I tend to encounter a lot of opinions about nutrition; it's something of an occupational hazard. Some are inquisitive, some assertive. Some are respectful, some are ... otherwise. Lately, I have been fielding a barrage about cooking oils somewhat preferentially, and canola oil in particular. Quite a bit of it is overcooked -- and I mean the correspondence, not the oil.
To address the relevant details requires something of a manifesto encompassing genetics, biology, food science, journalism, nutrition and the nature of expertise. I have written it accordingly. The brief version follows below; the truly decked-out version is the just-released third edition of my nutrition textbook, which runs to some 700 pages and 10,000 citations.
But since even the below is something of a tome, I will start with the crib notes for those who prefer to roll that way:
-- Katz Family-preferred oils include olive and canola for various reasons, detailed below.
-- For those who disagree about canola, it's not because they know something I don't know; I have Google, too. It's because they believe something I don't believe.
-- Information is not knowledge; information must be interpreted to be knowledge. Expertise facilitates interpretation.
-- Assertions are not facts. They are opinions until verified. In case you missed the memo, the earth is not flat, and the sun does not revolve around it. Assertions are not facts.
-- Genetic modification is the engine of evolution, and has been going on forever -- including genetic transfers across species. Willful genetic modification has been going on since the dawn of agriculture.
-- Genetic modification is like science in general: intended to do good (except in nefarious hands), capable of doing generally unintended harm. Rejecting the former for fear of the latter is a class failure to separate baby from bathwater.
-- No one knows the exact, specific health effects over lifetimes of one food at varying frequencies, doses and preparations in the context of varying diets. No one.
Now, away we go. As best I can tell, the principal concern about canola oil an association with the dreaded "GMO." I suspect everyone knows, but just in case: GMO means "genetically modified organism."
That's an interesting place to start. It refers to an organism, not an oil. There is no such thing, despite the frequent rants I hear, as "GMO canola oil." Rather, there are genetically modified canola plants. The plants produce seeds, and the seeds are crushed to generate the oil. There is more to the production story -- help yourself to the details if so inclined -- but that's the gist.
Genetic modification refers, ipso facto, to the modification of genes. Genes reside in DNA. Deoxyribonucleic acid is a protein-like compound. For the most part, the relevant products of genetic modification -- those that contribute to the widespread angst -- tend to be proteins as well.
How much protein or DNA is present in canola oil? Absolutely none.
In other words, the specific products of genetic modification, as well as the products once removed, are not present in the oil.
What lingering effect does genetic modification have on the oil? It influences the proportional concentration of different fatty acids. That, and perhaps an effect on the level of a couple nutrients -- namely vitamins E and K -- is the only effect genetic modification could have on a cooking oil, because that's all there is in it. Canola oil is 100 percent composed of fatty acids -- with a bit of native vitamins in the mix. The only possible difference, therefore, between an oil derived from a GMO source and an oil derived from a non-GMO source, is the mix of fatty acids. The likely health effects of any oil are best judged accordingly. On that basis, as noted, my own family uses canola fairly routinely.
Genetic modifications, some the simple product of age-old selective breeding practices, can be introduced specifically to enhance the native mix of fatty acids. There are variations on the theme of canola oil, and some are the product of plants genetically modified to be enriched with omega-3 fat. Others are low in omega-3, and proportionately higher in monounsaturated fat.
When the fussing is over and the facts considered, that really is the only effect of genetic modification a consumer of canola, or any other such oil, will encounter.
Which leads to my recommendation about the role of different oils in your diet: choose on the basis of fatty acid distribution and associated health effects; choose on the basis of heat tolerance and smoke point; choose on the basis of environmental effects if so inclined; and choose on the basis of taste. All the rest is just so much heat, but very little light.
Perhaps you are thinking I am a proponent of GMO. I am not a proponent, any more than I am an opponent. Being for or against GMO is like being for or against "science." Science is intended to do good, but can, of course, do unintended harm. GMO is simply one expression of that general theme. Genetic modification may harm people, perhaps in subtle ways like food intolerances. It might harm the planet, as well, by attenuating genetic adversity -- or in some other way.
On the other hand, it might help both in various ways. It might extend the shelf life of produce; protect fruit from early frost; and make plants more tolerant of heat and drought, an increasingly crucial issue. It might enhance nutrient composition, as it does with canola oil, and lessen reliance on pesticides by cultivating native pest resistance.
As for harms, the case has been made recently in Forbes that if we were going to see them anywhere, we would have seen them clearly in domestic animals. Feed animals have been dosed with a staggering amount of GMO products since 1996, and data on the general health of the herds and flocks exist for periods both before and after that date. As developed in the Forbes article, we can directly compare the general health of tens of billions of animals exposed to a GMO-free diet, and a diet derived almost entirely from GMO crops.
Not only can we, but we have. The results were recently published in the Journal of Animal Science. No difference was detected in the health of the animals; no difference was detected in the composition of their meat or milk. End of story.
If you are adamantly opposed to GMO, you may be inclined to dismiss this. Perhaps you want to argue that animals are not humans. OK, but in for a penny, in for pound. You are now obligated to dismiss every other finding in animal research for the same reason, no matter how much you like it. You will certainly have a hard time finding any other animal study involving 100 billion participants.
