31.  The average, animal-eating American daily eats three to four times as much protein as scientists not affiliated with the meat and dairy industries recommend.  But what’s wrong with extra protein?

Eating too much protein, especially animal protein, can cause you to excrete calcium through your urine, increasing your risk of osteoporosis (also called brittle bones and bone loss).  Too much protein can strain the kidneys, leading to their disease.

• PETA’s Vegetarian Starter Kit (PDF; 3.2 megabytes; version accessed on 12 August 2005).
• “Rethinking the Meat-Guzzler” (The New York Times, 27 January 2008).
• Mickey Z.’s “Fear of a Vegan Planet” (appears in Everything You Know Is Wrong: The Disinformation Guide to Secrets and Lies (2002); some of the information is repeated in “Go Vegan” (Mickey Z., 2004)).





Personal Note.  Veganism is about behaving responsibly.  I find it necessary to share here the sometimes contradictory details recently gathered about dietary-protein requirements and the effects of too little or much protein consumption.  The point here is how much protein we need, and what happens when we get too little or too much; this is not an exhaustive list of quotations, is not at all an attempt to list foods and drinks in which to find protein, and is not so much about calcium and what consuming the milk of non-human animals does to or for the body.  Boldface emphasis is added here; it does not appear in the originals.

1 •  In “3: Protein Needs and Excesses” (3 January 2008), I report that the average American ingests 100 grams of protein per day, and that the daily protein intake recommended by scientists not affiliated with the meat and dairy industry is 27 grams, and that 100 is “almost four times” 27; this information came from a friend’s reference (“The typical American ingests 100 grams of protein each day, roughly four to five times the amount recommended by scientists NOT affiliated with meat and dairy corporations...How much protein DO we need... 27 grams/day are actually needed. Twenty Seven grams.”) to a Mickey Z. article, “Fear of a Vegan Planet”, printed in Everything You Know Is Wrong: The Disinformation Guide to Secrets and Lies (2002).  We should point out that, if you divide 100 by 27, you get about 3.7, which is close to 4 but certainly is not 5.

2 •  In a version of its Vegetarian Starter Kit saved on 12 August 2005, PETA has this section:

In Western countries, our problem is too much protein, not too little.  Most Americans get at least twice as much protein as they need.  Almost everything contains protein; unless you eat nothing but junk food, it’s almost impossible to eat as many calories as you need for good health without getting enough protein.  Healthy sources include whole-wheat bread, oatmeal, beans, peanuts, peas, nuts, mushrooms, and broccoli.

By contrast, too much protein, especially animal protein, can cause people to excrete calcium through their urine and increase their risk of osteoporosis.  Too much protein can also strain the kidneys, leading to kidney disease.

Vegans do not need to combine foods at each meal to get “complete protein.”  All grains, legumes, vegetables, nuts, and seeds provide all the essential amino acids.

The same document also has this:

A study of 1,700 pregnancies at The Farm, a large vegan community in Tennessee, showed that vegan mothers-to-be have a record of safety that would delight obstetricians.  Only one in 100 women delivered their babies by Caesarian section, and in 20 years, there was only one case of pre-eclampsia (a condition involving hypertension, fluid retention, urinary protein loss, and excessive weight gain), which occurs in at least 2 percent of all pregnancies in the U.S.  Other studies have found similar results.

The same document also says

All pregnant women need to consume extra protein.  There’s plenty to be found in plant foods such as tofu, tempeh, beans, nut butters, and mock meats like veggie burgers and soy sausage, and these foods don’t come with the artery-clogging cholesterol and saturated fat found in animal products.

For calcium, pregnant women should eat plenty of green leafy vegetables such as broccoli or kale.  The calcium from most green vegetables is actually more absorbable than the calcium in cow’s milk.  Another reason to avoid cow’s milk:  The protein in it can cross the placenta and even enter a woman’s breast milk, possibly sparking the production of antibodies that lead to insulin-dependent diabetes.  Other plant foods rich in calcium include soy milk, almonds, figs, blackstrap molasses, sesame seeds, tahini, and calcium-fortified fruit juices.

