Doctor's Note

My 2008 video can be found here: Acrylamide in French Fries.

More on heterocyclic amines:

There are some things we can do to counteract the effects of these carcinogens, though:

I touch on polycyclic aromatic hydrocarbons in Meat Fumes: Dietary Secondhand Smoke and Is Liquid Smoke Flavoring Carcinogenic?
Certain fats may play a role in breast cancer survival as well: Breast Cancer Survival, Butterfat, and Chicken and Breast Cancer Survival and Trans Fat.

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  • Roseveg

    Please do a report on G6PD deficiency, the genetic disorder, that prohibits people from eating beans (and certain other foodstuffs). I suppose there are a lot of people who are not aware of this, and continue to eat beans thinking that their bean consumption is harmless, and beans make up a large part of some vegan diets.

    • David&Goliath

      Ugh…it is really rare and not worth commenting. By and large, those things you mentioned are very healthy and very anti-carcinogenic, and I assume logically, if someone were allergic to beans they would get specific physical problems to diagnose such. It seems you just wanted to say ‘something’ which is worse than nothing.

      • Ben

        hehe, reminds me of that saying: “better to remain silent and appear a fool then to speak and remove all doubt.”

      • guest

        Actually, the person brought up a very valid and established medical issue involving bean consumption. Many live are changed for the better as a result of abstaining from certain beans, if one has the G6PD deficiency.

    • JacquieRN

      Hi Roseveg, to help others understand the condition you referenced: just to be clear – beans do not cause G6PD.

      G6PD is Glucose-6-phosphate dehydrogenase deficiency, a genetic disorder that mainly affects red blood cells, which carry oxygen from the lungs to tissues throughout the body. A defect in an enzyme called glucose-6-phosphate dehydrogenase causes red blood cells to break down prematurely (hemolysis).

      If one has this deficiency, then hopefully they have been educated on how to manage:

      Factors such as infections, certain drugs, or ingesting fava beans can increase the levels of reactive oxygen species, causing red blood cells to be destroyed faster than the body can replace them. A reduction in the amount of red blood cells causes the signs and symptoms of hemolytic anemia.

      An estimated 400 million people worldwide have G6PD. This condition occurs most frequently in certain parts of Africa, Asia, and the Mediterranean. It affects about 1 in 10 African-American males in the United States.

  • HemoDynamic, M.D.

    Let me tell you the biggest of my worries–You stopping to produce these wonderful videos!
    You are my daily nutritional grand Rounds Physician.

  • guest

    Dr., how about saponins in grains and beans shown to compromise gut permeability. What do you think about this study?

    Would you suggest that vegans stick to just vegetables and fruits if they have gut permeability issues? I’m starting to take this seriously as everyday consumption of beans and grains seems a bit unnatural, as far as our human diet history is concerned.

    • KejDziA

      Well what do you think about this study?
      “Clinical studies have suggested that these health-promoting components,
      saponins, affect the immune system in ways that help to protect the
      human body against cancers, and also lower cholesterol levels. Saponins
      decrease blood lipids, lower cancer risks, and lower blood glucose
      response. A high saponin diet can be used in the inhibition of dental
      caries and platelet aggregation, in the treatment of hypercalciuria in
      humans, and as an antidote against acute lead poisoning. In
      epidemiological studies, saponins have been shown to have an inverse
      relationship with the incidence of renal stones… Saponins are thermal sensitive.
      During soaking and blanching, portions of saponins are dissolved in
      water and lost in the soaking, washing, and blanching liquors.”

      • Roseveg

        I’m actually familiar with those studies, but thanks anyway for including them here. While I do know of the benefits, I am also curious of potential negatives of saponins on gut permeability. I think the negative if worth exploring for people with certain health issues.

    • Thea

      guest: I can’t answer the gut permeability question, but I do have something to say about the lst part of your post: ” I’m starting to take this seriously as everyday consumption of beans
      and grains seems a bit unnatural, as far as our human diet history is

      My understanding of human diet history is quite the opposite. Eating grains and legumes seems like the most natural thing we could do. The following videos and articles with a key word of ‘paleo’ from this site provide a lot of insight into the matter.

      Don’t skip the video about beans and long life… That video is one in a series of videos on this site about beans. There is also a lot information about grains on this site.

