fat and cancer
Fred and Alice Ottoboni
Can I please get some of your responses/comments on the following?
Animal Fats Linked to Increased Breast Cancer Risk, Study Finds
July 15 (Bloomberg) -- Eating high-fat red meats and dairy products such
as cream may increase the risk of breast cancer in pre-menopausal women,
according to a study published in tomorrow's issue of the Journal of the
National Cancer Institute.
A diet high in animal fat raised the risk by as much as 54 percent, said
lead author Eunyoung Cho, a nutrition researcher at Boston's Harvard
Medical School and Brigham and Women's Hospital. The eight-year study
enrolled 90,000 women aged 26 to 46.
The findings suggest that the Atkins diet and other regimens that
encourage people to eat meat to lose weight may harm younger women, Cho
said. Her study found no link between breast cancer, which kills about
40,000 people a year in the U.S., and high levels of vegetable fat or
animal fat from chicken, turkey or fish, she said in an interview.
``I would not recommend that diet for pre-menopausal women, unless they
replace red meat with poultry and fish,'' Cho said.
Women at the high end of animal fat consumption got 23 percent of all
their calories from meats and dairy products, almost twice as much as
those who ate the least animal fat. Some researchers believe that a
high-fat diet may increase the risk of breast cancer by spurring the body
to make estrogen, which can contribute to tumor growth, Cho said.
A statement in March from the World Health Organization found that there
was insufficient evidence to link animal fat with cancer, and other
large-scale studies have found the same result, said Mary Young, executive
director of nutrition for the National Cattlemen's Beef Association in
``This is one study, and the authors themselves note that this study is
inconsistent with eight other studies that found no association between
red meat and breast-cancer risk,'' Young said in an interview. ``I would
encourage consumers to be confident about eating lean beef.''
Earlier studies of fat and breast cancer focused on older women who had
already started menopause, said Walter Willett, a Harvard Medical School
nutrition researcher who co-wrote the study. Those experiments may have
failed to find a link because menopause lowers women's estrogen levels, he
``This is the first detailed look at diet in an earlier point of life than
we've been able to study before,'' Willett said in an interview. ``We're
cutting into some new territory.''
Cho asked women enrolled in the Nurses Health Study II, a survey of
behavior and health risks in 14 states, to answer questions about their
diet twice. The work provides more evidence that women should moderate
their intake of animal fat, she said.
``Prevention of heart disease already provides a good reason to choose a
diet low in animal fat,'' Cho said. ``Adopting this kind of a diet early
in life could offer the benefit of cancer prevention, too.''
A study of 90,000 women over eight years has to be taken pretty
seriously. I would like to see few more details to make sure that
potential confounding variables were dealt with honestly (if that is
possible to establish
. My gut feeling is that this study is 'wrong.' But that may
just be my personal prejudices raising their ugly head.
article by Cho et al., Premenopausal Fat Intake and Risk of Breast Cancer,
J Natl Cancer Inst 2003;95(14):1079-85, draws a shocking conclusion based
on their actual data. The RR of breast cancer for the highest
quintile of animal fat intake falls between the the RRs of the 2nd and 3rd
quintiles of intake. This is not a dose-response. The 95% CI
for intakes of total fat, animal fat and saturated fat were barely
A number of obvious confounders was not considered,
such as supplement intake, frequency of examination for breast
Other studies indicate quite the opposite, for example,
Gertig D et al., Intl J Cancer 1999;80:13-17.
Fred and Alice Ottoboni
far, we have only been able to get hold of the abstract of the paper by
Cho, et al. On this alone, we agree that there is
something wrong with the paper. Joel, your noting that the data
given in the paper indicates that the response does not increase with
increasing dose (the highest quintile was between the 2nd and 3rd
quintiles) is insightful and pretty good evidence that there is something
wrong with the study conclusions.
We also agree with the comments of other Skeptics that
all the works from certain institutions on this subject need to be
viewed with suspicion and more suspicion.
have several comments. First, epidemiological studies are
interesting, but do not prove cause/effect. In communicable disease
epidemiology, the rule is that conclusions must be proved by hard science
(Koch's Postulates), such as isolating the organism and then causing the
disease in a test animal using this isolate. John Snow, proved his
case in about 1850, by removing the pump handle on the Broad Street
Pump. When the cholera stopped occurring in the neighborhood, Snow
knew that the source was the water from this pump (hard scientific proof).
