We are, without a doubt, facing a
nutritional crisis in Australia and the U.S. One manifestation is confusion as
to what constitutes sound nutritional principles 1,2. Recent scientific
advances have not led to consensus, but rather to substantial disagreement
among experts and further uncertainty for the public. The public are confused.
One such area of uncertainty is that there really is no credible scientific evidence
that saturated fat causes heart disease or, more generally, cardiovascular
disease. Although we are constantly told that saturated fats are “bad” and that
margarine is better than butter (which it is not), there is no evidence to
support this “bad fat” myth.
Unfortunately there are many myths
perpetuated by certain members of the food and drug industry as well as so-called
reputable groups who have strong vested interests in margarine. For example the
position paper by the Heart Foundation 3 states that:
· Saturated fatty acids (SFA)
intake is associated with coronary heart disease (CHD); and
· Replacing SFA with omega-6
PUFA (vegetable oils) to achieve a ratio of PUFA to SFA of greater than 1 will
reduce the risk of CHD.
The foundation also states, “Our
position on dietary fats and dietary cholesterol was developed from a review of
the latest scientific evidence and incorporates recommendations from our
previous papers.” In truth, though, all of this is out of date and absolutely
wrong. The first thing to note is that this evidence is based on research
from1999 that has never been updated.
All the research over the past decade and even more recent findings, including
our own research below, has shown exactly the opposite of these claims. Most
importantly if you look at our evolution it just does not make sense.
Despite half a century of rigorous
research, dietary advice from governments and doctors alike, and public
campaigns urging the reduction of dietary fat, cardiovascular disease is still
the leading cause of death in developed countries 4. We have
consistently heard that saturated fat increases the risk of cardiovascular
disease while polyunsaturated fats like vegetable oils and margarine have a
protective effect in reducing fat overall (in particular saturated fat) and, as
such, are supposed to be good for our health. During the past 40 years the
dietary instructions from governments and other authoritative bodies have told
us to avoid all animal fats. Average fat consumption decreased, average blood
cholesterol levels decreased but the rate of heart disease and the cost of its
treatment continued to rise. Replacement of saturated fat by polyunsaturated or
monounsaturated fat lowers both LDL and HDL cholesterol. However, overwhelming
research shows that cholesterol is not the public enemy it has been made out to
be, it is just a warning that you liver (and body) are under stress and you
need to take some action to reduce that stress, not the warning signs.
By contrast, replacement of
cholesterol with a higher carbohydrate intake, particularly refined
carbohydrates, can exacerbate the build-up of plaque in the arteries
(atherosclerosis) associated with insulin resistance and obesity that includes
increased triglycerides, small LDL particles, and reduced HDL cholesterol. Dietary
efforts to improve the increasing burden of CVD risk associated with atherosclerosis
should primarily emphasize the limitation of refined carbohydrate intakes and a
reduction in excess adiposity.
Unfortunately, poor studies and
vested interests have led us astray. For example, some older broad based
(ecological) studies found, through cross-examining per capita intake of
saturated fatty acids and other dietary fat items, a correlation with the death
rate from coronary heart disease 4. However, in some studies, equally
as strong coefficients were found in the number of radio and TV licences, and
almost equally as strong as the number of registered motor vehicles, suggesting
the implausibility of ecological-based study conclusions 4. The
evidence against saturated fat has at best always been circumstantial. That is,
saturated fat was said to elevate blood cholesterol and elevated blood
cholesterol was said to cause heart disease therefore saturated fat would cause
heart disease. There never has been any direct evidence that cholesterol or
saturated fat cause heart disease or even of a mechanism whereby heart disease
would occur.
Bias very likely exists in the
findings of the studies, with researchers choosing particular countries or data
sets to indicate a preferred result 4. An example of this is the
early work of Dr Ancel Keys, which launched this attack on saturated fat and,
at the same time, introduced the cholesterol myth back in the 1960s. In the
Seven Countries Study, Keys looked at Italy, Greece, Yugoslavia, Netherlands,
Finland, the United States and Japan reporting a strong straight-line
relationship between saturated fat intake, heart disease and cholesterol levels
5. He chose to ignore 14 countries that had good data available. Choosing
another seven countries—Finland, Israel, Netherlands, Germany, Switzerland,
France and Sweden—shows the exact opposite results and thus reveals the bias in
the early studies 5.
