bite my words

Dispelling nutrition myths, ranting, and occasionally, raving


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Revisiting Dr Esselstyn

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A reader recently commented on a blog post from over a year ago: <a Something's Greasy About Dr Esselstyn's Diet. He suggested that I take a look at some recently published research supporting the diet (and, I think, revise my previously stated opinion).

One of the links was to a series of case studies presented by Dr Esselstyn. As we know, case studies can be interesting, especially in cases of rare conditions, but are not readily generalized. As coronary artery disease (CAD) is a fairly common condition, I feel that it’s more prudent to focus on larger research studies when developing recommendations for the public.

The other link was to a study conducted by, you guessed it, Dr Esselstyn. The study followed 198 CAD patients who were counselled in plant-based nutrition for approximately 44 months. Upon follow-up it was found that 21 were non-compliant (what ever that means… more on this to follow). The remaining participants all showed significant improvement, and only one experienced a related medical incident (i.e. stroke) during those 44 months.

The biggest issue with this study is that there was no control group. There is nothing to compare the participants with. It’s entirely possible that a group, provided with all the same medical treatments and advice, minus the nutritional counselling would have fared just as well. It does seem unlikely, but without the inclusion of such a group, there is no way to be certain that the nutrition counselling (and subsequent adherence) was the reason the participants fared so well. In addition, there was no control for any potential confounding factors. The authors didn’t control for anything. That means that the success could have been due to physical activity/exercise, sleep, stress reduction, socioeconomic status, etc.

There are a few other issues I have with this research. The article states that:

Initially the intervention avoided all added oils and processed
foods that contain oils, fish, meat, fowl, dairy
products, avocado, nuts, and excess salt. Patients were also asked to avoid sugary foods
(sucrose, fructose, and drinks containing
them, refined carbohydrates, fruit juices, syrups, and molasses). Subsequently, we also
excluded caffeine and fructose

However, “We considered participants adherent if they eliminated dairy, fish,
and meat, and added oil.”

My issue with the diet prescribed by Dr Esselstyn was the lack of healthy fats. I have no issue with a vegetarian diet (yes, I’m still not convinced that oil, fish, and dairy products are unhealthy, especially for those who do not suffer from CAD) which is what the adherent participants followed. This means that they could have added nuts, seeds, nut butters, sugar, coffee, avocado, and so on, to their diets and still been adherent. A far cry from the original Esselstyn diet. In turn, I also wonder what the non-adherent participants consumed. Did they eat some fish or meat? Drink some milk? Or were they chowing down on fast food and Hungry Man dinners on the regular? Without knowing these things we shouldn’t be too quick to jump to the conclusion that the Esselstyn diet is superior to all other diets when it comes to treating CAD.

Naturally, there’s also the issue that (despite stating that the authors had no known conflicts of interest) Dr Esselstyn is the author of a number of heart health and lifestyle books that would surely take a hit in sales were research contrary to his hypothesis to be published.

Sure, this study warrants further research into the benefits of plant-based diets (and Dr Esselstyn’s very low-fat plant-based diet) for CAD patients. I’d like to see some larger studies with control groups conducted. Until then, I’ll still be cooking with oils and enjoying my guacamole.

 

 


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Diet, cancer, and blame

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I read these articles backwards. Starting with Dr Joel Fuhrman’s The Nutrition and Cancer Myth? in the Huffington Post and then reading the article An Apple a Day, and Other Myths in the New York Times, which it was written in response to.

To summarize: the NYT article was covering the annual meeting of the American Association for Cancer Research. The article reports that nutrition research has proven to be much less cut-and-dry than had been hoped and that there has been little evidence to date to support any specific connections between diet and cancer prevention (or cause). The HP article suggests that the former article was biased and based on “mainstream” science. Fuhrman argues that there are connections between diet and cancer.

Let’s talk a little bit about bias. The free dictionary defines bias as: A preference or an inclination, especially one that inhibits impartial judgement. Fuhrman accuses George Johnson of bias in his article. Johnson is a writer and science journalist for the NYT. I’m not sure what leads Fuhrman to accuse him of bias other than the fact that his article threatens his book sales. As a journalist, impartiality is essential to Johnson’s writing. Fuhrman, on the other hand has a vested interest in having people believe that cancer can be prevented through diet as the author of books such as Super Immunity and Disease Proof Your Child and the creator of the “nutritarian” diet.