The germ theory was not accepted at that time.
seems that chronic disease epidemiologists, particularly those at
Harvard, have a habit of drawing conclusions based on epidemiological
studies alone. Possible flaws in such studies tend to be ignored and
conclusions based on epidemiology alone are reported as fact. Such
flaws would be rapidly exposed if epidemiological conclusions
regarding chronic diseases were required to be proven by some kind of hard
science like biochemistry or human feeding studies. This failing is
one reason the American mainstream dietary recommendations are wrong to
the point of being responsible for causing disease rather than preventing
there are several (epidemiological) studies in the
literature showing that omega-6 fatty acids in the diet are associated
with breast cancer. Chemistry, a hard science, shows that omega-6
fatty acids are much higher in breast cancer tissue than in normal
breast tissue. Biochemistry, another hard science, shows that
high omega-6 to omega-3 ratios in the diet (and high glycemic
carbohydrates) stimulate the delta-5 desaturase enzyme to produce
arachidonic acid that is further processed by the Cox-2 and Lipoxygenase
enzymes to produce a surplus of cancer-stimulating eicosanoids.
could find no such data for the so-called saturated animal fats. In
fact what we found were papers that indicate that
saturated fat is beneficial insofar as it replaces omega-6 in the diet.
We also note from biochemistry that the human body produces saturated fat for
padding and for storage of energy. It is not likely that the
human body would routinely produce such fat if it was carcinogenic.
Evolution would have solved that problem many years ago.
is always possible that this flawed paper is simply another attempt to
slow the forces of Atkins and friends.
As Mary Young states, this study contradicts all other studies, not only
about red meat but also about the various types of fats. Compare
with Silvia Franceschi, et al. Intake of macronutrients and risk of breast
cancer. Lancet 1996; 347: 1351-6, for example, which showed that "The
risk of breast cancer decreased with increasing total fat intake . . .
whereas the risk increased with increasing intake of available
carbohydrates." And ". . . the intakes of saturated fatty
acids, protein and fibre were not significantly associated with breast
explanation can there be for the 5th quintile having less cancer than
the third or fourth?
also have to recognise that, even if it is true, this study may not apply
outside the USA. Meat is reared in that country on grains and soy. The
grains reduce the amount of CLA in the fat -- and CLA is a powerful
anticarcinogen. The soy contains phytoestrogens -- and breast cancer is a
hormone-related cancer. Growth-enhancing hormones and antibiotics are
also used in beef production, which is why US beef is banned in the EU.
Does this play a part?
if the women with the cancer were on Atkins, what supplements (that he
sold) were they also on?
far as I am aware, there is no evidence (and there never has been) against
beef or dairy products outside the USA. So perhaps, they should look to
their own production methods, and not worry us.
again, the NCI has to sell chemotherapy. Perhaps there is a hidden agenda.
in all there are too many unknowns in this trial. I -- and my wife --
will not stop eating beef based on this study. But then she is
- Once again a misleading paper from Willett´s group. First, as also
pointed out by others, the fact that the risk in the 4. quartile is the
greatest contradicts any causal association considering the large number
of individuals included in the study. As Eddie mentioned, confounding is
probably explaining the result – for instance was the number of smokers
almost twice as high in the 5. quintile than in the first. The authors did
correct for smoking in their multivariate calculation, but in another way.
For instance, it is not relevant to select between previous and current
smokers when it comes to cancer risk; number of smoking years had been a
let us assume that their figures reflect the truth. Then, to claim that the risk of breast cancer increases by 58% by
eating animal fat is close to criminal. Let me calculate in another way.
If you eat on average 14 cal % animal fat per day your chance not
to get breast cancer according to their study is 99.32 %. If you gorge in
18-21 cal.% (4. quintile) your chance not to get breast cancer goes
down to “scary” 99.12 %. But eat a little more, eg. more than 21 cal.
% animal fat (5. quintile) and your chance increases to 99.27 %.
Notice where the "research" comes from, Harvard.
Notice also that there MAY be a link between excess iron but this
is not mentioned. I think that this is yet another mistake attempting to
link the obvious (fat) without accounting for other factors that might be
operating at a molecular level. Were
the women overweight?
