Rebuttal to “If not ghee, don’t look beyond these 7 healthy cooking oils” article

Rebuttal to “If not ghee, don’t look beyond these 7 healthy cooking oils” article https://www.healthshots.com/healthy-eating/nutrition/7-best-and-healthy-cooking-oils-for-a-healthy-life/ by Aayushi Gupta (information obtained from Dr Anshu Chaturvedi, Department of Clinical Nutrition and Dietetics, Fortis Escorts Hospital, Jaipur)

As the title of this article suggests, the author shared with the readers the 7 healthy cooking oils other than ghee – the common solid fats used in Indian cooking. However, there are a few points highlighted in the article that are inaccurate.

The author says that ‘oils with the highest smoke point are meant to be the healthiest oils’. First of all, there is no ‘one oil fits all purpose’. It really depends on what you use it for. To choose a healthy salad dressing, for instance, oils with higher antioxidant content would be favourable, as they can provide many health benefits to our body. However, these oils usually have a lower smoke point, as they are generally less refined and high temperature can destroy the beneficial antioxidants. A good example of healthy dressing oil would be carotenoids and vitamin E tocotrienols rich-red palm oil. Hence it is unfair to say that ‘healthiest oils must have high smoke points’ as it is clear that oils with lower smoke points are healthy too.

Undoubtedly, smoke point is one of the important criteria to determine oil stability for high heat cooking. Typically, a stable oil is made up of monounsaturated and saturated fats, as their chemical structure is much more stable compared to polyunsaturated fats, and they can withstand higher temperatures. Polyunsaturated fats on the other hand, are less stable and are easily degraded at high temperature. Hence, they tend to break down and oxidise easily, causing the oils to turn rancid.

In this article, the author highlights sunflower oil as ‘high in oleic acid’ and it has ‘the highest smoke point’, hence it is ‘good for deep frying’. Two things to clarify here:

(i) Indeed, oils with high oleic acid (monounsaturated fat) composition are good for deep frying. However, sunflower oil is high in polyunsaturated linoleic acid (up to 60%) and only 30% monounsaturated oleic acid. This makes it less stable at high heat cooking, such as frying, due to its high polyunsaturated fat content (Figure 1);

(ii) The smoke point of sunflower oil is 225 oC, whereas other oils with higher monounsaturated and saturated fats composition, such as palm oil has an even higher smoke point than sunflower oil (smoke point of palm oil is 235 oC). Therefore palm oil is more stable for high temperature cooking, such as frying and roasting, as it does not break down easily and produces less to none toxic compounds [1].

 

Figure 1. Fatty Acid Composition of Common Edible Oils

 

The author explained that ‘repeated heating of any kind of vegetable oil destroys its quality by making more trans-fat’. Again, this claim is not entirely true. There are two types of trans-fat: (i) naturally-occurring trans fatty acids formed in ruminant animals (such as cows and sheep); (ii) industrially-produced artificial trans fatty acids, formed by partial hydrogenation of oils with high content of polyunsaturated fats. This is to improve the stability of oils, so that they can be used repeatedly in industrial and fast-food chain frying applications.

Naturally-occurring trans-fat can be found in many meat and dairy products but usually in small amounts. This does not impact our health very much if consumed moderately [2]. On the other hand, trans-fat produced artificially through partial hydrogenation, is the main culprit to the high amount of trans-fat content in our diet. According to WHO, although repeated frying at high temperature may increase trans-fat concentrations up to 3%, trans-fat in partially hydrogenated oils is way much higher, at 25 – 45% of the oil [3].

Fortunately, palm oil does not need to undergo partial hydrogenation, as it is naturally semi-solid, giving stability at high temperature. This is due to its unique balanced fatty acid profile and low polyunsaturated fat content (only 10%). Hence, it is naturally trans-fat free. Moreover, palm oil produces fewer harmful components, such as peroxides even after 5 times repeated frying, as compared to other oils, and still within the limit of allowable peroxide value for edible oils according to AOCS [4] (Figure 2).

 

Figure 2. Peroxide Values (meq/kg) in fresh and heated palm and soybean oils

The author claims that palm oil is not considered as a good option for cooking as it has more saturated fats in its composition, so people consuming it may be at higher risk of heart diseases. This statement completely disregards recent developments in the research of fats and oils where several studies have found that there is no link between saturated fat and higher risk of heart diseases (Table 1).

Table 1. Findings on Saturated Fat and Heart Disease

Reference Conclusion
Siri-Tarino et al., 2010 No significant evidence to show that saturated fatty acids are associated with increased risk of coronary heart disease [5].
Chowdhury et al., 2014 No association between dietary or circulating saturated fatty acids with coronary heart disease [6].
De Souza et al., 2015 Saturated fatty acids are not associated with all-cause mortality or coronary heart disease [7].
Harcombe et al., 2017 No significant association between coronary heart disease deaths and saturated fat consumption [8].
Marangoni et al., 2017 There is no evidence on the specific health effects of palm oil consumption as compared with other SFA-rich fats [9].

 

For frying purposes, it is important to consider many factors other than nutritional aspects of the oil, such as price, availability, frying properties, rate of breakdown (due to physical and chemical reactions such as oxidation, hydrolysis and polymerisation) and shelf-life of the end products. It is clear that palm oil has all the advantages over most edible oils and hence it is the best frying oil [10]. After all, with 50% unsaturated fats, palm oil is completely stable at high cooking temperature and hence it is highly recommended to use in Indian cuisine.

Lastly, the author named the title of this article – “If not ghee, don’t look beyond these 7 healthy cooking oils”. This does not seem to add up to the points that she made in the article, as ghee is made up of 70% of saturated fat. If ghee is good in cooking, why is palm oil the opposite, where palm oil only containing 50% of saturated fats?

 

References:

  1. MPOC. (2021). The Frying Oil Showdown: Which Is The Best Option?
  2. WHO. (2016) Brouwer IA. Effect of trans-fatty acid intake on blood lipids and lipoproteins: a systematic review and meta-regression analysis.
  3. WHO. (2018). REPLACE Trans Fat. (WHO/NMH/NHD/18.7).
  4. AOCS. (2003) Official methods and recommended practices of the American Oil Chemists’ Society. 4th ed. AOCS Press, Champaign, Illinois.
  5. Siri-Tarino PW, Sun Q, Hu FB and Krauss RM. (2010). Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. The American Journal of Clinical Nutrition. 91(3): 535-546.
  6. Chowdury R, Warnakula S, Kunutsor S, Crowe F et al. (2014). Association of dietary, circulating, and supplement fatty acids with coronary risk: a systematic review and meta-analysis. Annals of Internal Medicine. 160(6): 398-406.
  7. De Souza RJ, Mente A, Maroleanu A, Cozma AI et al. (2015). Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies. British Medical Journal. 351: 3978-3992.
  8. Harcombe Z, Baker JS and Davies B. (2017). Evidence from prospective cohort studies does not support current dietary fat guidelines: a systematic review and meta-analysis. British Journal of Sports Medicine. 51(24): 1743-1749.
  9. Marangoni F, Galli C, Ghiselli A, Lercker G et al. (2017). Palm oil and human health. Meeting report of NFI: Nutrition Foundation of Italy symposium. International Journal of Food Sciences and Nutrition. 68(6): 643-655.
  10. Minal, J. (2020). Characteristics of Palm Oli/Palm Olein as a Frying Oil. Palm Oil Dev, 72, 15-18.

Prepared by Vicky

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