or
supplementing with amino acid mixtures to make the combined amino acid
pattern look more like that of flesh, dairy, or eggs.12 (For a
thorough discussion of human protein needs see The McDougall Plan,
New Win Publishers.)
Diet for a Small Planet Helps and Harms
A popular book among
vegetarians, Diet for a Small Planet, by Frances Moore Lappe’
published in 1971, started a revolution that has had a positive impact for
the past three decades on the lives of millions of people. Unfortunately,
Ms. Lappe’ failed to understand the basic scientific literature on human
protein needs and the sufficiency of plants foods before she wrote her
influential book. She believed plants contained “incomplete proteins”
with insufficient amounts of certain essential amino acids to meet the
needs of people.13 As a result of this misunderstanding, she
placed great emphasis on combining vegetable foods to create an amino acid
pattern which resembles that found in animal foods. This emphasis is
unnecessary and implies that it is difficult to obtain “complete” protein
from vegetables without detailed nutritional knowledge. Because of her
complicated and incorrect ideas people are frightened away from
The impact of her
incorrect teachings of more than 30 years ago affects nutritional policy
even today. In 2001 the Nutrition Committee of the American Heart
Association published a long overdue review warning people of the dangers
of high protein diets, like the Atkins, the Zone, and Sugar Busters diets.14
Unfortunately, this one statement in an otherwise valuable report is
scientifically incorrect: “Although plant proteins form a large part of
the human diet, most are deficient in 1 or more essential amino acids and
are therefore regarded as incomplete proteins.” For a supporting
scientific reference the Committee cites Frances Moore Lappe’s 1971 book,
Diet for a Small Planet.
You may think this is
a trivial matter; however, incorrect information on our protein needs can
have grave consequences on your health and your family’s health. With the
American Heart Association teaching that plants fail to supply complete
protein you are almost certain to receive incorrect, potentially damaging,
medical advice. For example, say you go to your doctor after a heart
attack and mention that you are now going to become a pure vegetarian to
avoid future heart trouble. Your doctor may respond, “You can’t do that,
you will become protein deficient on an all plant food diet – the Heart
Association says so.” Or your child is sick with recurrent asthma and ear
infections and you want a dietary cure – you may be warned away from a
highly effective therapy because members of the Nutrition Committee of the
American Heart Association fail to understand basic scientific research
about human protein needs and plant foods. So this is no small matter.
I have confronted the
Heart Association about spreading misinformation that can result in
suffering as serious as death from heart disease – so far they have shown
no interest in making overdue corrections to their incorrect teaching.
(See my July, August and November 2002 Newsletters for more information
on this.) I recently shared my conflict with the Heart Association with
the world’s leading authority on human protein requirements, Dr. D. Joe
Millward from the Center for Nutrition and Food Safety, School of
Biological Sciences University of Surrey, UK. His response to me on July
10, 2003 was, “Contrary to general opinion, the distinction between
dietary protein sources in terms of the nutritional superiority of animal
over plant proteins is much more difficult to demonstrate and less
relevant in human nutrition. This is quite distinct from the AHA position
which in my view is wrong.” 15
So How Do You Know the Truth about Your Protein Needs?
Read the scientific
and look at the world picture. Notice that 60 percent of people alive
today and most of the people who have lived in the past have obtained
their protein from plant foods. They have lived successfully; avoiding
all the diseases common in our society. Even today plant sources provide
65% of the world supply of the protein we eat.
What about the
starving children in Africa? The picture one often sees of “protein
deficient” children in famine areas of Asia or Africa is actually one of
starvation and is more accurately described as “calorie deficiency.”11
When these children come under medical supervision, they are nourished
back to health with their local diets of corn, wheat, rice, and/or beans.
Children recovering from starvation grow up to l8 times faster than usual
and require a higher protein content to provide for their catch-up in
development – and plant foods easily provide this extra amount of
protein. Even very-low protein starchy root crops, such as casava root,
are sufficient enough in nutrients, including protein, to keep people
The World Health
Organization knows the truth. Since 1974 it has recommended that adults
consume a diet with 5% of the calories from protein – this would mean 38
grams of protein for a man burning 3000 calories a day and 29 grams for a
woman using 2300 calories a day. These minimum requirements provide for a
large margin of safety that easily covers people who theoretically could
have greater protein needs – such as accident victims or people with
infections. This quantity of protein is almost impossible to avoid if
enough whole plant food is consumed to meet daily calorie needs. For
example, rice alone would provide 71 grams of highly useable protein and
white potatoes would provide 64 grams of protein for a working man.16
For a pregnant woman the WHO recommends 6% of the calories come from
protein – again an amount of protein easily provided by a diet based on
starches, vegetables, and fruits.