Maybe it’s just my interpretation, but I didn’t read Johnson’s article as telling us to eat whatever we please because it won’t have any impact on whether or not we develop cancer. To me, it said that we shouldn’t beat ourselves up too much for our dietary choices if we develop cancer because nutrition may not have a huge (or even a small) role in cancer development. Cancer has myriad causes and victim blaming does little to advance our knowledge. To his credit, Fuhrman does acknowledge that there are a number of causes of cancer, some of which are outside of our control. However, he continues to cling to the notion that diet can play a large role in cancer prevention and treatment. Understandably, he has a vested interest in people believing this assertion.

Fuhrman cites a number of observational epidemiological studies to support his claim that diet can affect cancer development/prevention. Obviously, we can’t determine causality from these types of studies and, in the comparisons of developed and developing countries there are many factors other than diet which may result in varying rates of breast cancer. Fuhrman uses a small study of the consumption of flax muffins by women with breast cancer as support for the assertion that diet can prevent cancer. Of course there were only 32 women in the study, they were all post-menopausal, and they all were diagnosed with breast cancer. So, really, while interesting that the women eating the flax muffins saw greater cancer cell death than the women eating the muffins without flax (of import is that both groups saw cell death) it’s not translatable to the general population and says nothing about diet and cancer prevention.

Diet may prove to play a role in cancer prevention. However, the evidence does not yet support this. Don’t let nutritionologists scare you into believing that you are in control of cancer prevention and you can only do so by buying their book(s) and ascribing to their diet.


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Will canned fruit really kill me? Lessons from epi research

 

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One of my twitter friends retweeted the above tweet yesterday (identifying info removed to protect the guilty). I asked if they had a link to research to support this claim and received a link to this article in Science Daily in response. Dutifully, I followed-up with reading the full journal article. I just couldn’t fathom how eating canned or frozen fruit and vegetables could increase your risk of cancer.

For one thing, right off the bat, the authors are make no mention of frozen vegetables, they refer only to frozen fruit. Just to be clear, that was not a claim they were making.

It’s important to note that the study is observational epidemiological research. It’s impossible to infer causation from such research. At best we can say that there is a correlation between fruit and veg consumption and cancer diagnoses. We can’t say that fruit and veg consumption, or lack thereof, is causing the cancer.

The researchers questioned the participants regarding their fruit and vegetable consumption on the previous day, once a year, for seven years. This data was then linked to all-cause mortality up until 2013.  A few points to make here: 1. fruit and vegetable consumption included fruit juice and dried fruit, as well as pulses (e.g. lentils, beans, legumes) which many would categorize as meat alternatives; 2. dietary recall is notoriously inaccurate… can you remember everything you ate yesterday, including the quantities? 3. we are operating under the assumption that one day is truly representative of most days for the study participants, rather a large assumption.

Some potential confounding variables were controlled for; such as, physical activity, education, socioeconomic status, and BMI. However, it is not outside the realm of possibility that some variables were overlooked. As the researchers themselves point out, they didn’t look at total calorie consumption or other specific aspects of diet (e.g. sodium intake, macronutrient composition, consumption of fast food, timing of food intake, changes in diet, sedentary time, etc). Any of these things could have affected the apparent relationship between fruit and vegetable consumption and mortality from cardiovascular disease (CVD) or cancer.

As someone else on twitter pointed out, it’s also worth noting that the relative risk of dying was quite small. Out of 85, 347 participants, 1, 336 died from cancer and 1, 482 died from CVD. That’s a whooping 3.3% of all participants. Although the researchers found an inverse relationship between fruit and vegetable consumption (except for canned and frozen fruit for which they found a positive relationship) and all-cause mortality I question how meaningful this is. After all, suicide was the leading cause of death in both men and women between the ages of 20-34 years, accidental poisoning was second, and car accidents were third in England and Wales in 2012 (1). Is diet that much of a factor in such deaths? Why look at all-cause mortality? Why not focus solely on lifestyle related deaths?

Yes, it would appear that consuming more fruit and veg is correlated with reduced risk of dying, particularly from CVD. It’s certainly not going to harm you to eat more fruit and veg, unless you’re eating more canned and frozen fruit. So, why would that be? Well, remember the researchers didn’t examine the entire diet, nor did they distinguish between fruit packed in syrup and canned fruit packed in water, or frozen fruit without additives. It’s quite possible that other aspects of the overall diet (or the type of canned/frozen fruit) is responsible for the apparent increase in all-cause mortality in canned/frozen fruit eaters.

