Wednesday, November 14, 2012
Saturated Fats are not so bad for us: Truth and Lies
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 In truth, though, all of this is out of date and absolutely wrong.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.
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
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