The Quest for the Optimal Cooking Oil: Heat Stable, Low PUFA & Cholesterol Free - High MUFA Sunflower / Canola, Olive, Coconut & Avocado Oil Qualify for the TOP5

The oil is not he only thing that's damaged, when you're frying foods; and acrylamide is only the most prominent of these nasty compounds.

Alright, it's about time to acquit myself of a longstanding promise: the promise to finally write the unofficial second part to my article on cooking oils & fats from February 2014 that busted the myth of the "healthy" saturated cooking oils and fats (read more). It's an "unofficial" part II, because the previous article was actually intended to be "just" a rebuttal to the unwarranted craze about using butter, lard & co to fry in order to protect yourself from developing heart disease and other nasty ailments.

Needless to say that this part is going to focus on purportedly healthier alternatives ranging from high-oleic acid sunflower and canola oil to another often hyped dietary fat: coconut oil.

Lean more about frying & co at the SuppVersity

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The Healthy Taste of Olive Oil - Flavor's Enough!

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"Pimp My Olive Oil" - W/ Extra Antioxidants

Frying Does not Just Oxidize Oils, It Does Fat More!

Before we delve deeper into the discussion lets briefly recap what exactly we are looking for in the "optimal" frying oil: The optimal frying oil should...

• ... either contain a low amount of readily oxidizable PUFAs or contain significant amounts of antioxidants that protect these important, but sensitive fatty acids from being oxidized,
• ... be cholesterol-free, because dietary cholesterol can be a problem, if it's consumed in large amounts in its pro-atherogenic (=tending to promote the formation of fatty deposits in the arteries) oxidized form,
• ... have a high smoke point, i.e. can be heated to very high temperatures before enough volatile compounds such as water, free fatty acids, and short-chain degradation products of oxidation emerge from the oil that a bluish smoke becomes clearly visible.

All three suppositions are important because, the consumption of oxidized PUFAs, oxidized cholesterol (Valenzuela. 2003) and other volatile compounds from "burnt" oils and fats have consistently been associated with negative health effects.

• 

  Figure 1: The consumption of soy bean oil that was heated for 3h is associated with an increase in body fat that is independent of an increased intake of food (Penumetcha. 2013)

  The consumption of oxidized PUFAs has been associated with an increased cardiovascular disease risk and increases in body fat, of which recent studies indicate that it is not caused by an increase in food intake (Penumetcha. 2013).
  
  Some scientists in fact believe that the association between the consumption of high amounts of (high omega-6) seed oil is associated with heart disease & co not due to the fatty acid composition of these oils per se, but rather due to extensive use of these products in highly processed (convenient) foods, which in turn contain high amounts of oxidized polyunsaturated fatty acids and will thus drive the development of heart disease, diabetes & co.
• Oxidized cholesterol as it occurs at relatively high amounts un highly processed foods, has the potential cytotoxic, mutagenic, atherogenic, and possibly carcinogenic effects (Peng. 1985; Kumar. 1991; Valenzuela. 2003; Orczewska-Dudek. 2012). In that it's important to point out that not all heated animal products (e.g. eggs) will contain significant amounts of oxysterols, because the formation of these potentially unhealthy byproducts of the heating process depend on (a) temperature, (b) heating time and (c) storage & packaging.
  
  Against that background, soft-boiled eggs are healthier than hard-boiled eggs or fried eggs and a hot chocolate milk is less of a problem than repeatedly heated and extensively processed eggs, meats & co.
  

  

  Figure 2: Overview of the effects of storage, processing and heating on the levels of oxidized cholesterol in various food items (various sources).

  Why? Easy: They contain significantly lower amounts of the potentially unhealthy oxidized cholesterol - a dietary ingredient that can become a serious problem only if you consume high quantities on a regular basis, though.

• 

  Figure 3: Changes occurring during deep fat frying (Fritsch. 1982).

  Oxidized fatty acids and cholesterol are actually part of the volatile compounds that arise, when a cooking / frying oil starts to "smoke". In his 1981 paper in the Journal of the American Oil Chemists’ Society, Fritsch published a neat graphical illustration of what happens during the frying process (see Figure 3).
  
  As you can see, it's a complex series of changes and reactions that produce numerous decomposition products. As Fritsch points out, "the functional, sensory and nutritional quality of frying fats are changed and may reach a point where high quality foods can no longer be prepared," as these reactions proceed. In the end, the oil will be unpalatable.
  
  Unfortunately, the negative effects on your health will occur way before you will be able to detect the changes in viscosity, color or taste (specifically if the oils are used in processed products, where any off tastes would be covered by (artificial) flavorings, anyways) or see the smoke. That's also why the smoke point of a given fat  / oil is not exactly the best criterion to judge its suitability as "optimal frying oil".