Those who ate Atkins like food all the time
were SPECIFICALLY at risk? Did
they measure serum ferritin levels? How about Linda
A general point is that any trial can be ripped apart because
it did not
look at all possible confounding factors. I do not feel that, as a group,
should fall into the 'easy' trap of suggesting two basic things:
1: They did not include factor X, and we think factor X is important (We
surely assume that through randomisation factor X was equally shared in
various groups) You cannot possibly study all factors in one clinical
2: That in some way the researchers were dishonest in the way the prepared
or presented the trial data. Doing this means that any trial can be
dismissed. 'Oh that lot at Harvard, they would say that, wouldn't they.'
Other suggestions that instead of having quintiles, they should have had
deciles or some other data split are, again, easy statements to make. They
could be made about any trial.
We are, in my opinion, thus far, guilty of the same sin we accuse the
diet-heart zealots of suffering. Attacking and dismissing data without
treating it seriously. Or, simply stating that other trials have shown the
opposite, so this trial is probably wrong. I saw that one about the ALLHAT
study that showed no effect on CV morbidity and mortality on Pravastatin.
The refutation was (sic) 'some doctors reading this may think that statins
don't work, but we know that they do.'
I haven't yet seen an attack on the data that is robust and scientifically
valid. I sense an emotional attack on a trial because it attacks our
This doesn't mean, in any way, that the trial is correct. But we must, I
believe, presume innocence until found guilty.
Gulp! Malcolm is
right, and I am guilty of making nonscientific comments.
not yet seen the article, I don't mind stirring things up a bit by
injecting a few comments
to get things going, as it were. I
just don't have the time (got to work too) to keep up with the detail, so
I blast forward with emotional comments from time to time.
I do APPRECIATE the efforts made by others to make a more exact
analysis. So, Malcolm, if you will take my comments with a POUND of
salt, it might go down better.
coming issue of the Lancet has a comment on the article you presented.
Sounds interesting, available from Friday 18 July.
here is another one in today's Lancet. I haven't got the full study to
which this refers, but this explains it.
think what we are seeing is a rearguard action by the "healthy
diet" food police, to protect their reputations. Just imagine what
would happen in such a litigious society as the USA if people sued them
for all the obesity, diabetes, heart disease, cacner, etc that is caused
or exacebated by the "prudent" diet.
group had published a paper in March in which they analysed the data set
of the original NHS which had enrolled women of substantially higher age.
There they were unable to find a breast cancer risk for read meat intake (see
abstract below). Interestingly in their new paper by Cho et al. this NHS I
analysis was not even mentioned.
Holmes MD, Colditz GA, Hunter DJ, Hankinson SE, Rosner B, Speizer FE,
Willett WC. Meat, fish and egg intake and risk of breast cancer. Int
J Cancer. 2003 Mar
"Intakes of animal protein, meat, and eggs have been associated with
breast cancer incidence and mortality in ecological studies, but data from
long-term prospective studies are limited. We therefore examined these
relationships in the Nurses' Health Study. We followed 88,647 women for 18
years, with 5 assessments of diet by food frequency questionnaire,
cumulatively averaged and updated over time. We calculated the relative
risks (RR) and 95% confidence intervals (95% CI) for risk of developing
invasive breast cancer, over categories of nutrient and food intake.
During follow-up, 4,107 women developed invasive breast cancer. Compared
to the lowest quintile of intake, the RR and 95% CI for the highest
quintile of intake were 1.02 (0.92-1.14) for animal protein, 0.93
(0.83-1.05) for red meat and 0.89 (0.79-1.00) for all meat. Results did
not differ by menopausal status or family history of breast cancer. We
found no evidence that intake of meat or fish during mid-life and later
was associated with risk of breast cancer."
Nicolai - They will probably argue that the most recent
paper dealt with animal fat, not animal protein. But why didn´t they
present all their data in one paper? The reason is that these data can be
used to produce an endless number of papers with minimal effort. Choose a
new disease and then analyze the food stuff the victims of that disease
have eaten, but of course not all foods in one paper - fats in one,
proteins in another, vitamins in a third and so forth. Logically, one in
twenty comparisons will become statistically significant at the 5 % level,
and the show goes on. Fresh headlines and new scares.
Thank you everyone who responded. Great points all.