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Winter 2006 - The Low-Fat diet


Uffe Ravnskov
Dag Viljen Poleszynski

Jørgen Vesti Nielsen
Jacqueline Walker

Uffe Ravnskov

Eddie Vos

Morley Sutter

Leib Krut
Sally Fallon

Marshall Deutsch

Jacqueline Walker

Joel Kauffman

Uffe Ravnskov

Uffe Ravnskov
Three articles in this week's JAMA have been published about an 8-year long lowfat trial in more than 40000 women. No effect - neither as regards breast cancer, colon cancer, CHD or stroke.
Surprise - surprise! 

Dag Viljen Poleszynski
The studies prove nothing, but Norwegian "experts" are doing their best to make it appear as a support to high-carb diet!! If anything, it shows that even a 320 kcal/d energy reduction for 7½ yrs does not lead to significant weight loss when the diet is dominated by carbs!

Jørgen Vesti Nielsen 
There is one interesting thing in the JAMA weight study. Mean weigth change was -1 kg. The Standard deviation however was 10 kg. So the mean weight change was -1(+ -10) kg. That means that a large minority of the women actually increased in weight. About 17 % of them increased by more than 9 kg, and about 2.5 % increaseed by more than 19 kg. This is certainly not a normal distribution. One expects to find behind such a wide distribution 2 populations with different means, but merged in one. Probably the ones who increased and the ones who decreased. 

Jacqueline Walker
There seems to be a lot of post-hoc justification going on - on both sides of The argument. Of course from the usual suspects we get: 'Well, the low-fat intervention didn't Prevent [insert condition here] because it wasn't stringent enough (20% reduction target not met) or targeted enough ('good' fats were decreased as well as 'bad' fats, oh and we didn't know about trans fats then!) or the participants were all overweight anyway (!!!) [so this result doesn't count]...'
Or the best one I saw 'the diet advice didn't include salt reduction so that's why it didn't improve heart health' reported on
http://news.bbc.co.uk/1/hi/health/4690230.stm)  On the other hand the fact that 7-8 years of a low-fat diet did not produce weight loss has turned into an unexpected bonus allowing them to say that it 'does not result in weight gain' and take a pot shot at the anti-carbers! I bet they didn't set out to see whether a low-fat diet caused weight gain back in 1993! Of course low-carb people might shoot back that the % energy from carbohydrate only increased by a small amount in the intervention group, but clearly that did not make the intervention women put on weight. Actually there's no mystery as to why the intervention women on average lost a teensy bit more weight - on average they ate a teensy fewer kcal as well.

I'm not so sure either that the S.D. on the weight loss figures conceals anything. For the smaller ethnicity sub-groups it does - look at the error bars on the all the plots in Fig. 2 where they plot weight loss over time by ethnicity group They're overlapping all over the place except for the group as a whole and the largest group - non-Hispanic whites. But this is just the greater statistical variation you expect in small groups.

Of more interest are the plots of weight loss over time separated into age groups. As far as I can see they show a completely natural progression in older women – some weight gain up to and around menopause, then, eventually, with increasing age, weight loss. Thus, the older women lost weight (both groups) and the younger women put it on (both groups) i.e. contrary to the report of a weight loss by the end of the study - that was actually due to the older women. By the end of the study, the youngest women had putweight on - just that the intervention group had put on less. Similarly, contrary to the key claim of 'no weight gain' women of a 'normal' BMI did put weight on. 

I don't think you can discount some kind of 'placebo' effect or perhaps better to call it a Hawthorne effect. As Lorgeril pointed out in his Med. Diet presentation, you can't blind a nutritional study! And (and I wonder about this for the Lyon heart study too) the people in the intervention group get much more attention - they get 'intensive behavioural modification sessions' and 4 meetings a year and so on. The control group just get handed a brochure. There may well be a contribution from this attention and the additional focus it creates in the mind of the participants. To me, this may explain the infuriating way these studies (while although not proving their point) always seem to be able to say '.. a small but nonsignificant trend to less [insert condition here] in the target group...' thus keeping their hopes alive!

Uffe Ravnskov  
I agree. The authors had a further comment: "The possibility that the effect might have been greater if the diet had been initiated at younger age cannot be ruled out." I think it can because there was no difference in outcome between those who had a low intake of fat or SFA at baseline and those who had a high intake. It seems not too farfetched to assume that the diet recorded at baseline reflects these people’s usual diet.

Eddie Vos 
Jacqueline, I'm all with you -- until you mentioned Lyon.  The n=300 control group did nothing and the n=300 intervention group did nothing [human nature], EXCEPT receive free for the whole family a non hydrogenated canola oil based margarine --and indeed they replaced butter with it-- and they were supposed to try and use some olive oil [sure] andeat more fish [they did not] and eat more 'mediterranean' [10 more lentils/beans per day etc].  I.e. dietary advice [sorry dietitians] never works but people WILL take a gift, or buy canola instead of sunflower oil [same price]. 
To get Lyon into Lancet [after NEJM refused it since the cholesterol lipids did not change one iota], they negotiated with Lancet to make it politically correct and they put in the word 'Mediterranean' [and the ignored phrase: alpha-linolenic enriched].  Now, everybody promotes olive, Mediterranean et al while the blood fatty acid demonstrated difference in the n-3's [ALA and derived EPA] were the only significant changes that actually took place. 
 

