Understanding GM Food Safety

Dept. of Agronomy and Horticulture Author

10/12/2018 Added

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A food safety testing expert helps us understand how food safety testing is done before a genetically engineered product is ever allowed on the market.

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[00:00:04.140]The biggest challenge, really,
[00:00:05.520]is that most people have a lack of understanding
[00:00:09.540]of foods and what's in the food, and how different it is
[00:00:15.250]from one box of cereal to another, from one meal to another.
[00:00:20.560]The varieties of food crops
[00:00:22.860]that we grow are really highly diverse, and they have to be.
[00:00:27.130]To help produce food effectively
[00:00:28.980]in a wide range of environments,
[00:00:30.940]farmers have relied on biotechnology
[00:00:33.280]to help plants resist diseases, respond better
[00:00:36.150]to environmental stresses, and produce higher yields.
[00:00:39.830]This has been done for thousands of years
[00:00:41.790]using cross-breeding.
[00:00:43.650]Beginning in the 1990s, plant breeders were able
[00:00:46.590]to make very specific genetic changes through biotechnology
[00:00:50.500]to access a broader range of traits
[00:00:52.520]to solve complex agricultural problems.
[00:00:55.730]Because all living organisms use DNA to determine traits,
[00:00:59.680]it is possible to take a gene from one organism
[00:01:02.660]and move it to another in order to obtain that trait.
[00:01:06.050]This process is what we call genetic engineering
[00:01:09.300]or genetic modification, known as GM.
[00:01:13.410]Since genetic engineering allows us
[00:01:15.410]to take genes from anywhere,
[00:01:17.200]it allows for more solutions to problems
[00:01:19.530]than with cross-breeding.
[00:01:21.550]As people have considered this technology,
[00:01:23.870]they have raised a variety of concerns.
[00:01:26.480]There is confusion about what the real risks are,
[00:01:29.160]and which ones are simply sensational media.
[00:01:32.090]Let's clear the air.
[00:01:34.580]The risks of eating a genetically modified food
[00:01:37.760]are essentially the same as eating any food.
[00:01:40.410]You have to think about could it cause a toxic reaction,
[00:01:44.650]or could it cause an allergic reaction?
[00:01:48.120]We understand the mechanisms of those things,
[00:01:50.860]and regulators of genetically engineered
[00:01:53.740]or genetically modified foods have developed guidelines
[00:01:57.920]that help lead the developers and the scientists
[00:02:00.690]through an evaluation to reduce the risk of toxicity
[00:02:06.090]and of allergenicity from any food
[00:02:09.060]before it goes on to the market.
[00:02:11.470]Toxins will affect essentially everybody,
[00:02:14.920]and it's not always immediate.
[00:02:18.130]Quite often they're immediate reactions,
[00:02:20.170]and sometimes they're very long reactions.
[00:02:22.790]But it affects essentially everybody,
[00:02:24.680]and so if you have a hundred people, 99 of them will react,
[00:02:29.750]or 100% of them will react the same way.
[00:02:33.550]If you have an allergen, it's very individualized
[00:02:37.410]in terms of the reaction.
[00:02:39.210]It's an immune reaction.
[00:02:41.420]You have to be exposed to that food source before,
[00:02:45.370]and your body makes antibodies against it.
[00:02:48.690]And about 1% is the highest of any of the known allergens.
[00:02:53.490]1% of people might have a reaction,
[00:02:55.820]and they have to avoid that food.
[00:02:58.060]Everybody else can eat the food without any adverse effect.
[00:03:02.350]I think that most consumers have begun to listen
[00:03:08.570]to people who say there's no safety testing that is done
[00:03:12.530]on a genetically modified crop,
[00:03:14.410]whether it's corn or soybean,
[00:03:16.050]or on a genetically modified salmon.
[00:03:19.390]The truth is that the food crops
[00:03:21.300]that we're eating have been tested for thousands of years
[00:03:24.420]by people eating them, by experience.
[00:03:26.760]And a lot of what we know about safety
[00:03:29.430]is very well established, and again, people don't know that
[00:03:34.470]because they haven't been exposed to that
[00:03:37.210]in terms of what's really done with food.