Now that you're aware that checking it's not enough to look at the "Smoke Point" in the unreferenced Wikipedia article, let's get to the question that's been praying on your minds ever since I posted my article on cooking oils & fats on February 2014 (read more): Which oil, if not the allegedly superior animal fats, shall I use for cooking and frying?

Q: What's the optimal frying oil, now? A: It depends!

Now that we know that we want an oil that's relatively low in PUFAs, high in (natural) antioxidants, cholesterol-free and has a high smoking point, a few candidates come to mind:

• High oleic acid canola (or rapeseed) or high oleic acid sunflower oil - Both contain a low amount of PUFAs, no cholesterol, and have relatively high a smoking points of 194°C  and 200°C, respectively.
  

  

  Table 1: Ranking of the oils tested by Bertrand Matthäus; 1 indicates rank #1 = first place, 4 indicates rank #4 = last place (Matthäus. 2006).

  Accordingly, it's not surprising that high oleic acid rapeseed and sunflower oils come out on top of a comparison by Betrand Matthäus, in which the researcher compared the formation of  oligomer triacylglycerols, polar compounds and free fatty acids, as well as the results of a sensory evaluation of the oil itself and the French fries that were fried with high oleic acid rapeseed (HORO), high oleic acid sunflower (HOSO), partially hydrogenated rapeseed oil (PHRO) and, the worst choice, palm olein (PO).
  
  If you compare the high oleic acid varieties of sunflower and rapeseed oil that are made from seeds with a low PUFA and high MUFA content, you will yet realize that the the often derided sunflower oil is actually the most stable one. The rapeseed oil, on the other hand, produced the tastiest fries (according to the full text of the study). Since "only small differences in the chemical parameters of all oils were found" and "[o]nly the total result of the assessment of PO was significantly worse than the results of the other oils (p < 0.01)" (Matthäus. 2006), the rapeseed oil comes out on top of this comparison.

Using high MUFA rapeseed oil not just for frying, but as a major fat source in the diet leads to significant improvements in blood lipids in hypercholesterolaemic subjects (Gillingham. 2011)

You cannot seriously be suggesting sunflower and canola oil! Yes, I can! I know that both have quite a bad reputation, but if you look at the scientific evidence that's mostly unwarranted.

If you look objectively at the existing evidence, it is debatable whether this may not be superior to using olive oil or other high MUFA oils, but certainly superior to using other frying oils or animal fats. Plus: It works it cholesterol lowering and glucose metabolism improving magic not just in patients with high cholesterol levels (see figure on the left), but also in healthy young women (Uusitupa. 1994; Jones. 2014).

• Now, being resistant to oxidation is one thing. Having overall beneficial effects on one's health, however, is a totally different thing. A "thing" that was tested in a 2005 study, by Allman-Farinelli et al. in which the researchers were able to show that replacing saturated fats in the diet with high-oleic-acid oils like sunflower oil will favorably alter the low-density lipoprotein cholesterol, triglycerides, and factor VII coagulant activity" of healthy men and women and thus present "another useful source of MUFA for diets aimed at prevention of heart disease"(Allman-Farinelli. 2005).
  

  

  Figure 4: Evidence of the effect of canola oil on health-related risk factors.

  In a similar vein, canola aka eruchic acid free rapeseed oil, which is also available as high oleic acid cooking oil, has been shown to reduce TC concentrations in healthy or hypercholesterolemic individuals, compared with high-SFA or typical Western diets. Studies also indicate that it "may potentially promote immune and cardiovascular health through its antithrombic and antioxidative effect" (Lin. 2013). For the other benefits listed in the overview in Figure 4, the results are sometimes less equivocal. Overall, Lin et al. whose review of literature was obviously funded by the canola industry still claims that "canola oil can now be regarded as one of the healthiest edible vegetable oils in terms of its biological functions and its ability to aid in reducing disease-related risk factors and improving health" (Lin. 2013) - a claim that sounds a bit hyperbolic, in spite of the fact that their review of the literature supports many of the claims.
  
  Against that background I would stick to using canola, or if you live in Europe or can acquire it overseas rapeseed oil only in its high oleic acid variety and specifically for frying foods at high temperature, when you cannot live with the taste they would acquire if you used extra virgin olive oil, instead.
• The coconut miracle not ideal for frying!? -There is little doubt that virgin coconut oil belongs to the "healthy oils" - despite, or rather due to its low PUFA content. The question is: Is it also ideal for frying? If we go through our checklist, as prevoiusly said...
  
  • it contains only 1.7% PUFAs, 85.2% saturated and 6.6% monounsaturated fats, which means it's more or less PUFA free and thus not prone to heat induced oxidation
  • it's cholesterol free, so the problem with oxidized cholesterols that is rampant in fats from animal products is not a problem,
  • it's smoke point is relatively, low though, at only 163°C even the deodorized, bleeched coconut oil will form enough volatile compounds for the ugly bluish smoke to rise from your pan (Man. 1998).
  The question we have to answer is thus: Is the comparatively low smoke point reason enough to abstain from using coconut oil as a frying oil? For virgin coconut oil, the answer may be yes, for the refined, bleached, and deodorized version of coconut oil, however, the peroxide levels remains stable within the relatively narrow time window (smaller than 1h) you would use when you fry foods (see Figure 5).
  

