Defending
the McDougall Diet—If I Must
Headlines are made
worldwide when a study is published that
suggests people can continue to indulge in
lobster drawn in butter, bloody-raw tri-tip
beefsteaks, and crispy fried cheese. How can a
single study be so convincing? The answer is
simple: People love to hear good news about
their bad habits. “Now I don’t have to eat more
vegetables.”
Those of us who
follow a healthy diet and have experienced the
benefits know the truth. What is disturbing to
me, and must be to you, is how intelligent
researchers can come to conclusions so contrary
to ours. Money is at the root of many of these
studies, but often there is no apparent
financial conflict of interest. The dinner
table is a common source of confusion. Even the
most honest scientific researchers are befuddled
when in their right hand they hold a forkful of
bacon and eggs and in their left hand they hold
a study saying heart disease is caused by eating
foods high in cholesterol and fat.
Subconsciously, their right to gluttonous eating
is defended at all costs—even in the design and
interpretation of their research. From
experience, most of us know how threatened
people become over a vegetarian (vegan) diet.
So how do I really
feel about research appearing as national
headlines that contradicts my beliefs and
findings? I love it! Finally, these subjects are
being discussed. Throughout my career, my enemy
has been being ignored. I have been silenced by
shunning. Now, attention given to these matters
of human nutrition will bring the facts to light
and they can be debated. Eventually, the truth
will be known and commonly practiced.
In the past few
weeks three headline-grabbers have gained
worldwide attention. Each one deserves
consideration, but their overall findings do not
change the bulk of the scientific research,
common sense, and what I have taught for the
past four decades. Allow me to explain these
studies and give you my viewpoint.
Vegans Have
More Fractures
Comparative
fracture risk in vegetarians and nonvegetarians
in EPIC-Oxford by
Paul N Appleby
published in the European Journal of Clinical
Nutrition found a 30% increased risk of
fractures in vegans compared to people following
other diets and concluded, “In
this population, fracture risk was similar for
meat eaters, fish eaters and vegetarians. The
higher fracture risk in the vegans appeared to
be a consequence of their considerably lower
mean calcium intake.”1
Meat eaters were the fattest (the highest mean
BMI) and tended to be the least active group,
with vegans having the lowest mean BMI and
reported the highest levels of walking, cycling
and vigorous exercise. The causes of the
fractures for all groups were falls, traffic
accidents, other accidents, and unspecified or
multiple causes. More than 70% of the fractures
were caused by a fall. The most common fracture
sites were wrist/arm and ankle. Current use of
hormones (HRT) was highest in the female meat
eaters. The difference in age between the meat
eaters and vegans was nearly 11 years, with the
vegans younger.
For vegan subjects who consumed at least
525 mg/day calcium, there was no increase in
fractures rates. As a result, the authors
suggested vegans should consume for extra
calcium more almonds, sesame seeds, tahini
(sesame paste), calcium-set tofu,
calcium-fortified drinks and low-oxalate leafy
green vegetables, such as kale.
Additional Information directly
from the authors:
I
communicated with one of the lead authors, Tim
Key, about this well-publicized study.
Dear Dr.
McDougall,
Thank you for your e-mail and interest in our
recent paper. Paul (Appleby)
and I have just discussed your questions. As you
point out, the optimal intake of calcium for
preventing fractures has been controversial and
the evidence is somewhat conflicting. In our
data, the only nutrient clearly associated with
fracture risk is calcium, with a high risk among
people with an intake below the UK EAR of 525
mg/d. In the current paper, the vegans eating
at least 525 mg/d of calcium did not have an
increase in fracture risk (risk ratio 1.00).
The calcium comes from a range of foods and it
is hard to single out any particular foods as
the major sources for vegans (in contrast to
non-vegans where dairy products are the major
source). We don't think that our results should
be taken as an argument to eat dairy products;
simply that vegans do need to eat enough
calcium. Would you agree with the UK EAR of 525
mg/d as a reasonable minimum?