That brings me back to the tweet that started all of this. It came from someone who promotes health and fitness and who has a number of followers. Personally, I think that it’s irresponsible to tweet something like that. The tweet misinterpreted the findings by lumping frozen and canned fruit and vegetables together. It also sent a terrible message: if you can’t/don’t eat fresh fruit and veg you may as well not bother; you’re probably going to get cancer if you eat canned/frozen so you’re likely better off polishing off that box of Oreos. Sigh. Many people can’t afford, or don’t have easy access to fresh fruit and vegetables. Frozen and canned are preferable to none, especially if you make good choices. Frozen fruit and vegetables (without added sauces or syrups) are often more nutritious than their fresh counterparts as they are picked and frozen at peak-ripeness rather than under-ripe and spending time in transit, warehouses, on grocery store and fridge shelves. I would also argue that canned are preferable to that box of Oreos. If possible, choose fruit packed in water or juice, not syrup. Choose veg that are packed without added salt. If you can’t find vegetables without added salt, drain and rinse them well before using; you can get rid of up to 40% of the added sodium by doing this.

Don’t be discouraged if you feel that 7+ servings of fruit and veg are beyond your reach. Remember that every little bit helps; fresh, frozen, or canned.

 


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Another salt study

This headline made me cringe: Bread and cereal highest contributors to children’s salt intake: Study.
One, because we’ve known this for years, and it doesn’t just apply to children. In Western nations most people obtain the majority of their sodium from bread products.

Two, as the director of the Federation of Bakers points out toward the end of the article, it’s not because bread contains high amounts of salt, per se, it’s because people consume large quantities of bread products. Despite the focus of the article (and apparently the researchers) on pushing the food industry to lower amounts of salt in bread, it’s unlikely that this is the best response. For one thing, the industry is likely to replace the salt with something else that will turn out to be worse for us. For another, we should be focusing on encouraging people to consume a variety of foods, particularly those that are minimally processed, rather than emphasizing reformulating current packaged foods. Different bread is not the answer, less bread is.


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Forget sugar. Protein is the new smoking.

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A recent study in Cell Metabolism prompted numerous headlines proclaiming that protein (specifically animal protein) may be just as bad as smoking for your health. Before we jump on the anti-protein bandwagon let’s take a look at the actual study.

The researchers used the results from the NHANES (National Health and Nutrition Examination Survey) in combination with mouse and cellular studies. There were over 6, 000 participants in the NHANES which is quite a robust sample. Right off the bat it makes me suspicious that the researchers would also need to incorporate mouse studies. We also know that using nutrition data from self-reported surveys is far from ideal: people tend to under-report food intake. In this case the researchers used 24-hour recall. The pro to this is that it’s one of the more accurate methods for collecting dietary data. The major con to this is that the researchers are assuming that food/nutrient intake from one day is representative of intake every day. That’s a huge assumption. I know that I might eat animal protein at a couple of meals on one day while eating none on another. That would mean I could fall into either the low or high protein intake group depending on the day data collection was undertaken. We also know that mice are not humans (duh) and that research conducted using mice may not be translatable to a human population. Okay, not enthusiastic about the methods, but let’s take a look at the results.

The researchers found no association between all cause, cardiovascular disease, nor cancer mortality and protein intake in all participants over the age of 50. They did find an increase in mortality in participants in the high protein (20% or more of total daily calories from protein) group who had diabetes. Naturally, they could not say with certainty if the high protein intake was the cause of diabetes mortality. However, when they broke the results down further (splitting the group into those aged 50-65 and 66 and up), they found a relationship between high protein intake and all-cause and cancer mortality in the 50-65 age group. They reached the conclusion that animal-based proteins were the cause of this increased mortality because when they controlled for animal protein the “association between total protein and all-cause or cancer mortality was eliminated or significantly reduced”. This was not seen when plant-based protein was controlled for. Interestingly, the opposite was found in the over 66 years age group (i.e. higher protein intakes reduced risk of mortality from cancer or cardiovascular disease).

It appears that the researchers didn’t control for all confounding variables when they were examining mortality and protein intake. There is no mention of controlling for physical fitness, economic status, or employment status. These are important factors to consider when investigating the effect of diet on mortality.

So, what can we conclude from this study? High animal protein intake may increase your risk of mortality if you’re between the ages of 50-65. After that, it may have a protective effect. This suggests that protein plays different roles at different ages and also means that we cannot extrapolate the results to those under the age of 50. We also can’t be certain that the results are accurate due to the limits when using dietary recall data as well as the lack of control for certain potential confounding variables. There may be some benefits to including more plant-based sources of protein in our diets; however, it may be premature for us all to go vegan.

After writing this post, I read the review of this study on Examine.com in which they address the mouse study. They also make some really good points about the protein-human study, including the fact that there’s no differentiation between protein sources beyond separating animal and plant proteins (can we really assume roast chicken is the same as beef jerky?). I highly recommend taking a look at their review.