Dispelling nutrition myths, ranting, and occasionally, raving


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Only the thin die young

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I’m all for looking at overweight and obesity in new ways. I absolutely believe that it’s possible to be overweight and healthy. I am, however, sick of seeing claims that being overweight is protective against death. The implication being that those of us who are “healthy” weights are actually more likely to die than those who are slightly overweight.

Yet another article came out last week touting the headline: People deemed overweight may actually have a lower risk of dying than those who are healthy, study says. The fact that we’re all going to die notwithstanding there are other significant issues with such claims.

To start, I’d like to take exception to the headline itself. Who writes these things? If they had inserted weight after “healthy” it would have made quite a difference. As it’s written it implies that “healthy” and “overweight” are two discrete mutually exclusive categories. This is not the case. It’s entirely possible to be overweight and healthy. It’s entirely possible to be “healthy” weight and unhealthy.

Now that, that’s out of the way, let’s get to the bigger problems with the study results, as covered in the news article. When people are ill, especially mortally ill, they often lose weight. As a result, when looking at death rates and weight it’s incredibly difficult to tease these issues apart. Thus, claims that being overweight protecting against death are essentially meaningless and potentially detrimental. I say detrimental, because if people are dissuaded from eating healthily and exercising regularly by the suggestion that it’s healthier for them to be overweight then it’s quite likely that their health will suffer. We also know that many chronic diseases such as type 2 diabetes and hypertension can be better managed with weight loss, following a balanced diet, and incorporating regular physical activity. While it’s possible that being overweight is actually protective, it’s more likely that the apparent association between lower weight and death is a result of weight loss during illness.

The other significant problem with the claim that overweight is protective against death is that it doesn’t take into consideration quality of life. Many people who are overweight will be prescribed various medications to keep related conditions in-check. This may result in a longer lifespan than someone who’s “healthy” weight who, because of appearing to be in good health (as a result of the conflation of overall health and healthy weight) may go without similar treatment. The “healthy” weight individuals may lead shorter but higher quality lives without the side effects of medications (i.e. they may have shorter lifespans but longer healthspans).

To sum it up: yes, you can be healthy and overweight. You can also be unhealthy. Ditto for both for “healthy” weight. Regardless of your weight the best way to ensure that you lead the longest healthiest life possible is by taking care of yourself.

 


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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.