  

  Figure 5: After a 30 hours of frying (not shown) the US' favorite health killer, soybean oil, has peroxide values that exceed the measuring capacity of the assay, Yuki & Ishikawa used in their 1979 study (Yuki. 1979)

  As you can see in Figure 5 this is in stark contrast to soybean oil, of which you probably know that it is heavily abused as frying oil in the US.
  
  Unfortunately, its comparatively low peroxide values don't tell you the full truth about the usefulness of coconut oil. Compared to similarly bleached and deodorized palm oil, coconut oil will have higher %FFA levels, which are indicative of an increased oxditation & hydrolysis of fatty acids and are responsible for the "soapy" flavor that made the test product in a 1998 study by Man, et al. hardly palatable. From a product quality perspective, frying with palm oil would thus be (and for most companies is) the preferable choice. From a mere health perspective, though, frying with coconut oil - especially at lower heats that do not exceed the smoke point of 163°C (vs. 229° for palm oil), is yet a good and tasty choice.
• Avocado oil, the exotic alternative - There is unfortunately little research on the long-term health effects of using avocado oil for frying.
  

  

  Table 2: The fatty acid composition of cold-pressed and refined avocado oil does not differ (Haiyan. 2007)

  As you can see in Table 2, avocado oil, irrespective of whether it is refined or cold-pressed ("virgin"), has a high omega-9 fatty acid content. In conjunction with the similarly oxidation resistant saturated fatty acids, it makes up roughly 84.7% of the fatty acids.
  
  

  

  Table 3: Comparison of selected properties, like baseline FFA and peroxide value (PV | both indicative of the presence of unwanted byproducts of storage or processing induced oxidation), antioxidant content,  persticides & co in avocado oil and olive oil (Reed. 2001)

  The risk of consuming exuberant amounts of oxidized fatty acids is thus relatively low, despite the 12.6% of fatty acids with a higher susceptibility to oxidation (note: lard contains 13.6% or more of those highly volatile fatty acids | Enig. 1983).
  
  There is no cholesterol in avocado oil, so oxidized cholesterols are not an issue. Compared to olive oil, avocado oil contains an increased amount of beneficial antioxidant, is naturally lower in peroxides and free fatty acids (this does not mean that there will be necessarily less after processing) and is usually, just as olive oil, pesticide free (Reed. 2001).
  
  Against that background it's worth taking a look at the results of a 2012 study from the University of Navarra in Spain, which found that ...

  "Avocado oil was richer than olive oil in total phytosterols at time 0 h (339.64; 228.27 mg/100 g) and at 9 h (270.44; 210.30 mg/100 g) of heating. TBARs was higher in olive oil after 3 h, reaching the maximum values in both oils at 6 h of heating treatment. Vitamin E was higher in olive oil (35.52 vs. 24.5 mg/100 g) and it disappeared earlier in avocado oil (at 4 vs. 5 h). The stability of avocado oil was similar to that of olive oil." (Berasategi. 2012 | my emphasis)

  Since no regular consumer will fry his foods for more than 3h, the previously presented evidence clearly indicates that avocado oil is an allegedly more expensive, albeit slightly superior alternative to olive oil, the last oil on our list (see below).
• Olive oil, refined or, even better, extra virgin - If it was not for the price and the taste, the whole world would probably long have switched over to olive oil as their go-to oil for everything. I am not going to (re-)cite the plethora of epidemiological evidence in favor of its beneficial health effects, here. Instead I will briefly go through our three items from the initially presented list.
  
  Olive oil has a relatively low omega-6 and virtually no omega-3 fatty acids (10.5g PUFA total per 100g). It's fatty acid profile, alone, does therefore tell us that it could be a suitable candidate for the "optimal" frying oil.
  

  

  Figure 6: Effect of air, light and deep-frying on p-AV of olive, corn and soybean oil (Naz. 2004). Please not that improper storage will also increase the oxidative damage to your cooking oils.

  Olive oil is cholesterol free, so the oxidation of cholesterol during the frying process is not an issue, either; and when it is heated it turns out to produce a relatively low amount of unwanted peroxidation products (see Figure 6). This would render olive oil or, as I examined previously, extra virgin olive oil (read more | see red box in particular) the perfect cooking oil, if it was not for its taste, which is not compatible with every dish you may be cooking.