      FYI: My bottom line is: While what our ancestors ate is interesting, it’s not my goal to eat like my ancestors. Our world is different than the world my ancestors lived in. It’s my goal to live a long and healthy life. (The NutritionFacts website gives us the latest information to help us meet that goal.) So, even if my ancestors never ate beans, if eating beans is a very healthy thing for me to do today, I’m going to want to do it. Something to think about.

      • I would add that we should eat consistent with our anatomy and physiology and consistent with the best health… avoiding chronic diseases and disability. Europeans developed the ability to digest lactose over the last 10,000 years or so but that doesn’t make dairy a healthy food choice. Anytime we consume animal products given the availability of adequate whole plant based calories with increase our risks of a number of diseases and conditions. For me it is about stacking the odds in our favor while helping the environment and reducing suffering.

        • Thea

          Thanks for adding on Dr. Forrester! Great points and well said.

      • guest

        I think you might be missing the point: while yes, there’s good stuff about beans, this doesn’t negate or throw out the potentially harmful aspects of beans due to gut permeability issues, as well as certain beans causing distress for certain folks. Mutually exclusive topics at hand here, and I think the original poster of the gut permeability issue was looking to explore what could be harmful in beans, not looking for a debate or opinions on the positiveness of beans. When science looks to explore an issue, it sticks to the issue it is exploring. To not do this would be the equivalent of the researchers who looked into the gut permeability issues of beans deciding to stop their research in its tracks because of the good qualities of beans. It just doesn’t work like that. The premise is to explore the gut permeabilit issues.

  • David&Goliath

    If one were to eat McDonald’s french fries once a month, or less (as I), and that were the only thing one ate there, then I suspect that the opportunity for cancer development (because of FF eating) would be virtually nonexistent, being of course that one continue being a semi-vegan, which being a vegan or vegetarian does not guarantee the absence of cancer, but only appreciably attenuates it.

  • I know French fries has always been bad for you because at high temperatures, cheap oils like canola oil go bad. Just as worse as hydrogenation. What would happen if you fried in avocado oil. Avacado oil is supposedly nutritious and has an unsupposedly high smoke point of 525°, actually the highest of all smoke points. Would this mean that the french fries would be; Harmful, Harmless or Healthful.

    Thanks for answering! :)

    • Timar

      I have seen a paper (I can’t find it right now, sorry) comparing a variety of different oils for frying potatoes. Refined canola oil actually came out very good, about as stable as extra virgin olive oil. High oleic sunflower was also OK, but ordinary sunflower oil or soybean oil were not very stable (not unexpectedly as they contain a lot of polyunsaturated fatty acids). Contrary to popular belief the smoking point is no indicator of the oxidative stability. Some very heat stable oils or fats have low smoke points and vice versa.

      • Luke Davis

        What about brushing the fries with oil and baking them?

        • That would limit some of the damage, but Dr. Greger advocates a whole food, plant-based diet which excludes the use of fats that have been commercially isolated from their original fibrous containers.

          • Actually he advocates for a Science based diet.

          • Timar

            That’s right. About 90% of your daily calories should come from scientific papers. Be aware though, that some of the inks used for printing contain carcinogens. Maybe Dr. Greger will make a video on this issue.

        • Timar

          As long as the temperature is the same (e.g. below 180°C) it shouldn’t make much of a difference. Frying has the benefit that less of the oil that ends up on the fries is exposed to oxygen, but baking, on the other hand, has the benefit of reducing the amount of oil.

          Dietary dogmas aside, I think it is perfectly fine to eat fried foods in limited amounts, as long as you do it yourself and use fresh canola or olive oil every time.

          I would never give up my delicious crispy fried falafel. But I eat only a few of them with whole grain pita, hummus, and a whole lot of salad and vegetables. This is what makes all the difference – compared to a heaping of french fries with mayonaise, for example.

          • Toxins

            I would be cautious when advocating for olive oils and canola oils. Lets remember that they are empty calories, extremely calorie dense and as such should be classified as junk food. Those on a very low fat, whole plant based diet would see no benefit from adding oil, and it would actually cause more harm then good.

          • Timar

            Someone who classifies virgin olive oil, a food which was already esteemed for its health-giving properties by the ancient Hebrews and Greeks and worshipped as a gift of God (or the Goddess Athena), as “junk food” exposes himself as a philistine extremist (IMHO).

            Especially as we now have hundreds of studies, among them the large-scale PREDIMED randomized controlled trial, scientifically verifying the ancient wisdom about olive oil’s healthfulness.