With best
wishes, Tim Key
In another
communication, Mr. Key felt his research methods
accounted for the differences in age, HRT use,
and activity. He wrote, “The fact that we saw no
increase in fracture risk in vegans with calcium
of at least 525 suggests that this is likely to
be the explanation for the overall findings…For
physical activity the measurements are not as
good, and vegans did report more activity which
increases the risk for accidents, but we have
adjusted for this as well as we can.”
I asked Mr. Key,
“In general, how do you explain your findings in
face of world population data showing
populations worldwide with the lowest calcium
intakes have the fewest fractures – and the
exact opposite results for protein?2,3
His answer was, “As you know this is complex and
controversial. The ecological comparisons need
to consider other factors too, like vitamin D,
height, weight, environment, completeness of
statistics, and weight-bearing physical
activity.”
Comments:
The reason I
believe this study found more fractures in the
vegan group is these healthier, younger people
were far more active and as a result sustained
more injuries. Their increased physical
activity leading to more fractures is noted by
the fact that they were on average 11 years
younger, were less fat (lower BMI), and were
reported to walk, cycle and do other vigorous
activities more than the meat, fish, and dairy
groups.
The most serious kind of fracture caused by weak
bones (osteoporosis) is a broken hip. In this
study the vegans had no hip fractures, compared
to 30 in the meat eaters, 9 in the fish eaters,
and 14 in the vegetarians (dairy). The
observation that the fractures were of the
wrist, arm, and ankle, and not the hip, to me,
means the fractures were due to trauma caused by
physical activity and not due to weakened bones.
The average intake
of calcium for the vegans was 603 mg/day for men
and 586 mg/day for women—these levels exceeded
those intakes of populations where osteoporosis
is rare to unknown—like in rural Asian and
African populations where intakes are commonly
400 to 500 mg daily. 2,3 Since the
vegans frequently participated in outdoor
activities it is highly unlikely they had any
deficiency of vitamin D—made from sunlight.
The conclusion of
this study that the lack of calcium was the
reason for the increased fractures in the vegans
is in direct conflict with the bulk of the
scientific research.4 For example,
results of two excellent studies reported in
2006 in leading medical journals found no
reduction in fractures following the use of
large doses of calcium supplements.5,6
In the Women's Health Initiative study of
36,282 postmenopausal women taking 1000 mg of
calcium daily, and in a double-blind,
placebo-controlled study of elderly women
receiving an extra 1200 mg of calcium daily,
fractures were not prevented by even these
extraordinary intakes.
In contrast to
these studies, and most others, on the lack of
influence of calcium intake on fracture risk,
the authors of this study conclude calcium is
the problem and this is based on findings in
only 74 people with fractures following a vegan
diet. You should be asking, how could such
meager and contradictory evidence be so
influential? Answer: People love to hear good
news about their bad habits.
1)
Appleby P, Roddam
A, Allen N, Key T. Comparative
fracture risk in vegetarians and nonvegetarians
in EPIC-Oxford. Eur J Clin Nutr. 2007
Feb 7; [Epub ahead of print]
2) Abelow B. Cross-cultural
association between dietary animal protein and
hip fracture: a hypothesis. Calcific Tissue
Int 50:14-8, 1992.
3) Frassetto LA . Worldwide
incidence of hip fracture in elderly women:
relation to consumption of animal and vegetable
foods. J Gerontol A Biol Sci Med Sci.
2000 Oct;55(10):M585-92.
4) Lanou AJ. Bone
health in children. BMJ. 2006 Oct
14;333(7572):763-4.
5)
Wactawski-Wende
J, Kotchen JM, Anderson GL, Assaf AR, Brunner RL,
O'Sullivan MJ, Margolis KL, et al.
Calcium plus vitamin D supplementation and the
risk of fractures. N Engl J Med. 2006 Feb
16;354(7):669-83.
6)
Prince RL, Devine
A, Dhaliwal SS, Dick IM. Effects of
calcium supplementation on clinical fracture and
bone structure: results of a 5-year,
double-blind, placebo-controlled trial in
elderly women. Arch Intern Med. 2006 Apr
24;166(8):869-75.