Figure 7: Rice bran oil, despite a high PUFA content is pretty heat stable. It still didn't make the top list in this article - also to keep the article from turning into an ebook ( Debnath. 2012 ;-)

Bottom line: It's still 2014 and I have finally managed to put out the unofficial part II to my article on cooking oils & fats from February 2014 that busted the myth of the "healthy" saturated cooking oils and fats (read more). I have to admit. It's far from being as all-encompassing as I would have liked it to be, but even though I did not list ricebran oil (a relatively high PUFA content, but with a smoke point at 258°C for refined rice bran oil still pretty heat stable (De. 1999) | cf. Figure 7), which is an excellent cooking oil, as well and skipped many of the details on the oils I did discuss, the main message is clear: If you want to fry foods there is a range of cholesterol-free low PUFA oils you can choose from, with the high MUFA canola/rapeseed and sunflower oil being the cheapest and probably still most commonly used frying oils and avocado oil being the most expensive and I would guess least used of the candidates investigated in this article | Comment on Facebook!

References:

• Allman-Farinelli, Margaret A., et al. "A diet rich in high-oleic-acid sunflower oil favorably alters low-density lipoprotein cholesterol, triglycerides, and factor VII coagulant activity." Journal of the American Dietetic Association 105.7 (2005): 1071-1079. 
• Berasategi, Izaskun, et al. "Stability of avocado oil during heating: Comparative study to olive oil." Food Chemistry 132.1 (2012): 439-446.
• Chan, Shu-Hui, et al. "Cholesterol oxidation in whole milk powders as influenced by processing and packaging." Food chemistry 47.4 (1993): 321-328. 
• De, B. K., and D. K. Bhattacharyya. "Deacidification of high-acid rice bran oil by reesterification with monoglyceride." Journal of the American Oil Chemists’ Society 76.10 (1999): 1243-1246. 
• Debnath, Sukumar, et al. "Effect of frying cycles on physical, chemical and heat transfer quality of rice bran oil during deep-fat frying of< i> poori:</i> An Indian traditional fried food." Food and Bioproducts Processing 90.2 (2012): 249-256.
• Enig, M. G., et al. "Fatty acid composition of the fat in selected food items with emphasis on trans components1." Journal of the American Oil Chemists’ Society 60.10 (1983): 1788-1795.
• Fritsch, C. W. "Measurements of frying fat deterioration: a brief review." Journal of the American Oil Chemists’ Society 58.3 (1981): 272-274. 
• Gillingham, Leah G., et al. "High-oleic rapeseed (canola) and flaxseed oils modulate serum lipids and inflammatory biomarkers in hypercholesterolaemic subjects." British Journal of Nutrition 105.03 (2011): 417-427.
• Haiyan, Zhong, et al. "Endogenous biophenol, fatty acid and volatile profiles of selected oils." Food chemistry 100.4 (2007): 1544-1551. 
• Jones, Peter JH, et al. "High-oleic canola oil consumption enriches LDL particle cholesteryl oleate content and reduces LDL proteoglycan binding in humans." Atherosclerosis (2014).
• Osada, Kyoichi, et al. "Oxidation of cholesterol by heating." Journal of Agricultural and Food Chemistry 41.8 (1993): 1198-1202. 
• Kumar, Naresh, and O. P. Singhal. "Cholesterol oxides and atherosclerosis: a review." Journal of the Science of Food and Agriculture 55.4 (1991): 497-510.
• Lercker, G., and M. T. Rodriguez-Estrada. "Cholesterol oxidation: presence of 7-ketocholesterol in different food products." Journal of Food Composition and Analysis 13.4 (2000): 625-631.
• Lin, Lin, et al. "Evidence of health benefits of canola oil." Nutrition reviews 71.6 (2013): 370-385. 
• Man, YB Che, and WR Wan Hussin. "Comparison of the frying performance of refined, bleached and deodorized palm olein and coconut oil." Journal of Food Lipids 5.3 (1998): 197-210.
• Matthäus, Bertrand. "Utilization of high‐oleic rapeseed oil for deep‐fat frying of French fries compared to other commonly used edible oils." European Journal of Lipid Science and Technology 108.3 (2006): 200-211.
• Morgan, J. N., and D. J. Armstrong. "Quantification of Cholesterol Oxidation Products In Egg Yolk Powder Spray‐dried with Direct Heating." Journal of food science 57.1 (1992): 43-45.
• Missler, S. R., B. A. Wasilchuk, and C. Merritt. "Separation and identification of cholesterol oxidation products in dried egg preparations." Journal of Food Science 50.3 (1985): 595-598.
• Naz, Shahina, et al. "Oxidative stability of olive, corn and soybean oil under different conditions." Food Chemistry 88.2 (2004): 253-259.
• Orczewska-Dudek, Sylwia, et al. "Cholesterol and lipid peroxides in animal products and health implications-A review." Annals of Animal Science 12.1 (2012): 25-52.
• Paniangvait, P., et al. "Cholesterol oxides in foods of animal origin." Journal of Food Science 60.6 (1995): 1159-1174.
• Peng, Shi-Kaung, et al. "Cholesterol oxidation derivatives and arterial endothelial damage." Atherosclerosis 54.2 (1985): 121-133.
• Penumetcha, Meera, et al. "A diet containing soybean oil heated for three hours increases adipose tissue weight but decreases body weight in C57BL/6 J mice." Lipids in health and disease 12.1 (2013): 26. 
• Pie, Jae Eun, Khira Spahis, and Christine Seillan. "Cholesterol oxidation in meat products during cooking and frozen storage." Journal of Agricultural and Food Chemistry 39.2 (1991): 250-254.  
• Reed, A. B., et al. "New Zealand extra virgin olive oils." Food New Zealand Feb/March 2001 (2001): 20-24. 
• Uusitupa, Matti, et al. "Effects of two high-fat diets with different fatty acid compositions on glucose and lipid metabolism in healthy young women." The American journal of clinical nutrition 59.6 (1994): 1310-1316.
• Valenzuela, Alfonso, Julio Sanhueza, and Susana Nieto. "Cholesterol oxidation: health hazard and the role of antioxidants in prevention." Biological research 36.3-4 (2003): 291-302. 
• Valsta, Liisa M., et al. "Effects of a monounsaturated rapeseed oil and a polyunsaturated sunflower oil diet on lipoprotein levels in humans." Arteriosclerosis, Thrombosis, and Vascular Biology 12.1 (1992): 50-57. 
• Yuki, E., and Y. Ishikawa. "Tocopherol contents of nine vegetable frying oils, and their changes under simulated deep-fat frying conditions." Journal of the American Oil Chemists’ Society 53.11 (1976): 673-676.