Human Breast Milk – Your Final Assurance
Your greatest need for
protein is when you grow the most. The greatest time of growth in a human
being’s life is as an infant. We double in size during the first 6
months. The ideal food for a baby is mother’s milk. Therefore, breast
milk is the “gold standard” for nutrition – during your time of greatest
need for all nutrients, including protein. Five to 6.3 percent of the
calories in human breast milk are from protein.9,17 This is
the maximum concentration of protein we will ever need in our food
supply. Knowing this value tells us that at no other time in our life
will we ever require more protein. Consider the protein content of the
foods we consume after weaning – these are even higher in protein – rice
is 9%, potatoes are 8%, corn is 11% and oatmeal is 15% protein.16
Even though all the
scientific knowledge accumulated over the past 100 years clearly shows our
bodies were designed to live best on a diet lower in protein than dictated
by common belief, we continue on the same disastrous dietary path. As
Russell Henry Chittenden explained 100 years ago, “The poorer man emulates
his richer neighbors as soon as his circumstances permit, and resources
that could be much more advantageously expended for the good of the family
and the home are practically wasted – to say nothing of possible injury to
health – under the mistaken idea that this more generous method of living
(a high-protein, high-meat diet) is the surest road to health and
strength.”2 Dr. Chittenden also believed that knowledge and
the truth would prevail. He wrote, “Habit and sentiment play such a part
in our lives that it is too much to expect any sudden change in custom.
By a proper education commenced early in life it may, however, be possible
to establish new standards, which in time may prevail and eventually lead
to more enlightened methods of living...” The past century of declining
health for people living in developed countries has proved Chittenden
wrong – so far. However, with widespread communication via the Internet
his predictions may soon become reality.
1) Carpenter K. A
short history of nutritional science: part 2 (1885-1912). J Nutr.
2) Chittenden, R. H.
(1904). Physiological economy in nutrition, with special reference to the
minimal protein requirement of the healthy man. An experimental study. New
York: Frederick A. Stokes Company.
3) Millward DJ.
The nutritional value of plant-based diets in relation to
human amino acid and protein requirements. Proc Nutr Soc. 1999
4) Millward DJ.
Metabolic demands for amino acids and the human dietary
requirement: Millward and Rivers (1988) revisited. J Nutr. 1998
5) Osborne T.
Amino-acids in nutrition and growth. J Bio Chem. 1914; 17:325-49.
6) Rose W.
Comparative growth of diet containing ten and nineteen amino acids, with
further observation upon the role of glutamic and aspartic acid. J Bio
Chem. 1948; 176: 753-62.
7) Bicker M. The
protein requirement of adult rats in terms of the protein contained in
egg, milk, and soy flour. J Nutr 1947;34: 491.
8) Bell G.
Textbook of Physiology and Biochemestry, 4th ed., Williams and
Wilkins, Baltimore, 1959, p. 12.
9) Reeds PJ.
Protein nutrition of the neonate. Proc Nutr Soc. 2000
Rose W. The amino acid requirement of adult man.
Nutr Abst Rev. 1957;27:63l-47.
11) McDougall J.
(1983). The McDougall Plan.
Clinton, NJ. New Win
12) M. Irwin, Hegsted
D. A conspectus of research on protein requirements of man. J Nutr.
13) Moyer G. Frances
Moore Lappe’s new edition says it all. Nutrition Action, Oct. 1982. p.
14) St. Jeor S,
Howard B, Prewitt E. Dietary protein and weight reduction. A statement
for health professionals from the Nutrition Committee of the Council on
Nutrition, Physical Activity, and Metabolism of the American Heart
Association. Circulation 2001;104:1869-74.
15) Personal Communication with John McDougall, MD on
July 10, 2003.
16) J Pennington.
Bowes & Church’s Food Values of Portions Commonly Used. 17th
Ed. Lippincott. Philadelphia- New York. 1998.
17) Reeds PJ.
Protein and amino acid requirements and the composition of complementary
foods. J Nutr. 2003 Sep;133(9):2953S-61S.