November 21, 2013

The Latest Scare Study: Or Why Eating Meat Does Not Cause Diabetes

I've received several worried emails over the past week written in response to a study which is being highlighted by the vegan/low fat/low-carb-diet-haters, who are using it to supposedly prove that eating a low carb diet rich in meat will acidify your blood and give you diabetes.

This article is summarized here:

Dr. Weil, who has earned millions promoting his own brand of faddish health advice summarizes it here:

I went and read the actual study, which you can find in its full form here:

Dietary acid load and risk of type 2 diabetes: the E3N-EPICcohort study

Here's my take on it:

I am always very suspicious of the findings of any large study that draws its conclusions from questionnaires purporting to measure what people are supposed to have eaten over a set period of time. And it turns out that this is exactly what was done here.

The measures of blood acidity used in this study, PRAL and NEAP, are not determined by measuring blood acid in the participants. Instead, they are computed using a formula which was  applied to the answers given in response to a standardized dietary questionnaires filled in by study participants.  You can read a critique of the methodology used to establish the forumulas used to convert these questionnaire responses to estimated blood acidity here: Critique on equations of net endogenous acid production (NEAP) and indirect proof of constant organic acid excretion

But even if this study is wrong that the formulas are flawed, since the level of blood acids are not actually measured, the reliability of the study result all comes down to the quality of the questionnaires used. And that is something I have personal experience with, as I was a subject years ago in a study of low carb dieters, a study that used one of these standardized nutritional survey questionnaires.

As the study proceeded I filled out this multiple-choice questionnaire several times. At one point, the nutritionist running the study mailed me my personal dietary analysis based on the answers I had given. Since this occurred during the year when, to lose weight successfully, I had taken to actively logging every bite I ate using LifeForm software, and carefully measuring portion sizes, too, I was able to compare my actual intake, as tracked in my log with what the questionnaire said I had eaten.

The questionnaire's results weren't even close. It ascribed to me a much higher calorie intake than what I was actually eating, and even more significantly, came up with  a completely different breakdown of carbs, protein, and fat--one that gave me a much higher carb intake than what I was actually eating. One that would have completely knocked me out of the ketogenic state that random tests with ketone strips confirmed I was maintaining.

The total failure of the questionnaire to reflect my dietary intake didn't surprise me, though, because the multiple choice questions that made up the questionnaire were written in such a way that it was impossible for me to give accurate answers.  For example, there was no option to answer "never" to many of the questions about my intake of high carb foods like potatoes. Instead I had a choice of reporting I had eaten potatoes "1 to 5" times in the previous month.

And though the questionnaire might ask about how often I had eaten red meat, or even about how often I had eaten "hamburger" it did not ask any questions that would make it possible to determine whether the "meat" I reported eating was the pink slime laced with MSG eaten at McDonalds or a home cooked burger made of high quality ground sirloin.

Even worse, there was no way that the questions posed by the questionnaire could determine if the "red meat" I had eaten had been accompanied by a big white bread bun and a big serving of fries. A person eating a stack of pancakes with syrup, eggs, and ham for breakfast who fills in this questionnaires is scored as eating "meat", in these questionnaires, though any future sorry metabolic outcome linked to eating this kind breakfast more likely to be due to its high carb intake, the high fructose in the syrup and the phosphates and other chemicals in the ham.

So these fatally flawed questionnaires will point the finger at "meat" when the real nutritional culprits may be something else entirely.

That's why I would not don't take this study too seriously. If you had a study where blood acid levels were actually measured in a large population over a long period of time and the measured high blood acids were found to be correlated with a nasty health outcome, it would be worth thinking about, but the costs of that kind of study are prohibitive, so it isn't likely to happen.  But as we have no way of even knowing if the participants in this study really had high levels of acid in their blood, and if the higher level of diabetes found in people who said they ate a lot of meat was caused by the meat or what they ate alongside of the meat, the rest of the study's conclusions are really a stretch.

That said, as I have written before, people eating low carb diets should be careful to eat quality, unprocessed meats and, as discussed in an earlier blog post, it is very wise to avoid eating meats laced with the inorganic phosphates that will damage your kidneys and heart. A low carb diet whose protein component is made up largely of fast food burger patties, processed foods, and supermarket bacon is not a healthy diet.

If you are going to eat a lot of meat (which many of us who eat low carb diets do not do) it is a good idea to eat organic meats if you are going to be eating a lot of meat fat,  because pesticides and other environmental toxins do tend to be deposited in animal fat.

Also,because the fatty acid composition of the fat of the animals we eat reflect the fats they eat, the fat from animals fattened on the currently fashionable "vegetarian" animal  feeds made up of corn and corn oil may contain higher levels of inflammation-producing omega-6 fatty acids than meat did in the past.  So it may no longer be a good idea to eat the fat found in supermarket meats. if you can find meat from pastured animals, that would be a better choice. I am coming to think it might be healthier to get the fat component in your diet from butters made from pastured cows and from non-processed imported cheeses rather than from consuming big chunks of animal fat.

November 14, 2013

Study: Lower Your Cholesterol and Raise Your Risk of Death Following Mainstream Diet Advice

You've been hearing for decades about how a healthy diet is one that lowers your intake of saturated fats and replaces them with "healthy" unsaturated oils. This, you have been told, will lower your cholesterol and your risk of having a heart attack.