Produce Your Own No-Bullshit-Bulletproof Frying Oil W/ the Right Herbals: Sage & Rosemary Work Best! + Rosmarinic Acid As Potent as Metformin - Anti-Diabetes & Add. Benefits

Rosemary and Garlic Steak - This is only one out of thousand recipes you will find all over the Internet that inform you how to use rosemary and reap (some) of the health benefits (thing about dosage for taste vs. for medical effects) I am about to outline in todoay's SuppVersity article.

I know that I still owe you the 2nd par of the "Perfect Frying Oil" series, and I promise I will write it as soon as I have found convincing evidence to argue that there actually is a "perfect frying oil". In the mean time, I'd suggest you focus on the "tricks" I am about to reveal in today's SuppVersity article and produce your own no-bullshit-bulletproof frying oil by adding... no, not butter and coconut oil, but sage, thyme, and rosemary.

If you belong to the extremely studious 10% of the SuppVersity students, you will probably remember that you can easily produce an anti-bacterial marinade based on green tea, lemon and turmeric (read more). If you put this "no-bullshit-bulletproof" marinade on your meats and fry them in oil you've made "no-bullshit-bulletproof" with sage, thyme, or rosemary that would be truly bulletproof ;-)

You can learn more about potential negative sides of too many / the wrong antioxidants:

NAC = GSH ￪, Anabolism ￬

Too Much "Vit C" For Gains?

Protein requ. of athletes

Block inflamma- tion, choke fire

C + E Get Avg. Joes Ripped

ROS Management Not Eradication

But enough of the sarcasm for today. A recent study from the Faculty of Agriculture at the South Valley University does in fact confirm that adding sage, thyme or rosemary to a commercially (canola based) frying oil can more than double its induction period, i.e. the time it takes until the oil is literally inedible ... and profoundly unhealthy.

Figure 1: Oxidation stability (y-axis) of refined rapeseed oil treated w/ different herbs during frying for 0-32h (Taha. 2014).

As you can see in Figure 1 thyme and rosemary, or "Rosmarinus officinalis", as the science geeks would say, are the most potent of the three additives. With an increase of approx. 63% over that of pure rapeseed oil (the North American SuppVersity readers know "rapeseed" as "Canola oil", which is actually a special, mostly GMO variety of rapeseed oil - of which you can expect that it will react similar - unless it's the "high MUFA" version, in that case I would expect increases but by no means as pronounced increases in oxidative stability).

Accordingly, both, the rosemary and sage enhanced oils retained a significant albeit highly reduced alpha- and gamma-tocopherol content even after 32h of frying, while the control oil and the thyme-enhanced oil lost all its vitamin E after only ~14h and ~29h of frying, respectively.

There's one "on the other hand": You will probably know by now, that there no SuppVersity article with a simplified bottom line that does not at least mention the "other hands", i.e. things you should keep in mind, when reading the bottom line. For the study at hand this is the increase in free fatty acids with frying time. This is another, albeit very unspecific marker of the deterioration of a given oil during the frying process. In view of the superior outcome for both the oxidative stability, as well as the reduced depletion of tocopherols (vitamins E) I will still whole-heartedly conclude that adding sage and especially rosemary to your oils is a good idea.