Atkins Is
Better Than Ornish, Stanford Study Says
Comparison of
the Atkins, Zone, Ornish, and LEARN diets for
change in weight and related risk factors among
overweight premenopausal women: the A TO Z*
Weight Loss Study: a randomized trial by
Christopher Gardner in the March 7, 2007 issue
of the Journal of the American Medical
Association found, ‘In this study,
premenopausal overweight and obese women
assigned to follow the Atkins diet, which had
the lowest carbohydrate intake, lost more weight
and experienced more favorable overall metabolic
effects at 12 months than women assigned to
follow the Zone, Ornish, or LEARN diets.1
While questions remain about long-term effects
and mechanisms, a low-carbohydrate,
high-protein, high-fat diet may be considered a
feasible alternative recommendation for weight
loss.”
*The “A to Z”
stands for the four diets investigated: Atkins,
Traditional (LEARN), Ornish, and Zone.
This twelve-month
randomized trial was conducted in the United
States from February 2003 to October 2005 among
311 free-living, overweight or obese,
nondiabetic, premenopausal women, who were
divided into four equal groups. Participants
were recruited from the community by media (like
the newspaper) advertisements. They were given
one of four books: Dr. Atkins’ Diet
Revolution, Enter the Zone, The LEARN Manual for
Weight Management, Eat More, Weigh Less.
Each group attended a one hour weekly class
headed by a dietitian for eight weeks. The Zone
and the LEARN diets had specific goals for
calorie restriction, while the Atkins and Ornish
groups had no specific energy restriction
goals. The weight losses after one year were
Atkins 10.3 pounds (-4.7 kg), Zone 3.5 pounds
(-1.6 kg), LEARN 5.7 pounds (-2.6 kg), and
Ornish 4.8 pounds (-2.2 kg). For me, a 3 to 10
pound weight loss for overweight and obese women
after a year of dieting is not very impressive.
Comments:
Twenty-four years
ago, when I started windsurfing, 500,000 more
people worldwide were sailors than there are
today. Why is the popularity of this sport
falling when it provides an unsurpassed
adrenaline rush of traveling 32 miles per hour
across the water’s surface while standing on a
two-inch thick foam board? The answer is:
the learning curve is huge. I remember how
it took me six agonizing days before I got my
first ride. Once past the difficulty of learning
days, windsurfing has meant 24 years of fun and
great exercise for me.
Whether or not
someone follows a diet depends upon how easy it
is to learn. The Atkins Diet is the easiest to
follow—you simply drive by a fast food window,
order a burger, throw away the bun, and scrape
off the pickles and ketchup, and you’re on the
diet. The Ornish (like the McDougall Diet) is
much harder to learn. The foods are unfamiliar.
They can take time and effort to prepare. The
social stigma associated with being a vegetarian
is daunting. With such a steep learning curve
few people succeed. This conclusion is
substantiated by the observation that at 12
months the group on the Ornish diet (a diet of
10% of the calories as fat) was actually
consuming 29.8% fat.
So what this study
really means is changing eating habits is
difficult and the majority of people are
unwilling or unable to make meaningful dietary
changes for any length of time. We need no more
studies like this one to remind us of the fact
that “diets fail” for most people—but not for
everyone. How about for those people who have
gotten past the learning phase and adopted a
diet for a lifetime? I, for example, have
discovered that a healthy plant-food based diet
is the most delicious and the healthiest way to
eat (kind of like windsurfing is a really fun
exercise).
Studies of
successful dieters needed
What we now need
are studies that look at the long-term results
for people who do follow various diets. (It may
be difficult to find people who follow low
carbohydrate diets long-term. Atkins, himself,
could not follow his own recommendations—when he
died he was reported to be obese with heart and
artery disease.2)
The first place
food affects the body is the bowels. Future
investigations need to report the results of the
effects of a McDougall-Ornish type diet and the
Atkins Diet on bowel movements. In his own
research Robert Atkins reported 70% of people
following his diet are constipated.3
Anyone following the McDougall Diet knows the
effects on bowel movements (often 3 times daily,
easy to pass, and large).
