Tuesday, March 07, 2006

Repetition Turns Myths into Truths if You Can Just...

..."Pay no attention to the man behind the curtain!"
The Wonderful Wizard of Oz

A month has passed since the publication of the null findings from the Women's Health Initiative Dietary Modification Trial and the media continues, in earnest, to try to convince you to stick with a carbohydrate-rich, low-fat diet. The repeated myths continue with a strong emphasis on eating less total fat but more monounsaturated and polyunsaturated fats in liquid vegetable oils instead of saturated fats in butter or meat. Emphasis is also placed on eating less animal foods and more plant foods with grains highlighted.

A few individuals are pointing out the flaws in the reasoning used to convince us that we should ignore the WHI null findings and continue to believe instead a low-fat diet is better for us in the long-term - the fatal flaws include things like trends are not useful, obesity remained an issue in both groups, risks increased in some women in the intervention group, etc. But this isn't stopping the "old guard" from basically telling us to ignore the evidence, just dismiss the fact that the study found no differences between the groups!

That very fact - that there was no difference - should be setting off alarm bells!

Basically, the Standard American Diet (SAD) is no worse than a low-fat diet - or conversely - a low-fat diet is no better than the SAD.

So, the one thing I totally agree with in all the media reports is this - the findings aren't a license to go out and eat whatever thinking it doesn't matter in the long-term. It does - and I'll tell you why...what few are willing to state is the obvious - neither diet is good for you or your long-term health.

And that is what you should care about!

We know, without a doubt, that the standard American diet, as it is today, is unhealthy for long-term health. Just look around you - two out of three adults are overweight, one of the two is obese. An estimated 25% of all adults have features of Metabolic Syndrome. Millions have Type II Diabetes. Cancer is now the leading cause of death in the United States. Cardiovascular disease is a close second. And now our children are out-pacing adults in diseases once thought to be only effecting the aged.

We also know, without a doubt, that a carbohydrate-rich, low-fat diet reduces intake of essential nutrients - especially fat soluable vitamins D and E, preformed vitamin A and often vitamin K; limited intake of animal foods limits our intake of complete protein (the best source for our essential amino acids) and vitamin B-12; and that switching to liquid vegetable oils significantly increases our intake of omega-6 and may disrupt the balance of our intake of omega-3 fatty acids negatively. Add to this our knowledge that a carbohydrate-rich, low-fat diet lowers HDL and increases triglycerides while also, often, increasing glucose and insulin and you start to understand the growing prevalence of Metabolic Syndrome, obesity and diabetes in this country.

Whether you eat the SAD or the recommended and highly touted carbohydrate-rich, low-fat diet, your chances of optimizing your health in the long-term are just not happening. Period. The proof is in the pudding - and the pudding is the WHI Dietary Modification Trial and numerous other studies - including, but not limited to the Nurses' Health Study, the Framingham Heart Study, MRFIT, the MRC trial, the Malmo Diet and Cancer Study, the Puerto Rico Heart Health Program, and the Caerphilly Study among others.

Taken together - the high number of studies that find a low-fat diet is not protective and/or does not reduce the risk of disease in the long-term and the known health related problems that crop up repeatedly if you eat the Standard American Diet - the findings should be making us dig deeper to find the answers to what type of diet really does give us a better chance to optimize our health in the long-term!

It's not like we're clueless - there are thousands of studies out there (yes, thousands) that keep telling us the same thing again and again:

  • Essential Fatty Acids (EFA's) are critical, especially omega-3 fatty acids
  • Intake of the full spectrum of Essential Amino Acids (EAA's) is critical
  • Meeting nutrient requirements for vitamins, minerals and trace elements daily is critical and some, like vitamin B-12, are best met with quality animal food sources
  • Non-starchy vegetables are rich in nutrients and fiber
  • Body weight is important but not the end all be all of long-term health - interestingly, when we meet our basic nutritional requirements, weight often takes care of itself
  • Stress is damaging both to our mental health and our endocrine system, increasing our nutrient requirements
  • Low-level, chronic inflammation is deadly
  • Failing to get adequate sleep and rest is damaging to our body
  • Physical activity in our daily life keeps our body "tuned" and "toned"
With this simple list - the question is, how does one eat and what lifestyle modifications will lead to a good chance of long-term health?

To start to answer that, let's step back for one moment and ask a better question first - what type of dietary approach reduces the risk of overeating with the highest odds of meeting critical nutrients that provide long-term health benefits?