Although both will work, there are a couple of things that speak in favor of rosemary, which are not directly related to the results Taha et al. (2014) present in their latest study. If you look at the results of a recent study from the University of Madras, for example you will see that rosmarinic acid, one of the major active ingredients in rosemary will also have protective effect on your glucose and lipid metabolism (Jayanthy. 2014).

In said study, the provision of 100mg/kg of rosmarinic acid (human equivalent: 8mg/kg) reverted almost all of the detrimental changes in liver and glucose metabolism in a rodent model of diet-induced diabetes. And as the authors point out, the obtained results were almost comprable to those of the anti-diabetes drug, metformin (see Figure 2).

Rosemarinic acid is on par with metformin!

Noot bad, given the fact that the same compound from the fragrant, evergreen, needle-like leaves and white, pink, purple, or blue flowers of the perennial shrub from the Mediterranean has a whole host of additional benefits. It...

Figure 2: Effect of Rosmarinic acid (100mg/kg | human equivalent: 16mg/kg) and metformin (200mg/kg | human equ.: 32mg/kg) on the insulin sensitivity in a rodent model of experimental diabetes (Jayanthy. 2014)

• inhibits seasonal allergic rhinoconjunctivitis in humans (Takano. 2004) and the immune over-reaction to mite allergens (Sanbongi. 2004).
• has potent (in-vitro) anti-Parkinson's effects (Wang. 2012)
• ameliorates diabetic nephropathy in a rodent model of diabetes (Tavafi. 2011).
• appears to help with arthritis and rheumatoid joint degeneration (Youn. 2003; Khanna. 2007)
• induces apoptosis (cell death) in various cancers, including human colorectal cells (Xavier. 2009)
• has anti-hypertensive and pro-metabolic (glucose + fat metabolism) effects in rodents on high fructose diets (Karthik. 2001)

And that's only the tip of an iceberg, which involves potential beneficial effects on all types of auto-immune diseases and a whole host of other metabolic benefits. In spite of the fact that the rosmarinic acid content of regular rosemary is limited, rosemary is thus one of the herbs you should consider adding to your kitchen cabinet... and frying oils ;-)

Table 1: Total polyphenol (gallic acid equ.) and ORAC (trolox equ.) values of common cullinary herbs (Zheng 2001).

Bottom line: It's funny how many of the common herbs humans all across the world have been using for centuries for culinary reasons turn out to have profound health effects. Rendering frying oils bulletproof with sage, thyme and obviously rosemary is after all only one of the many examples. Making your meats bacteria resistant with green tea, lemon and turmeric is another one, and in the end, even the citric acid + vitamin C people have drizzling on their fish filet for centuries will have beneficial health effects. Fascinating, isn't it? And certainly healthier than butter in a pot of hot coffee ;-)

How to you do it: If you want to do it exactly the way the scientists did it, add 50g of plant material (best freshly grounded!) to 1l of the oil of your choice, stir it for 24h and vacuumfilter the particles afterwards. Then you put it in the fridge and store it there for ~1 week. If you can't filter the oil, use less oil and prepare a fresh concoction every week (e.g. 20g + 400ml oil).

Reference:

• Jayanthy, G., and S. Subramanian. "Rosmarinic acid, a polyphenol, ameliorates hyperglycemia by regulating the key enzymes of carbohydrate metabolism in high fat diet–STZ induced experimental diabetes mellitus." Biomedicine & Preventive Nutrition (2014).
• Khanna, Dinesh, et al. "Natural products as a gold mine for arthritis treatment." Current Opinion in Pharmacology 7.3 (2007): 344-351.
• Sanbongi, C., et al. "Rosmarinic acid in perilla extract inhibits allergic inflammation induced by mite allergen, in a mouse model." Clinical & Experimental Allergy 34.6 (2004): 971-977.
• Taha, Eman, et al. "Stabilization of refined rapeseed oil during deep‐fat frying by selected herbs." European Journal of Lipid Science and Technology (2014).
• Takano, Hirohisa, et al. "Extract of Perilla frutescens enriched for rosmarinic acid, a polyphenolic phytochemical, inhibits seasonal allergic rhinoconjunctivitis in humans." Experimental Biology and Medicine 229.3 (2004): 247-254.
• Tavafi, Majid, et al. "Rosmarinic Acid Ameliorates Diabetic Nephropathy in Uninephrectomized Diabetic Rats." Iranian Journal of Basic Medical Sciences 14.3 (2011).
• Wang, Jieyu, et al. "Neurorescue effect of rosmarinic acid on 6-hydroxydopamine-lesioned nigral dopamine neurons in rat model of Parkinson's disease." Journal of molecular Neuroscience 47.1 (2012): 113-119.
• Youn, Jeehee, et al. "Beneficial effects of rosmarinic acid on suppression of collagen induced arthritis." The Journal of rheumatology 30.6 (2003): 1203-1207.
• Xavier, Cristina PR, et al. "Salvia fruticosa, Salvia officinalis, and rosmarinic acid induce apoptosis and inhibit proliferation of human colorectal cell lines: the role in MAPK/ERK pathway." Nutrition and cancer 61.4 (2009): 564-571.
• Zheng, Wei, and Shiow Y. Wang. "Antioxidant activity and phenolic compounds in selected herbs." Journal of Agricultural and Food chemistry 49.11 (2001): 5165-5170.