          • Toxins

            Again, lets examine whether olive oil is a health food or not. Jeff Novick puts it best:

            “Due to very effective marketing and advertising, we have become convinced that oil is not only a food, but a health food. This is crazy. To be a food, something must be able to support healthy life and be of some benefit.

            Oil is a highly refined processed and extracted food “product”. It has no protein or essential amino acids (which we need), it has no carbohydrates, or sugars (which we need), it has no fiber (which we need), it has no minerals (which we need) and has virtually no vitamins (which we need) except for a small amount of Vit E and some phytosterols.

            But, on the other hand, it is pure fat and the most calorie dense food on the planet. While all oils have a mixture of mono, poly and saturated fat, most oils are very low in the essential fat omega 3 (which some of us may need more of), very high in the omega 6 (which most of us need to lower) and most oils also have high ratios of omega 6 to omega 3 (which most all of us need to lower).

            So, basically you are getting lots of calories (oils has almost 2.5 x more calorie per TB than sugar). lots of omega 6s, some saturated fat (depending on the oil) and virtually no nutrients.

            The definition of a junk food is a food that is high in calories (and/or fat, sugar, salt) and has little if any nutrient value at all. Oil, is more of a junk food than sugar. And, I hope that in a few years, we will all come to understand it and see it, as such.”


            Those consuming very low fat, healthy whole plant based diets will see no purported benefits from consuming olive oil. I can say this with confidence because the American diet today is so unhealthy that any slightly healthier food choice will show benefits. You can tell I like Jeff Novick (mainly because of his genius and understanding of dietetics), because I am going to quote him again,

            “Move Over Walnuts, Kale, Goji Berrries, Sweet Potatoes, Purple Cabbage, etc., & Make Room For The Next Super Food: Carrots!
            “Carrot intake might be inversely associated with prostate cancer risk.”

            When you understand that the typical diet consumed today is **so** bad, possibly being the worst diet ever consumed by humans in recorded history, then you understand that you can look at a group of those eating this diet and take *any* one healthy (or healthier) food (or food with some healthier aspects to it), and look at those who eat more of it compared to those who eat less of it (or none of it) and almost always see a difference. But that does not make it into a health food, let alone a super food.”


            It is surprising that we nitpicked the Mediterranean diet and identified oil as the reason their diet is more healthful, not the higher intakes of fruits and vegetables. A few interventional studies have shown harmful arterial function to oil consumption after the fasting state.

            The participants of the study ate a meal containing 3.5 tablespoons of olive oil and the examiners measured their arterial function after 3 hours. “Contrary to part of our hypothesis, our study found that omega-9 (oleic acid)-rich olive oil impairs endothelieum function postprandially.” They also make note that “In terms of their postprandial effect on endothelieum function, the beneficial components of the Mediterranean and Lyon Diet Heart Study diets appear to be antioxidant-rich foods, including vegetables [and] fruits”


            It was even noted that “In a clinical study, olive oil was shown to activate coagulation factor VII to the same extent as does butter. Thus, olive oil does not have a clearly beneficial effect on vascular function.”


            Fresh or deep fried, it makes no difference, as olive, soybean and palm oils all produced an increase of triglycerides after consuming 3 tablespoons of each in a soup.


            Oil is admittedly tasty, after omitting it though for so long and having had it on cooked veggies (unknowingly), I found the taste extremely unappealing, and the texture of “sliminess” in my mouth also unappealing. I can understand why one would want to keeping eating oil for personal reasons, but it is a far stretch to call it healthy, maybe healthy for the person whos diet consisted of highly processed, high saturated fat and high animal product type foods. Especially those battling weight loss or who are trying to prevent heart disease, avoiding oil is another step towards healthier eating.

          • Timar

            You can of course always cite some diet Guru you favor or nitpick some highly reductionistic studies, measuring a few isolated biomarkers and some of which are of methodologically questionable quality. That doesn’t diminish the vast amount of evidence for the health benefits of olive oil deriving from a) RCTs, among them the the large-scale, long-term PREDIMED, b) numerous high-quality epidemiological (cohort) studies and last but not least c) ancient empirical knowledge accumulated over the lifetime of more than 200 generations living in the Mediterranean region.*

            Besides, olive oil is hardly adversited at all here in Europe. There is no need to advertise it, because it it is traditionally considered a health food for thousands of years. Fortunately, the US with its commercial excesses and cultural oblivion is not yet representative of the world at large.