Next investigators
should look at calcium balance and see what
happens to the bones on these high-protein,
high-acid diets, like Atkins, the Zone, and
South Beach. As a first phase, this can be
simply done by measuring the amount of calcium
excreted in the urine over 24 hours. Research
consistently shows that a decrease in animal
protein decreases loss of calcium from the bones
into the urine.4 Next biochemical
markers of bone turnover can be measured in the
urine. These reflect the rate at which bone
material is being lost. High protein diets have
been shown to increase bone turnover based on
these markers.5
Decreases in blood
sugar, cholesterol, and triglycerides have been
found with the Atkins Diet, but these changes
are a result of suppression of appetite,
followed by semi-starvation, which are the
underlying mechanisms of this ketogenic diet.
Similar blood chemistry results can be
accomplished by giving patients cancer
chemotherapy, which causes them to lose their
appetite and starve—the same as the Atkins Diet.6
Rather than
checking risk factors, like cholesterol and
triglycerides, more direct measurements of the
effect of diet on the heart and blood vessels
needs to be made. For example, a relevant
measure would be the compliance of the artery
walls, which is determined by ultrasound
measurements over the ascending aorta (the large
artery leading from the heart) and the right
carotid artery (neck). Previous results show a
27% decrease in arterial compliance after a
single meal consisting of 67% of the calories as
fat.7 Reduction in blood flow in the
heart arteries is also seen after one high-fat
meal by use of a PET scan.8
Immediate effects of a single high-fat meal can
be seen by a visual examination of the eye (conjunctival
capillaries) and the oxygen content of the
arterial blood. Research has shown that a diet
high in fat (67% of the calories) fed to people
causes the circulation in the eye to visually
sludge, along with a decrease in the oxygen
content of the blood by 20%.9,10
Long-term effects
on the heart arteries would require months and
years to assess. Reversal of atherosclerosis
has been demonstrated by angiograms and PET
scans after following the Ornish Diet for 12
months and longer.11 The only study
of patients on the Atkins Diet has shown a
worsening of blood flow at one year from all
that saturated fat and cholesterol with an
overall cumulative progression of artery disease
(atherosclerosis) of 39.7%.12
I believe the
trend has shifted away from the popularity of
high-protein diets of the 90s and the first half
of this decade. People have tried to lose
weight eating all meat and cheese—they felt sick
and were constipated, and their weight loss was
temporary and trivial. In addition, we are
learning that one of the planet’s greatest
sources of pollution is livestock—so even if
these high animal-food diets were good for
humans—and they are not—they are undeniably
killing our planet.
1) Christopher D.
Gardner; Alexandre Kiazand; Sofiya Alhassan;
Soowon Kim; Randall S. Stafford; Raymond R.
Balise; Helena C. Kraemer; Abby C. King.
Comparison of
the Atkins, Zone, Ornish, and LEARN Diets for
Change in Weight and Related Risk Factors Among
Overweight Premenopausal Women: The A TO Z
Weight Loss Study: A Randomized Trial.
JAMA. 2007;297:969-977.
2) McDougall
Newsletter. Atkins Was Grossly Overweight and
Sick– But the Media Loves the Dead Guy.
February 2004.
3) Yancy WS Jr,
Olsen MK, Guyton JR, Bakst RP, Westman EC. A
Low-Carbohydrate, Ketogenic Diet versus a
Low-Fat Diet To Treat Obesity and Hyperlipidemia:
A Randomized, Controlled Trial. Ann Intern
Med. 2004 May 18;140(10):769-777.
4)
Giannini S,
Nobile M, Sartori L, Dalle Carbonare L,
Ciuffreda M, Corro P, D'Angelo A, Calo L,
Crepaldi G. Acute effects of moderate
dietary protein restriction in patients with
idiopathic hypercalciuria and calcium
nephrolithiasis. Am J Clin Nutr. 1999
Feb;69(2):267-71.
5)
Harrington M,
Bennett T, Jakobsen J, Ovesen L, Brot C, Flynn
A, Cashman KD. The effect of a
high-protein, high-sodium diet on calcium and
bone metabolism in postmenopausal women and its
interaction with vitamin D receptor genotype. Br
J Nutr. 2004 Jan;91(1):41-51.
6) McDougall
Newsletter. Proof that the Atkins Diet Works
Like Chemotherapy
By Sickness-Induced Starvation. September 2003.
7) Nestel P.