[00:03:39.900]When you develop a new GM food, whether it's a soybean,
[00:03:44.020]or a corn, or a peanut, or a GM salmon,
[00:03:48.870]you have to go through the same kinds of tests
[00:03:51.480]for all of those individual genetically engineered events.
[00:03:56.910]The primary concern is is the gene producing a protein
[00:04:01.780]that's an allergen?
[00:04:03.110]So how do you evaluate that?
[00:04:05.300]The real issue is are you transferring a protein
[00:04:09.650]from one source to another source
[00:04:12.450]that's already an allergen?
[00:04:14.690]To determine if your transgene source
[00:04:16.840]will introduce an allergen or toxin,
[00:04:19.050]scientists use a series of four main tests,
[00:04:21.950]which include source history, sequence comparison,
[00:04:25.950]serum testing and pepsin digestion.
[00:04:29.160]When a scientist is considering which potential genes
[00:04:32.110]they could use to solve a problem,
[00:04:33.880]the first thing they consider is the history of the source.
[00:04:37.220]What does that mean?
[00:04:38.860]Well let's imagine that we want
[00:04:40.240]to make soybeans resistant to a disease.
[00:04:42.960]A good resistance gene is found in peanuts,
[00:04:45.370]spinach and panther mushrooms.
[00:04:47.790]The gene from each source would do the job,
[00:04:50.150]but some of them would not be considered.
[00:04:52.190]Let's think like the scientist to find out why.
[00:04:55.780]The peanut has been eaten for thousands of years,
[00:04:58.400]but it is also known to be the most common allergen,
[00:05:01.250]with 1% of people reacting.
[00:05:03.920]This protein will have to go through further testing
[00:05:06.290]to see if it involved in giving an allergic response.
[00:05:10.380]The panther mushroom is known to be poisonous.
[00:05:13.360]Even if the gene that we transfer
[00:05:14.970]does not make the toxic protein,
[00:05:16.950]we don't consider this option
[00:05:18.480]without specific additional tests.
[00:05:21.590]People have eaten spinach for thousands of years
[00:05:23.970]with no known reactions.
[00:05:25.840]We even feed it to babies.
[00:05:27.840]Spinach, the source of the gene,
[00:05:30.160]has the best history and will pass step one.
[00:05:34.350]For the new GM protein, what we do
[00:05:36.860]is consider the sequence of the protein,
[00:05:40.270]compare it to known allergens,
[00:05:43.030]because if you are allergic to peanut,
[00:05:46.130]you're allergic to certain proteins.
[00:05:48.810]If we take proteins that are similar to a peanut allergen
[00:05:52.870]to one of the proteins that cause allergy,
[00:05:55.340]if we transfer a similar protein into a new food like rice,
[00:05:59.730]then you could have the same kind of reaction
[00:06:01.870]that you had if you actually ate the peanut.
[00:06:05.150]And so we look at the sequence of the protein,
[00:06:07.560]and we have a database here at the University of Nebraska,
[00:06:12.090]an allergen database of essentially all the proteins
[00:06:16.530]that are known to cause allergy.
[00:06:19.210]So the new protein sequence is compared to the database.
[00:06:23.380]Every protein has a unique sequence,
[00:06:25.780]and the sequence determines all its properties,
[00:06:28.630]such as how it does its job, or how our body recognizes it.
[00:06:32.860]Similar sequences give similar properties.
[00:06:36.040]This means that scientists can use the information
[00:06:38.670]contained in a protein sequence to detect risk
[00:06:41.570]before they ever move a gene anywhere.
[00:06:44.190]This is done by comparing the sequence
[00:06:46.270]of the transgenic protein to a database
[00:06:48.650]of all known allergens and toxins.
[00:06:52.010]If the transgene source has a history of allergenicity,
[00:06:55.240]like peanut, or if the protein sequence is similar
[00:06:58.330]to a known allergen, we can use blood
[00:07:00.580]from people who are allergic to detect
[00:07:02.670]whether the protein we want to transfer
[00:07:04.540]will cause allergic reactions.
[00:07:06.950]This is done through tests
[00:07:08.080]called IgE antibody-binding assays.
[00:07:10.990]In these tests, blood is drawn from a patient
[00:07:13.390]who is allergic to the known allergen.
[00:07:15.790]The serum from the blood contains antibodies,