            *Yes, they have always eaten a lot of fruits and vegetables. But they got the bulk of the calories needed for hard physical labor from whole grains, legumes and olive oil. In the 1950s, when Ancel Keys initiated the Seven Countries Study, Cretans had the highest life-expectancy in the western world and got more than 30% of their total caloric intake from olive oil alone.

          • Toxins

            I think you should not be so defensive in your argument. I am saying that the standard American diet is so unhealthy, that any food that is slightly healthier will show benifit. Current studies demonstrating the health benifits of olive oil compare those who are already consuming unhealthy diets to those who consume healthier ones. This is evident in the isle of crete example you cite.

            “The information that has been translated into the “Mediterranean Diet” came from a study that found low rates of heart disease amongst those living on the Isle of Crete in the late 1950’s. While this people did consume olives, avocados, olive oil and other monunsaturated fats, their diets were predominately fresh fruits, vegetables, whole grains, and legumes with small amounts of animal protein.

            Part of the reason for this was the community was very economically depressed as they were recovering from a recent time of war. Additionally, they were very active, walking an average of 9 miles a day.

            This dietary and exercise pattern, that was evident on the Isle of Crete in the late 50’s, no longer exist there (nor anywhere else in the Mediterranean). Rates of obesity and heart disease on the Isle of Crete have risen since
            the original study, as their diet and fitness patterns have changed.”

            Jeff Novick is no gypsy guru, he is infact one of the most well respected plant based dieticians in the world, and he works closely with Dr. John McDougal. Jeff Novick is well respected by many (including Dr. Greger), and the information he shares is not out of the wind; he is very good at evaluating the evidence.

            Those on a whole, plant based diet have no need, nor would benefit from olive oil.

            If we want to play the population game, the Okinawans are more noteworthy to cite.

            Back in the 1950’s the Japanese rural Okinawan group of people had the most centenarians per capita. How did they live so long? Here is their diet

            Caloric Restriction, the Traditional
            Okinawan Diet, and Healthy Aging
            The Diet of the World’s Longest-Lived People and Its Potential Impact on Morbidity and Life Span
            Ann. N.Y. Acad. Sci. 1114: 434–455 (2007).

            TABLE 1. Traditional dietary intake of Okinawans and other Japanese circa 1950

            Total calories 1785
            Total weight (grams) 1262
            Caloric density (calories/gram) 1.4
            Total protein in grams (% total calories) 39 (9)
            Total carbohydrate in grams (% total calories) 382 (85)
            Total fat in grams (% total calories) 12 (6)
            Saturated fatty acid 3.7
            Monounsaturated fatty acid 3.6
            Polyunsaturated fatty acid 4.8
            Total fiber (grams) 23
            Food group Weight in grams (% total calories)

            Rice 154 (12)
            Wheat, barley, and other grains 38 (7)
            Nuts, seeds Less than 1 (less than 1)
            Sugars 3 (less than 1)
            Oils 3 (2)
            Legumes (e.g., soy and other beans) 71 (6)

            Fish 15 (1)
            Meat (including poultry) 3 (less than 1)
            Eggs 1 (less than 1)
            Dairy less than 1 (less than 1)

            Sweet potatoes 849 (69)
            Other potatoes 2 (less than1)
            Other vegetables 114 (3)
            Fruit less than 1 (less than 1)
            Seaweed 1 (less than 1)
            Pickled vegetables 0 (0)
            Foods: flavors & alcohol 7 (less than 1)

            Data derived from analysis of U.S. National Archives, archived food records, 1949 and based on survey of 2279 persons.

            Some points

            Their diet was 85% carb, and 6% fat. Sweet potatoes (a Japanese sweet potato) made up almost 70% of their calories. Nuts were less than 1% of calories (the equivalent of 1/10 of an ounce a day) Oil was less than 2% of calories (which is about 1 tsp a day) and sugars were less than 1% of calories (less than a tsp a day)

            The total animal products including fish was less than 4% of calories which is less then 70 calories a day. That is the equivalent of around 2 oz of
            animal products or less a day

          • Timar

            1) I still haven’t seen a single good argument for avoiding olive oil, so I’m certainly not defensive.

