 Spuds that like you
Eating high levels of resistant starch reduces toxic stress on the body and improves overall health, writes Anne Pichon in Chemistry & Industry |
 In the longest study of its kind (14 weeks), Spanish researchers confirmed the long-term beneficial effects of starch consumption on bowel health but also revealed a reduction in white blood cells in the blood. White blood cells are produced as a result of inflammation, so a reduction suggests an overall beneficial effect, according to Lena Ohman, and expert in immunology at the Department of Internal Medicine, Göteborg University, Sweden.
The Spanish researchers, led by José Francisco Pérez at the Universitat Autònoma de Barcelona, Spain, fed pigs either raw potato starch (RPS) or raw corn starch. They found that long-term ingestion of RPS induced pronounced changes in the digestive tract (Journal of the Science of Food and Agriculture doi:10.1002/jsfa.2835). ‘RPS diets probably promoted a lower cytotoxicity of the colonic digesta,’ according to Pérez. Digesta refers to undigested food and bacteria in the digestive system.
Preliminary and as yet unpublished research by the same group also looked at leucocytes, both in the peripheral blood and in the guts. They observed a reduction in leucocyte levels of about 15% in RPS pigs. Pérez said this ‘may reflect lower microbial aggression coming from the digesta, and indicate that the local barriers of protection are working better in RPS animals.’ This is consistent with the observed reduction of lymphocytes – a type of leucocyte – in colonic tissue.
Starch consumption is thought to reduce the risk of large bowel cancer and irritable bowel syndrome (IBS). Ohman’s team previously found that the overall lymphocyte levels do not vary for IBS patients, but that lymphocytes are transferred from the peripheral blood to the gut, which supports the hypothesis of IBS being at least partially an inflammatory disorder. She said the dietary-induced reduction in lymphocytes in RPS-fed pigs is interesting, and although IBS patients show extremely diverse food sensitivities, a diet of resistant starch may be worth trying in such patients.
But pigs’ diets do not contain as much fat as the human diet, and the high fat levels in the human diet could cancel out the positive effective of a high intake of carbohydrate. Fermentation of carbohydrates is also higher in pigs than in humans.
Raw potatoes contain high levels of resistant starch – starch that is not digested in the small intestine and so is shunted into the large intestine where it ferments. Resistant starch is also found in potato salad, legumes, grains, green bananas, pasta and cereals.
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