In the same document, a vegan mother writes about her vegan children:

My children have never had a problem with protein, calcium, or iron.  Most kids and adults eat too much protein, and because they get it from animal products, they get a whopping dose of artery-clogging fat with it.  Too much protein actually causes the body to lose calcium, so drinking cow’s milk is one of the least effective ways to strengthen bones.

3 •  In “Rethinking the Meat Guzzler” (The New York Times, 27 January 2008), Mark Bittman writes that Americans

each consume something like 110 grams of protein a day, about twice the federal government’s recommended allowance; of that, about 75 grams come from animal protein.  (The recommended level is itself considered by many dietary experts to be higher than it needs to be.)  It’s likely that most of us would do just fine on around 30 grams of protein a day, virtually all of it from plant sources.

4 •  In a version of its Vegetarian Starter Kit available on 31 January 2008, PETA says

“Eating a high-protein diet is like pouring acid on your bones,” according to one researcher.  When you get your protein from plant sources, you get all the amino acids that you need, without all the saturated fat and cholesterol found in meat, eggs, and dairy products.

The same document has this:

According to medical authorities, vegetarians get plenty of protein without having to pay particular attention to their diets.  Healthy vegetarian protein sources include whole grains, oatmeal, beans, peanut butter, brown rice, peas, lentils, tofu, soy milk, nuts, seeds, mushrooms, and vegetarian burgers and hot dogs.  By contrast, consuming too much animal protein has been scientifically linked to osteoporosis—according to a 2003 U.S. Department of Agriculture (USDA) report, vegetarian women had stronger bones than women who ate meat.

That document also offers this, about the Atkins diet, popularly seen as consisting of high amounts of meat:

There has not been a single study indicating that high-protein diets like Atkins work for more than a year; in fact, two studies showed that weight loss on the Atkins diet reversed or stalled after just six months, and Atkins himself died at 258 pounds.

The only weight-loss plan that has been scientifically proved to take weight off and keep it off for more than a year is a vegan diet.

5 •  Wikipedia’s “Protein in nutrition” article, on 31 January 2008, offers this, referring, in the first paragraph, to federal-government guidelines of the United States and Canada:

According to the recently updated Dietary Reference Intake guidelines, women aged 19–70 need to consume 46 grams of protein per day, while men aged 19–70 need to consume 56 grams of protein per day to avoid a deficiency. The difference is due to the fact that men's bodies generally have more muscle mass than those of women, or this may be attributed to weight difference by taking 0.8 g(of protein)/kg of body weight.

Because the body is continually breaking down protein from tissues, even adults who do not fall into the above categories need to include adequate protein in their diet every day. If enough energy is not taken in through diet, the body will use protein from the muscle mass to meet its energy needs, leading to muscle wasting over time.

Other recommendations suggest 0.8 gram of protein per kilogram of bodyweight per day while other sources suggest that higher intakes of 1-1.4 grams of protein per kilogram of bodyweight for enhanced athletes or those with a large muscle mass. [2].

How much protein needed in a person's daily diet is determined in large part by overall energy intake, as well as by the body's need for nitrogen and essential amino acids. Physical activity and exertion as well as enhanced muscular mass increase your need for protein. Requirements are also greater during childhood for growth and development, during pregnancy or when breast-feeding in order to nourish a baby, or when the body needs to recover from malnutrition or trauma or after an operation.

The recommendation of 0.8 grams of protein per day per kilogram of body weight means these equivalents, rounded to the nearest whole gram:  a person of 80 pounds should consume 29 grams of protein per day;  90 lbs., 33 g;  100 lbs., 36 g;  110 lbs., 40 g;  120 lbs., 44 g;  130 lbs., 47 g;  140 lbs., 51 g;  150 lbs., 54 g;  160 lbs., 58 g;  170 lbs., 62 g;  180 lbs., 65 g;  190 lbs., 69 g;  200 lbs., 73 g;  210 lbs., 76 g;  220 lbs., 80 g;  230 lbs., 84 g;  240 lbs., 87 g;  and 250 lbs., 91 g.  Multiply your weight in pounds by 0.3632 to find out how many grams of protein you need per day, according to those American and Canadian government guidelines.

