Microbiomes and GMOs

What's up everyone? This post reviews an article that I stumbled upon on Twitter. I don't think that I ever anticipated that joining Twitter would cause me to read more papers, but it's been a very pleasant surprise. The paper has a freakishly long title, way longer than 140 characters: "High-Throughput Sequence-Based Analysis of the Intestinal Microbiota of Weanling Pigs Fed Genetically Modified MON810 Maize Expressing Bacillus thuringiensis Cry1Ab (Bt Maize) for 31 Days" and is publicly available. The jargon-free title of the paper would be "DNA sequencing analysis of the bacteria in the gut of baby pigs fed an insect-resistant-GM-corn for 31 days". The study is independently funded and its authors claim no conflict of interest.

The reason I wanted to read this paper is that a) it combines two trendy topics: GMOs and microbiomes (hence the buzzword-laden title to this blog), and most importantly, b) I wanted to find out if this paper lent credibility to the Institute for Responsible Technology's hypothesis that GMOs are to be blamed for poor gut health. Here's a quote from their website, which I'll explain further below:

"A recent analysis of research suggests that Bt-toxin, glyphosate, and other components of GMOs, are linked to five conditions that may either initiate or exacerbate gluten-related disorders:

Intestinal permeability

Imbalanced gut bacteria

Immune activation and allergies

Impaired digestion

Damage to the intestinal wall"

As you may know, trillions of bacteria live in our gut. These little critters help digest our food, generate vitamins for us, and breakdown many different compounds. The collection and distribution of these bacteria is known as our "microbiome". There's a lot of research going on right now exploring different aspects of our microbiomes, but it's a fairly new field: we don't know what constitutes a "good" or "healthy" microbiome or if such a thing exists at all. We know that the composition of the bacteria in our gut fluctuates a lot and very quickly (as examples, this study suggests that microbiomes change very quickly when you eat meat; this study suggests that jet lag impacts your microbiome, possibly causing metabolic imbalances). Odds are, your microbiome is changing at this very moment to account for many different factors, particularly if you had to deal with the ridiculous daylight savings time change this weekend. 

So what does this have to do with GMOs? One of the many arguments made by the Institute for Responsible Technology and other anti-GMO groups is that the Bt-toxin, which is a bacterial protein introduced into specific crops such as corn and cotton to make them insect resistant, negatively impact our gut. Here's an overview on how the Bt-toxin (or protein) works from UCSD: "The Bt toxin dissolve in the high pH insect gut and become active. The toxins then attack the gut cells of the insect, punching holes in the lining. The Bt spores spills out of the gut and germinate in the insect causing death within a couple days." Basically, if a bug that is sensitive to Bt eats a crop that has the Bt-toxin transgene, then it will die pretty quickly.

The reason why this same pathway doesn't work in humans is because a) our guts don't have high pH (our stomach has low/acidic pH), and b) we don't have the receptors in our gut that recognize Bt. 

So, that's why I was curious to read this paper. Would a single statement from the Institute for Responsible Technology finally be correct/accurate? Aren't you excited??? Let's get started!!

The paper starts by outlining the importance of this field of research (my comments/thoughts in brackets): any change in the microbiome caused by a GM-plant could impact the host [i.e. the person], particularly if the individual is immunocompromised; the European Food Safety Authority guidelines recommend examining the impact of GMOs during animal feeding trials, but most research examining the Bt-toxin has examined the impact of the protein on bacteria of the soil [which is also important from an ecological standpoint]; in vitro [in a petri dish] tests suggest that the Bt toxin has anti-bacterial properties and that it doesn't actually get completely degraded in the intestine, so it's important to figure out what it does in vivo [in a living organism]. 

The paper also reviews results of previous Bt-corn feeding studies that have examined the microbiome: 2 feeding studies in cows found no impact, a study in sheep also found no impact, but a feeding study in rats found a difference in the distribution/location of a bacteria after feeding Bt for 90-days (I've said it before and I'll say it again: if you read that there are no studies about GMOs and their safety, you are being misled). The authors explain that their study is important because a) the pig's digestive system is similar to that of humans and b) the DNA sequencing analysis that they perform is far superior to that used in previous studies. 

We interrupt this post for BioChica's shameless self-promotion: please read my previous post on DNA sequencing if you need an introduction to the technology.

The experiment seems pretty well designed: once the pigs were weaned, they were randomly split into two groups of nine pigs each (i.e. n=9/treatment). One group was given feed that was made from Bt-corn and the second group was given feed that was made from the non-genetically modified strain of the corn (i.e. the non-GM isogenic parent line). The pigs weren't given antibiotics at any point and were allowed to eat and drink freely. It would have been good to have the numbers of how much they ate/drank to determine if there was any difference.