What you probably didn't hear is that a study published in the British Medical Journal (BMJ) February of this past year found that though the first claim is true--swapping out saturated fats for vegetable oils will lower your cholesterol--if the oil you use instead of saturated fat is full of omega-6 fatty acid, like safflower oil or corn oil, the second claim is completely false.

The study found that when men who had already had a heart attack replaced saturated fats with safflower oil and ate margarine made with safflower oil they significantly raised the risk that they would die of a heart attack, stroke or, in fact, any cause of death, over the next five years.

How significantly was that risk raised? The study states: "Among the control and intervention groups combined, an increase of 5% of food energy from unspecified PUFA [polyunsaturated fatty acids] predicted about 30% higher risk of cardiovascular death and all cause mortality.

A reduction in SFA [saturated fat] and increase in the PUFA:SFA ratio were also associated with increased risks of all cause and cardiovascular mortality." In short, the more they replaced saturated fat with "healthy" polyunsaturated oil the more likely they were to die.

I was only made aware of this study last week, when the Canadian Medical Association Journal (CMAJ) published an opinion piece questioning whether the government should be putting "heart healthy" labels on corn oil and other polyunsaturated fats. (Details HERE.) They cited the February BMJ study in their write-up.

What doesn't come across in the small amount of press the CMAJ article got is something that makes the BMJ study even more significant:  The data that this finding was based on was 40 years old. It was collected during the Sydney Diet Heart Study, a  randomized controlled trial conducted in 1966-73.

This was one of the many landmark interventional studies whose result was used to convince doctors that replacing saturated fats with polyunsaturated fats would lower cholesterol and, by implication, prevent heart disease.

But while the authors of the original study published the finding that the polyunsaturated fats would lower both cholesterol and triglycerides, they did not look to see whether lowering cholesterol with this intervention actually helped prevent heart-related deaths.

They eventually admitted in a study published in 1978--a full 5 years after they began to publish their results--that there was a higher "all cause mortality" in the group eating the safflower oil, but they did not look at whether these deaths were from cardiovascular-related causes. This was a surprising omission, given the point of the dietary intervention--to lower cholesterol in order to prevent heart attacks.

So it was only in the last few years that a new group of researchers were able to go back to the original study's raw data and take another look at it. When they did so, they discovered what they term "previously missing data."  This "missing data" was the data that led to the conclusion that there was a 30% greater risk of cardiovascular death among the people in the study who ate the cholesterol-lowering oil.

Getting at this missing  data was not a trivial process. The original study data had been stored on 9-track tape--the kind you can see at left--which used to be used by IBM 360 series mainframe computers. There are only a very few data recovery specialists around who can still read these kinds of tapes.

Once they recovered the data, the researchers did a very careful analysis, teasing out other factors that might have affected the death rate and, most significantly, analyzing whether the transfat associated with the margarine the test subjects ate might have explained the higher death rate. They conclude it did not.

They also point out that this re-analysis of the data echoes what was found in two other re-analyses of 1960-70s era cholesterol/heart diet trials: Linoleic acid, with its high proportion of Omega-6 fatty acid and complete lack of Omega-3 fatty acid is really toxic stuff.

You can read the whole BMJ study here:

Use of dietary linoleic acid for secondary prevention of coronary heart disease and death: evaluation of recovered data from the Sydney Diet Heart Study and updated meta-analysis.

Omega-6 Fatty Acids Promote Inflammation

The researchers believe that the reason that the polyunsaturated oils used in these cholesterol-lowering diets were so toxic was because the vegetable oils used were very high in Linoleic Acid, an Omega-6 fatty acid, and devoid of the  countervailing Omega-3 fatty acids you need to consume to keep Omega-6 fatty acids from promoting inflammation.

So, okay. Safflower oil is now out of your diet. But it turns out that safflower oil is not the only common vegetable oil that is rich in linoleic oil.  Corn oil  is very high in it, too. You can see a complete list of oils sorted by their percentage of Linoleic acid HERE.

Finally, though health nuts who still fear that eating saturated fat will kill them will tell you that canola oil and flaxseed oil are healthier alternatives, neither of these oils has been a part of the human diet for any significant period of time the way animal and dairy fats have been.

Canola oil does contain Omega-3 fatty acids, but the process used to take away its rank smell and keep it from going rancid is likely to damage them. Damaged Omega-3 oils is not healthy. Flaxseed oil is the recently renamed stuff we used to call linseed oil and use for mixing up oil based paint--which it often tastes like.  It's safe to eat if you keep it refrigerated and don't let it go rancid, but since it is not a traditional food, I would suggest eating it in small quantities.

Palm oil is another fat that has recently made its way into our food system, as manufacturers are using it as a replacement for the hydrogenated oils full of transfat. But while there may be health benefits from consuming the palm oil eaten in traditional societies, the industrially processed palm oil that is appearing on supermarket shelves is very different stuff and may very well be harboring transfat-like molecules that escape the FDA labeling requirements. And besides that, it often tastes--and refuses to melt--suspiciously like lipgloss. Treat it with caution.

Stick to the traditional healthy vegetable oils and fats like olive, coconut , and melted butter, and you are more likely to actually improve your health.