bite my words

Dispelling nutrition myths, ranting, and occasionally, raving


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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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Grocery store lessons: flour

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When the Internet exploded a little while back with the news that Subway (and a number of other fast food restaurants) included the ingredient azodicarbonamide (a chemical also found in things such as yoga mats) I felt a little smug. After all, it’s extremely rare for me to eat at Subway, and even more rare for me to eat at the other places mentioned. Then I saw a post by a friend of mine on facebook indicating that azodicarbonamide can be found in flours on grocery store shelves. That lead me to take a look through my cupboards.

Lo and behold, there it was in the ingredient list for my healthy whole wheat flour. Interestingly, not for my unbleached all-purpose white flour, nor for my organic gluten-free flours. It turns out that perhaps the fast food companies aren’t to blame for this one. This goes back to the ingredient suppliers.

Now, azodicarbonamide may be safe for us to consume in the quantities that it’s present in our flour. It may not be. I don’t know. Personally, I’d rather avoid consuming unnecessary additives regardless. I know that in the future I’ll be checking the ingredients in my flour before I buy it. I’m also feeling a whole lot less smug about baking my own bread.


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Follow Friday: You’re drinking the wrong kind of milk

Just Mooching Around (geddit?)

A friend shared this article on twitter last week. While I can’t vouch for the science behind it (any readers able to?), I did find it very interesting. I know a number of people who have mentioned that they have “lactose intolerance” here, in North America, but when they travel overseas to places like France they have no trouble digesting any dairy products. I wonder if this could also help to explain the people who’ve told me that the local East Coast Organic milk is the only kind they can tolerate. Perhaps it has less to do with what the cows are eating, and more to do with the breed of cow. Something to chew on.


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Let them drink pop: Water doesn’t = weight loss

Water-Soda-Poster

Big News: “Water not a ‘magic bullet’ for weight loss“. While I don’t dispute any of the information presented in the article, I do take issue with a major fact that is not presented in the article. 

The article states that the vast majority of research has shown no increase in weight loss for those who consume more water versus those who do not. Drinking water does not increase caloric burn. The article also dismisses the pervasive myth that beverages such as coffee do not contribute to overall hydration – YAY! All true. 

The article then quotes the RD as saying, “if you don’t like water it’s OK.” The idea is that you can obtain your hydration from other beverages (and foods). While absolutely true from a hydration standpoint, I think that this statement does a disservice to those who are attempting to lose weight. While I’m sure it was not her intent, I think that this could easily be interpreted to mean that it’s fine to choose beverages such as juice, pop, and coffee with sugar and cream rather than a glass of water. Yes, these will all hydrate you, however, they will also add non-satiating calories to your diet. If you drink just one 8 oz glass of orange juice, one 12 oz can of Coke, and one medium double-double (sorry, non-Canadian readers) a day you’ll be adding 458 calories to your daily intake. Compare that to zero calories from three glasses of water. 

Obviously weight loss is not as simple as replacing caloric beverages with water (or non-caloric beverages) but that can certainly be a part of it. To suggest that all beverages are equal is untrue and misleading. Water doesn’t boost your calorie burn but it can minimize your overall caloric consumption if you replace caloric beverages with it. 

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