When we review theses studies, we
find no relationship with saturated fat and heart disease of any type. When we
review updated data, this lack of relationship clear. The
top seven consumers of saturated fats (France, Switzerland, Netherlands,
Iceland, Finland, Austria and Germany), with saturated fat energy percentage
ranging from 15.5% to 13.7 %, all have a lower death rate from CHD than the
seven bottom consumers of saturated fats (Georgia, Tajikistan, Azerbaijan, Moldova,
Croatia, Armenia and Macedonia)—with saturated fat energy percentage ranging
from 7.5% to 5.2%. Similarly, countries with the top five highest
cardiovascular death rates (Belarus, Kazakhstan, Russian Federation, Ukraine
and Azerbaijan) are in the lowest 50% of saturated fat consumers. These facts
appear to be the exact opposite of what we are told by governments and doctors.
The lowest death
rate in the bottom seven consumers of saturated fats (Croatia) of 17 per 100,
000 is same as the highest death rate in the top seven consumers (United
Kingdom and Ireland). This may also be confounded by socioeconomic differences
with the more developed countries being closer to the top with better health
care facilities and less poverty. As in the men, the highest consumer of
saturated fat (France) also has the lowest death rate from cardiovascular
disease with 4 per 100, 000 for women and 22 per 100,000 for men. For years
this was called the French paradox and was an excuse to make up another myth
that alcohol is good for you. The bottom five death rates (France, Switzerland,
Iceland, Italy and Spain ) are all in the top 50% consumers of saturated fat. The
top five highest death rates (Turkmenistan, Uzbekistan, Azerbaijan, Kazakhstan
and Moldova) are in the bottom 50% consumers of saturated fat. The death rates
for coronary heart disease in women are also significantly less than for men in
comparison of the two graphs, indicating a possible gender difference. This is
not reflected in Australian data with both a higher prevalence (20% of women
and 17% of males) and death percentage (37% for women 32% for men) of CVD
existing in women 6.
Even the famous Framingham study,
which originally hinted at a problem with saturated fats, now shows there is no
association between dietary fat and heart disease and indeed the association of
elevated cholesterol and heart disease is limited to a small segment of the
study population 9. In the Framingham Heart Study, researchers
working with a population-based cohort study, a total of 832 men, aged 45
through 65 years, found the risk of ischemic stroke declined with total fat,
saturated fat and monounsaturated fat (e.g., olive oil) but not polyunsaturated
fat such as margarine and vegetable oils 10. In effect, increased
intakes of fat, saturated fat, and monounsaturated fat (olive oil) were
associated with reduced risk of ischemic stroke in men. The exact opposite of
what we have been told.
The evidence continues to mount
that there’s no benefit and, in fact, probable harm from a low-fat diet. I
cringe when I hear people talking about a low fat diet and laugh at all the
marketing around low fat foods which are usually both full of sugars and low
nutrient density carbohydrates. Two recent studies underscoring this finding
are the Women’s Health Initiative and the Nurses’ Health Study. The Women’s
Health Initiative studied 48,835 women and demonstrated no benefit from a low-fat
diet in terms of heart disease or breast cancer 11. The Nurses’
Health Study, which has followed 90,000 female health professionals, demonstrated
no reduction in heart disease or cancer as a result of a low-fat diet 12.
A meta-analysis of the research of
27 separate studies found that modification of dietary fat did not lead to a
significant reduction in either deaths due to cardiovascular disease or overall
risk of death 13. Ten years later, the same researchers examined
another 21 studies and found exactly the same results 14. The
researchers reported that pooled results of all the studies showed low-fat
eating or replacing saturated fat with polyunsaturated fats had no benefit
whatsoever and may even be harmful. Similarly, examination of the 33 data sets
from prospective cohort studies in a meta-analysis found no plausible evidence
for a consistent association between saturated fatty acid intake and risk of
coronary heart disease (CHD) 4. A separate analysis which examined
16 studies with CHD as the focus and eight studies with stroke as the focus,
showed no association between dietary saturated fat intake and prevalence of
disease 15.