6 •  In its 1997 statement of its position on vegetarian diets, the American Dietetic Association says

Plant sources of protein alone can provide adequate amounts of essential amino acids if a variety of plant foods are consumed and energy needs are met.  Research suggests that complementary proteins do not need to be consumed at the same time and that consumption of various sources of amino acids over the course of the day should ensure adequate nitrogen retention and use in healthy persons (22).  Although vegetarian diets are lower in total protein and a vegetarian’s protein needs may be somewhat elevated because of the lower quality of some plant proteins, protein intake in both lacto-ovo-vegetarians and vegans appears to be adequate (16).

7 •  Wikipedia’s “Protein in nutrition” article details problems that can occur if you don’t get enough protein:  these include reduced intelligence, mental retardation, decreased immunity (from lower numbers of white blood cells), and death.  The distended cheeks and bellies shown here are a symptom of kwashiorkor, a disease commonly (but controversially) believed to be caused by insufficient protein intake.

8 •  Wikipedia’s “Protein in nutrition” article also has a section on excess protein intake, pointing out that a reduction in protein consumption is recommended for those with kidney disease and that “Many researchers think excessive intake of protein forces increased calcium excretion.”

9 •  “A Threshold for Low-Protein-Diet-Induced Elevations in Parathyroid Hormone” (in American Journal of Clinical Nutrition, July 2000) reports on an 18-day study performed by the School of Allied Health, at the University of Connecticut.  Eight healthy young women were divided according to specific protein intake (0.7 grams per day; 0.8 g/day; 0.9 g/day; 1.0 g/day) that they were given in the last four days of the study.  The conclusion was “Our data suggest that in young healthy women consuming a well-balanced diet, the current recommended dietary allowance for protein (0.8 g/kg) results in short-term perturbations in calcium homeostasis”, meaning that the women’s bodies’ calcium didn’t stay quite the same when they consumed exactly the recommended 0.8 grams of protein per day per kilogram of body weight.  Also, the study found that the women consuming the two lower amounts of protein had higher levels of parathyroid hormone—which results in an increased resoprtion of bone calcium.  Resorption of bone calcium is when calcium is transferred from the bones to the blood.  This did not occur in the women consuming the higher amounts of protein.  In other words:  a study of not even three weeks, among just eight young healthy women, found that, in just four days, consuming exactly the recommended daily amount of protein, or less protein, resulted in removal of calcium from the bones.

10 •  “Changes in Bone Turnover in Young Women Consuming Different Levels of Dietary Protein” (in The Journal of Clinical Endocrinology and Metabolism, March 1999) reports on an 18-day study performed by the School of Allied Health, at the University of Connecticut.  Sixteen healthy young women were divided according to the specific protein intake (“low”, “medium”, “high”) that they were given in the last four days of the study.  It was observed that “Urinary calcium excretion was significantly higher on the high than on the low protein diet.”  The conclusion: “Our data suggest that at high levels of dietary protein, at least a portion of the increase in urinary calcium reflects increased bone resorption.”  In other words:  a study of not even three weeks, among just eight young healthy women, found that, in just four days, consuming “high” amounts of protein resulted in removal of calcium from the bones.

11 •  “Dietary Protein, Calcium Metabolism, and Skeletal Homeostasis Revisited” (in The American Journal of Clinical Nutrition, September 2003) reports on “short-term dietary trials”, involving healthy adults, performed by the School of Allied Health, at the University of Connecticut.  It was observed, in twenty women, that raising dietary protein to what was considered a high-protein diet resulted in hypercalciuria, an increase of calcium in the urine; according to Wikipedia, chronic hypercalciuria can impair kidney function and cause nephrocalcinosis (which includes blood in the urine).  Also, “The increased dietary protein was accompanied by a significant increase in intestinal calcium absorption”.  Also, “Dietary protein intakes at and below 0.8 g/kg were associated with a probable reduction in intestinal calcium absorption sufficient to cause secondary hyperparathyroidism.”  Secondary hyperparathyroidism is bad and comes from there being too little calcium in the blood.  It is said that low-protein diets “could be detrimental to skeletal health”.  “Of concern are several recent epidemiologic studies that demonstrate reduced bone density and increased rates of bone loss in individuals habitually consuming low-protein diets.  Studies are needed to determine whether low protein intakes directly affect rates of bone resorption, bone formation, or both.”  In other words:  high-protein diets cause problems, and low-protein diets (including those with exactly the recommended daily intake of 0.8 grams of protein per kilogram of body weight per day) cause other problems.  So what counts as a medium-protein diet?  In this study, two ranges are given: 0.8–1.2, and 1.0–1.5, grams of protein per kilogram of body weight per day.  A table in the paper on this study shows that more than half of American men aged 20–39 consume high or very high amounts of protein; the same is true of almost half of American men aged 40–59.  The paper mentions that four different epidemiological studies have found higher rates of hip fracture as dietary protein increases:

