Dispelling nutrition myths, ranting, and occasionally, raving


Leave a comment

Prebiotic vs probiotic

Drawing

 

I came across this short but confused and confusing article a few weeks ago. The article is referencing a study on the effect of prebiotics on maternal weight gain (in rats) during pregnancy. Fairly straightforward until I read the statement: “Dr. Raylene Reimer gave prebiotics – found in food like yogurt or sauerkraut – helped to reduce fat in pregnant rats who were on a high fat and sugar diet.” See my confusion? Either the study involved prebiotics, which are fibre, or the study involved probiotics, which are bacteria (found in cultured and fermented foods such as the ones given in the example).

I found the actual journal article on the study to find out if the research had involved prebiotics or probiotics. It was prebiotics. So, the author of the news article was correct in stating “prebiotics” but confused about what prebiotics actually are. No wonder so many people confuse the two when talking about prebiotics and probiotics. And, to be fair, the terms are incredibly similar.

My trick for remembering the difference between the two? “Pre” means before, and I always think of prebiotics as being what probiotics need before they can grow. Before you can have a healthy gut microbiome, you need food for that bacteria to flourish. That food is the fibre (like that found in grains, vegetables, fruits, nuts, and seeds).


4 Comments

Are apples the key to curing obesity?

url-1

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.


5 Comments

Grocery store lessons: Probiotic tea

V01070

Catching up on my magazine reading recently I came across this probiotic tea. While more and more research is coming out to support the use of probiotics to promote healthy gut flora, which is important to overall health, I was still pretty skeptical seeing this. After all, most probiotics prefer a cool temperature and how much would you actually get by drinking a cup of tea?

I checked out the GanedenBC30 (the brand name for the bacillus coagulans used in the tea) website. Apparently their probiotics are much hardier than most strains of probiotic. They’re able to survive extreme heat, extreme cold, and the acidic environment of the stomach.

Here’s the thing: I don’t have the resources to conduct research to determine if this claim is true. The only research I can find (shout out to Vanessa for her assistance!) was financially supported by Ganden. Also, the research didn’t demonstrate the ability of the bacteria to survive extreme conditions. One study looked at the benefit of bacillus coagulans in mice with c. difficile infection. It found that there was improvement in stool consistency. However, we know that mice are not humans and results found in them may not be translatable to us. In addition, two of the authors of the paper were employees of Ganden. Another study looked at the effect of GanedenBC30 on inflammation in human blood samples. Once again, the results were positive. And, once again, the study was funded by Ganden. The  third study actually looked at the effect of GanedenBC30 on gas-related symptoms in humans. Despite stating that there was a benefit to consuming the probiotic, there was no statistically significant difference demonstrated between the placebo group and the probiotic group on many variables. Once again, this study was funded by Ganden.

What to take from all this? Ganden owns the right to this particular strain of probiotic. Thus, any research conducted using it must be approved by them. Considering this, how likely do you think it is that we’ll see any research disputing the benefits of GanedenBC30? Especially, considering that negative findings are rarely reported anyhow. Despite this,  Medline Plus states that there is “insufficient evidence” to support any of the claims attributed to bacillus coagulans. Even if we take Ganden’s word for it and accept that bacillus coagulans is beneficial to our health there are still a lot of additional assumptions we have to make regarding its consumption in tea.  We have to assume that the bacteria can indeed survive on in the tea on the store shelf for a prolonged period. We have to assume that the bacteria can indeed survive steeping in boiling water and passing through stomach acid. We also have to assume that enough bacteria will survive this process to actually be of benefit when they reach the intestines. 

I don’t know about you, but that’s too many assumptions for me. Personally, I’ll stick to my regular tea and get my probiotics from fermented foods and the occasional capsule.


Leave a comment

Bacteria: the next weight loss craze?

url-3

Recent research has indicated that a change in gut microbial flora following gastric surgery may contribute to weight loss in patients. This conclusion was reached following a study on mice. A group of mice underwent gastric-bypass surgery, their gut microbial flora was monitored, and then some of that bacteria was transferred into mice that had not undergone surgery.

There were also two other groups of mice that underwent “sham” surgeries (their intestines were snipped apart and then reconnected). One of these groups continued to be fed a high calorie diet post-surgery while the other was put on a restricted diet.

There are a few things about this study that intrigue me. I think it’s important to note that the mice place on the restricted diet lost the same amount of weight as the mice that underwent the true bypass surgery. To me, this indicates that the level of obesity in these mice may not have been the same as the level required for weight loss surgery in humans.

I also find it curious that the mice that received the gut flora apparently had no pre-existing gut flora of their own. I’m not sure if this is an error in reporting but you would be extremely hard-pressed to find a human without pre-existing gut-flora (perhaps if they’d been on a very high dose course of antibiotics). We also know that gastric bypass surgery can result in nutrient deficiencies and it’s possible that the presence of the bacteria found in these post-surgical mice might also increase the risk of malnourishment.

Finally, and most importantly, even if weight loss in mice can be attributed to the presence of certain bacteria in the gut, mice are not the same as humans. Do mice have the same gastro-intestinal flora as humans? Do they react to surgery in the same way as we do? Do they have the same relationship to food as we do? I would hazard to guess that the answer to all of these questions is no.

While this research is very interesting, and may in the long-term provide us with further insight into obesity and weight management, at this point I would be extremely cautious when interpreting the results.