The most recent definitive examination
of all the competent studies on saturated fats and heart disease shows that
over a five- to 23-year follow-up of 347,747 subjects, there is no association
between the intake of saturated fat and heart disease or stroke. The
meta-analysis of prospective epidemiologic studies showed that there is no
significant evidence for concluding that dietary saturated fat is associated
with an increased risk of CHD or cardio vascular disease (CVD) 16.
Even in animal trials, evidence
shows positive effects of saturated fat. One study published in the American Journal of Physiology-Heart and
Circulatory Physiology investigated heart functioning by evaluating gene
expression profiles of rats fed high dietary fat after a heart attack 17.
The research demonstrated that a high-fat diet improved overall cardiac mechanical function (the heart’s ability
to pump)—that is, heart functioning was seen to improve on the high-fat diet.
The links between dietary fat,
saturated fatty acids, serum cholesterol and cardiovascular disease are all
part of the same “diet-heart hypothesis” with milk and dairy products—especially
those with high fat content (butter, whole milk, cheese)—being publicly
demonised due to saturated fats’ association with increased serum cholesterol 4,15,19-21.
This, despite the fact that numerous studies found that overall consumption of
dairy products (typically high saturated fat content) was not associated with
mortality 21,22.
The cholesterol hypothesis
separates cholesterol into two types for the sake of simplicity, low-density lipoproteins
(LDL) or “bad cholesterol” and high-density lipoproteins (HDL) or “good
cholesterol” 23. Cholesterol has been so successfully publicly
demonised that lowering cholesterol is earning pharmaceutical companies more
than 20 billion dollars annually in the US with the sale of the top two statin
drugs, Zocor (simvastatin) and Lipitor (atorvastatin), alone 23.
Despite this, supporters of the diet-heart hypothesis seem to have forgotten
cholesterol’s essential and natural role in human biochemistry, with 80% of
total body cholesterol being manufactured by the liver 24. They also
ignore the basic science studies demonstrating that blood fat profiles, the
presumed cause for concern, is largely determined by consumption of
carbohydrates, not fat consumption 25,26.
In a recent review of dietary
guidelines, researchers were scathing of the guidelines for critical
weaknesses, including use of an incomplete body of relevant science;
inaccurately representing, interpreting, or summarizing the literature; and
drawing conclusions and/or making recommendations that do not reflect the
limitations or controversies in the science. This is a mild way of saying
scientific lying. The researchers also said that it “does not provide
sufficient evidence to conclude that increases in whole grain and fibre and
decreases in dietary saturated fat, salt and animal protein will lead to positive
health outcomes” 27. It seems that dietary guidelines around the
world are lead by the money not the science.
This is all summed up in a major
independent, international review by The Expert Consultation held jointly by
the World Health Organization (WHO) and Food and Agriculture Organization (FAO)
in late 2008 which found no evidence that saturated fat causes heart disease. The
WHO/FAO report states: “Intake of SFA [saturated fatty acids] was not
significantly associated with CHD mortality…. SFA intake was not significantly
associated CHD events [e.g., heart attacks]…. fatal CHD was not reduced by…
low-fat diets.”
For the sake of our health, and the
health of our parents and children, it’s time to change our thinking and start
questioning what we are told about saturated fats and for that matter a lot of
the information we are spoon fed.
References
1. Boyle
et al. 2008;
2. Nestle
2007
3. Heart
Foundation (October 2012
4. Parodi
2009
5. Kendrick
2007
6. Australian
Institute of Health and Welfare, 2010
7. Luzzi
(1998
8. European
Heart Network (2008).
10. Gillman
et al. 1997
11. Howard
et al. 2006
12. http://www.channing.harvard.edu/nhs).
13. Hooper
et al. 2001
14. Hooper
et al. 2011
15. Hu
et al. 2010
16. Siri-Tarino
et al. 2010
17. Berthiaume
et al. 2010
18. Hu
et al. 2010;
19. Bonthuis
et al. 2010;
20. Elwood
et al. 2010;
21. Gibson
et al. 2009
22. Bonthuis
et al. 2010;
23. Bowden
2010
24. The Great Cholesterol Deception, 2011
25. Volek
et al. 2008;
26. Forsythe
et al. 2008
27. Hite
et al. 2010
Acknowledgements Matthew
Partridge
