Massive review shows conventional advice to reduce or change fat intake does not prevent disease or save lives

If you have any interest in health at all, you’ll be familiar with the concept of altering fat intake to reduce risk of disease and premature death. One central theme here is that certain types of fat (e.g. saturated fat) increases risk of ‘cardiovascular’ diseases such as heart disease and stroke, while others (e.g. polyunsaturated fats) have a protective effect. Either replacing saturated fat with polyunsaturated fat and/or reducing fat overall is supposed to be good for our health – but is it?

In recent years there have been quite a number of studies which have failed to find a link between saturated fat and cardiovascular disease. These studies cast considerable doubt on the wisdom of cutting back on saturated fat.

Yet, studies such as these that are ‘epidemiological’ in nature and only tell us of a lack of a relationship between saturated fat and cardiovascular disease. To really know whether cutting back on saturated fat and/or replacing it with supposedly healthier fats is beneficial to health we need to conduct studies that test just that, with what are known as ‘intervention’ studies.

Many studies of this type have been conducted over the last few decades. These were reviewed back in 2000 by a group of British researchers [1]. This review was actually a ‘meta-analysis’ (grouping together of similar studies) of 27 individual studies. The results revealed that modification of dietary fat did not lead to a significant reduction in either deaths due to cardiovascular disease or overall risk of death.

This meta-analysis was recently brought up-to-date by the same group of researchers [2]. Another decade’s worth of data was added in the form of another 21 studies. The studies in this review basically came in three forms:

1. studies where fat intake was reduced (usually by replacing fat with starchy foods) compared to usual or ‘control’ diet

2. studies where fat intake was modified (e.g. saturated fat replaced with polyunsaturated fat)

3. studies where fat intake was both reduced and modified

Let’s take a look at the results:

Reduction of dietary fat, modification of dietary fat, or both did not reduce the risk of death due to cardiovascular disease.

Reduction of dietary fat, modification or dietary fat, or both did not reduce overall risk of death.

The authors of this study report that there was evidence that reduction and/or modification of fat led to a significant reduction in risk of ‘cardiovascular events’ (basically a collection of fatal and non-fatal heart attacks and strokes). However, before cracking open the champagne, there’s a couple of things worth bearing in mind here.

First of all, dietary fat change did not lead to a significant reduction in risk of either heart attack or stroke when taken in isolation.

Also, some of the studies used in the analysis did not just employ changes in dietary fat, but other strategies too (for example, nutritional supplements were given to the treated group). This obviously makes it impossible to discern what elements of the treatment were effective.

Crucially, when such studies were removed from the analysis and studies that utilised fat modification were used, overall risk of cardiovascular events was not changed at all.

Here’s an interesting excerpt from the authors’ discussion:

“It is important that individuals and populations are receiving clear, evidence-based advice about the types of dietary fat changes which are most effective in reducing cardiovascular risk, as well as ways to achieve those changes. Further research comparing low fat and modified fat changes on cardiovascular disease risk factors would be feasible and helpful. This review suggests that modified fat intake, or modified and reduced fat intake combined (but not reduced fat intake alone) are protective against combined cardiovascular events. No clear effects of these interventions on total or cardiovascular mortality were seen.”

I’d agree regarding the importance of the public getting evidence-based advice. But why the need for further research? Are the results not clear? The pooled results of 48 studies show that low-fat eating or replacing saturated fat with polyunsaturated fats is an unmitigated failure. Why do we need more research? In the hope of keeping the fallacy alive?

What do the authors mean when they say “No clear effects of these interventions on total or cardiovascular mortality were seen.” Let me reword this line for the authors and call a spade a spade: “Conventional dietary advice regarding fat consumption has been proven to have no effect on risk of heart attack or stroke or cardiovascular mortality or total mortality – they don’t prevent disease nor save lives. We should abandon them.”

References:

1. Hooper L, et al. Dietary intake and prevention of cardiovascular disease: systematic review. BMJ 2001 322(7289):757-630

2. Hooper L, et al. Reduced or modified dietary fat for preventing cardiovascular disease.
Cochrane Database Syst Rev. 2011 Jul 6;7:CD002137.

