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While it seems highly unlikely that such a result will be translated into pushing vindaloo as a functional food, it may see increased use of spices and herbs as functional ingredients in the rapidly expanding functional food market.
The potential health benefits of herbs and spices have been consistently researched, with studies of the anti-cancer effects of turmeric from curcumin, and capsaicin from red chilli pepper spending significant time in the spotlight recently.
And the review, authored by the late John Paterson, and his colleagues Gwen Baxter and James Lawrence from Dumfries and Galloway Royal Infirmary, and Professor Garry Duthie from Rowett Research Institute, adds to this by looking at the science behind the potential benefits of dietary salicylic acid.
Diet's impact on colorectal cancer
The health benefits of salicylic acid are not in question because the compound is the metabolite of acetylsaliclylic acid, more commonly known as aspirin. Recent reports have reported that a daily dose of 75-80mg of aspirin may halve the risk of colorectal cancer.
The question remained, therefore, whether salicylic acid from fruit, vegetables, and herbs and spices such as paprika, curry powder, thyme and oregano, is also available in bioactive quantities from the diet, and if this could impact on colorectal cancer risk.
Colorectal cancer accounts for nine percent of new cancer cases every year worldwide. The highest incidence rates are in the developed world, while Asia and Africa have the lowest incidence rates, thereby begging the question whether such incidence may be related to dietary salicylic acid intake.
“Possibly,” Prof Duthie told NutraIngredients.com, “but causality is not proven.”
“However, [it has been reported that] the plasma concentrations of salicylic acid in Southern Indians are four times higher than in Scots, suggesting a higher dietary intake of salicylic acids in India presumably from spices. Rates of colon cancer are low in India,” he said.
Foods that contain salicylates
An article by the Dumfries group (J. Ag. Food. Chem., Vol. 54, pp. 2891-2896) reported that a portion (549g) of a vindaloo-style curry contained about 86g of total salicylates.
Moreover, an article in the Journal of the American Dietetic Association (1985, Vol. 85, pp. 950-960), reported that curry powder and paprika contain over 2000mg of salicylates per kilogram, although these findings were not repeated in an additional study.
And despite the fact that a study from 1996 concluded that amounts of bio-available salicylates in a “normal” diet were too low to have any effect on the risk of diseases, the new review concludes: “It is, therefore, feasible that sufficient salicylates could be obtained from regular consumption of plant-based diets to decrease disease risk by PGHS-2 inhibition… an enzyme implicated in colon cancer pathogenesis.”
Studies underway
Prof Duthie told this website that he was continuing to work with the Dumfries group to further explore the bioavailability of salicylic acid from the diet.
“We are also conducting studies to try to ascertain potential anti-cancer mechanisms of salicylic acid in model systems at the molecular level,” he said.
Excessive consumption of salicylic acid-rich vindaloo curries is not recommended, while extreme intake of the pure compound can result in stomach irritation and bleeding, said Prof Duthie.
“This is one reason Bayer acetylated it to produce aspirin to try to reduce its acidity and minimise side effects,” he said. - (Decision News Media, August 2006)
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