Toxic Tortillas?

[cornivore]

'Am I being too corny', I wondered, since I'd gotten some corn flour (masa) to try cooking with, as a staple food (perhaps). I wasn't sure if it was the healthiest choice, although I might have assumed this (after reading that masa had enhanced bioaccessibility of niacin, calcium, and protein, compared to regular corn, which is also the largest crop in the world). I wasn't exactly suspicious (based on such information), yet I was curious about whether mycotoxins were associated with the flour that I had been experimenting with lately (as they were with rye, for instance). So I took a look at what else came up for that in the U.S. National Library of Medicine (via NCBI search).

What I found is that corn flour could be more likely to have issues with mycotoxins than other common flours, because corn is less resistant to this kind of contamination. The first study I saw said that the process of producing masa probably reduces mycotoxins, yet other studies have determined that it probably does not, because populations who often eat corn tortillas have seemingly been exposed to mycotoxins from such foods, and may have higher rates of disease as a result.

Mycotoxins during the Processes of Nixtamalization and Tortilla Production

Because aflatoxins, particularly AFB1, are a severe health threat and are often found in maize produced in warmer climates, strategies for reducing aflatoxin contaminations are of special importance. Interestingly, traditional nixtamalization is in several studies described to have a high potential for lowering aflatoxin concentrations.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6520960/

Aflatoxins: A Global Concern for Food Safety, Human Health and Their Management

Mycotoxins, including aflatoxin, have affected most crops grown worldwide; however, the extent of aflatoxin toxicity varies according to the commodities. Aflatoxin can infect crops during growth phases or even after harvesting. Exposure to this toxin poses serious hazards to human health. Commodities such as corn, peanuts, pistachio, Brazil nuts, copra, and coconut are highly prone to contamination by aflatoxin, whereas wheat, oats, millet, barley, rice, cassava, soybeans, beans, pulses, and sorghum are usually resistant to aflatoxin contamination. However, agricultural products such as cocoa beans, linseeds, melon seeds and sunflower seeds are seldom contaminated.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5240007/


Intervention trial with calcium montmorillonite clay in a south Texas population exposed to aflatoxin

Although chronic exposure to AFs [Aflatoxins] is one of the major risk factors of HCC [hepatocellular carcinoma] in many developing regions of the world, such as Southeast Asia and Sub-Saharan Africa, the U.S. food supply is highly regulated and typically presents less risk of exposure. However, there is a potential for increased exposure in individuals consuming diets that can be relatively high in foods prone to contamination, such as corn and corn-based products (e.g. cornmeal, corn tortillas, etc.). It has been estimated that there will be 35,660 new cases and 24,550 deaths in the U.S. due to HCC in 2015. The State of Texas reports the highest HCC mortality in the U.S. and end-stage liver disease mortality is significantly higher in Latino populations. Specifically, South Texas Latinos have the highest HCC rates in the country, which are 3 to 4 times higher than those of non-Latino whites. Although the causative factors for this disparity are not well delineated and may be attributed to a variety of factors including hepatitis infection, exposure to environmental and dietary carcinogens are also potential risk factors in this population.

Previously, we have shown that AF exposure in a predominantly Latino community in San Antonio, Texas may be a contributing factor in the significantly increased incidence of HCC in the region, where levels of AF in blood and urine correlated with consumption of corn tortillas and rice.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5145309/


Association between aflatoxin-albumin adduct levels and tortilla consumption in Guatemalan adults

Tortillas are produced from a dough (masa) that is made by boiling maize meal with lime, which is then washed out in an alkaline-cooking process known as nixtamalization. Nixtamalization might reduce exposure to aflatoxins; however, its effectiveness in common practice remains inconclusive.

Our main objective was to examine whether maize consumption and, tortilla consumption in particular, was associated with AFB1-lys adduct levels among adults, in a country that is estimated to have the highest incidence of liver cancer and stunting in the western hemisphere.

There was a statistically significant association between tortilla consumption and AFB1-albumin levels. The LSM of AFB1-albumin was higher in the highest quintile of tortilla consumption compared to the lowest quintile. These findings indicate that tortilla may be an important source of AFB1 exposure in the Guatemalan population.

A previous study in Mexico found that women consumed 6 tortillas a day on average and those with high intake of tortillas had 3-fold higher average urinary fumonisin B1 (another mycotoxin that contaminates maize) levels compared with women who consumed fewer tortillas.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6541741/

Okay then, maybe I was being too corny.

[brimstoneSalad]

Interesting. I would expect any kind of corn flour to be of lower quality than whole corn products like popcorn or frozen whole corn (sold as a vegetable).

It would be good to know if there are better corn flours if this exposure is epidemiologically significant, and it kind of sounds like it may be.
This might be really meaningful for those who follow gluten free diets.

