This is a link to a rather long post by Denise Minger (famous for her relentless review of The China Study) on Mark's Daily Apple, which examines a "study" which concludes whole grains are better for you than refined grains. Denise shows how to examine such a study, and how quite often, the 'conclusions' of such studies are not as clear as they may be purported to be. It also shows how, with these epidemiological studies, there are very serious structural issues, primarily, that there are so many confounding variables. Because of the inevitability of confounding variables, epidemiological or observational studies are not satisfactory for drawing cause and effect relationships. Their purpose in science is to discover hypotheses which can then be tested via intervention studies.
In other words, Denise does a bang up job of showing what any of us should know before we read the first word of this study - which is that observational studies cannot be used to determine causality, and anyone who claims otherwise is ignorant or advancing an agenda by means which are not 'scientific.'
http://www.marksdailyapple.com/will-eating-whole-grain-fiber-help-you-live-longer/#comment-727063
This "study" is akin to folks who say things like "scientists say" or "scientists think"in order to give authority to some opinion or another. The opinions of 1,000 scientists, like the opinions of 1,000 NBA basketball players, really has no bearing on scientific proof. Either good intervention studies have been conducted and reviewed and causality is proved, or not.
That's not to say that you cannot learn a lot from the opinions of folks who vigorously engage the pursuit of truth via the scientific method - but their opinions are no more equal to truth than my labrador's opinions are.
This bring us to the problem for the science of diet and health. Humans are long lived and not often comfortable being caged and controlled for their entire lives, and therefore they are extremely hard to test via intervention study. Intervention studies are expensive and not often done, and when they are done, they are not always done well - one recent study supposedly tested "low carb" diets against low fat diets, but the "low carb" diet was 150g/day of carbohydrate, which was "lower carb" but not low carb for many folks (it might be "low carb" for a 300 pound professional athlete, but I'm nearly certain the test population wasn't 300 pound professional athletes).
In short, the science of human diet and health is immature and will remain that way. This is why any science you can conduct on yourself may be more valuable that the conclusions of most "studies." The best way to do such experimentation is with an objective measure of a key short term variable, such as blood glucose measuring to determine the glycemic impact of a meal - see this post by William Davis for an example.
In other words, Denise does a bang up job of showing what any of us should know before we read the first word of this study - which is that observational studies cannot be used to determine causality, and anyone who claims otherwise is ignorant or advancing an agenda by means which are not 'scientific.'
http://www.marksdailyapple.com/will-eating-whole-grain-fiber-help-you-live-longer/#comment-727063
This "study" is akin to folks who say things like "scientists say" or "scientists think"in order to give authority to some opinion or another. The opinions of 1,000 scientists, like the opinions of 1,000 NBA basketball players, really has no bearing on scientific proof. Either good intervention studies have been conducted and reviewed and causality is proved, or not.
That's not to say that you cannot learn a lot from the opinions of folks who vigorously engage the pursuit of truth via the scientific method - but their opinions are no more equal to truth than my labrador's opinions are.
This bring us to the problem for the science of diet and health. Humans are long lived and not often comfortable being caged and controlled for their entire lives, and therefore they are extremely hard to test via intervention study. Intervention studies are expensive and not often done, and when they are done, they are not always done well - one recent study supposedly tested "low carb" diets against low fat diets, but the "low carb" diet was 150g/day of carbohydrate, which was "lower carb" but not low carb for many folks (it might be "low carb" for a 300 pound professional athlete, but I'm nearly certain the test population wasn't 300 pound professional athletes).
In short, the science of human diet and health is immature and will remain that way. This is why any science you can conduct on yourself may be more valuable that the conclusions of most "studies." The best way to do such experimentation is with an objective measure of a key short term variable, such as blood glucose measuring to determine the glycemic impact of a meal - see this post by William Davis for an example.
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