GMO is not all good, and we should invoke the precautionary principle as we proceed. But it certainly is nothing like all bad, despite the rants. The rants are much like those against vaccines, and those, too, are misguided. You can sign up for diatribe if you want; but you have to ignore the data to do it.
And that is probably just what most zealots on these health topics do: ignore the data, completely or selectively. If you are staunchly opposed to GMOs, I suspect you stopped reading this column long before now. But if you are opposed and still reading -- first of all, thank you. We need more of that! Now, consider how many full research papers on GMO you have read. Consider how many toxicology articles you have scrutinized, start to finish.
I don't mean to presume, but I very much suspect the answer is: none. What leads most of us to our extreme positions is opinions, perhaps based on social media, compounded by preconceived notions, based perhaps on blogs, based on other blogs, based in turn on other blogs, based originally on a headline in an article the first author never actually read, about a research paper they CERTAINLY didn't read. This, all too often, is what journalism has become in the age of the blogosphere. I recommend you proceed with extreme caution. This is GMI -- generically modified information -- and while GMO may or may not harbor toxicities, GMI does for sure.
[Read: GMOs -- From a Farmer's Perspective .]
If the concept of genetic modification still just creeps you out, consider that every domestic plant and animal -- every one -- is a product of willful genetic modification. That's what selective breeding is.
But perhaps it's just the use of test tubes that bothers you. But genetic modifications achieved in test tubes are responsible for such things as the eradication of smallpox, the near eradication of polio and overcoming the challenges of infertility.
So then maybe it's the transfer of genetic material across species that bothers you. That, after all, is just unnatural.
Except that it isn't. It happens so routinely in nature that the delivery vehicle for the genetic materials transferred has a name; it's called a plasmid. In nature, plasmids transfer genes among bacteria -- and that may seem trivial to you. But it is an established fact of biology that the genetic variation among bacteria is far greater than the genetic variation in all other members of the animal kingdom, combined. Bacteria differ from one another genetically more than penguins do from people, dogs from dolphins and monkeys from mackerel. When bacteria exchange DNA across species, it is at least as profound as anything we can hope to achieve in our laboratories. And it occurs all the time, with no help from us.
As for those cooking oils, my family and I have good reasons for our choices. Olive oil is great, and a standout feature of the healthful Mediterranean diet; but good olive oil tastes like olives, and so fails the taste test for many baked items -- desserts in particular. That's where canola oil comes in. I consider it a very good choice. Canola offers a fairly high smoke point, as do sunflower and safflower oils, making these good choices when high temperature is in the mix. There are other great oils, of course, but trade-offs with each. Flaxseed oil is a great source of omega-3 fat, but degrades with exposure to light let alone heat. Walnut oil is highly nutritious, but can be expensive and hard to find. The same is true of avocado oil.
Coconut oil may prove to be a good choice for cooking, but the data are still evolving. What we know now is that coconut oil is rich in lauric acid, a short chain (12-carbon) saturated fat that appears to be innocuous. The data are still coming in, and as of yet, the jury is out.
Because of data, and despite diatribe, canola oil along with olive oil aappear routinely in Katz family recipes. You are at liberty to disagree, of course; but yes, in fact, I am an expert. In modern culture, that appears not to matter -- but it really should. For starters, I have the same access to the Web as you; I can find all the arguments you find. But in addition, I have 40,000 hours of post-graduate training in health and medicine; well over 10,000 hours devoted to nutrition; some 6,500 hours writing three editions of a nutrition textbook that has withstood the scrutiny of peers for nearly 15 years; and 25 years of research, teaching and patient care into the bargain. Bottom line: I think I am at least as well qualified to choose a cooking oil as most of the people telling me what's what.
Am I, courtesy of all that training, absolutely certain about the exact health effects of any given oil? No, of course not. We really don't have the studies to say exactly what one food at some specific frequency and dose of use over the course of a lifetime in the context of widely varying diets does to health on average.
But I do know quite a bit about dietary patterns and their influence on health, and how various oils fit generally into such patterns. That is more than enough to guide both my personal decisions and recommendations -- and inform the fabulous cuisine with which my wife has nourished our family for years, and recently committed to sharing with others.
Besides, I can live with a bit of uncertainty. Bertrand Russell pointed out who tends to be the most certain of everything, and frankly -- I don't want to join that camp. They overcook everything.
For Katz Family-approved recipes, freely available to all with love, visit: http://cuisinicity.com/.
David L. Katz, MD, MPH, FACPM, FACP, is the founding director of Yale University's Prevention Research Center; president of the American College of Lifestyle Medicine; editor-in-chief of the journal Childhood Obesity; chief science officer for NuVal LLC; and director of the Integrative Medicine Center at Griffin Hospital. A clinician, researcher, author, inventor, journalist and media personality, Dr. Katz is the recipient of numerous awards and recognitions, including an honorary doctoral degree and widely supported nominations for the position of U.S. Surgeon General. He has authored nearly 200 scientific papers and chapters, 15 books, and hundreds of on-line columns and blogs -- with a resulting following of well over a quarter million people. A two-time diplomat of the American Board of Internal Medicine, and a board-certified specialist in preventive medicine/public health, he is recognized globally for expertise in nutrition, weight management and the prevention of chronic disease. He has been acclaimed by colleagues as the "poet laureate" of health promotion.