            2) The PREDIMED trial didn’t compare people consuming the SAD with people consuming olive oil. It was a Spanish study on poeple with cardiovascular risk factors, comparing a control group following a pretty much traditional Spanish diet, including plenty of fruits and vegetables, which had been instructed to lower the intake of all fats and saturated fats in particular with the intervention group, which hadn’t been instructed to lower fat intake but instead given 1 liter virgin olive oil per week to consume on top of their habitual ~30% fat diet. The olive oil group fared significantly better than the control group.
            Interestingly, people in both groups had an exceptionally low event rate compared with similar cohorts from the US or Northern Europe.

            2) It is only our modern, decadent lifestyle that enables raw foodists to nourish themselves on (tropical) fruits and vegetables alone. People working physically or excercising need more calories than can be practically provided by fruits and non-starchy vegetables. Virtually all the evidence suggest that as long as your minimum carbohydrate requirements are met, virgin olive oil is at least as a healthy source of calories as whole grains are. Monounsaturated fatty acids have a more favorable effect on blood lipids than carbohydrates. By combining whole grains with oilve oil you get the best of both worlds (fiber and minerals from the grains and the olive oil’s vitamin E and powerful polyphenols).

          • Toxins

            1. I will refer to my first comment, when I say that olive oil is a processed food, in that it lack ANY nutritional value except for fat. This by definition is junk food. It is like saying that added raw cane sugar is beneficial for health because of the minute antioxidant content, when it has similar nutrition profile, but flipped fat for carbs. Just look at the nutrition profile.

            2. The problem with the study you cite is that the control group still exceeded 30% (close to 40%) of dietary intake from fat, and barely met 25 grams of fiber. Would you call this low fat? By no standard would I. In fact, this diet indicates overall unhealthful eating. Thus as I said earlier, a very low fat diet (10%) would not receive benefit from olive oil because it provides no nutritional value. If saturated fat and omega 6 is low, olive oil will only hurt the quality of the diet.

            3. Your statements regarding raw foodism and caloric intake is out of the wind. Firstly, the raw food diet is well established to be completely unnecessary to human health and in fact, evidence exists that those consuming cooked whole unrefined plant foods in addition to raw foods are better off.

            Secondly, getting enough calories from starchy vegetables and grains is extremely easy to do. To say that one must add pure empty calories to the diet to meet caloric needs is absurd and unfounded. Nuts have plenty of vitamin E, as do other plant foods. Vitamin e is not a scarce nutrient, and the trace amount in olive oil is not a reason to consume it.

            4. Caloric restriction vs plant based diet prove equally beneficial

            Consuming pure empty calories vs whole plant foods will always fail to show benefit. Whole plant foods contain naturally occurring fats, and plenty of essential omega 3 fats..

          • Timar

            1. Besides this argument is principally a naive fallacy, as I have explained, it is also factually wrong. The nutritional value of a food is obviously not reducable to its micronutrient content. This is long obsolete, 20th century reductionist thinking. Hence, the USDA database won’t tell you much about the nutritional value of olive oil, because apart from vitamin E it doesn’t contain much essential nutrients, but plenty of potent, fat-soluble polyphenols. Hence, a much more valuable source for evaluating the nutritional quality of olive oil is the Phenol-Explorer database
            ( ). Of course polyphenols are not all equal, so you can’t compare food by the total amounts of polyphenols they contain. The oil soluble polyphenols found almost exclusively in olive oil are among the most powerful polyphenols known to us, because in contrast to most water-soluble polyphenols they are actively absorbed and have significantly higher half-lifes in plasma and tissues. In fact, the intense burning sensation a good, extra virgin olive oil produces in the throat is due some of these polyphenols which are chemically similar to a certain class of antiinflammatory drugs, producing the very same sensention if you chew on the tablet.

            It is absolutely silly to compare virgin olive oil with sugar. It’s not even woth commenting on that, except for: read the scientific literature (that is to say, all the literature, not just the few isolated studied that fit into your preconceptions).

            2. The conclusion that can be drawn from PREDIMED trial is that consuming a very high amount olive oil is healthier than consuming a moderately high amount of olive oil – simple as that! (Note that the olive oil in the intervention group did NOT substitute for less healthy fats, as the control diet lowered their intake of saturated fats to a greater extend as the intervention group)

            3,4. I agree with you on the raw food diet.
            It should be clear by now that the contention that olive oil is “emtpy calories” is not only subject to the reductionist fallacy but also factualy wrong – and can only be held in complete and probably wilful ignorance of 6000 years of culinary tradition and more than 60 years of scientific research on the Mediterranean diet and the health benefits of virgin olive oil and the unique polyphenols it contains.