20 Responses to Massive review shows conventional advice to reduce or change fat intake does not prevent disease or save lives

  1. alex 13 July 2011 at 11:19 am #

    Surely epidemioligical studies CAN prove a lack of causation if they show no relationship between to variables?

  2. Poisonguy 13 July 2011 at 1:17 pm #

    That’s not what one gets when reading the abstract at Pubmed, unfortunately. And most, including journalist, won’t read past that.

  3. TerryJ 13 July 2011 at 1:19 pm #

    Typo
    “modification or dietary fat”

    should be
    “modification of dietary fat”

  4. John Briffa 13 July 2011 at 2:02 pm #

    TerryJ

    Thanks – corrected now

  5. Marina Donald 15 July 2011 at 7:01 pm #

    What about trans-fats? I thought they were the real problem both for obesity and cardio-vascular health.

  6. Lesley 15 July 2011 at 7:51 pm #

    Hello Bee listen the Johns last podcast, statins reduce inflammation within the body. So much to understand and not enough lifetime to get to grips with a fraction of it.:-)

  7. Trish Cherry 15 July 2011 at 8:11 pm #

    Not much was said about reducing carbs. Mixing fat and carbs together is not good.

    Most people will think that they can just eat high fat foods, and not bother about other aspects of good eating.

    They need to know that meats have plenty of unsaturated fats as well as saturated. Its not Okay to eat meat in processed forms or pastry and pies. It is the fat in meat that is healthy not the fat in processed foods.

  8. Dale callaway 15 July 2011 at 11:29 pm #

    OKay.. So fats can get off the screen! The question remains:
    What can we eat or not eat to protect us?

  9. MrAntiWeetabix 16 July 2011 at 12:10 am #

    Who funded this study?

  10. John Walker 16 July 2011 at 12:28 am #

    Who funded? Ah the perennial question, which if answered, usually shows the results are suspect!

    JW

  11. George 2 16 July 2011 at 1:17 am #

    Surely there must be a way of collating all the gathering anecdotal individual ‘evidence’ that is out there?

    I now eat loads of natural fats. I feel like a new man!

    BP from 149/90 to 117/70. (I’m 59)

    Waist from 38in to 30in.

  12. Bee Hepworth 16 July 2011 at 1:17 am #

    I understand that there has been a noticeable reduction in deaths from cardiovascular disease in recent years. This has been put down to a reduction in the consumption of saturated fats and the dispensing of statins. I read your blogs enthusiastically Dr B, especially those on stains and fats, so I’m puzzled as to what you think this reduction is due to if not to the aforementioned!

  13. Maryann Napoli 16 July 2011 at 1:24 am #

    The same convoluted wording appears in a recent updated Cochrane review entitled, “Reducing Dietary Salt Intake for the prevention of CAD”. The reviewers found that cutting down on salt reduces blood pressure one or two points but there is no evidence that this will reduce the risk of heart attack, stroke or prevent CAD. Link to abstract within this article http://medicalconsumers.org/2011/07/12/reducing-salt-intake-has-no-effect-on-heart-risk/

  14. DanC 16 July 2011 at 5:55 am #

    Meta-analyses are the biggest fraud ever perpetrated by the medical community. None of the underlying studies are accountable to the scientific method (that is, none of them can be reproduced to yield the same results) so combining these studies just magnifies the the error.

    Just like the American Tobacco Industry and cigarette smoke, this smells of the BCSFA? (British Cattlemen’s Saturated Fat Association?). Dr B plays his hand and theirs again.

  15. Alan C 16 July 2011 at 12:15 pm #

    Very interesting post Dr B. I have personally felt very weak, sick, depressed and un-manly on low fat diets. Then I read about traditional diets and increased saturated and monounsaturated fats, reduced “carbage” and consumed vitamin D from cod liver oil.

    Since making these changes I feel and look better, my sex drive has returned (to the relief of my wife), and I have never been fitter- Running the 2 mile cooper test in under 12 minutes, squatting 140kg (I am an athlete). I have less colds and my overall well-being has improved. I have normal blood pressure and cholesterol levels.

    Whether or not saturated fat causes heart disease to me is besides the point (although I think it does not) because I can see many more benefits to consuming it than not.