[cornivore]

Well, I guess this would include hominy, which is nixtamalized whole corn. Supposedly that process can make corn more nutritious as a staple food. In the article about Guatemala, they said that it was important to ensure the crop was not contaminated with mycotoxins. Although the article about Texas said this should be ensured with the U.S. regulations, yet corn is still prone to contamination, and people in Texas seem to be eating more mycotoxins in the corn tortillas (because they are encountering the same kind of disease as tortilla eaters in Guatemala). The first article above also mentioned that mycotoxins may be reactivated somehow in the process of making tortillas, even though the process of making flour for them was supposed to reduce the mycotoxins (if I read this correctly): "On the one hand, the toxins can be physically removed during steeping and washing. On the other hand, mycotoxins might be degraded, modified, or released/bound in the matrix by high pH and/or high temperature. This also applies to the subsequent baking of tortillas."

[cornivore]

Right, here's their full explanation of that (I hadn't read so much, because I thought the rest was about the mycotoxins having to do with alternative methods of making flour—when I was wondering about the traditional outcomes—well, I didn't read all of any article, but often those are only abstracts, so I'm used to guessing the rest)...

The modification of aflatoxins during alkaline treatment is not necessarily permanent, however, and might be reversed upon exposure to acidic conditions, as present in monogastric digestive systems. Price and Jorgensen addressed this issue by acidifying the suspended samples in the course of aflatoxin extraction (original pH around 11; acidified: 5–6), mimicking acidification in the human stomach. In fact, in doing so, part of the undetectable modified aflatoxin(s) was reconverted into fluorescent form(s). After acidification, the total aflatoxin reduction in the tortillas amounted to only 20%–46%, instead of 48%–73% when lacking such a step. For masa, the reduction in fluorescent aflatoxin(s) was approximately 14%–56% without and 4%–29% with acidification. Additionally, Méndez-Albores et al. showed that the reduction in aflatoxin concentrations by nixtamalization is partly reversible. After acidification, aflatoxins became, to some extent (approximately 5% of the concentration in raw maize), detectable in the dried nejayote, which originally had a pH of 12. When the extracts of the samples were acidified (initial pH of samples: 8.2–8.3), aflatoxin concentrations were around 57% and 34% higher compared with those in the alkaline extracts of masa and tortilla, respectively. However, compared with the raw maize, the aflatoxin levels were still very low with reductions of 78% in masa and 91% in tortillas (for the alkaline extracts, reductions amounted to 86% and 93%, respectively). Pérez-Flores et al. found that only very low amounts of aflatoxins in the extracts of masa and tortillas were recovered by an acidification step. Here, the pH of masa and tortillas was again around 8.2 prior acidification (and adjusted to 3). Different from Price and Jorgensen, in the two latter studies, not the suspended samples, but the sample extracts were acidified. However, when treated with weak bases and during ammoniation, AFB1 was found to interact with matrix macromolecules, including non-protein fractions. Hence, it is tempting to speculate that the extraction efficiency of the modified aflatoxin(s) is dependent on the pH of the matrix and that it is higher under acidic conditions. If this is true, matrix-associated aflatoxins potentially present in tortillas could be also released in the stomach...
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6520960/

I guess the rest is interesting too, but as far as reading this much, it could explain how even though the regulations might require testing for mycotoxins, it may not be an accurate indicator for them being present in the food anyway (if those can be reactivated by stomach acid, or other acidic food ingredients, perhaps). They also note that raw maize tends to have higher levels of aflatoxins in testing, yet the Guatemalan study noted that higher levels in blood tests occurred only with tortilla consumption, not maize in general, so it could be that it is only reactivated in corn flour products, and not whole corn (which causes illness if it contains enough mycotoxins, but probably doesn't if it tests negative for them, while the reverse may be true of corn flour, in essence).

A maze of maize? I might go through all of this information later, yet I'd read enough to learn that it wasn't entirely conclusive anyway. Bizarre as these articles are, so far I'd conclude that tortillas and corn in general wouldn't be my first choice as a kind of staple food, since I have other foods to choose from, which are less prone to contamination (as they say it may become more widespread with global warming, which can overwhelm the good agricultural practices that prevent mycotoxic matters). Although, I wouldn't assume that eating something else in mass quantities would be without similar risks (just as those who ate fewer tortillas had fewer problems with that). Shoot, I've eaten whole packages of corn tortillas in one sitting, just never made a habit of it (well, I'm no Texan)!

I'm no Korean either, but or further reading, this article looks to be interesting as well, because corn involves so many products, it's a wonder how likely any of them could be involved:

Distribution Analysis of Twelve Mycotoxins in Corn and Corn-Derived Products... It has to do with Korean corn; however, they mention other studies, as such.

Corn can be used directly as food or can be processed into food products such as corn flakes, corn flour, corn meal, corn oil, baby food, and starch. The ease of exposure to Fusarium mycotoxins in corn and the risks associated with them have prompted intensive studies into their occurrence in corn and corn-derived products. The worldwide occurrence of and human exposure to mycotoxins including FUMs [fumonisins], DON [deoxynivalenol], and ZEN [zearalenone] in corn and corn-based products have been well documented and reviewed in the literature. These studies have revealed high levels of contamination by these mycotoxins, especially in corn. Furthermore, there have been many reports of mycotoxin contamination and concentration in corn caused by repeated transportation and storage in conditions appropriate for fungal growth during corn milling and further processing.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6115783/

I've been to Korean supermarkets in the USA though, and they do play some really corny songs there (maybe those were inspired by something they ate).