          • Toxins

            1. I find it interesting you are calling me the reductionist when you are picking out the single beneficial thing in olive oil, polyphenols, when they are overly abundant in the plant kingdom. In addition, why not consume the whole olive, as it is far healthier then the olive oil. The reductionist method can be easily applied when certain macronutrients do not satisfy a requirement for health. Something that is stripped of all the fiber, vitamins and minerals, and if all that remains is a small amount of polyphenols as the beneficial component, then why not just substitute it for a vitamin? It seems absurd to me that your argument is based on the tiny amount of nutrients in something that is literally pure fat and the most calorie dense food on the planet, especially when this minute amount of phytonutrients are found in much greater abundance in other plant foods, such as berries, leafy greens, and other commonly consumed plant foods. Because people have used something for generations does not make it a health food. Is red wine a health food because of the tiny content of retinol? No, of course not. You are applying the reductionist mindset to olive oil, when you should be looking at the food as a WHOLE, which you are not doing.

            2. The only conclusion one can take from that study is that those consuming a high fat, still unhealthy, diet do better with more olive oil. These conclusions canot be applied to one consuming a whole foods, plant based diet that is very low fat. Those on a low fat, plant based diet are consuming a massive quantity of phytonutrients and are getting enough essential fat, what purpose would extra empty calories serve one on this nutrient dense diet? Perhaps weight gain and increased risk of CVD.

          • Timar

            Obviously you didn’t care to properly read or comprehend my argument before replying as I actually anticipated your very response in my argument, but I repeat it once more: phytonutrients are not all equal (hence comparing plant foods by the total amount of polyphenols they contain or even the ORAC score, as Dr. Greger did some years ago, is rather pointless), there are vast differences in their physiological properties and potency and olive oil polyphenols (partially because of their fat-solubility) are the most potent polyphenols we know of, they are orders of magnitude more potent than most other polyphenols found in plant foods. Most of those fat-soluble polyphenols are not present in the fresh olives, but are formed during the pressing of the olives by enzymatic processes (one of the many examples where rudimentary processing beneficially affects the nutritional value of a food). Only trace amouts of those polyphenols are found in brined olives, so the only significant dietary source for them is virgin olive oil. Your assertions that olive oil equals empty calories and that monounsaturated fat from olive oil would be an inferior source of calories compared to carbohydrates from whole plant foods are both painfully wrong. and if you had read my responses you could have learned why. This is my last response, however. I’m not going to further waste my time with someone who so recklessly indulges in wilful ignorance and dogmatism.

          • Toxins

            I know you have tried to discount the interventional studies I shared showing impaired arterial function from olive oil (for admittedly the wrong reasons), but even more recent research has shown this effect. “Our main finding was that, in comparison with olive oil, walnuts reverse the impairment of endothelial function associated with eating a fatty meal. The fact that a single walnut meal positively effects postprandial vasoactivity further supports the beneficial effects of walnuts on cardiovascular risk”

            Olive oil is not the super food you believe it to be.

          • Luke Davis

            The same marketing the Meat Industry uses on meat-eaters and all people is the same tactic the Vegan Industry uses on vegans. Healthy Coconut Oil? I’m sorry no, its 92% saturated fat. Safflower oil? Ok, shut up ads!

          • Toxins

            Effective marketing is indeed how many health claims are made in the US. The egg board is notorious for this.


          • Veganrunner

            Toxins, you rock!

          • Toxins

            Thank you, some people love their oil a little too much.

          • Veganrunner

            And the most logical reason to stay away from it is that all the good stuff is tossed out! Pretty easy to understand.

      • Timar

        Here is a table showing the heat stability of different oils and fats. I have translated it from a presentation made available by the “German Society for Lipid Science”[1]

        Clarified butter 6.5 – 7.5
        Lard 1.5 – 2.5
        Canola oil (refined) 7.0 – 8.5
        Canola oil (virgin) 3.0 – 5.5
        Peanut oil 3 – 4
        Olive oil (virgin) 7.0 – 8.5
        Sunflower oil (refined) 1.5 – 2.5
        Flaxseed oil 0.3

        The number is the time (in hours) at which the oil passes the legislative threshold that would define it as inedible (rancid) while constantly heated to a temperature of 170°C.