Morley Sutter 
I have been concerned for some time about the thinking (or lack of it)  that surrounds so many reports in the press, both medical and lay. The paper that I have put on the group site attempts to rank evidence and I would appreciate any comments.  The paper has appeared in the BC Medical  Journal. It's fascinating to read the rationalisation that is being written in the Canadian press (Globe and Mail) to attempt to paper over the lack of effect of diet as reported in the JAMA.  I have decided that the cholesterol myth is a  meme aided and abetted by vested interests, both academic and commercial.
 

Leib Krut 
T
he academicians and members of the profession in general are so invested in the "fat" story that it would be professional and academic suicide to accept the truth. Drowning people are said to grasp at straws, but these straws have somehow kept them afloat, largely because no one really wants to confront the reality of a 50 year old bit of nonsense that began with what was long ago shown to be fraudelent data. 
Well, the sun did ultimately stop orbiting the earth,................  

Sally Fallon 
The newspapers are putting their spin on the recent Women's Health study results, saying that although the study showed that lowfat was worthless, the results indicated that we should avoid trans and SATURATED fats.  Has anyone taken a close look at the data.  I would like to know whether the study found negative evidence about saturated fats. 
See this link for a media portrayal of the Nurses Health Study: http://tinyurl.com/lapdb

Marshall Deutsch 
THe study showed that the women on the low fat diet had significantly lower LDL levels but no significant difference in cardiovascular disease. In other words, it showed that if there is any relationship between LDL level and cardiovascular disease it is too small to be detected in a study on a very large group of middle-aged women. Why have I seen no comment pointing it out? Am I missing something here? 

Jacqueline Walker 
Sally and sceptics, I don't know, I despair sometimes I really do - when I see the findings of those recent studies misrepresented to that extent... especially in the popular press which is all most people read... 
And surely Willett saying: 

' What the findings do show, yet was often lost in news reports, is that eating more fruit and vegetables as well as less saturated and trans fats cuts the risk of heart disease and cancer.'

That evidence is 'quite strong'  is an outright porky! It doesn't show anything of the kind! Even the ' weight loss' results (weight gain more like) as I and others have already pointed out are mis-explained. And as for 'even bad carbs aren't so bad' - that was not being tested guys !  - so you can't really validly comment about what effect it did or didn't have. 
(Footnote: strictly speaking -  I know I made this same error when commenting the longitudinal weight changes between age subgroups in my previous email on this topic. However, it was interesting to look at, added an extra perspective on what was going on and I did acknowledge that the low fat group did end up less heavy than the control group (because they ate fewer calories typically).
Would they publish letters to the editor or even a rebuttal article to correct this woman's nonsense?

As regards Sallys question. In a word, NO.  The study found no significant increase in CVD outcomes in the low-fat group EXCEPT, they found the hazard ratio for women in the low-fat intervention group who already had CVD to increase 1.26 (CVI 1.03-1.54) and this was significant (P=0.006). Interestingly they put this bit in at the end of a section in a sentence which completely omits to mention the direction of the 'interaction between the intervention and the [baseline] disease'). However, they did do some fancy calculations on CHD risk and found some groups where this fell where saturated fat and trans fat consumption was lowered. Now this can usually safely be ignored because 'risk' usually just means the application of a model incorporating LDL levels, triglycerides, diabetes, BP etc. 
However, it's not clear how this was calculated. The paper says: 

"Trends for changes .... were examined by evaluating CHD risk for individuals stratified by quartiles of achieved levels of key nutrients in year 1, using the rate in the comparison group as reference. Analyses were adjusted for age, baseline CHD,  ... randomization group.."

My question is - is this using actual CHD outcomes for the intervention individuals or not? It's not clear because then they talk about a 'CVD risk model' which includes the usual suspects (BP, cholesterol level etc.). And then they compare each quartile intervention group with the WHOLE comparison group! 
If anyone can help me out here - it's in 'Additional Analyses' in the Results section. 

Joel Kauffman  
Jacqueline is certainly correct that the researchers in past work have used corrections for TC, LDL, etc., in the wrong direction for the age group. I found that by using their raw data for events, opposite conclusions would emerge.  

Uffe Ravnskov
What is particularly shocking is that the effect of the low-fat diet on clinical events was never tested before it was recommended to the public. To get a drug into clinical practice demands that it has been shown to be harmless or at least without serious side effects, first in various laboratory animals, then in healthy voluntary test subjects, and finally its therapeutic value must have been proven in a number of clinical trials. But dietary advices are given to millions of people based on speculation only.

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