Elsewhere in America, a prior article says some of that is more likely to occur only in certain products:

Control of fumonisin: effects of processing

Of about 10 billion bushels of corn that are grown each year in the United States, less than 2% is processed directly into food products, and about 18% is processed into intermediates such as high-fructose corn syrup, ethanol, and cornstarch. The vast majority of the annual crop is used domestically for animal feed (60%), and about 16% is exported. Thus, any program for controlling residues of fumonisin (FB) in food must recognize that most of the crop is grown for something other than food. Studies on the effects of wet milling on FB residues found these residues nondetectable in cornstarch, the starting material for high-fructose corn syrup and most other wet-milled food ingredients. Similar effects are noted for the dry-milling process. FB residues were nondetectable or quite low in dry flaking grits and corn flour, higher in corn germ, and highest in corn bran.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1240684/

That sounds a little less cornball, unless the studies of tortilla toxicity were right about it being tricker to detect than once thought, like the masked mycotoxins...

Food processing, can on the other hand also chemically alter mycotoxins, however most of the food-processing compounds are less toxic than their precursors. Microorganisms used in fermentation processes may transform mycotoxins into products that are also not detected by analytical methods conventionally used for mycotoxin monitoring... The definition of masked mycotoxins implies that the analysis of the mycotoxin content of samples containing these compounds leads to their underestimation.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3561696/

It almost sounds like there are mini mycotoxic kernels that behave like popcorn, in some kind of microcosmic way, and the tests would only detect the popped corn (which hasn't popped yet).

[cornivore]

I would expect any kind of corn flour to be of lower quality than whole corn products like popcorn or frozen whole corn (sold as a vegetable).

I was just reading a little more about it, to see if cornstarch was usually cleaner than corn flour (kind of like white sugar vs brown sugar). It seems to be the cleanest kind of corn flour, more often than not. Okay, it isn't really flour, but they call tapioca starch a flour, so maybe it's used that way too (for breading and such). Popcorn on the other hand isn't necessarily as clean by virtue of its processing.

Removal of Mycotoxins during Food Processing

In case of popcorn, we added oil to the popcorn in which deoxynivalenol had been detected. After popping, the popcorn for 5 minutes, we observed 140-220 ppb of deoxynivalenol, which was 196 ppb before cooking. When popped, the mycotoxin is found not to be decomposed by cooking...

Cornstarch is manufactured as follows. The manufacturing processes of corn starch are shown in Fig.3. Corn is cleaned, and steeped in hot water added 0.2% of sulfur dioxide at 40-50 hours. The object of steeping is to prepare corn for subsequent separation of starch and by-products by wet milling. The actual milling operating is carried out on steeped corn in several stages. The object of the milling process is to provide for as complete separation of component parts of corn kernels. After milling, we get corn starch, sugar and corn oil. And also we get corn steep liquor, germ, fiber and gluten using for feed.

Corn is often found contaminated with fumonisins. The fate of fumonisins was examined in manufacturing processed of corn starch made of fumonisin-contaminated raw corn. From the raw corn, 2.59 ppm of fumonisin B1 and 0.45 ppm of fumonisin B2 were detected, however, no fumonisins were found in the corn starch.

https://www.jstage.jst.go.jp/article/my ... l2_88/_pdf

The Food Safety Hazard Guidebook also says that levels of fumonisins in processed corn products are usually much lower than those found in unprocessed maize (and another article notes that cornstarch and corn oil do not generally contain fumonisins)... So the more processed it is, the fewer mycotoxins may be involved. It isn't necessarily that simple though, given the problem with tortillas.

[brimstoneSalad]

Popcorn on the other hand isn't necessarily as clean by virtue of its processing.

I didn't mean the popping part, but the sorting for the highest grade kernels which pop best which might cull out some of the really moldy ones that might have ended up in flour.

But it sound also like the mycotoxins can't hide in popcorn in the way they might in tortillas and lime processed flours.

[cornivore]

mycotoxins can't hide in popcorn in the way they might in tortillas and lime processed flours...

Yeah, that would seem to be why those are suspected of causing more health problems. Well, I didn't look into what all may be associated with popcorn, but wasn't planning on eating much of it (I tried air popping a bunch of my own before and it's like fart fuel... I wonder if those toxins go airborne, and now you know the people eating corn tortillas could let mycotoxic ones... maybe silent but deadly). Anyway, I hope not. There are always piles of those things in every store, so I guess some people eat piles of them.

[cornivore]

I was wondering about that too, if people eat tortillas everywhere in America, what makes Texas stand out as having the highest incidence of disease suspected in relation to corn tortillas in the diet (is it that they produce their own corn which is more susceptible to contamination)? Maybe that explains it, since there's an article describing one of their bad years for corn production in which the weather influenced contamination of perhaps the entire crop: Aflatoxin Outbreak Plagues Drought-Stressed Texas Corn...

[brimstoneSalad]

Not buying food from Texas seems like good advice all around; they have serious arsenic problems with their rice too.

[cornivore]

Oh yeah, looks like something else to read labels for, I see that both the corn tortillas and tortilla chips here are made in TX.