Dr Varun Bansal, Consultant Cardiac Surgeon, Indraprastha Apollo Hospitals
Soybean oil is one of the most commonly used vegetable oils in cooking and food processing and is often cited as a healthier alternative to animal fats or other vegetable oil.
Derived from the seeds of the soybean plant, this oil is rich in polyunsaturated fats, particularly omega-6 fatty acids. Yet over a period of several years, research has shown that excessive consumption of soybean oil might have many long-term effects on our health.
One of the primary supportive arguments for the consumption of soyabean oil are for its polyunsaturated fats and omega-6 fatty acid content, which is beneficial to maintaining heart health. Omega-6 fatty acids are believed to lower bad cholesterol for low-density lipoprotein (LDL) levels when consumed in moderation. However, many studies have suggested that excessive consumption of only omega-6 fatty acids, especially from processed vegetable oils can lead to an imbalance in the omega-6 to omega-3 ratio in the body, which is crucial for maintaining a healthy heart.
The excessive intake of omega 6 fatty acids can also promote inflammation and contribute to the development of atherosclerotic plaques which are the major causative factor for heart disease and stroke.
Several studies have mentioned that higher doses of soy protein might be associated with greater LDL reduction among those with increased baseline LDL, but not with high-density lipoproteins (HDL) or triglycerides.
When consumed in large quantities, soybean oil may also contribute to the accumulation of fat in the liver, a condition known as non-alcoholic fatty liver disease (NAFLD), which can also increase the risk of heart disease. Soy’s potential contribution to obesity and metabolic disorders leading to increased fat accumulation and insulin resistance over time has been mentioned in a study published in the Journal of the American Medical Association (JAMA).
One of the controversial effects of long-term soybean oil consumption is its potential to modify the hormonal balance in the body. Soybean oil contains phytoestrogens, which are plant compounds that have a chemical structure similar to the hormone estrogen. While these compounds are generally considered to have mild estrogenic effects, their long-term consumption in high amounts may lead to hormonal imbalances, particularly in individuals who are sensitive to estrogen fluctuations.
Research on the impact of phytoestrogens found in soybean oil showed mixed results, but some animal studies suggest that exposure to high levels of these compounds could affect reproductive health, growth patterns, and even brain function.
Indeed, results from the Honolulu-Asia Aging Study (HAAS) raised concern that soy intake might impair cognition. This study found higher midlife tofu intake among men was associated with indicators of cognitive impairment and brain atrophy in late life. A post-hoc analysis using the men’s intake as a surrogate showed the relationship between cognitive decline and tofu intake also applied to their spouses. It was theorized that soy isoflavones were acting as estrogen receptor antagonists.
While soybean oil is often promoted as a healthier alternative to saturated fats, its long-term consumption may have unintended negative consequences for our health. To mitigate these risks, it is important to consume soybean or any other oil in moderation and consider alternative cooking oils with a better balance of omega-3 and omega-6 fatty acids. In conclusion, moderation and variety are keys to maintaining a healthy diet, in addition to regular exercise.
- Balk E, Chung M, Chew P, et al. Effects of Soy on Health Outcomes: Summary. 2005 Aug. In: AHRQ Evidence Report Summaries. Rockville (MD): Agency for Healthcare Research and Quality (US); 1998-2005. 126. Available from: https://www.ncbi.nlm.nih.gov/books/NBK11870/
- Messina Mark , Duncan Alison , Messina Virginia , Lynch Heidi , Kiel Jessica , Erdman John W. The health effects of soy: A reference guide for health professionals.Frontiers in Nutrition. VOLUME=9, YEAR=2022. URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2022.970364. DOI=10.3389/fnut.2022.970364. ISSN=2296-861X