    We all know of the appalling Ancel Keys study and we’ve all read “Fat and Cholesterol are Good for You” by Uffe Ravnskov, right?

    I’ve made up my own mind from study and personal experience. I eat more fat because it makes me healthier!!!

    Eat your fat, balance Omega 3 + 6, lower grains, lift weights, run, meditate, get sun exposure, take ALA + vitmain C + CoQ10, perform coffee enemas = NEVER BEEN SO FULL OF LIFE!!!

    Well off topic but hey it might do someone some good.

    Peace out Dr B!

  16. Joseph Putnoki 16 July 2011 at 2:49 pm #

    To the timely and important article I wish to add:

    the cholesterol con and the animal fat hysteria dominate today. Both the food and the drug industry mislead and/or confuse good doctors and frighten patients into the arms of the pharmaceutical industry. What is needed is to look at the statistics of circulatory diseases and deaths prior to 1950 and contrast it to the deterioration till today.
    The rot set in some 150 years ago when heart disease was the sixth on the list of killer diseases. In a few decades it climbed to the top. What happened?* Our ancestors existed on then Palaeolithic diet till about 10000 years ago when agriculture was invented and we started to eat grains as staple food. We are omnivores though. Our diet contained both fatty acids of animal and plant origin. Omega 6 from plants, pro inflammatory and omega 3 long chain animal origin (mainly sea animals) and the ratio was 1:1. Both fatty acids are needed how ever when the balance gets distorted to present levels of more then 30:1 inflammation is getting out of control and becomes chronic. Arterial inflammation sets in motion of the cascade of events ending in atherosclerosis. Regardless of cholesterol levels. Corrupted studies cited as evidence for the need to lower cholesterol and medicate with statins. This is criminal! More in a moment,**

    Drs. Evan and Wilfrid Shute of London, Ontario, Canada were the first medical doctors to realize that an adequate vitamin E status is vital to the health of the heart. In 1945 they discovered that 200 IU per day of vitamin E was beneficial in reversing heart disease and in treating angina pectoris. By 1954 the Shute brothers had treated over 10,000 heart disease patients with miraculous results(1). Unfortunately, when they tried to publish their findings in medical journals their scientific papers were rejected and the medical establishment continued to ignore their findings for another 40 years. A glimmer of hope occurred in 1959 when the United States Food and Drug Administration (FDA) formally recognized that vitamin E was indeed essential to human health.
    RDA Inadequate
    In 1959 the average North American diet provided about 20 mg/day of vitamin E, so based on the observation that very few people suffered from any of the more or less obscure vitamin E related deficiency diseases recognized by the medical establishment, the RDA (Recommended Daily Allowance) for vitamin E was set at 30 IU (20 mg) per day. In 1974 this level was lowered to 15 IU/day when the FDA realized that the average diet now only provided 10 IU or less per day(2). In other words, the RDA was adjusted to conform to the inadequate and steadily decreasing level of vitamin E in the American diet. The absurdity of this whole situation can perhaps best be illustrated by the fact that an eminent scientist and member of the RDA panel, who in 1974 supported the contention that a vitamin E intake of 10-30 mg/day would be adequate for an adult, publicly stated in 1991 that he was himself taking 400 IU of vitamin E every second day. To quote “…The knowledge that undesirable products of lipid peroxidation in human tissues can be decreased by taking vitamin E have persuaded me to personally take a 269 mg (400 IU) supplement of d-alpha- tocopherol every other day(3,4).”

    Vested interests run contradictory studies claiming vitamin e- vas ineffective or even causing heart disease! The investigators used synthetic form of the vitamin which is 8 times less absorbed plus the dose was too low. It was a sham: they designed the trial to get the wanted outcome rather then a properly conducted ethical one. This is in fact the case at present.

