Dispelling nutrition myths, ranting, and occasionally, raving


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Follow Friday: Grapefruit for diabetes

Photo by Emma on Flickr used under a Creative Commons Licence.

Photo by Emma on Flickr used under a Creative Commons Licence.

I had been planning on writing a post about the latest headlines heralding grapefruit juice as the greatest thing since Metformin. According to the news articles you’d think that grapefruit juice will prevent obesity and diabetes. Read, and interpret, the actual research and you get a slightly different story. Fortunately, the NHS has saved me the trouble and written a great critical review.


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DDT and obesity

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You know how I feel about mouse studies. It’s very difficult to create circumstances that accurately mimic real life in the lab. It’s even more difficult to create circumstances using mice that can be assumed to be the same for humans. A recent study reported that perinatal exposure to DDT caused an increase in diabetes and insulin resistance in mice.

It was quite interesting that the only difference between the mice exposed to DDT in the womb, and those not exposed, appeared to be a decrease in body temperature. They ate the same amount of food, exercised the same amount, and yet they gained weight, apparently because of decreased thermogenesis.

What are the implications of this for those of us who are human though? Well, if you live in a country where DDT is not banned as a pesticide, or is used to control malaria, it may be a concern. It may also be a factor in women (apparently the DDT did not have the same effect on male mice as it did on the females) who were exposed to DDT in the womb before DDT was banned (1972 in Canada and the US). However, it does nothing to explain the current rise in obesity rates and rates of type 2 diabetes in North Americans of all ages. Type 2 diabetes rates in children continue to rise. This study does bring more validity to the argument that pesticide exposure may be playing a role in the obesity epidemic. However, DDT is certainly not the culprit in our neck of the woods.


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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.


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Keeping the math in diabetes

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I was innocently reading twitter last night when I saw the following tweet from a Holistic Nutritionist: 

Are you Diabetic? Get away from the numbers! No carb counting, no constant testing, just REAL FOOD! That’s the answer.

I completely understand what she was getting at. I speak with many newly diagnosed diabetics who are overwhelmed and have no idea what they can eat. I also get a lot of them looking for “diabetic” cookies, granola bars, and sweets. This is during their first grocery shop after diagnosis. I loathe the vast majority of sweets marketed to people with diabetes. Most of them would not fall under the heading of “real food”. They’re full of sugar alcohols and highly processed ingredients. And despite that, they still often have a considerable amount of sugar. What so many people don’t understand is that people with diabetes can eat “real food”. They don’t need to have specially formulated bars and snacks. In fact, the diet that’s recommended for people with diabetes is the diet we should all be following: lots of vegetables along with protein, healthy starches, and dairy (or alternative) products. So, yes, “real food” is the recommended diet for all.

This is where I get ranty… This advice is dangerous. If I was newly diagnosed as diabetic I would not find this helpful. Yes, constant testing of blood sugar is no longer recommended. That doesn’t mean that people with diabetes shouldn’t check their blood sugar at all. It can be very helpful for people with diabetes (especially those who have just been diagnosed) to figure out what foods and activities may trigger highs and lows. It can also help people to become attuned to what high and low blood sugar feels like. Carb counting is also a useful tool for those with diabetes. Consistent quantities of carbohydrates are needed to ensure that appropriate doses of medicine are prescribed. Carb counting helps to make sure that appropriate serving sizes of carbohydrate are being consumed and can help reduce the need for medications. For those with insulin pumps, carb counting is necessary to determine how much insulin should be administered at meal times.

Yes, “real food” is important but taken alone it’s a simplistic solution. The numbers are useful tools to help people figure out when, what, and how much of “real foods” to consume.


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Something sour: Vinegar and blood sugar control

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I saw this tweet: “Add 4 teaspoons of vinegar to your diet daily to lower your blood sugar. This may help prevent diabetes #OzTip” from Dr Oz the other day and I immediately thought “blog fodder!”

Googling the subject of vinegar and blood sugar and diabetes, I thought maybe there was something to this lower effect of vinegar on blood sugar after all. WebMD said:

The effect of vinegar on blood sugar levels is perhaps the best researched and the most promising of apple cider vinegar’s possible health benefits. Several studies have found that vinegar may help lower glucose levels.

However, they carry on to state that:

a 2007 study of 11 people with type 2 diabetes found that taking two tablespoons of apple cider vinegar before bed lowered glucose levels in the morning by 4%-6%.

Umm… if this is the best evidence they could come up with then I’m not so sure about using vinegar to lower blood sugar. 11 is an extremely small sample size. As it turns out, most of the evidence supporting the use of vinegar for blood sugar control comes from very small studies. I found one study that compared the consumption of vinegar, vinegar pills, and pickles in 27 people (so, only nine in each treatment group). They found that vinegar had a modest (0.16% in HbA1c) lowering effect on the morning blood sugar of participants while those consuming pickles and vinegar pills actually saw a slight increase in HbA1c. The other study I found was even worse. It included only 11 participants (I think that this is the one the WebMD article was referring to). They found that fasting blood sugar was reduced by 2% in the control group and 4% in the group ingesting vinegar at bedtime. I also think it’s interesting to note that this footnote accompanied the study:

The costs of publication of this article were defrayed in part by the payment of page
charges. This article must therefore be hereby marked “advertisement” in accordance
with 18 U.S.C Section 1734 solely to indicate this fact.

Yes, these results are interesting but with such small sample sizes they’re essentially meaningless. Until larger studies are able to produce similar results I don’t think that advising anyone to consume vinegar at bedtime for blood sugar control is prudent.