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Dispelling nutrition myths, ranting, and occasionally, raving


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A bit more about food combining

PB&B sandwich photo by Kevin Reese. Used under a Creative Commons Licence.

PB&B sandwich photo by Kevin Reese. Used under a Creative Commons Licence.

After I wrote about the utter nonsense of food combining last week I had a reader contact me to suggest that perhaps I could elaborate on the positive side of food combining. To be clear, this is not what is traditionally meant by “food combining” which is a complicated way of eating which erroneously is believed to aid digestion and is more based on not eating certain foods in conjunction with others than with eating a variety of foods together.

I mentioned in my previous post that combining some foods can be beneficial in terms of absorption. Fat soluble vitamins (ADEK) need to be consumed with fat in order to be absorbed. This is one of the many reasons that a low-fat diet has been decried by dietitians. Skimmed milk with added vitamin D? No sense to it unless you’re washing down a croissant (or an avocado, nuts, or other fat-containing food of your choice).

In addition to aiding absorption of fat-soluble vitamins, certain foods can help with the absorption of other nutrients. Foods containing vitamin C can help with the absorption of iron, particularly from plant foods in which the iron is less bioavailable than in meats. For example, eating peppers with your spinach salad can help you to absorb more iron. Or having an orange with your oatmeal, tomatoes and beans, etc. Of course, there are also instances where nutrients can hinder the absorption of other nutrients. Tannins and fibre may decrease the absorption of some minerals and medications. Oxalate (found in spinach and some other fruits and vegetables) can impede the absorption of calcium.

As my astute reader pointed out, there’s also the benefit of glycemic control imparted by eating certain foods together. As any reader of Wheat Belly can (and likely will) point out to you, whole wheat bread has a higher glycemic index than white sugar. The thing that’s not taken into consideration when latching onto that fact is that we rarely eat whole wheat bread in isolation. Turn your bread into a peanut butter and banana sandwich or chicken salad sandwich and you’ve altered the glycemic load of the meal because you’ve added other macronutrients. Consuming fat, protein, or fibre can all help to mitigate the effect of carbohydrates on blood sugar. This is why, if someone with diabetes is experiencing low blood sugar it’s much better to give them candy or juice than a chocolate bar. On the flip-side, this is why most dietitians will recommend that you consume two food groups at snacks. Having a piece of fruit and a few nuts or cheese and crackers, berries and yoghurt, veggies and hummus… will help to prevent a spike in your blood sugar and keep you feeling full for longer that if you were to just have a piece of fruit. It also helps you to meet your nutrient needs if you include a vegetable or fruit as part of your snack.


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Food combining

Photo by Tom Ipri on flickr used under a Creative Commons Licence

Photo by Tom Ipri on flickr used under a Creative Commons Licence

Not long ago I had the pleasure(?) of overhearing a conversation about digestion over a meal. One woman was explaining why she wasn’t having carbs at her her meal (this despite the fact that the hummus she ate certainly contain carbohydrate, as did some of the vegetables with her meal). Her logic was that to aid digestion it’s better to consume food groups separately. Hence, she was just eating vegetables and meat. Someone else piped in that this made sense and added that eating foods in a specific order must also be beneficial. I did my best not to bite off my tongue and eat it along with my vegetables, meat, and (gasp!) rice.

Not everyone knows about how digestion works and I can see how these myths perpetuate. But please give your body some credit; it can handle more than one macronutrient at a time.

I’ve addressed the issues of food “layering” and combining before. Just a quick reminder: digestion starts in the mouth with amylase breaking down starches. Your stomach does an excellent job of churning all of the food you eat, breaking it down, and making it into an acidic stew. Believe me, nothing is sitting in there on top of everything fermenting. Most of nutrient absorption occurs in the intestine. Consuming more than one food at a time may actually aid in nutrient absorption as some nutrients, such as the fat soluble vitamins ADEK, need other nutrients to be absorbed (in this case fat).

This doesn’t even address the fact that many foods taste better together. Think: chocolate and peanut butter, apples and cheese, bread and butter. There’s no need to deny yourself the pleasure of these foods. Variety is the spice of life and choosing healthy foods is complicated enough without adding the element of what to eat with (or without) something else.


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Are apples the key to curing obesity?

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A few weeks ago the media was reporting that apples may provide the cure for obesity. I was a little more sceptical. I mean, how many overweight and obese people do you know who eat apples? Probably lots. If apples were capable of curing obesity everyone would be thin.

