Mustard oil is one of the favourite ingredients used in Indian cuisine. It is distinctive for its aroma and strong flavour, but it’s the high smoking point of around 480 F that makes mustard oil a primary choice for sauteing or deep frying in the kitchens of India, Pakistan, Bangladesh, China, and other parts of South Asia.
According to the United States Department of Agriculture, 100 gram of mustard oil contains 884 calories, 11% saturated fat – 59% of which is monounsaturated fat (MUFA) and 21% polyunsaturated fat (PUFA). MUFA in mustard oil is composed of 30-40% erucic acid and 20-28% oleic acid; 9 to 9.5% of PUFA is omega-3 alpha-linolenic acid and 10-12% is omega-6 linoleic acid.
Mustard oil is thought to be cardio protective due to its high content of monounsaturated fatty acids, which is found to reduce the risk of cardiovascular diseases.
However, the beneficial aspect of mustard oil to protect heart health is controversial.
A 2004 study from India by Tanuja Rastogi and colleagues involving 350 cases of acute myocardial infarction found that intake of alpha-linolenic acid-rich mustard oil was associated with a lower risk than was use of sunflower oil.
A 2019 review study by Rupender Kaur and colleagues suggested that mustard oil reduces the adhesive impulses in blood platelets, which is helpful to minimise the risk of a heart failure.
In a randomised control trial, Shyam Prakash and colleagues investigated the effects of two types of mustard oil among 350 participants. Type-I contained erucic acid and glucosinolate and Type-II was absent of these two components. The authors reported, Type-I mustard oil decreased serum triglycerides and increased HDL cholesterol, compared to Type-II oil.
On the contrary
A 2016 comparative study between ghee and mustard oil consumption among 137 people aged between 40-80 years by Saumen Manna and colleagues found coronary heart disease was 50.9% higher in participants who were consuming mustard oil.
A 2018 study from India by Hanjabam Sharma and colleagues involving 200 healthy males found consumption of ghee was linked to “lower cholesterol and triglyceride levels than those who consumed higher amounts of mustard oil.”
Significantly, mustard oil is banned for cooking purposes in countries like Europe, the US and Canada and only used for external purposes like skin care, hair treatment and massage.
Decade-long experimental animal studies suggested that consumption of erucic acid caused cardiac damage. The Food and Drug Administration, US, has prohibited mustard oil from cooking due to its higher erucic acid level (20-40%), which has been found to damage the heart in male rats. In a 2016 scientific report, the European Food Safety Authority linked long-term exposure of erucic acid with myocardial lipidosis in young rats. A technical report addressing toxicological review and risk assessment of erucic acid by Food Standards Australia New Zealand revealed their concern for human health from erucic acid due to multiple experimental reports linking erucic acid and heart lesions in rats.
Fumiaki and colleagues investigated prospective associations between long chain monounsaturated fatty acids like erucic acid and cetoleic acid exposure, and incident congestive heart failure (CHF) among 7,271 participants in 2013. The authors found a positive correlation between higher incidence of CHF and long chain fatty acids.
Although there is mixed report on use of mustard oil as a cooking medium, other benefits of mustard oil include blocking microbial growth, reducing inflammation, lessening joint pain and inhibiting cell growth in certain types of cancer.
Mustard essential oil is a powerful antimicrobial agent as reported by several studies. A 2016 comparative study between Cinnamon essential oil and mustard essential oil indicated that the latter had “10 times more bactericidal/bacteriostatic effect than cinnamon essential oil.”
A 2015 test tube study evaluating the antifungal effect of black mustard essential oil found the oil to inhibit mold growth for 30 days in a bread-type product.
Mustard oil is anti-inflammatory due to the presence of alpha linolenic acid omega 3. A 2012 meta-analysis by Young-Ho Lee and colleagues analysed 10 randomised control trial involving 183 rheumatoid arthritis patients and concluded that the use of >2.7 g/day omega-3 PUFA for more than three months reduced consumption of nonsteroidal anti-inflammatory drugs among participants.
A study involving 60 rural women of 51-55 years age from Puducherry, India (Remya Mohan, 2014) found to reduce knee pain, an early sign of osteoarthritis, by applying massage with warm mustard oil. However, it is advised to run a patch test by applying a small amount to check for any allergic reaction.
A 2010 study by Arup Bhattacharya and colleagues found allyl isothiocyanate, a compound found in mustard oil to inhibit bladder cancer growth by 34.5% in lab rats.
Controversial evidence on mustard oil consumption has divided the scientific community on giving a clean chit to ‘kacchi ghani’ (cold pressed) mustard oil as a cooking medium for universal use in India or other South Asian nations. Ban on this oil by the EU, USFDA means there is need for more assertive evidence to establish mustard oil as safe for consumption.
Due to the presence of high erucic acid, the safe use of mustard oil should be limited as a flavouring agent until we have sound food safety data. Households consuming mustard oil on a regular basis should reduce its consumption by turning to other cooking mediums such as ghee, coconut oil, cold pressed peanut or groundnut oil.
Dr Subhasree Ray is Doctoral Scholar (Ketogenic Diet), certified diabetes educator, and a clinical and public health nutritionist. She tweets @DrSubhasree. Views are personal.
(Edited by Prashant Dixit)