What’s wrong with saturated fat?

There has been so much media coverage lately about saturated fat, with newspaper and magazine articles, and even peer reviewed journal articles claiming that saturated fat isn’t that bad after all. This news is well received by people who love to hear good news about their bad habits. It allows people to avoid the difficulty of change and to keep eating the foods that are making them sick.

Lurking in the background behind the saturated fat issue are powerful industries whose products are relatively high in saturated fats. Most guides to healthy eating include the advice to eat less saturated fat, but they shy away from naming those foods we should eat less of for fear of offending the meat and dairy industries. So we end up with recommendations that mix food advice, e.g. eat more fruit and vegetables with nutrient advice e.g. eat less saturated fat. Why not just say “eat less cheese”?

The saturated fat/high cholesterol/atherosclerosis/heart disease link is well established. Nothing has changed to refute decades of research which link high fat animal products with heart disease, diabetes, cancer and other diseases. The only real challenge to the ‘saturated fat is bad’ paradigm is whether some of the adverse effects of foods high in saturated fat might be due to other features of these foods such as animal protein, carnitine, choline or haeme iron. For practical purposes it doesn’t really matter whether it’s the saturated fat or something else – it’s still meat and dairy foods that are contributing to chronic disease.

Many of the stories woven to refute the health hazards of saturated fat are based on several key scientific publications:

  1. Chowdhury, R., Warnakula, S., Kunutsor, S., Crowe, F., Ward, H. A., Johnson, L., . . . Di Angelantonio, E. (2014). Association of Dietary, Circulating, and Supplement Fatty Acids With Coronary Risk: A Systematic Review and Meta-analysis. Annals of Internal Medicine, 160(6), 398-406.
  2. Malhotra, A. (2013). Saturated fat is not the major issue. BMJ, 347, f6340. doi: 10.1136/bmj.f6340
  3. Siri-Tarino, P. W., Sun, Q., Hu, F. B., & Krauss, R. M. (2010). Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. American Journal of Clinical Nutrition, 91(3), 535-546. doi: 10.3945/ajcn.2009.27725 (NB This research was funded by the dairy industry)

It all sounds quite plausible until you actually look at the fine detail of the evidence given, which takes considerable time and skill… few health professionals do this, so what hope has the general public got? We are indebted to people like Plant Positive, Dr John McDougall, Dr Michael Greger, T Colin Campbell and others who invest the time and effort to cut through the smoke and mirrors. Below is an extensive list of resources that will help you understand what’s behind the sensational headlines.

Resources

Two recent (January 2015) videos from Dr Michael Greger explain how industry works to confuse the public on the saturated fat issue. The second video presents powerful evidence that saturated fat does indeed raise blood cholesterol and the risk of heart disease:

An extensive analysis of this topic is provided by Plant Positive. His whole website (and YouTube channel) is designed “to correct specific falsehoods and flawed arguments that pervade the popular and academic discussion of nutrition”:

Saturated fat articles:

Cholesterol **February 2015 update**

In Feburary 2015 it was reported that the new US dietary guidelines will withdraw their recommendation to limit dietary cholesterol. Below are some responses from plant-based practitioners:

Saturated fat and cardiovascular disease **June 2017 update**

In June 2017 the American Heart Association published a ‘Presidential Advisory’ written by a team of highly experienced researchers who conducted a thorough review of the scientific literature into the effects of dietary saturated fat:

David Katz, MD wrote several articles trying to counter the pushback from low carb/high fat advocates in the days and weeks following publication of the AHA paper:

Other responses:

Books:

  • Campbell, T. C., & Jacobson, H. (2014). The low-carb fraud. Dallas, Texas: BenBella Books, Inc.

Related pages:

Page created 4 July 2014
Last updated 8 July 2017

The Canary and other Organs

Atherosclerosis is a whole body disease affecting every artery. Therefore any organ can potentially be compromised by impaired blood supply. A partially blocked artery may cause symptoms such leg muscle pain on exertion. A sudden complete blockage may result in a stroke. Diseased small vessels can cause dementia and kidney failure. Even in the absence of artery narrowing, an unhealthy artery may be unable dilate, resulting in erectile dysfunction.