My first concern was that this research was conducted on mice. That means that it may (likely) is not translatable to humans. A couple of things to consider: these mice were fattened up by being fed a very specific high-fat diet. Obesity is a complex condition with myriad factors. Unless the reason for people being overweight is due to consuming a similar diet to these lab mice, it’s quite likely that they will not respond to this weight loss treatment in the same manner as the mice. I also wondered how much apple the mice were fed. How much apple would humans need to consume to see similar results? Here’s where it gets crazy: the mice did not eat the apples. Yep, that’s right. We have no idea how much apple would be beneficial to humans as we don’t know how much would be beneficial to mice. Rather than feeding the apples to the mice, the researchers made a slurry of apple compounds and mouse faeces. They found increased levels of certain bacteria that are commonly found in the faeces of slim mice in the cultured faeces of obese mice. Their results were not statistically significant. They showed a trend toward increased levels of some bacteria and butyric acid, and decreased levels of other bacteria in the faeces-apple slurries of obese mice but none of the changes (save the decreased bacteria) were large enough to be statistically significant.

It’s impossible to say whether or not eating apples (how many, how frequently) would have similar effects on the fecal microbiomes of mice or humans. We also don’t know if these microbial changes do occur if they would result in weight loss. Without knowing this, it’s a ridiculously huge leap to suggest that consuming apples could be a treatment for obesity. This didn’t stop the authors from concluding that:

These results suggest that dietary fibre and phenolic compounds remaining in apples after IVD might help to prevent metabolic disorders driven by an altered microbiota in obesity, and potentially protect from an obesity-disturbed balance of microbiota.

It also didn’t stop the media from publishing articles with headlines like: “An apple a day could keep obesity away: Granny Smiths promote friendly bacteria helping us feel fuller for longer” and “Granny Smith apples can help prevent the damage of obesity“.

I do think that research into our microbiomes is going to provide insight into many illnesses and conditions. However, our individuals microbiomes are extremely variable. Suggesting that this research using mice will translate to obesity treatments for humans. It’s also extremely unlikely that consuming one healthy food will negate the effects of an overall unhealthy diet. That being said, apples are nutritious and it’s certainly not going to hurt you to have an apple a day.


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Book Review: Health at Every Size

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Thanks to Helen at Food & Nonsense starting the RD book club I finally got around to reading Linda Bacon’s Health at Every Size. Unfortunately, due to time differences, the tweet-up to discuss the book is taking place at 6 am on a Sunday morning for me. I’ve scheduled this post to go live at that time as my feeble attempt at participating in the discussion without waking up ;) If you’d like to check out the discussion just search for the #RDBookclub hashtag (was that redundant? Probably) on twitter.

Helen was also kind enough to post some discussion questions so here goes…

1. Do you agree with the HAES assertion that health not weight should be the focus of nutrition interventions?

Absolutely. The focus should be on health and well being, never on numbers on a scale. That being said, weight management is one of the main reasons that people seek out advice from dietitians. I don’t think that we can just ignore this fact. As health care professionals it’s our job to help people to understand that the numbers on a scale don’t necessarily matter all that much when it comes to health. That being said, weight is often inextricably intertwined with health and nutrition.

2. Is a health approach practical in todays aesthetic focused society?

This is an excellent question and one that I found myself thinking about quite a bit as I was reading the book. It’s all well and good that we know that people can be healthy at many different weights but how do you translate that into acceptance and understanding? As much as we tell someone that they are healthy at their current weight, if they’re unhappy with that weight should we help them to lose weight or help them to accept themselves as they are? Oftentimes, neither of these options is feasible.

3. Do you feel that the main concepts in the book were adequately backed up by the research presented?

For the mist part I did. Although I must confess that I didn’t take the time to seek out all of the research Bacon used to back-up her arguments. A couple of things did bother me: One, I didn’t like how much she mentioned that if you do this or that you’ll probably end-up losing weight. If your book is about being healthy no matter what your size, and you’re preaching fat acceptance, then I don’t think that weight loss should be a frequently touted benefit of your approach. Two, I’m not sure how credible her evidence to support that overweight and obese people generally live longer than their lower-weight counterparts is. Weight loss is an extremely common side effect of many serious diseases. Thus, thinner people may be more prone to dying than larger people as a result of an underlying illness causing weight loss, not as a result of being thin. If we’re talking health at every size we need to be careful not to tip the scale in the other direction. People who are overweight, obese, average, or underweight may all be healthy. Also, death is not the only thing to look at. Obese and overweight people may be living for longer but how many of them are healthy during these extended life spans? Health span may be a more important consideration than life span.