        As that threshold is probably set way too high I think it is wise to apply a large safety factor and divide it by 10. Hence you can safely use canola or olive oil for up to one hour of frying, but you shouldn’t use lard or sunflower oil – or any other highly polyunsaturated vegetable oil for frying, broiling, etc.

        [1] (German)

  • Elizabeth

    I confess — I wish French Fries were healthy. :-) I love these videos and have learned so much from them! But just once, I’d like a surprise from Dr. Greger in my Inbox like, “New study: hot fudge sundaes reduce risk of stroke and kidney stones!” :-)

    • Thea

      Elizabeth: Oh my gosh! Me too. You and I totally on the same page here.

      • Luke Davis

        Come over to my house! I will make one for you! Haha.
        Be it scientifically healthy that is.

  • Julot Julott

    Make your low fat fries(2-5% fat) in oven at maximum 200C with just potatoes and oil without any additives unlike mcdonald ones, dont over-fry them and its really not that bad, that is so tasty you dont even need salt or any other crap~

  • Thea

    I thought I would share Jeff Novick’s method for “steak fries” from his Fast Food: Burgers and Fries DVD. He starts by baking potatos whole. Then the big trick is to let the potatos completely cool. That helps get the right texture before doing the next step. Then you cut the potatoes into shape. And then season with spices like curry or garlic and onion, etc. And then the second big trick is to put under a broiler for about 3-5 minutes. This gives you a nice firm outside while keeping the center soft. And none of this involves oil.

    You would get a better idea of what I’m talking about if you watch the DVD. Also, I’m thinking it’s possible that the dark bits that form when you do the broiler step may not be all that great for one’s health. But it is worth sharing the idea if nothing else for people trying to get oil out of their diets. I served these fries at a potluck with barbeque sauce for dipping. The GIANT batch of Jeff’s fries completely disappeared by the end of the potluck. People loved them.

    • DGH

      Hi Thea, back when I ate almost anything, I would LOVE McDonald’s or NY-style french fries, with copious amounts of vegetable oil and salt. Then I went low carb and didn’t touch potatoes for a very long time. After becoming fully vegan, I will only eat a small amount of potatoes as a side dish at a restaurant on occasion. I have to admit, I just don’t miss french fries (or for that matter potatoes) as much as I suppose I should. They are filled with high-glycemic index starch carbohydrate which will send my blood sugar level (and insulin) skyrocketing. That alone is enough to deter me from ever ordering a side of french fries, although I have one friend who eats them all the time when we are out. It comes down to personality type. I have no problem with self-deprivation, in fact, I’m too good at it sometimes (scary!).

      • Thea

        DGH: Thanks for sharing. I still love fries, but rarely, rarely order them, because I know they are so bad. However, if I’m with a friend who orders them like you mention, I’m not above asking to have one. ;-)

      • Toxins

        I think you would find Jeff Novick’s comment on white potatoes and the glycemic index very interesting.

        “The idea that white potatoes are problematic for diabetics stems partly from the concept of the glycemic index, and partly from the inaccurate way that potatoes have been categorized in some scientific studies.

        The glycemic index measures the extent to which a
        food raises blood sugar levels after it is eaten.1 Because white potatoes have been characterized as having a high glycemic index, it is often assumed that they can worsen diabetes. However, the glycemic index has not been found to be a useful concept when devising optimal diets for diabetics.2,3 One of the major problems with the glycemic index is its variability; not only do blood sugar responses to similar foods differ between individuals, they can vary significantly in the same person on different occasions.4 A recent review of the scientific literature conducted by the American Diabetes Association concluded that there is little difference in blood sugar control between “low-glycemic index” and “high-glycemic index” diets.5 For this reason, in their most updated guidelines, the American Diabetes Association has deleted a statement suggesting benefit from the glycemic index.6”

        • Thea

          Toxins: I have missed your commenting lately. This post reminds me why I value your participation so much. Thank you for passing this information on! I’m very interested in the topic of diabetes and greatly appreciate it.

          • Toxins

            I am glad you found my comment helpful Thea, I do enjoy reading and moderating and learning here on NF. As school is coming to a close for the spring, you may see more of me here.

          • Timar

            True believers among themselves, how moving ;)

          • Toxins

            Your love of olive oil is also quite romantic

        • Timar

          This is exactly the kind of sophistry I have come to expect from Jeff Novick. His core “argument” is: the GI is irrelevant because it varies considerably from individual to individual and from time to time. Now think about it for one second! You could relativize pretty much everything we know about nutrition with exactly the same argument: The amount of micronutrients in fruits and vegetables also varies considerably, yet noone would argue that median values of nutrients in foods, like those gathered in the USDA database, are an extremely valuable tool for estimating the nutrient-richness of a particular food or dietary pattern.

