Eating potatoes gives your immune system a boost

Eating potatoes is not only good for bowel health, but also for the whole immune system, especially when they come in the form of a potato salad or eaten cold. In a study on an animal model, researchers in Spain found that pigs fed large quantities of raw potato starch (RPS)1 not only had a healthier bowel, but also decreased levels of white blood cells, such as leucocytes and lymphocytes in their blood. White blood cells are produced as a result of inflammation or disease, generally when the body is challenged.

The general down-regulation of leucocytes observed by the Spanish researchers suggests an overall beneficial effect, a generally more healthy body.2 The reduction in leucocyte levels was about 15 percent. Lower lymphocyte levels are also indicative of reduced levels of inflammation, but the observed reduction in both lymphocyte density and lymphocyte apoptosis is surprising.

In what was the longest study of its kind, pigs were fed RPS over 14 weeks to find out the effect of starch on bowel health. “The use of raw potato starch in this experiment is designed to simulate the effects of a diet high in resistant starch”, said study leader Jose Francisco Perez at the Universitat Autonoma de Barcelona,3 Spain.

Humans do not eat raw potatoes, but they do eat a lot of foods that contain resistant starch, such as cold boiled potatoes, legumes, grains, green bananas, pasta and cereals. About 10 percent of the starch eaten by human is resistant starch - starch that is not digested in the small intestine and so is shunted into the large intestine where it ferments. Starch consumption is thought to reduce the risk of large bowel cancer and may also have an effect on irritable bowel syndrome (IBS).4 

Immunology expert Lena 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 support the hypothesis of IBS being at least partially an inflammatory disorder. She says the decrease in lymphocytes observed by the Spanish is therefore interesting, and a diet of resistant starch may be worth trying in IBS patients. Ohman is currently at the Department of Internal Medicine, Goteborg University, Sweden.5  The study is published in the journal Chemistry and Industry, the magazine of the SCI.6

词汇：

immune adj. 有免疫力的，免疫的

boost vt. n. 提高，举起

bowel n.（常用复数）肠

salad n. 色拉（西餐中的一种凉拌菜）

Spain n. 西班牙

starch n. 淀粉

leucocyte n. 白细胞

lymphocyte n. 淋巴细胞

inflammation n. 炎，炎症；发炎部位

down-regulation n. 下调，向下调节

Spanish adj. 西班牙的

indicative adj. 指示性的；象征性的；预示性的

density n. 密度

apoptosis n. 细胞凋亡（细胞的自然死亡）

simulate vt. 模仿，模拟

resistant adj. 有抵抗力的；耐久的

Barcelona n. 巴塞罗那（西班牙港口）

legume n. 豆，（豆）荚

pasta n. 面食

cereal n. （常用复数）（作为主粮的）谷物类

digest v. 消化

intestine n. （常用复数）肠

shunt v. （使）分流

ferment v. （使）发酵

immunology n. 免疫学

peripheral adj. 周围的；表面的

gut n. 肠

hypothesis n. （学说的）假设，假定

inflammatory adj. 发炎的，炎性的