This question, instead of the first one, addresses two issues - weight and meeting nutritional requirements.The answer to that question is easy - a controlled-carb dietary approach.

A controlled-carb approach offers an opportunity for nutrient-density that is superior to a low-fat diet along with a high level of satiety that is missing in a low-fat diet. Tomorrow we'll go step-by-step with a definition and comprehensive look at what a controlled-carb nutritional approach looks like and tap the evidence to see just how strong the data is and why the evidence supports it as the one dietary approach that can optimize health in the long-term!

5 comments:

  1. I'm curious what your specific answer is to the McDougall/Ornish critics who argue that the low-fat dieters in the WHI study weren't compliant, and that the diet wasn't low-fat enough.

    You've argued in the past that studies without compliance are a waste of research dollars, yet here you seem to be arguing that a study with non-compliant dieters "shows" that a "low-fat diet is no better" than the standard American diet.

    It seems to me that the "low-fat dieters" were actually eating a standard American diet...or close to it anyways.

    BTW, I agree entirely with your premise about high carb diets. But I just don't understand using the WHI study as evidence that low-fat diets are good, bad, or indifferent.

    The study participants' diets just didn't seem to me to be sufficiently different (at least after year one) to extrapolate to the diet the study authors wanted to study, or to lower-fat versions like Ornish or McDougall.

    What am I missing?

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  2. You've argued in the past that studies without compliance are a waste of research dollars, yet here you seem to be arguing that a study with non-compliant dieters "shows" that a "low-fat diet is no better" than the standard American diet.

    After reviewing the data from the full-text, it is pretty clear that the intervention group was eating significantly less fat than the controls at year 1 and year 6. At baseline both groups averaged 37.8% of their calories from total fat, with 12.7% from saturated fat.

    By year one, the intervention group was down to 24.3% total with 8.1% from saturated....by year 6 they ate 28.8% total fat and 9.5% as saturated fat. At both time measures the control group was consuming much more - at year 1, the controls ate 35.1% total fat and 11.8% saturated fat; at year 6 they were eating 37% of calories from fat and 12.4% from saturated fat. In fact, the control group averaged a higher-than-average intake of total fat (US average is about 32-34%) and a higher-than-average saturated fat intake (US average is 11%).

    So, while some are crying foul - that the low-fat group didn't comply - they most certainly DID achieve a dietary pattern we're told is optimal or better for us in the long-term - 30% or less calories from total fat with 10% or less calories from saturated fat.

    Whether they were compliant with the WHIDMT goal of 20% or not is moot here - my contention is that they were within the current recommendations for macronutrient intake and had no benefit to their health and no reduction of risks - basically at the end of the study they were no better off than the control group eating whatever they wanted - and if you look at the data tables in the full-text - page 662 - top left graph - you'll see that in year 9, the intervention group tops over the control group for "MI, CHD Death, or Revascularization" - basically their risk is higher than the control at that point...going from 93/10,000 in year 8 for the intervention group and 105/10,000 in the control to 141/10,000 in the intervention group and 120/10,000 in the control....if that trend bears out - what does that mean? Yup - a higher risk for the control...which at year nine still isn't "statistically significant" but if the trend keeps going -- when does it become significant?

    Also noteworthy - page 663 - last item detailed in the HR graph - those without history of CVD...straight out findings favor the control group, p=.006, the HR with 95% confidence doesn't cross the 1 - the only item, I might add, that is a significant finding when you're look at the confidence interval and hazard ratios as a range - yet hardly anyone is talking about it, but it's right there!

    So far as the "Ornish-set" - such a dietary patten, with 10-15% total fat - doesn't have long-term data (greater than 5-years) or a controlled trial in a healthy population where one group eats the ultra-low-fat diet and the other different mixes of macronutrients. Therefore, my reply would be "show me the data that supports that a strict reduction of fat and animal foods in a healthy population will provide a benefit - if you don't have it, get to work....!"

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  3. Yup - a higher risk for the control...

    That should have read a higher risk for the intervention group!

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  4. Thanks much for the explanation. I still think the numbers re the difference between the intervention and the control sound more impressive than they are practically. And in either case, it wouldn't be correct to extrapolate these findings to a VLF diet a la Ornish (not that I think you did).

    But I see your point (which I originally didn't grok). This study does suggest that your garden variety low-fat diet (a la AHA) does not lead to any short-term health benefits.

    Thanks!

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