    Back to what happened*: as flour became part of our staple diet it was stone ground containing all the grain’s ingredient. It did not last too long before got stale and insects emerged. When the steel roller mill been invented the grains could be milled at finer gaps which allowed the incremental closer rolling and sieving separating the starch as fine white flour from the husk and the seed germ. The white flour lasted 7 months without becoming stale or bugs emerging as there were no nutrients for the bugs. It became popular. It could be shipped to any part of the world. But at what cost? The husks removed contained the B vitamins and some minerals and the seed germ the vitamin E. Increasing pollution and changed industrial agricultural food production practices exhausted the soil of nutrients and killed the living microorganisms and the worms. The artificial fertilizing, the chemical spraying increased and the vigor of the produce declined and pests increased. At present time it became essential for those of us who can’t grow our fruits and vegetables or raise animals to take quality supplements that are missing from what we buy. But there is also an issue: the health food industry and the supplements are not guaranteed uniformly nutritious or of quality. Lot of cheating with organics claimed at high price and lot of useless supplements too. And the drug and the food industry are hostile to supplements as well.

    Back to more in the moment**:

    there is something wrong with SOME fats of vegetable and animal origin. The processed seed oils for cooking especially the cottonseed oil with high pesticide residue. Vegetable oils are from vegetables, or their seed or fruits like grape seed, almond or walnut oils, we eat the fruits and vegetables of these but we don’t eat cotton! The omega 6 overload from the processed vegetable cooking oils fuel inflammation not mediated by omega 3. The omega 6 overload further increases as the livestock now mostly housed in feedlots, their food contain ingredients like corn and other oilseeds foreign to grazing animals who has to learn to eat them being fattened up quicker. Their fat if grazing on unpolluted pastures would contain some omega 3 , not as much as fish and other sea animals but these feedlot animals’ fat contain extra omega 6!

    I will say more some other day.

    Be well!

    joseph.

  17. Pete Grist 16 July 2011 at 5:31 pm #

    Given the tendency to see farming as the worst thing to hit mankind, it’s surprising we’re all living longer! Perhaps the problem with these studies is that they looked at what people are eating now rather than past events in their lives? Those born in the 1940s onward seem to be healthy enough and I remember a diet rich in meat, pies and saturated fat, but mainly butter, lard and suet – not processed. You also needed it to keep warm in winter!

    I would have thought the drop in smoking is the main cause of the reduction, but could it relate to childhood diets in the depression of the late 20s and early 30s?

  18. doug cook 16 July 2011 at 7:15 pm #

    There are dozens and dozens of ‘risk factors’ for cardiovascular disease and yet the approach worldwide focuses on one: LDL and the use of statins. What frustrates me is that we never talk about LDL sub-fractions; that small dense LDL IS a problem and the best way to minimize the production of it is to eat more fat [really more mono and saturated and less omega-6 fats], moderate carb and less sugar..this will profoundly reduce the production of small dense LDL, drop triglycerides, boost HDL and with less omega-6 incorporated into the LDL, less oxidation.

    More emphasis needs to be place on the ratio of omega-6:omega-3, more dietary antioxidants to protect LDL oxidation and phytochemicals to enhance endothethial function.

    Statins have been found to be beneficial for several reasons that have nothing to do with LDL lowering, and why isn’t their a dialogue around the face that cholesterol levels are at an all-time low, statin use is at an all-time high yet the incidence of CVD remains unchanged from what I understand.

    A good review on the role of statins, LDL and CVD is written by anthony colpo

    Journal of American Physicians and Surgeons Volume 10 Number 3 Fall 2005

    AND statins don’t reduce/change the production of small dense LDL

    http://www.ncbi.nlm.nih.gov/pubmed/20844614

  19. Richard David Feinman 20 July 2011 at 10:32 pm #

    The principle that associations don’t prove causality is made up by people untrained in science. There is always an idea behind an association and science, in any case, doesn’t run on these arbitrary classifications. And Alex is right. Negative results are always stronger than consistency. I tried to discuss in my blog:
    http://wp.me/p16vK0-69.
    It is the strength of the recommendation on fat that means it shouldn’t fail at all, not once. No meta-analysis is needed. Dr. Briffa is right. Enough is enough.

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  1. Is The Paleo Diet Heart Attack Proof? » Paleo Diet News - 24 August 2011

    [...] heart disease.  Dr. John Briffa, a UK-based supporter of a low-carbohydrate, paleo-centred diet, writes about the results of two studies reported in the British Medical Journal: Many studies of this type have been conducted over the last few decades. These were reviewed back [...]

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