In the 1990s, the investigative focus shifted to bone as the source of the extra urinary calcium excreted during a high-protein diet.  As noted, increasing dietary protein from 75 to 125 g/d results in an increase in urinary calcium by an average of 1.6 mmol/d (7).  If the additional calcium lost is entirely from bone, it would result in a 1–2% annual loss in skeletal mass in an adult woman, comparable to the rate of bone loss in early menopause.  Three reviews summarize the complex literature on dietary protein’s potential impact on bone (26–28).

One mechanism by which high dietary protein could induce bone loss may be related to the metabolic acid load engendered by such a diet.  Meat and fish, which are high in sulfur-containing amino acids, generate appreciable fixed metabolic acid loads, whereas fruits and vegetables generate little acid and, in fact, may under certain circumstances generate more base than acid.  While renal metabolism represents the principal mechanism by which fixed metabolic acid loads are handled by the body, renal buffering may be incomplete, particularly with aging.  Under those circumstances, the skeleton may be called on to act as a buffer to neutralize acid generated from high-protein diets.  Liberation of buffer from bone comes at the expense of mineral dissolution and ultimately bone loss [cited in (26)].  Consistent with this hypothesis is the finding that the magnitude of urinary calcium excretion during a high-protein diet is dependent, to a large extent, on the sulfur amino acid content of the diet (29–31).

In 1986, Hegsted reported in a cross-cultural study that as dietary protein intake increased, so did hip fracture rates (32).  Subsequently, Abelow et al found a similar positive correlation between animal protein intake and cross-cultural age-adjusted hip fracture rates (33).  Three subsequent epidemiologic studies have reached the same conclusion (34–36).  In contrast, Munger et al reported higher fracture rates at low-dietary-protein intakes (37).

The paper also has a section specifically addressing how the origin (animal vs. vegetable) of the protein may affect bone health.

12 •  “Low Protein Intake: The Impact on Calcium and Bone Homeostasis in Humans” (The Journal of Nutrition, March 2003) is yet another report on a study done at the School of Allied Health, at the University of Connecticut.  It’s similar to item 11 in this list.

13 •  “The Impact of Dietary Protein on Calcium Absorption and Kinetic Measures of Bone Turnover in Women” (in The Journal of Clinical Endocrinology and Metabolism, January 2005) also is a report on a study done at the School of Allied Health, at the University of Connecticut.  This experiment involved thirteen women over twenty-four days, leading the researchers to the conclusion that, “at least in the short term, high-protein diets are not detrimental to bone.”


I’ve been at this entry for about four hours and so will stop with that many sources.  While not being a professional scientist in any field, I find myself leaning towards a few conclusions on the basis of the above information:

• Like any human being, Mickey Z. doesn’t get everything right.  What makes it harder is the lack of citations to trace the information compiled in Mickey Z.’s writings.

• Too much protein:  Bad.

• Too little protein:  Bad.

• Effect of too much protein on bones:  Uncertain.

• Effect of too little protein on bones:  Uncertain.

• Getting all your dietary protein from plants, not animals:  It’s fine.  Hooray!

• A healthful daily protein intake:  1 gram per kilogram of body weight, or 0.454 gram per pound of body weight.  (In other words, if you want to know about how many grams of protein you should consume per day, just take your weight in kilograms—or take your weight in pounds and multiply it by 0.454.)

• The average American indeed consumes significantly more than a moderate amount of protein, which is detrimental to health.