Carcinogens in natural foods - the Ames test

I have previously written about the difference between natural foods and "unnatural foods" in terms of how much carcinogens they contain. I did one post on "Irrational fear of pesticides", and another post that I called "natural foods contain more carcinogens than unnatural foods".

Just now I found a video clip from Physics for Future Presidents, a UC Berkeley lecture series that you can watch for free online, in which Richard Muller, an entertaining physicist explains what this is all about. Watch and enjoy.

Popular fallacies of alternative and complementary medicine

In the most recent issue of the magazine "Skeptic", Harriet Hall, also known as "SkepDoc" writes about three fallacies that you will encounter very frequently if you engage in discussion about alternative or complementary medicine. I will of course not plagiarize Hall's article, but what I am writing here is her article, filtered through my brain (I have written about related matters here and here)...

The fallacies that you will inevitably hear are the following three;
(1) It is "natural" (and hence better for you)
(2) It has been used for a long time (and if it didn't work people would have stopped using it)
(3) It works for me (or a friend or a spouse or a friend of a friend...)

So natural is good by default ehh? In this form the statement sound very categorical, and hence, put in this fomr, the claim can be falsified by a single unambiguous counter-example, and there are plenty... Curare, a compound extracted from nature (and thus a natural compound?) will paralyze you and hence is not recommended unless you need to be still during a surgery. There are many different, naturally growing mushrooms, which will kill people who try to eat it. There is also the fen-phen scandal where a product which was advertised as an alternative medicine was later shown to have severe side effects, despite the fact that the active ingredient was "natural".

Ok, sure, there are a few extreme counter-examples, but still, isn't natural products better in general? Well this is certainly debatable and I would not jump to verdict just yet, however, the evidence to date actually tells the opposite story, namely that natural is often worse than "synthetic" (or whatever you won't to call it). Plants which are sprayed with pesticides are protected from potential predators and therefore they can use all their energy to grow. Now that I think of it, it is rather similar to us humans, in peacetime we can spend our energy on building schools and being nice to children and that sort of stuff... Plants which are not sprayed are not given their protection and therefore they have to use allot of energy on chemical warfare (or the plant-equivalent thereof). Basically they produce chemicals which will make the predator (us), sick.

But don't synthetic pesticides make you sick too? In large quantities they might (just like natural pesticides). However, pesticide control is rather strict and the chemicals used are tested so that they are of minimal danger to us... I have written more about this issue here.

The second argument says that if something has been used for a long time then it is because it is good. Again there are many counterexamples. Some people persist in using astrology even though it has been falsified over and over again. Astrologers cannot do what they claim to be able to do, and add to that the fact that their quackery is based on an astronomical model that is very out-dated. Still people are still using it… If we would have strictly gone by the "old is good" rule we would still be drilling holes in people's head to relieve headaches (here you can buy your own drill kitJ), and what about all new techniques and medicines that are developed? Are we to discard them because they are new? The fact of the matter is that we cannot rely on tradition. The way to test whether a therapy is good or bad is to do a proper, scientific test where it is possible to isolate the effect of the medicine from other factors such as placebo.

The last argument (it works for me), is the one that I have most sympathy for. In my opinion we should have respect for individual differences as well as the power of people's belief to cure them or at the very least make them feel better. If someone starts taking extra vitamins to bolster their immune system and then they do not get sick for a long time then everything is great (as long as they don't overdose which could be dangerous). Similarly, when I tell people that I am studying the brain I am often told about some therapy or mental training that I have never heard about before but which has changed their life. In those cases I normally just say that I am happy for them. However, the mistake that is often made is to assume that just because you have experienced miracles everyone else will too. Even with most conventional medicines which have a proven effect that is greater than placebo, it doesn't work for everyone. The point is that what works for you might not work for other people. Most alternative therapies have not been tested (or they have been tested with no effect). The responsible policy if you ask me is that doctors advocate therapies which have a proven effect, but do not prevent people from spending their money on other therapies (as long as they are not harmful)…

Irrational fear 1: Pesticides

About three months ago I wrote a post on natural foods and the highly exaggerated danger associated with pesticides. I cited research done by Bruce Ames (see picture), Professor of biochemistry and molecular biology at UC Berkeley. In this very interesting interview, Bruce Ames gives his view on organic foods. In the following excerpt from this interview Ames explains that the reason why he is against spending more resources on natural foods is not that it contains more carcinogens but rather that the production and in consequence also the products is more expensive. More expensive fruits and vegetables means less consumption which will result in more cancers:

Ames: Yes. I'm much more interested in preventing cancer. Then we have to get out to the public what's important. If you tell them about trivia all the time, they get completely confused, and it's counterproductive. I just think all this business of organic food is nonsense basically. We should be eating more fruits and vegetables, so the main way to do that is to make them cheaper. Anything that makes fruits and vegetables more expensive may increase cancer.