          • Toxins

            The argument was not to debunk glycemic index, it was to quell the fear of potatoes, if you bothered to read on from the cited paragraph.

            I find the glycemic index to be a mixed bag, but overall unhelpful. The variability component is more extreme than you may perceive.

    • Tommasina

      Sounds super yummy, Thea! If I were at that potluck, I think I would hover around that plate. ;)

    • Timar

      Sounds like a rather complicated way to create a shallow imitation of a food that is not particularly worth imitating in the first place.

      Moreover, there is no rational (as opposed to religious) basis for avoiding oil alltogether. Adding (not frying them in) some decent oil to your potatoes actually makes them healthier: it blunts the blood sugar response to their high GI carbohydrates and dramatically improves the absorption of the fat-soluble carotenoids they contain.

      • Thea

        Timar: Sorry for the confusion. Actually, it’s really easy! And for those of us trying to watch our calorie counts, it’s not only easy, but a great calorie saver. If you watch Jeff Novick’s DVD From Oil To Nuts, you will see very good reasons for avoiding all oil – at least in terms of being part of a daily diet. (When I eat dessert, it is dessert. So, I don’t worry about junk food like sugar and oil. I just try to limit dessert in general. If someone’s weakness is not dessert, but say traditional french fries, then I would say, go for it. But try to seriously limit the fries (to 1 or 2 times a year?).)

        Concerning your claim that adding oil makes a potato healthier, I find the information Toxins re-posted from Jeff Novick on the health of plain potatoes to be quite compelling. Re:

        ” A recent review of the scientific literature conducted by the American Diabetes Association concluded that there is little difference in blood sugar control between “low-glycemic index” and “high-glycemic index” diets.5 For this reason, in their most updated guidelines, the American Diabetes Association has deleted a statement suggesting benefit from the glycemic index.6″”

        re: “…of a food that is not particularly worth imitating in the first place.” Sounds like you are not all that interested in french fries. You are lucky there! For me, I think french fries are great and appreciate having an alternative (and easy!) way to prepare them.

        • Timar

          I agree with you that it is most important to eat an overall healthy diet while avoiding excess calories and that an occasional disgression from such a diet is perfectly fine – as long as occasional remains occasional, which for many people it does not…

          However, I’m also convinced (and I can assure you that this conviction has quite some scientific background) that healthy oils such as virgins olive oil can be an integral part of a perfectly healthy dietary pattern. Of course it is possible to follow a healthy diet without any added oils, but such a diet takes much pleasure and cultural richness out of eating without providing significant benefits (maybe even the opposite).

          In my opinion, eating an unnecessarily restrictive diet only provokes food cravings. It is the opposite of a “balanced” diet, and thus tends to throw our desires out of balance. Personally I can’t remember the last time when I craved french fries or candies.

      • Toxins

        ” there is no rational (as opposed to religious) basis avoiding oil altogether” You do love your oil Timar! I think the rationale is quite compelling as we have discussed in length.

  • Michael

    What is the difference in carcinogenic levels for fries baked without oil compared to fries baked with oil?

  • RealityCheck131

    As usual, Dr. Greber sucks at science.

  • Good information. We should get rid of these junk food. I learn some great tips from: . such as which oil we should choose, what kind of food do we need to use. so on.

    Keep away cancer start from our mouths.

    • JacquieRN

      Hi John, I took a look at the site. I don’t see anything research-related here. Do you want to provide research?

      • I got health information from the TLS® Health Guide & Journal. It’s includes the instruction and journal. – keep good journal help us reach goal more easyer. or subscribe their monthly subscribtion. They have 12 weeks lifestyle change let people use 12 weeks to get a habit to a health way. Most they will teach us eat low GI food and keep some execise.

        • JacquieRN

          Thanks for letting me know. Good luck to you on this diet. I do see that it does include, meat, dairy, and seafood products. Processed foods stuff, oil, sugar, splenda, etc. in the packaged meals. Not the most healthful it seems.

  • TofuForBrains

    What about using an air fryer without oil? Do we have any data? (Not just potatoes, but for other veggies, tofu, etc. as well?) Thank you!!