4. How should nutrition professionals use this information in their day to day practice?

I think that nutrition professionals should use this information to help themselves overcome their personal biases and to educate their clients that weight is not the be all and end all when it comes to health. We should also use it to help clients realise that our own weight is not an indication of our health nor of our ability to do our jobs well. I can’t tell you how many people I’ve had tell me that I’m a dietitian they might actually listen to because I’m slim, as though larger dietitians don’t have exactly the same knowledge and education as I do. As with any field, our weight is not an indication of our ability to perform our jobs well.

5. Were there any ideas in this book that you reject or find difficult to accept?  Why?

I think I covered this in question three. Oops! I was also bothered with a very small point in which Bacon was advising people on how to choose whole grains (p.79). She says, “Look for the word “whole” in the ingredients list.” Not entirely accurate. This is the point where I pondered whether or not it was okay to write in a library book. You need to see the words “whole grain”. Unfortunately, “whole” on its own is not sufficient. Anyway… This is a very small quibble in the scheme of things.

I did also find it difficult to accept that there is no relationship between obesity and disease states. While I absolutely believe it’s possible to be healthy (and conversely unhealthy) at any weight I do still believe that there is increased risk of developing certain conditions such as heart disease, some cancers, type 2 diabetes when you’re obese.

6. What is the main thing you took from this book? How has it been helpful to you?

The main thing I took from this book is the importance of self-worth and acceptance. We all need to stop aspiring to look like other people and learn to be happy being ourselves. Many of us also need to step away from the scale and stop letting the numbers on it define us. I also really enjoyed the chapters on food and fat politics.

For some more interesting perspectives on the HAES movement check out the following links:

http://www.weightymatters.ca/2013/12/guest-post-why-i-am-walking-away-from.html

http://www.weightymatters.ca/2012/03/why-haes-may-never-go-mainstream.html

http://www.drsharma.ca/obesity-the-science-behind-health-at-every-size-haes.html

http://www.sciencebasedmedicine.org/does-weight-matter/


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How important are the enzymes in your food?

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This headline: Cancer fighting with food caught my eye. As did the preview in my Google alert:

Eat as much raw food as you can, because anything you cook over 116 degrees is devoid of enzymes, which are necessary for breaking downfood so …

Reading through the article I realised that there was a lot more that I could address. However, I don’t feel like spending hours writing a super long post so I’m only going to address the initial statement that caught my eye.

There are pros and cons to both raw and cooked food. I’d like to think that it goes without saying that cooking meat (eggs, fish) and heating milk (aka pasteurization) is important for food safety, but it’s never wise to make assumptions. Yes, cooking can destroy certain nutrients, vitamin C is notoriously easily destroyed by cooking (1). However, the article’s not talking about vitamins here, it’s talking about enzymes.

The statement is a little puzzling to me. The enzymes contained in foods are not the same as our digestive enzymes. No matter the method of preparing food, most healthy people will release digestive enzymes to aid in the breakdown of food into particles small enough for absorption. These enzymes include amylases to breakdown starches, lipases to breakdown fats, and proteases to breakdown proteins. Yes, some foods such as papaya and pineapple contain the enzymes papain and bromelain, respectively, which both breakdown proteins. Protip: this is why your chicken stored with pineapple salsa will be mush when you reheat it. Aside from that, the enzymes in plant foods are proteins used in plant processes, not in our digestive processes.

There may be some benefits to consuming plant-based enzymes but there is currently no evidence to support a raw food diet for optimal nutrition and there is certainly no reason to expect that the enzymes in foods will aid with your digestion of them. In addition, it’s well-known that cooking can actually increase the bioavailability of certain nutrients. Cooking tomatoes makes lycopene (a carotenoid that may provide a number of health benefits, not least of which, reducing risk of prostate cancer) more available to us. Cooking spinach and other leafy greens makes the lutein (an antioxidant important for eyesight) in them more available for us to absorb.

The key here, as always, is variety. There are pros and cons to both raw and cooked vegetables eating an assortment of both is ideal.

Let’s also not forget that enjoyment is important as well. Eating is not just about obtaining nutrients. It’s also a pleasurable activity. I prefer raw carrots but cooked mushrooms. It’s far better to consume a vegetable in a manner you enjoy it than to not consume it at all.