Post-prandial remnant lipids impair arterial
compliance. J Am Coll Cardiol
37:1929-35, 2001.
8)
Cook B, Cooper D,
Fitzpatrick D, Smith S, Tierney D, Mehy S.
The Influence of a High Fat Meal Compared to an
Olestra Meal on Coronary Artery Endothelial
Dysfunction by Rubidium (Rb)-82 Positron
Emission Tomography (PET) and on Post Prandial
Serum Triglycerides. Clin Positron Imaging.
2000 Jul;3(4):150.
9) Friedman M.
Serum Lipids and conjunctival circulation after
fat ingestion in men exhibiting type-A behavior
pattern. Circulation 29:874, 1964.
10) Kuo P. The
effect of lipemia upon coronary and peripheral
arterial circulation in patients with essential
hyperlipemia. Am J Med 26:68, 1959.
11)
Ornish D,
Scherwitz LW, Billings JH, Brown SE, Gould KL,
Merritt TA, Sparler S, Armstrong WT,
Intensive lifestyle changes for reversal of
coronary heart disease.
JAMA. 1998 Dec 16;280(23):2001-7.
12)
Fleming RM.
The effect of high-protein diets on coronary
blood flow. Angiology. 2000
Oct;51(10):817-26.
Fish Is Now
Health Food for Pregnant Women
Maternal seafood
consumption in pregnancy and neurodevelopmental
outcomes in childhood (ALSPAC study): an
observational cohort study
by Joseph R.
Hibbeln in the February 17, 2007 issue of the
Lancet reported, “Maternal seafood
consumption of less than 340 g per week in
pregnancy did not protect children from adverse
outcomes; rather, we recorded beneficial effects
on child development with maternal seafood
intakes of more than 340 g per week, suggesting
that advice to limit seafood consumption could
actually be detrimental. These results show that
risks from the loss of nutrients were greater
than the risks of harm from exposure to trace
contaminants in 340 g seafood eaten weekly.”
The study
examined 11,875 pregnant women living in
Bristol, UK, who completed a food frequency
questionnaire assessing seafood consumption at
32 weeks gestation. Outcomes of the children
from age 6 months to 8 years were reported in
women consuming none, some (1-340 g per week),
and >340 g per week.
This study
reported that the women in the high seafood
group compared to the low seafood group were:
more likely to breast feed (87% vs. 72%), have
higher incomes (49% vs. 30%), own their homes
(87% vs. 70%), and
be non smokers (77% vs. 61%). All these factors
tell about a better educated, more successful
group of people who have come to believe through
instructive messages that eating fish is
healthful. These same advantaged people rear
children with measurably better development
compared to the children of disadvantaged
people.
Comments:
There are no
greater emotional issues than the unborn and
children; not surprisingly this article received
much attention in the press. Unfortunately, the
interpretation as reported in national headlines
was incorrect. This study actually showed women
who eat less fish have lower incomes, less
education, and more difficult living conditions
in general—and their offspring suffer
proportionally. During pregnancy, these women
also eat a less nutritious diet (more junk and
fewer plants). A study published in 1998 by
these same investigators of these same women
found, “Women with greater difficulty in
affording food had lower intakes of protein, fibre, vitamin C, niacin, pyridoxine, iron,
zinc, magnesium and potassium than did women
with little or no difficulty. They were more
likely to use cooking and spreading fats with a
high saturates content, and less likely to eat
fish, fruit, vegetables and salad.” These
investigators took on an impossible task of
separating fish intake out from all the other
variables in these women’s life and came to an
erroneous conclusion.
The primary
explanation given in this study for why women
who ate fish had children with higher levels of
mental and emotional function was because they
received a higher quality of fat before birth
from their mothers eating more fish. These
omega-3 “good” fats are found in high quantities
in fatty fish. However, it is important to
understand that animal systems lack the ability
to synthesize omega-3 fats, thus fish cannot
make essential fats. Sea weeds and algae
synthesize these fats which are then stored in
the fish flesh; along with contaminants,
cholesterol, animal protein, and calories. The
human body has no difficulty converting
plant-derived omega-3 fat, alpha linolenic acid,
into DHA or other n-3 fatty acids, supplying our
needs even during gestation and infancy.3
Therefore, the
wise consume will choose plant foods as their
source of essential fats and other nutrients and
avoid all the harmful ingredients of animal
products higher up on the food chain.