Penis

Often the first sign of whole body artery disease is erectile dysfunction. The penis has one of the highest concentrations of endothelial cells in the body. Nerve signals cause these endothelial cells to produce more nitric oxide which dilates the arteries to inflate the penis with blood. Anything that narrows arteries or impairs endothelial cell function can disrupt this process which makes the penis a sensitive indicator of artery disease and provides an early warning for heart disease. It has been said that “the penis is the canary in the coal mine”. (Early coal miners carried canaries to warn them of toxic gases underground). Women have similar erectile type tissues and are also affected ( see NutritionFacts.org Cholesterol and Female Sexual Dysfunction  ).
A short video on diet and erectile function: Raise the flag with a vegan diet

Brain

The human brain is an energy hungry organ and is responsible for a significant part of our resting energy use. The high-energy needs of neurons combined with their sensitivity to low oxygen levels makes a good uninterrupted blood supply to the brain critical. Neurons die within minutes of sudden loss of blood supply such as when a stroke occurs, leaving that part of the brain permanently impaired. Strokes also occur on a very small scale. Brain scans of older people on the usual Australian diet are often speckled with scar tissue as a result of these mini-strokes. This damage contributes the decline in brain function which begins as early as one’s forties. Those most severely affected develop vascular dementia. Alzheimer’s disease is different but clearly related to vascular disease, sharing the same risk factors as heart disease. There is an impending epidemic of dementia because of the escalation in diabetes and obesity. You can avoid being part of this statistic. See Neal Barnard’s new book: Power Foods for the Brain

Vision and Hearing

The light receptors and nerve cells at the back of the eye are also very sensitive to lack of oxygen. The blood vessels on the back of the eye can be viewed directly and impaired passage of red blood cells can be observed following a fatty meal. The macular is the area responsible for our central spot of high resolution vision and has an even more precarious blood supply. Macular degeneration is most likely the result of impaired local blood supply and other dietary factors.

The nerve cells of the inner ear have a precarious blood supply and are similarly damaged by arterial disease.

Kidneys

The kidneys are another high blood flow tissue that is frequently affected by artery disease, particularly disease affecting the smaller vessels that feed the individual filtering units. Early kidney damage is revealed by the leakage of small amounts of blood proteins into the urine, microalbuminuria. This is associated with dietary intake, of animal protein, animal fat and cholesterol (see NutritionFacts.org Preventing Kidney Failure Through Diet )

Legs

Obstruction of some of the main arteries running down the legs is extremely common in older persons, particularly if they are diabetics or smokers. Usually this happens gradually and enough blood finds its way down side channels to keep the legs alive. Surgery is frequently performed to bypass blockages of major vessels, but if nothing is done to prevent progressive artery disease, amputation can be the end result.

Lower Back Pain

… is also linked to atherosclerosis (see NutritionFacts.org Cholesterol and Lower Back Pain )

HDL and LDL

Blood cholesterol is complex. Your blood test results will include measurements of some of the individual lipoproteins, HDL and LDL. But there are further levels of complexity that should make us wary of dismissing the risks of elevated blood cholesterol on the basis of “good cholesterol” levels and ratios.

Cholesterol and other fats do not dissolve in blood and are transported in the blood as lipoprotein particles. These are small globs of cholesterol, fat, and special proteins that give each type of particle their characteristics.

Your blood cholesterol report will usually start with “total cholesterol”, which is the total amount of cholesterol in all of the lipoprotein particles in the serum. (Serum is the liquid between the blood cells).

LDL particles (low density lipoprotein) transport cholesterol from the liver to other parts of the body. LDL is often called “bad” cholesterol because abnormally high levels cause artery disease. There is nothing “bad” about LDL when it’s not elevated.

HDL particles (high density lipoproteins) transport cholesterol back to the liver for recycling. HDL is often called “good cholesterol” because high levels are considered to protect arteries from cholesterol build up.

Triglyceride is a measure of the ordinary fat being transported in the blood. Several lipoprotein particles are involved and the fat comes both directly from food and from fat synthesized by the liver. High triglyceride levels are associated with low HDL levels and qualitative changes to LDL that increase heart risk.