True or False? Butter, Ghee, Lard & Tallow - Are Saturated Animals Fats the Kings and Queens of the Frying Pan?

Even if animal fats were the best frying fats, this wouldn't turn  doughnuts into "health food" and french fries into raw carrot sticks.

If you "liked" the SuppVersity on Facebook (www.facebook.com/SuppVersity) you will probably already have seen the controversies and questions my post "Scientists on the Quest for the Perfect Frying Oil" (read more) has triggered. Eventually, it all revolves about yet another of those nutritional wisdoms that's circulating on the Internet: "Ghee, tallow, lard, ... saturated animal fats and the coconut micacle, of course, are the best and only frying oils you should use." (next best Internet source)

How on earth could F. Aladedunye, and R. Przybylski, the authors of the previously cited study even dare stating that high-oleic low-linolenic rapeseed, high-oleic sunflower oils are good frying oils?

But enough of the sarcasm: In today's installment of "True or False" (read previous installments) we will focus solely on the cholesterol-containing animal fats, and save the one and only "coconut miracle" (Coconut oil - virgin, of course - must be good for everything, right? There have after all (E)-Books been written about it ;-) for another installment of this series. So, where do we start then? I guess, we could start by rendering down a big packet of butter in my frying pan... but *wtf* what's that? It's turning tar black!? Can that really be the ideal frying fat? Probably not, but if regular butter sucks, what about clarified butter aka "ghee", then? It's easier to process and there are not tarry clouds floating in the pan, when you heat it.

"But don't we all know that cholestrol ain't bad for us?"

Unfortunately, there are other problems with ghee;  problems that are related to the heat-induced oxidation of cholesterol and the presence of large amounts of cholesterol oxides in commercially available "clarified butter" even before you even start heating it as it was reported by Kubow et al. in 1993 (12.3% w/w of total sterols).

If rancid fish full of oxidized PUFA ain't bad for us (read previous article), why would we want to use saturated animal fats for frying then? Please note that the overwhelming evidence says that oxidize PUFAs are bad for you.

Not a problem? We all know the whole cholesterol thing is a hoax that was made up just to put everyone on statins? Well, even if that were the case, the "whole cholesterol thing" is about the effects of intact, not oxidized cholesterol on heart health. The oxidized sterols in your "healthy" clarified butter, on the other hand, don't just make it into the bloodstream (Staprans. 1994 & 2003), they will also be incorporated in various tissues (Vine. 1997) and lead to a rapid (+100%) increase the formation of fatty streak lesions in the aorta of lab animals (Staprans. 2000) and have been linked to the unexplained high risk of atherosclerosis in Indian immigrant populations in the US (Jacobson. 1987) as well as the occurrence and progression of atherosclerosis in general (Leonarduzzi. 2002; Gargiulo. 2011).

As mentioned before, butter is unfortunately, not the only high cholesterol item on the Internet's list of "best, because highly saturated, frying oils". Next to butter (215mg of cholesterol / 100g) you will also find lard (95mg of cholesterol / 100mg) or tallow (109mg of cholesterol / 100mg) on these lists.

"I always pour away the oil! I am safe, right?" If I had not heard this argument before I would certainly not mention that the oxidized cholesterol does make it into the fried products. In a study from 1991, Zhang et al. report that the average content of the measured forms of oxidized cholesterol in french fries that had been fried in fresh, previously unoxidized tallow at a fast food restaurant ranged from 1.6-3.8 mg/100g and thus 3-8x more than Pie et al. found in a rare steak (>0.5mg /100g after 3 minutes of cooking) or cooked pork (>0.56mg /100g) in 1991 or those reported by Al-Saghir et al. for cooked farmed salmon (0.33-0.9mg/100g; cf. Al-Saghir. 2004 -- the table on the left is a fully referenced overview of COP levels in various foods from Otaegui-Arrazola. 2010).

Needless to say that neither tallow nor lard or any other of these animal fats contain enough antioxidants to protect their cholesterol from being oxidized (Ryan. 1981; Park. 1986a,b).

Figure 1: Even if you believed that cholesterol was bad for you, the ~50% reduction in intact cholesterol that occurs, when you heat tallow at temperatures of 155°C and 190°C should not be a reason to celebrate (Park. 1986a)

Interestingly, Park et al. have been able to show that this process starts at temperatures as low as 135°C (the recommended frying temperature for most products is 160°C+) and does not increase with higher temperatures. For pure cholesterol Osada et al. determined 120°C as the lowest temperature that induces oxidative changes (Osada. 1993).