When I cite this information people often ask where Bruce Ames gets his money from. Is he really trustworthy? This is a fair question when you take into account the fact that the food industry is a big industry, and if organic foods would suddenly become the public choice it would certainly be rather detrimental to many companies. What many people seem to forget though is that producers of organic foods also have money waiting for them, should they manage to sway the public opinion. Unless it is suggested that organic food producers have a superior morality, immune to economic incentives, this is not a valid argument, after all the economic incentive is there for both sides. Maybe those the people who tell us that organic is the way to go do so because they would get rich if people followed their advice?

I feel quite confident that Bruce Ames is not bought by the food industry. Why? Partially, I believe Ames is a good guy because of what my intuition tells me. When I read the interview (referenced above) with this scientist he just doesn't strike me as a man who has sold his soul to the devil, quite the contrary in fact. However, the main reason why I don't think Ames is bought by the food industry is that he is also the man who first proved that many synthetic pesticides are carcinogenic. For quite a while he was a hero to all the natural food proponents.

Bruce Ames showed that indeed many man made chemicals are carcinogenic, but what reason do we have to assume that natural pesticides aren't also carcinogenic? Ames did not make this assumption and when he tested natural pesticides, which are created by the plants themselves as a protection, he found that pretty much the same proportion of natural pesticides was carcinogenic. Furthermore, Ames discovered that plants which are not treated with synthetic pesticides (i.e. natural foods) contain more potent carcinogens than plants which have been treated with pesticides. (Things can be more or less carcinogenic; for example, even though mushrooms contain 50% carcinogens they are very weak and therefore doesn't do a lot of damage whereas coffee contains much stronger carcinogens.) Read my previous post if you want to understand why. Add to this that 99.9% of the pesticides that we ingest are natural pesticides and you will understand why this post is about irrational fear.

Here we are worrying about 0.1% of the pesticides we ingest which according to the data are, if anything, less mutagenic than the other 99.9%. That is what I would call irrational fear…

Benefits of Omega 3 supplements?

Yesterday a woman from a company that sells Omega 3 fatty acid (see picture) capsules called me up and gave me a nice cheap offer that I would later accept. I have been taking Omega 3 supplement in different periods in my life and think I have experienced some sight improvement in my overall health. Whether this experience is due to the Omega 3 fatty acids, the placebo effect or just me fooling myself into believing that they do something to me, I don't know and I would certainly not make any strong claims about their efficacy based on what I have felt. I have reasoned that they are probably not harmful, I don't eat a lot of fish, and well they might be good for you, so I will try it.


Just for the fun of it I asked the woman how omega3 could help me. I was, I must admit, astonished by the list she provided me with. Here are some of her suggestions: "It stabilizes mood", "It makes you sleep better", "I reduces cholesterol", "I reduces the risk of dying from heart problems", "it brings oxygen to your muscles", "It improves the effect of exercise", "it help you concentrate" and she went on and on and on… To see whether the company also knew something about the mechanisms that give rise to these astounding changes I asked the woman how Omega 3 helps give oxygen to muscles, because I had never heard that claim before. Her answer was not very satisfactory, she said "well you know, the Omega3 goes to the muscles, and then more oxygen goes there as well", hmmm I kind of asked why but never mind that…


Now I do not claim to be an Omega 3 expert, but I am almost a hundred percent sure that the woman's claims were at least a little bit inflated as well as biased. Take her claim that Omega 3 stabilize mood. A quick search for the words Omega 3 and mood on PubMed gave me a couple of articles, and sure enough it seems that people with Omega 3 deficiency have a higher incidence of mood disorders. But wait, maybe everyone does not have a deficiency!? I was told that Omega 3 is good for mood, but this appears to hold only if I have too little of it. Not what I was told! Furthermore, the sources I have reviewed they invariably say that definite conclusions about the efficacy of Omega 3 are premature (which is of course not the same as saying that it doen't have an effect). The claim that there are no bad side effects associated with Omega 3 supplements is also false. According to Wikipedia Omega 3 can, increase bleeding, increase the probability of stroke (though I have also seen sources claiming the opposite), give rise to more oxidative agents which makes you old and causes cancer, and suppress immune function. I know Wikipedia is not the most reliable source so please correct me if I am wrong. When I explicitly asked the woman whether there were any side effects I got a simple no, then a nervous laughter, and then she said "sound like it is too good to be true right". Indeed it does I thought to myself.

I am not suggesting that people should not use Omega 3 supplements. Omega 3 has many important functions in the body and we are only able to get it via the diet (it is an essential fatty acid). What makes me react though is the enormous exaggeration of benefits that is so common when it comes to dietary supplements. Go into any "Hälsokost" store and you will see various natural products which when explained to you sound no less than miraculous. If everything they said was true I will bet you that these products would be used at hospitals as well. Or as one skeptical doctor put it, there is no doctor who would not give his or her right arm or first borne son for the type of miracles that some supplements offers according to those who sell them. Some readers will probably object here and say that it is in the interest of hospitals not to cure people (because you don't get money from people who are healthy), but I think this argument falls when you take into account the fact that hospitals has gotten better and better over time. Furthermore, people will pay for health care that actually help them, so if a hospital would go to far, say stop using antibiotics, then people would stop going to that hospital (except perhaps the Amish).