Cholesterol test results also include a ratio of HDL relative to total cholesterol (or sometimes LDL). A lot of emphasis is placed on this ratio in Australia. Your doctor may tell you that it doesn’t matter how high your cholesterol level is, as long as the ratio is good. We disagree.

Total cholesterol, HDL and LDL are useful measurements but are far from the whole story. Both types of particles come in different sizes and composition: some LDLs are worse than others and not all HDLs are beneficial.

LDL particles vary in size. Large lower density particles are more likely to predominate with healthy lifestyles and are less damaging to arteries. Small dense particles are associated with high cholesterol diets, diabetes and obesity and cause cholesterol plaque build up in arteries. The most damaging form of LDLs are the small dense oxidised LDL particles. The oxidative stress of a fatty high cholesterol meal increases oxidised LDL for several hours.

The protective, cholesterol recovering and recycling properties of HDL are of more importance in populations with high cholesterol levels, such as Australia. In populations with very low total cholesterol levels, due to plant strong low fat diets, the average HDL levels are also low, yet the incidence of heart disease is very low. You don’t need high HDL levels to remove cholesterol from your arteries when there is not much there to start with.

HDL particles also vary in quality. The HDL measurement in your pathology result is the total volume of HDLs but it may be that the number of HDL particles that is more important. It is the efflux capacity of HDL that really matters – that is its capacity to pick up and carry cholesterol. This capacity may be reduced by the same dietary patterns that oxidise LDL particles.

HDL might not be the anti-heart disease entity we once thought it was. That there is a strong inverse association between HDL levels and heart disease is not in dispute. Low HDL levels in people with high cholesterol levels are a strong heart risk predictor. But this low HDL may be a marker of a more general adverse profile of cholesterol particles associated obesity and insulin resistance. But very high HDL levels may not offer extra protection. A recent genetic study by Dr Sekar Kathiresan (The Lancet 2012), suggests that inherited high HDL levels does not protect against heart disease.  Furthermore, pharmaceutical trials of drugs that artificially elevate HDL levels have so far failed to reduce heart risk.

Some foods, such as vegetable oils and alcohol, improve LDL and HDL levels but do not lower heart risk.

The limits of only measuring fasting cholesterol levels and ignoring what happens after meals is discussed in the endothelium and atherosclerosis page.

The documentary, “The Last Heart Attack” includes discussion about the differing types of LDLs and HDLs.

Diet and Cholesterol

Changing to a whole foods plant based diet results in dramatic falls in blood cholesterol levels. The medical myth that diet has little effect on cholesterol stems from the fact that the current cholesterol lowering diet recommended in Australia is not effective. A diet rich in animal “protein” foods, with or without vegetable oil, will always raise cholesterol. In general, animal products raise blood cholesterol and whole plant foods lower blood cholesterol.

Cholesterol, fats and fibre

Dietary cholesterol raises blood cholesterol. However saturated fat has a much more powerful effect on raising blood cholesterol. Saturated fats stimulate the liver to synthesize more cholesterol which makes a big difference because most of the cholesterol in our bodies is made by the liver rather coming from the diet. This is why eggs, which are high in cholesterol but relatively low in saturated fat, don’t raise cholesterol as much as some other animal products. (Eating more eggs, however, is associated with more artery disease).

Only animals produce cholesterol. It is found in meat, chicken, fish, eggs and dairy foods. All plant foods are free of cholesterol. Most animal foods contain at least moderate amounts of saturated fats. Some commonly eaten foods such as cheese are alarmingly high in saturated fats. Chicken and lean red meat are promoted as low fat “protein” foods but both contain significant amounts of saturated fat (and to make matters worse, much of the red meat and chicken eaten by those on high protein diets are not the super lean cuts that are used for advertising these foods). Some plants do contain saturated fats: palm oil, coconut, and some nuts are actually quite high in these. But unsaturated fats are more common in the plants.

Only plants produce chemicals called phytosterols which prevent the intestine from reabsorbing the cholesterol that the liver has disposed of through bile. Oats are just one example of a whole plant food that contains sterols that lower cholesterol. Oats are also a nutritious mix of fibre, nutrients, protein and slow release carbohydrate. Cholesterol lowering sterol enriched margarine has no fibre, almost no nutrients, is very high in calories and contains considerable saturated fat. No contest.