[00:07:18.220]and is applied to the samples of transgenic protein.
[00:07:21.620]The scientist then determines whether the protein reacts
[00:07:24.340]with the antibodies in the blood sample.
[00:07:26.640]If so, the protein is likely to be an allergen,
[00:07:29.400]and the project is scrapped.
[00:07:31.230]If not, these people will be safe
[00:07:33.230]when they consume products with this protein.
[00:07:36.380]Allergenic proteins typically take longer
[00:07:38.740]to digest in the stomach.
[00:07:40.730]This property allows us to test the protein
[00:07:43.150]we want to transfer to see
[00:07:44.570]if it could be a potential new allergen.
[00:07:47.140]If the protein takes too long to digest,
[00:07:49.920]it raises suspicion as to whether the protein
[00:07:52.230]could become an allergen.
[00:07:53.950]If it breaks down quickly,
[00:07:55.420]we've accumulated one more piece of evidence
[00:07:57.790]that this protein will be safe.
[00:08:00.700]So now that we have looked at all the steps,
[00:08:02.930]let's take a look at how they would play out
[00:08:04.910]with a few examples.
[00:08:07.400]We want to use a gene from peanut.
[00:08:09.720]We know that this source has a history of allergenicity,
[00:08:12.830]so we will certainly need to do serum testing,
[00:08:15.290]but we won't skip the sequence comparison.
[00:08:18.360]If the protein doesn't pass the serum test,
[00:08:20.910]the project will be scrapped,
[00:08:22.380]because it poses a risk to people with peanut allergies.
[00:08:25.960]However, if it does pass, we'll also do the pepsin test.
[00:08:31.070]We want to use a gene from onion.
[00:08:33.500]Onions do not have a history of toxicity,
[00:08:35.790]and rarely cause allergies.
[00:08:38.130]Let's say that when we compare the protein
[00:08:40.080]with the database of known allergens,
[00:08:42.120]we find it is very similar to a milk allergen.
[00:08:45.500]We would then need to do serum testing
[00:08:47.420]with the blood of people with milk allergies
[00:08:49.560]to see if they react.
[00:08:51.330]As before, if there is clear evidence
[00:08:53.570]of antibody binding, the project stops.
[00:08:56.590]If not, we move on to the final step of pepsin digestion.
[00:09:01.710]We want to use a gene from spinach.
[00:09:04.230]There is no known history of toxicity
[00:09:06.407]or allergenicity in this source.
[00:09:08.900]When we ran it through the database,
[00:09:10.540]it wasn't similar to any known allergens.
[00:09:13.330]Since this protein isn't associated
[00:09:15.320]with any known sensitive population
[00:09:17.350]like the peanut or onion examples,
[00:09:19.420]it doesn't make sense to do serum testing.
[00:09:22.440]We then finish testing with the pepsin digestion.
[00:09:26.760]These four steps of safety testing
[00:09:28.870]come from international guidelines
[00:09:30.720]implemented by the United Nations.
[00:09:33.210]Although we've shown these steps in a very linear process,
[00:09:36.480]the tests can be performed in a different order.
[00:09:39.430]And since each country is responsible
[00:09:41.380]for the food safety of their citizens,
[00:09:43.450]some tests are performed multiple times.
[00:09:46.380]In addition to these food safety tests,
[00:09:48.680]government agencies are responsible
[00:09:50.560]for ensuring safety for the environment.
[00:09:53.960]People make a lot of claims,
[00:09:55.800]and most of the consumers have little understanding of food,
[00:10:00.450]and they just listen to that.
[00:10:02.840]And then how do you as a scientist communicate to people
[00:10:06.600]that we can evaluate the potential risky properties of food,
[00:10:11.930]and we can make sure that we're not putting in something
[00:10:14.950]that would increase celiac disease,
[00:10:17.180]that we're not putting in something
[00:10:18.780]that would represent a major source of allergy or toxicity.
[00:10:22.910]But communication, then, is the real key to things,
[00:10:25.780]'cause that's difficult thing for me to do,
[00:10:28.950]and for most scientists,
[00:10:30.360]to be able to talk to the public
[00:10:33.010]and help alleviate their fears.

Understanding GM Food Safety

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Understanding GM Food Safety

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