Food Safety Focus (88th Issue, November 2013) – Incident in Focus
Cottonseed Oil and Food Safety
Reported by Ms. Melva CHEN, Scientific Officer,
Risk Assessment Section,
Centre for Food Safety
Recently, two Taiwanese companies were found to be selling various edible oils such as olive oil, peanut oil and sesame oil adulterated with the cheaper cottonseed oil. Media reported that cottonseed oil can be risky to health since cottonseeds contain a toxic substance called gossypol that can cause infertility. This article discusses cottonseed oil and its safety.
Cottonseed oil is extracted from cottonseeds which are by-products of cotton fibre production. Cottonseeds are rich in oil and proteins and are therefore used for cottonseed oil production and as a feed supplement for cattle and sheep. According to the Food and Agriculture Organization of the United Nations, cottonseed oil is a type of vegetable oil used mainly as food. China is the world's largest cottonseed oil producer, followed by India, Pakistan, the USA and Uzbekistan. Cottonseed oil can be used to make salad oil (mayonnaise, salad dressings, sauces and marinades), cooking oil for frying in both commercial and home cooking, and margarine or shortening for baked goods and cake icings. Besides, limited quantities may be used for producing industrial products such as soaps and cosmetics. Although cottonseed oil is not commonly sold as cooking oil in retail stores in Hong Kong, it is present in some foods such as bakery products and fried snacks.
History of Crude Cottonseed Oil and Infertility
The link between crude cottonseed oil and infertility was found in the 1950s. Investigators had been puzzled by the outbreaks of infertility reported in a number of rural communes in China. Eventually they discovered that the phenomenon was caused by the use of crude cottonseed oil (where the oil was being pressed out of the seeds without further processing) for cooking. After using this oil for years, the men became infertile and many women had amenorrhoea (absence of menstruation). Further investigation revealed that the culprit was gossypol, a yellow compound produced in cotton plant.
Cottonseed oil is extracted from the seeds of cotton plants.
(Photo by courtesy of the US Department of Agriculture)
Gossypol is Removed from Oil Refinery
Gossypol is concentrated in the cottonseed but can also be found in other parts of the cotton plant. It acts as a natural defensive agent against predators, provoking infertility in insects. In men, it affects sperm production. Nevertheless, gossypol is not genotoxic. During cottonseed refining process, gossypol is removed to produce edible oil. In 1967, the Codex Committee on Fats and Oils concluded that gossypol did not present a problem in cottonseed oil, since cottonseed oil was normally sold refined and thus virtually free of gossypol. Taiwan authority announced on 25 October 2013 that gossypol was not found in any of the cottonseed oil and other cooking oils tested in response to the recent incident.
Although refined cottonseed oil is edible, it is illegal to sell adulterated or counterfeit cooking oils in Hong Kong. Cooking oils should be fit for human consumption and comply with legal requirements including requirements of trade descriptions and food labelling. The Centre for Food Safety will continue to monitor the latest development of the incident and the safety of cooking oils.
Key Points to Note:
- Cottonseed oil is normally sold refined which is virtually free of gossypol and safe for consumption.
- Cottonseed oil may be present in some foods such as bakery products and fried snacks.
- It is illegal to sell adulterated or counterfeit cooking oils in Hong Kong.
Advice to the Public
- Maintain a varied and balanced diet.
- Reduce the use of oils/fats when preparing food because excessive intake of oils/fats, regardless of the type, increases risk of overweight and obesity.
Advice to the Trade
- Label food products properly.
- Source cooking oils from reliable suppliers.
- Make sure the cottonseed oil used is refined and safe for consumption.