Some types of fats produce favourable looking changes in blood cholesterol but do not reduce heart risk. Olive oil for example, improves the ratio of good and bad cholesterol but is still damaging to arteries. The solution to the health damaging effects of a fatty diet is to eat less fat not different fat.

For cholesterol lowering properties, whole plant foods win. They have no cholesterol, are generally extremely low in saturated fats, and they inhibit cholesterol reabsorption. The heart health benefits of whole plant foods go beyond just lowering fasting cholesterol. Plants are rich in phytochemicals that have antioxidant and anti-inflammatory qualities that reduce chemical damage to the endothelium and dampen down the inflammatory response in the artery wall. See Endothelium and atherosclerosis. Once again, the health damaging effects of the usual Australian diet are not just due to what people are eating but also what they are not eating.

The effectiveness of diet

The standard cholesterol lowering diet recommended by Australian health authorities has changed little over the past forty years. It includes generous quantities of meat, dairy foods and oils. The fat content of up to 30% of calories is still high by international standards and the meat and dairy, and even the margarine and olive oil contribute substantial amounts of saturated fats. The fibre content is low. The bottom line is that this type of diet has failed the field tests, lowering blood cholesterol by less than 10%. This has led the medical profession and the public to conclude that diet has very little effect on blood cholesterol and that high blood cholesterol must be caused by genes and other factors.

The main effect of genes is to influence the extent to which your cholesterol will become elevated when your body is exposed to a diet rich in animal products and low in dietary fibre. If you live on a low-fat plant based diet these “susceptibility” genes become irrelevant. The Apo E4 cholesterol gene mutation causes much anxiety in those that have it as it is associated with dementia and heart disease, but international studies suggest that these risks are negated by a heart friendly diet. There are some exceptions: one in every few hundred Australians carry a genetic mutation that causes high LDL cholesterol levels. Even these individuals can lower their cholesterol to moderate levels by diet alone.

All communities who consume low-fat plant-based diets have very low blood cholesterol levels. The China Study observed that in some regions average blood cholesterol levels were as low as 2.4. However some argue that these people were living a non-Western lifestyle and perhaps their low cholesterol was related to hard physical work, low stress or malnutrition. Previous theories attributing their low cholesterol levels to genetic or childhood epigenetic changes have been dispelled by the rapid rise in cholesterol and heart disease in newly Westernised Chinese city dwellers. This has occurred within one generation.

There are numerous studies showing that a low-fat mostly plant-based diet results in a dramatic reduction in blood cholesterol levels in those living an otherwise normal Western lifestyle. Nathan Pritikin became well known following the success of his live-in program which included a very low-fat predominantly plant-based diet and exercise program. Blood cholesterol levels fell by 25% in those that started with average cholesterol levels and by 36% in those who started with even higher levels. In the Lifestyle Heart Trial conducted by Dr Dean Ornish, average cholesterol levels also fell by about 25% (without cholesterol lowering drugs). Dr Caldwell Esselstyn virtually cured heart disease in a group of 18 subjects whom he treated for over 20 years with a no oil plant based diet. Average cholesterol levels fell from 6.3 to 3.5 (some subjects also used medication). Rip Esselstyn, author of Engine2, recorded average decreases in cholesterol of about 30% in those that followed his no oil plant based diet.

It seems that a whole foods plant based diet typically lowers blood cholesterol by 30%. The fact that falls in blood cholesterol are greater for those with higher initial levels makes sense because what is in effect happening here is that blood cholesterol levels are falling to levels that are normal for humans. See Normal Cholesterol

Engine2 and Forks Over Knives Facebook page frequently have inspirational testimonials describing dramatic falls in blood cholesterol levels. These testimonials are individual case studies that alone carry no statistical significance but together constitute evidence that diet does indeed lower cholesterol effectively.

