“Popcorn and breakfast cereals may contain ‘surprisingly large’ servings of healthy antioxidants,” The Guardian reported. The nutritional value of these foods was previously attributed to their high fibre content.
“Popcorn and breakfast cereals… may contain ‘surprisingly large’ servings of healthy antioxidants,” The Guardian reported. It said that the nutritional value of these foods was previously attributed to their high fibre content, but research now suggests that the benefit of grain-based foods comes from “the significant presence of antioxidants known as polyphenols”.
The Guardian's story on popcorn is based on research presented at a conference in the US. The research claims that popcorn and wholegrain breakfast cereals contain similar levels of antioxidants as fruit and vegetables. However, this is a preliminary report that has not yet been published and it is probably too soon to conclude that popcorn can boost health or protect from cancer.
The theoretical effect of polyphenols in improving important measures of health or in preventing disease needs to be confirmed in further research. The salt and sugar content of most commercial popcorn should also be considered before consuming large quantities of it.
What are polyphenols?
Polyphenols are chemicals found in fruit and vegetables including berries, walnuts, olives and grapes, and other foods including chocolate, wine, coffee and tea.
Polyphenols are a type of antioxidant thought to remove free radicals from the body. Free radicals are chemicals that have the potential to cause damage to cells and tissues in the body. Polyphenols have up to 10 times the antioxidant effect of vitamins C and E.
How do polyphenols affect you?
Observational studies that have examined the link between these foods and health have claimed that it is their polyphenol content that reduces the risk of death, heart disease, cancer and other illnesses.
Fibre used to be commonly believed to be the active ingredient for these benefits but, recently, polyphenol antioxidants have been thought to be more important.
Where did the study come from?
This study was conducted by Dr Joe Vinson, a chemist, and colleagues from the University of Scranton in Pennsylvania. The study received internal funding from the University of Scranton. It was presented at the 238th National Meeting of the American Chemical Society in August.
What did the research involve and what were its findings?
The researchers measured the total polyphenol concentration in commercial hot and cold breakfast cereals and snacks. They did this by mixing the food with an alkali that released the polyphenols that were bound to the fibres in the food. The researchers then used standardised tests to measure the levels of polyphenols.
They found that “wholegrain cold cereals have significantly more [polyphenol] antioxidants than processed grain types.” Wheat has more than corn, which has more than oats or rice. Among the salty snacks, popcorn has the most antioxidants per gram.
What did the scientists say?
The researchers claim that wholegrains provide a significant 10% of a person’s daily polyphenol intake in the average US diet and that about two-thirds (66%) of these wholegrains are from cereals, pasta, crackers and salty snacks.
The lead scientist is quoted as saying that raisin bran has the highest amount of antioxidants per serving, “primarily due to the raisins”, and that porridge oats have “disappointingly low levels”.
How reliable is this research?
This research has not been published, so it is not possible to say how well it was conducted. It appears to have answered the question it set out to address, which is what the polyphenol content of some foods is. However, between the presentation of this study at a conference and its portrayal in the media, the relevance of these findings to human health has been exaggerated. For example:
- Wholegrain foods are already known to be healthy. Any mention in the newspapers of their potential benefits, such as for the prevention of cancer or heart disease, were not investigated by this study.
- There is no general comparison of the other content of these foods. For example, the fibre content is mentioned but not analysed. Salt and sugar content are also important and before any claim of universal benefits from popcorn is made the relative content of these will need to be assessed.
- It is possible that the polyphenol content of food is one of the factors determining antioxidant activity. However, it is not the only antioxidant, and more research will be needed to determine which antioxidant (if there is one) could be responsible for the healthy effect of wholegrain food.
If people choose popcorn as part of their diet, they should be careful to avoid sugary and salty versions.