The Bt-corn and the control corn were grown in neighboring plots to ensure that they had the same environmental conditions (this is an important aspect to the study since previous papers that I've reviewed suggest that the environment plays a bigger role in differences between GM and non-GM crops than whether the crop is a GMO). The Bt-corn and its corn were tested to determine if there were any differences in their nutritional composition (i.e. does the GM-corn have more/less sugars, carbs, amino acids, etc. than the non-GM corn?) and there were no alarming differences. The authors made feed for the pigs out of the Bt-corn, making sure that the ONLY GM ingredient was the Bt-corn. For the control pigs, they made the exact same feed using the control corn. The pigs were fed the corn for 31 days and then euthanized. Fecal samples (i.e. pig poop) were collected on day 1 and day 31. Once the pigs were euthanized, samples were collected from different points along the intestine. Then, DNA was collected from all the stool samples.



Apparently, this cute little mammal's
digestive system is quite similar to our own

Once they had the DNA, they performed a specific analysis which allows you to determine what species were in the sample (including bacteria), as well as their distribution (for the science-y people, they amplified the v4 portion of the 16S rRNA using universal primers, sequenced on a 454 and then BLASTed against a 16s-specific database). They included a negative control throughout the DNA analysis. They compared the results from the two groups of pigs and did the necessary stats.

So... after all that work, what did the data say?

The authors go through the different families of bacteria found in each area of the intestine and any differences seen between the two treatments. There were no differences in the abundance of the most prevalent types of bacteria between the two treatment groups. There were differences in the abundance of some of the minor families of bacteria, most of which the authors attribute to sampling (for example, the bacteria was found in 5 pigs in one treatment and only 2 pigs in the other treatment). Other differences in the abundance of the less prevalent bacteria were primarily attributed to differences in the amount of fiber between the corn leading to differences in the amount of food ingested (which points again to the fact that the authors really should have measured the amount of food and water that the pigs were taking in). It's important to note that the differences observed were within the "normal" amount for corn.

The authors conclude by stating that the biological importance of these small differences remains to be seen, but that, in any case, they didn't cause any issues in the intestines of the pigs examined. The authors point out that they didn't observe any anti-bacterial effects caused by the Bt-toxin, possibly due to the fact that the amount of Bt-toxin in the feed was approximately 4000x lower than the amount used in the in vitro studies where the anti-bacterial effect had been observed/measured.

I'd like to take a moment to say "Holy Crap!! 4000x lower?? No wonder the real world relevance of in vitro studies is always an important question!!"

The final paragraph of the study reads (my explanations in [brackets]): "In conclusion, 31 days of Bt maize consumption had only minimal impact on microbial community structure in the ceca [gut] of pigs, resulting in statistically significant differences in abundance of only 2 of 39 bacterial families and 2 of 54 genera [subfamilies] detected. However, the low abundance and frequency of detection of some taxa [types of bacteria], as well as the lack of information on their role within the intestine, make interpretation of some of the data difficult. Nonetheless, results from the present study indicate that dietary Bt maize [corn] is well tolerated at the level of the intestinal microbiota following 31 days of exposure, as the differences observed are not believed to be of major biological importance and were not associated with any adverse health effects."

So there you have it. The paper suggests that Bt corn doesn't cause a leaky gut, doesn't kill the bacteria in your gut, and doesn't have a negative impact on your intestine. Next time you're bloated and gassy, you won't be able to blame the GMOs :P

I have no doubt that some will read this and point to the small differences observed and yell "Aha!! There ARE differences!" The paper clearly questions the biological relevance of these differences, and as I mentioned earlier in this post, the paper adds more evidence to an existing body of data suggesting that Bt causes no harm in the gut. Some will say "31 days isn't enough!!", but again, as I mentioned at the beginning of this post, evidence suggests that changes in our microbiome take place quickly and that it's always in flux. If I were an academic scientist, I wouldn't want to investigate the question of Bt impact on microbiomes any further because of the high likelihood that I wouldn't find anything new. We hear a lot about the shortage of grant money and funding in science. Can you honestly tell me that it's the best use of your tax dollars to do yet another study on this topic with all the data that already exists? Anyhoo, that's my rant for this evening...

Till next time!

Update 11/6/2014: I got the following comment about the article that is worth noting "They also didn't use very strict p-values or do multiple test corrections - pretty amazing how few significant hits they found without it!"

GMOs and toxins leach through your skin

Last week, the tweets were flying furiously in a "Right to Know" campaign regarding fem care products (for more information, see here). Apparently, there's concern over the fact that feminine hygiene products are not labelled, we do not know what's in them, and that may include GMO cotton. Two "experiments" were performed:

Every item here is potentially toxic
Wikipedia Commons

1) Two pads were incinerated in someone's backyard: one was Always and one was organic cotton. The Always pad burned differently and released a lot of "toxins".
2) Two tampons were submerged in ultra-purified water on someone's kitchen table: one was O.B and one was organic cotton. The O.B tampon supposedly released a lot more fibers, which are assumed to be rayon, and the O.B tampon also developed spots, which are assumed to be mold.

Based on these experiments, there's a petition to Procter & Gamble to disclose the make up of their fem care products.