Resources

  • Blocking the First Step of Heart Disease – In this short video, Dr Michael Gregor discusses how we can prevent atherosclerosis in our coronary arteries by increasing our intake of fiber-containing plant foods and decreasing our intake of trans fat, saturated fat, and cholesterol found in junk food and animal products.
  • Cancer Reversal Through Diet? – This video starts off by discussing a landmark study by Dr Dean Ornish, way back in 1993, which showed that intensive lifestyle changes can reverse atherosclerosis, opening up narrowed arteries. The discussion then moves to cancer prevention: a welcome side effect for a heart disease treatment program.
  • TEDxCambridge – Caldwell Esselstyn on making heart attacks history – Dr Caldwell Esselstyn discusses the results of his heart disease reversal diet.
  • Vegans with High Cholesterol – Sarah Taylor

Normal Cholesterol

“Normal” blood cholesterol levels in Australia are not normal or supportive of good health. These “normal” levels result in an enormous burden of heart disease and a population in which almost everyone has artery disease by age 65. The national goal of less than 5.5 mmol/l is well up into the zone in which artery disease develops. The medical profession knows this and the official safe level for cholesterol following a heart attack is less than 3.8 approximately (the target being LDL<1.8). So, we have the situation where you can be reassured by your doctor that your cholesterol level of 5 is OK, suffer a heart attack later that day, and be told the next morning that your cholesterol needs to be less than 4 to prevent further heart attacks (which they think can only be achieved with statins). A whole foods plant based diet can lower your cholesterol to a safe level without the inconvenience of having to have a heart attack first.

Humans have a similar cholesterol metabolism to herbivores. This is an observation rather than an argument for or against eating meat. It is easy to experimentally induce artery disease in herbivores: you just replace some of their usual fibrous unprocessed plant foods with some saturated fat and cholesterol.

It is well established that there are multiple risk factors for heart (artery) disease including obesity, inactivity, family history and diabetes to name just a few. Blood cholesterol often gets buried among these, even in education aimed at doctors. Statistical analyses often underestimate the contribution of high cholesterol to heart disease because they choose a cut off point for normal vs high cholesterol that is way above the safe level of less than 4. Therefore all of the heart disease that occurs in those with cholesterol levels of 4.0 to 5.5 (or sometimes even higher) are considered to have been caused by risk factors other than high cholesterol. It has recently been proposed by leading cardiovascular expert Prof Roberts (see Eliminating the #1 Cause of Death ) that there is only one risk factor for heart disease – high blood cholesterol. The other risk factors only come into effect when cholesterol is elevated above 3.8.

A lean fit person with ”normal” cholesterol can still develop heart disease, and conversely, heart disease rarely occurs in people with very low cholesterol levels even if they are not very fit. There is individual variation in just how much blood cholesterol your arteries can tolerate before becoming diseased and blocked, and there is variation in how much fatty food it takes to raise your blood cholesterol to dangerous levels. This is where genetics and other lifestyle and dietary factors can swing the outcome. Fortunately nearly all of us can overcome the genetic factors with a whole foods plant based diet and avoid heart disease altogether. A recent large multi-country study found that known modifiable risk factors accounted for 90% of heart attacks (Yusuf et al 2004).

A normal, safe, cholesterol level is difficult to define precisely but may be as low as 3.8mmol/l. Unrealistic without medication? No, this level is normal in populations where the diet is predominantly plant based and consequently heart disease is uncommon. It is interesting that the individual spread of cholesterol levels in Australia overlaps so little with the range of cholesterol levels found in low risk populations. An interesting observation of The China Study was that the incidence of heart disease (between different provinces) increases as cholesterol levels increase from 4.0 to 4.5, levels that have been regarded as in the safe range in Australia. Even within developed countries, very low cholesterol levels are protective – Framingham Heart Study director, William Castelli, MD, reported that in 35 years of the Framingham study, no subject with a cholesterol level under 150 (3.85 in our units) ever suffered a heart attack (Esselstyn 2007,p.30)

The current medical focus solely on fasting cholesterol may be misguided. It ignores what happens in our arteries for hours after each meal (see Endothelium and atherosclerosis). It’s like assessing diabetes by only measuring fasting blood glucose and ignoring very high levels that may follow high fat meals.

NOTE: cholesterol is measured in different units in USA. Multiply cholesterol by 40 (39 to be precise) to translate into their units. 150 in USA units (mg/dl) = 3.8 in Australian units (mmol/l), or use a cholesterol conversion website (see below).

See also:

Resources: