Industrial seed oils like soybean, sunflower, canola, rapeseed are present in almost every Indian kitchen today. They are highly processed and extracted from seeds. But these oils were not part of our diet until the 20thcentury when the technology to extract them evolved. Extraction of these oils involves chemical solvents. The oils are often chemically altered during purification or refining.
Consumption of vegetable oils has increased drastically in the last few decades replacing fats like butter, ghee, lard because they are composed of saturated fats. Westernisation of diet brought some of these oils to the Indian kitchen. Palm oil, not a seed oil, ranks first in the list of edible oil consumed by Indians, with soyabean oil coming second. Together, both make up 65-75 per cent of total oil consumption. In comparison to saturated fats, refined vegetable oils are considered ‘heart healthy’ due to the presence of polyunsaturated fatty acids. However, new evidence that shows industrial seed oils contain a large amount of omega-6 fatty acids is raising concern among scientists and nutritionists.
Health risk associated with industrial seed oils
Omega-3 and Omega-6 ratio
Omega-3 and omega-6 fatty acids are essential polyunsaturated fatty acids, and found in vegetable oils. Research shows omega-3 fatty acids are anti-inflammatory, prevent chronic inflammatory diseases, whereas omega-6 is inflammatory. A delicate balance between omega-6 and omega-3 fatty acids is crucial for our health. The paleolithic diet ratio of omega-6 to omega-3 used to be 1:1. Today, that stands at 10:1 to 20:1. This leads to many diseases including cardiovascular disease, cancer, and inflammatory and autoimmune diseases. A 2002 study by US’ Center for Genetics, Nutrition and Health showed that a lower ratio suppresses these bad effects. A ratio of 4:1 was associated with a 70 per cent decrease in total mortality among heart disease patients. A ratio of 2-3:1 suppressed inflammation in patients with rheumatoid arthritis, and a ratio of 5:1 had a beneficial effect on patients with asthma.
Avoid vegetable oils that are high in Omega-6 such as soybean, corn, cottonseed, sunflower, peanut, sesame, and rice bran oil. Here is a chart by Healthline that shows commonly consumed fats and oils. Avoid all that have a high proportion of omega-6. Olive oil, lard, butter, and coconut oil contain the lowest amount of omega-6 and are recommended for healthy cooking.
Industrial seed oils are unstable, easily oxidised
Polyunsaturated fatty acids present in industrially processed seed oils break down easily when exposed to heat and produce reactive oxygen species and trans fats. Trans fat is linked to increased risk of heart diseases as revealed by multiple research papers. Reactive oxygen species damage DNA, lipid and protein membranes of cells.
Most industrial seed oils contain synthetic antioxidants
These include BHA, BHT, and TBHQ to prevent oxidation. These compounds are found to cause hormonal imbalance, suppress immune function and are ‘reasonably anticipated’ to be carcinogenic in nature. Concentrations of 0.75 per cent of BHA and BHT can be harmful to the blood as suggested by an in vitro study conducted on mice.
Industrial seed oils and heart diseases
The traditional recommendation of vegetable oils over saturated fats such as butter and ghee to reduce the risk of heart diseases has now become controversial.
A large review by Norman J. Temple in 2018 suggests a switch from saturated fatty acids to carbohydrates did not lower the risk of coronary heart diseases. The same study concluded that refined carbohydrates, especially sugar-sweetened beverages, increased the risk of heart diseases. Another review found no consistent benefit to all-cause or cardiovascular disease mortality from the reduction of dietary saturated fat.
Oils that are best for Indian kitchens
An ideal cooking oil is one with a high smoking point to withstand heat, not industrially processed, and doesn’t oxidise easily. There are three cooking oils best suited to Indian kitchens.
Coconut oil has a smoking point of approximately 350°F that is suitable for baking, frying, and cooking. It contains medium-chain triglycerides such as lauric acid, which are beneficial for heart health, brain, and weight loss.
Sesame oil has a higher smoke point of approximately 410°F. This oil contains sesamol and sesaminol, two heart-healthy antioxidants. Sesamol is a potential anti-carcinogenic agent. Sesaminol exhibited preventive effect against Parkinson’s disease. Sesame oil can be used for sautéing, all-purpose cooking, and as a garnishing oil. Unlike other seed oils, sesame oil is less prone to getting oxidised because it has a high smoking point and sesamol antioxidant to prevent rancidity when opened for use. Buy the cold pressed versions of sesame oil for best benefits.
Ghee is an anti-inflammatory fat, and contains conjugated linoleic acid (CLA) that promotes fat loss. CLA also reduces the risk of diabetes. People with the most CLA in their bodies have a lower risk of heart disease.
Industrial seed oils are high in omega-6 and should be avoided to achieve optimal health. Traditional fats like butter or ghee are better options for cooking. Selecting a vegetable oil high in omega-3 is better for heart health, and can prevent inflammation and chronic illnesses. However, quantity matters because fats are high in calories. Further, no single food is completely good or bad. The lifestyle mantra should be eating everything in moderation, choosing healthier options and avoiding processed, refined products as much as possible.
Dr Subhasree Ray is Doctoral Scholar (Ketogenic Diet), certified diabetes educator, and a clinical and public health nutritionist. She tweets @DrSubhasree. Views are personal.