There are many
adverse consequences from consuming fish. The
focus of recommendations by two US government
agencies—the US Department of Health and Human
services, and the US Environmental Protection
Agency—to limit fish intake by pregnant women to
less than 340 grams (10 ounces) a week was based
on contamination of the fish with environmental
chemicals, especially methylmercury (a known
neurotoxin).1 Fish also causes a
rise in blood cholesterol levels similar to the
rise caused by beef and pork.4 Their
highly-acidic animal proteins accelerate calcium
loss,5 contributing to osteoporosis
and kidney stones. No dietary fiber or
digestible carbohydrates are present in
fish—thus having a negative impact on bowel
function and endurance. Although omega-3 fats
“thin” the blood, preventing thrombus formation
(heart attacks); this same anticoagulant
activity can increase the risk of bleeding.6
These fats also have antiinflammatory
properties, which can be beneficial (reducing
arthritis pain) as well as deleterious (causing
immune suppression, increasing the risk of
cancer and infection).7 Fatty fish,
commonly recommended salmon for example, is half
fat and loaded with calories, adding to one’s
risk for developing obesity and type-2
diabetes. Furthermore, omega-3 fats inhibit the
action of insulin, thereby increasing blood
sugar levels and aggravating diabetes.8
Finally, let’s not
forget the environmental consequences of telling
people they need to eat more fish. Since I was
a child (fifty years ago) 90% of the large fish
that swam in the oceans have been eaten—these
big ones are the ones that make little ones.
Soon there will be no fish left and then people
will have to seek the truth about where to
obtain essential fats and other nutrients for
their health. They will discover plants are the
sources of these life-giving substances.
Unfortunately, by then, billions of people will
have suffered needlessly and damage to the
environment will be unrecoverable.
References:
1)
Hibbeln JR, Davis
JM, Steer C, Emmett P, Rogers I, Williams C,
Golding J. Maternal seafood
consumption in pregnancy and neurodevelopmental
outcomes in childhood (ALSPAC study): an
observational cohort study. Lancet. 2007
Feb 17;369(9561):578-85.
2)
Rogers I, Emmett
P, Baker D, Golding J. Financial
difficulties, smoking habits, composition of the
diet and birthweight in a population of pregnant
women in the South West of England. ALSPAC Study
Team. Avon Longitudinal Study of Pregnancy and
Childhood. Eur J Clin Nutr. 1998
Apr;52(4):251-60.
3) )
Langdon JH.
Has an aquatic diet been necessary for hominin
brain evolution and functional development?
Br J Nutr. 2006 Jul;96(1):7-17.
4) Davidson MH,
Hunninghake D, Maki KC, Kwiterovich PO Jr,
Kafonek S. Comparison of the effects of lean
red meat vs lean white meat on serum lipid
levels among free-living persons with
hypercholesterolemia: a long-term, randomized
clinical trial. Arch Intern Med. 1999
Jun 28;159(12):1331-8.
5)
Robertson WG,
Heyburn PJ, Peacock M, Hanes FA, Swaminathan R.
The effect of high animal protein intake on the
risk of calcium stone-formation in the urinary
tract. Clin Sci (Lond). 1979
Sep;57(3):285-8.
6)
Dyerberg J, Bang
HO. Haemostatic function and platelet
polyunsaturated fatty acids in Eskimos.
Lancet. 1979 Sep 1;2(8140):433-5.
7)
Meydani SN,
Lichtenstein AH, Cornwall S, Meydani M, Goldin
BR, Rasmussen H, Dinarello CA, Schaefer EJ.
Immunologic effects of national cholesterol
education panel step-2 diets with and without
fish-derived N-3 fatty acid enrichment. J
Clin Invest. 1993 Jul;92(1):105-13.
8) Hendra TJ,
Britton ME, Roper DR, et al. Effects of fish
oil supplements in NIDDM subjects. Controlled
study. Diabetes Care. 1990
Aug;13(8):821-9. |