The concern is that the contents of the fem care products will leach into our systems, since "our skin is the largest and most absorbent organ in our body" (that's from Dr Mercola's site, highlighting the dangers of inorganic fem care products).

I'll begin with the fact that there's no evidence for the causation or even association between synthetic fem care products and health issues. Let me outline the steps I took:

• I checked Snopes.com for any information on tampons and pads. There are two false urban legends regarding tampons being associated with toxic shock syndrome, as well as the presence of asbestos in tampons. There is also a false urban legend regarding the use of sanitary pads being linked to cases of uterine and bladder cancer. 
• I went to pubmed and typed in "feminine hygiene products". I found 1337 hits. That's not a typo. 1337 various studies have been carried out examining different aspects of feminine hygiene products ranging from their use in HPV detection, HIV prevention, and health education. Study methods range from the examination for irritation with new film surfaces to the analysis of changes in bacterial cultures with feminine care products.
• I checked the American Cancer Society's webpage, which stated that the link between tampons and cancer is "absurd". I searched on the American Medical Association's webpage, and couldn't find anything.
• After that, I stopped.

With 1337 studies performed, the alleged toxicity of fem care products is not an issue to our doctors or to the FDA. Instead of speculating that it's due to payoffs from big corporations like P&G or Unilever, I will propose that it's because it's not a problem.  

There are several issues at hand. One is that the team or individual behind this whole movement has not done their homework. If I was able to find this information during my lunch break at work, then so could they. This is perhaps best highlighted by the fact that O.B tampons are not made by P&G and that their petition on change.org is to the incorrect person. As to the burning of the products, I hate to say it but that experiment is up there with putting salt water fish in fresh water to see if they'll die. Always products contain glue, plastic liners, and other oil-based compounds which anyone would expect to burn differently from an organic cotton pad. As for the mold, if you look at the pictures those brown specs are present even at 2 hours. But even at 24 hours, the likelihood that it's mold is pretty low, and it's probably just cotton fibers. 

Second is that if you are going to argue that toxins from GMOs and from hygenic products leach into your system through your skin, here's a list of items that you should be aware of:

• The cotton clothes you wear are probably made of GM cotton
• The natural baby care products may contain ingredients from GM crops. 
• The fabric in your car and child's car seat might contain GM cotton
• The production of many types of fabrics and plastics require alcohol, which might be ethanol made from GM corn or soybeans
• Your wool clothes might be from animals that are fed GM alfalfa 
• Your leather furniture might be from animals that are given GM feed
• The taxi that you take might be running on ethanol gas from GM corn, as well as the municipal vehicles in your area. All that GM DNA might be in the air...

And then there's all those toxins from all the other things that come into contact with your skin and how they might impact your health:

• Your cell phone cover is in your hand or in your pocket for most of the day, and probably contains "toxins" that make the plastic durable and robust
• The mouse on your computer has a rubber wheel, which may contain natural rubber from a farm that douses its trees with pesticides
• Your desk and table are probably made of composite wood that release tons of formaldehyde that you're breathing and is entering your pores
• and a million different things

There is no evidence that any of this is true. In the past, I've shown how we might create a sharknado or a zombie apocalypse, in similar hypothetical statements. At this point, we're beyond sharknados. We're at sharktopi (is that the plural of a sharktopus?). 

My next point is regarding your "right to know". I am willing to bet Baby-Boy's two chubby cheeks that in the highly unlikely scenario that P&G responds to your request, the list of ingredients in their feminine care products will include compounds with words like "poly-X" or "ethyl-Y" or "nitro-Z" and you will be displeased because they won't sound "natural". Someone out there will do a bit of research and will probably discover that those compounds are also present in other ominous things like trash bags or the sole of your shoes, and you will panic. So instead of making a ruckus and trying to get a giant corporation to disclose trade secrets which they are not legally obliged to provide, why don't you just buy organic fem care products and be done with it?

Finally, the video with the fem care product bonfire was put together by a company that sells "100% natural fem care products". So isn't there a possibility that you're being duped by a company that's trying to sell their product into believing that there's an issue when there really isn't one?

I'd like to close with a personal note. My sister, the mother of two phenomenal kids, is a chemical engineer and has been working for P&G for over 5 years. She started as an intern and has worked with them in two different countries, so I've met a few of her friends and colleagues. And she worked in their fem care product lines. I've always felt that the mark of a good product is brand loyalty, especially from its own employees. And I have never seen a company with employees as loyal to their products as P&G, with the possible exceptions of Google and Apple. So if you think that they put products out there without proper testing, you're wrong. If you think they'd create products that would knowingly endanger you, you're outta whack.

I've said this before and I'll say it again: yes, big corporations (correction: ALL corporations including companies that make "100% natural tampons") are in the business of making money and to create a crummy product or a product that would be recalled would not be conducive to their goals.

Also, P&G makes awesome commercials for the Olympics :)

YAY TEAM CANADA!!!!