So go on, eat Omega 3, it might do you good. But remain skeptical about the claims made concerning its efficacy.

”Natural Foods” contain more carcinogens than ”Unnatural Foods”

If you are like me, the first thing you will react to in the headline is my discrimination between natural and unnatural foods. It is my impression that people who call natural foods "natural foods" refer to foods which have not been treated with pesticides. Personally I don't think this makes them more natural, and it definitely does not necessarily make them better. I suppose that natural foods are more natural in the sense that it is what we used to eat back in the days when we did not have the kind of technology that we have today, though based on that one could argue that primitive foods would be a more appropriate label. I must admit that I have never actually heard anyone talk about unnatural foods, I just assume that if someone asserts that foods which have not been treated with pesticides are natural, then they must think that foods which have been sprayed with pesticides must somehow be unnatural.

In any case, people who eat natural foods often claim that it is better for you. Why? Well according to the people I have talked to, natural foods are less toxic to you because they have not been sprayed with pesticides. Pesticides, according to these people are quite poisonous and ingesting them will result in all kinds of bad effects such as cancer. Therefore natural foods, which have not been sprayed with any pesticides must be better for you. The problem is that all foods, including natural foods, produce their own pesticides. In a moment I will argue (convincingly I hope), that natural foods in fact have a larger concentration of pesticides and that the pesticides in natural foods are even more toxic than the synthetic pesticides that we produce and spray on our "unnatural foods".

So how come natural foods have pesticides in them? If you think about it the answer is quite obvious. All plants need defenses against plant eaters. If a plant cannot avoid predation, then natural selection will take care of that plant in no time. That is, any plant without defenses will die and only the ones that do have a proper defense will be able to survive, reproduce, and thus send their genes into the next generation. Now plants are not particularly mobile, and therefore they cannot run away from their predators. So what do they do? They evolve defenses which either makes them hard to eat (e.g. thorns on cactuses), or they evolve chemical or pesticides that will either kill or hurt the predator when they try eating the plant. These substances are called natural pesticides. Natural pesticides are the chemicals contained within plants in order to make organisms that eat them sick or even kill them.

So we have two types of pesticides. There are pesticides that we produce in our industries and spray on plants to protect them from other organisms, and there are pesticides that the plants make themselves for the very same reason. What is the difference between these two types of pesticides? You may be thinking that since we have been exposed to natural pesticides (the ones the plants make) for a longer time, we would be able to handle them better, not so. The defenses we have in our body to protect us from pesticides are general, that is they don't care whether it is a natural pesticide or a synthetic pesticide, in fact they treat almost all different pesticides the same way. Throughout our evolutionary history, as we have included more things in our diet, we been exposed to new "natural pesticides". To our body the synthetic pesticides that we spray on plants are simply yet another novel pesticide. If you are still not convinced, consider the fact that there are quite a few types of pesticides that we have been exposed to for thousands and thousands of years which still today can be very bad for us.

I hope to have established that there is no general qualitative difference between the pesticides that we produce in our industries and the pesticides that plants produce. However, in all fairness this is not entirely true. The synthetic pesticides that we use today are selected based on their ability protect the plants on which they are sprayed, and importantly only mild toxins are used, that is our body can take care of them relatively easily. This means that if a plant is sprayed with synthetic pesticides that plant doesn't need to make its own pesticides because it is already protected. Of course, to the extent that the synthetic pesticide is toxic, the plant will also become more toxic, but normally this effect is very small. Now if, on the other hand, you do not spray a plant, then that plant will have to form its own pesticides, and the stronger the better. The plants that do not do this, as I mentioned before, will die. In consequence, each new generation of natural food crops will be the offspring of the most toxic plants in the previous generation. This should logically mean that the natural pesticides in natural foods are much more toxic than the natural pesticides in foods that have been sprayed.

This question has in fact been tested experimentally by Bruce Ames at the University of California, Berkeley. How did he test this? Well first, being a cruel scientist, he created a bacteria that lacked an enzyme that was critical for its survival. The only way for the bacteria to survive was if it, through random mutations got a working gene capable of producing the vital enzyme. Now, Ames would create say a thousand colonies of these unfortunate bacteria. Then he would squirt something, say a natural pesticide, on all the different colonies and see how many would grow. Ames could infer that if a bacterial colony would start growing then mutations had occurred in that colony, in other words the substance squirted on them must have been mutagenic and therefore carcinogenic. If you compare natural pesticides and synthetic pesticides in this type of test you will see that the natural pesticides will leave much more survivors than the synthetic ones. This may be good news for the bacteria, but not for us, because more mutations means higher risk of cancer. In other words the predictions stated above has been confirmed in the experiments performed by Ames.

What do I want to say with this? Well, I do not want to give the impression that I think natural foods are necessarily bad. Doing a very quick literary review I found a few studies claiming that there are more nutrients in organic relative to normal foods (organic foods is an extreme form of natural foods). However, all I want to say is that I think that our fear of synthetic pesticides is probably a little bit exaggerated, and that in many cases the toxins produced by the plants themselves are far worse.

Ps: For a good chapter on carcinogens in foods see Ames here in Handbook of toxicology