In 1986, a group of researchers who conducted research for the French government found that 78% of the total cholesterol that was lost (23% of total cholesterol) from beef tallow during deep frying was recovered in form of the four best known forms of oxidized cholesterol, i.e. Triol-, 7a-, 7/3-, and 7-Oxo-cholesterol (Bascoul. 1986).

The latter have been shown to decreases barrier function of cultured endothelial cell monolayers (induce leaky gut; Hennig. 1987) and smooth muscle cells (Zwijsen. 1992).

Aside from their previously mentioned effect on the progression of atherosclerosis and their direct effect no the gut lining and other protective barriers in your body. These cholesterol oxidation products (COPs) have also been shown to promote the growth of colon (Kendall. 1992) and other forms of cancer (Sevanian. 1986; Gabitova. 2014), figure in the development of type II diabetes (Mol. 1997), block the production and blood pressure lowering effects of nitric oxide (Brown. 1999) and have been implicated in the development and progression of Alzheimer's disease (AD) and vascular dementia, as well as kidney failure (Sottero. 2009)

Total amounts of COPs (mg/100g) in the extracted fat of raw, fried w/out and w/ corn, olive and partially hydroge- nated vegetable oil, and steamed salmon (Al-Saghir. 2004).

Surprising interactions between frying oils and fried foods: I already mentioned that (a) oxidized cholesterol from frying oils migrate into the fried foods, and (b) the cholesterol in the foods is oxidized, as well. Now, the previously cited study by Al-Saghir et al. (2004) happened to compare the amount of oxidized cholesterol (COPs) in cooked farmed salmon for different cooking oils and found that the salmon that had been fried in partially hydrogenated vegetable oils had the lowest, the steamed salmon the highest content of oxidized cholesterol (0.98mg/100g) - luckily, frying with olive oil can protect you from both, the transfats in partially hydrogenated veg. oils and the COPs in steamed salmon.

And while all the non-enzymatically produced COPs in fried (and other) foods are  "bad guys", the enzymatic conversion of cholesterol in the body (see Figure 2, bottom) can produce compounds of which Otaegui-Arrazola, Menéndez-Carreño, and Ansorena write in their 2010 review that they play important biological role.

Figure 2: Not all oxysterols are created equal. Those your body creates by enzymatic reactions figure in cholesterol homeostasis (Otaegui-Arrazola. 2010)

In fact, certain oxysterols can suppress the activation of the master transcriptional regulators of lipid homeostasis (SREBPs) by binding to an oxysterol sensing protein in the Endoplasmic Reticulum, while others accelerate the degradation of the key cholesterol biosynthetic enzyme, HMG-CoA reductase, and/or serve as natural ligand activators of a nuclear receptor (LXR) involved in coordinating many aspects of reverse cholesterol transport (Gill. 2008).

These "good oxysterols" do thus appear(!) to play a subtle but important role in the control of cholesterol homeostasis. In the context of this true or false question, their existence, functions and benefits are however irrelevant. Apropos, question! What's the answer to our question, after all?

The best advice I can give you is to stop consuming fried foods.

We may not be able to trace obesity, diabetes, heart disease, cancer and dementia back to a specific frying oil - what we can do, though, is to draw the links between these and the general consumption of fried foods.

So, no more fried Big Macs or Snickers Bars, and all the other delicious "all American style" foods, folks!

Note: You may or may not have realized this, but at least with respect to the formation of oxidized cholesterol products, the "healthy" steaming turned out to be even worse than frying in Al-Saghir's 2004 study (see light-blue infobox)

Are butter, ghee, lard & tallow the best or the worst frying fats? While it stands out of question that the cholesterol oxidation products (COPs) are bad for you, we don't have a study that proves that the amount you'd consume if you were frying your eggs in butter in the morning will cause all sorts of ailments from "A" as "Alzheimer's" to "Z" as in "diabeteZ" ;-)

The previously cited animal studies have - as usual - been conducted with very high amounts of oxidized cholesterol in the diet and the "Ghee is the reason for increased heart disease in British Indians" hypothesis Jacobson et al. proposed in their 1982 article in The Lancet would not explain, why Indians who live in India didn't have a similarly high heart disease risk at that time... that being said, from 1960 to 1995 the prevalence of heart disease in urban areas of India increased from a meager 1% to almost 10% (Gupta. 1995; compare that to "only" 8.7% in US citizens aged 50years or older; Alexander. 2003). Moreover, US Indians who use >1kg of ghee to fry their foods have a record-breaking 4x increase in atherosclerosis risk compared to their non-ghee eating peers (Gupta. 1997).

You see, we can go back and forth on this and still won't make any progress. Personally, I would not use ghee, tallow or lard for frying; and whether coconut oil, or maybe olive oil, of which you know that it is cholesterol-free and learned that it reduces the rate of cholesterol oxidation (Al-Saghir. 2004) are better alternatives is going to be a topic for another installment of True or False - so stay tuned for more!

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