In Vivo Suppression of Atherosclerosis by Dietary Oats Avenanthramides

Abstract

The consumption of oatmeal and oat bran has been shown to reduce total and low density lipoprotein (LDL) cholesterol levels in plasma, which are major risk factors for coronary heart disease (CHD). Oats, in addition to containing soluble fiber (β‐glucan), are a good source of protein and lipids as well as several antioxidants including vitamin E, phytic acid, phenolics, and Avenanthramides (Avns), unique soluble bioactive compounds present only in oats. Avns can inhibit inflammation in arterial endothelium by suppressing NF‐κB, which regulates expression of several inflammatory cytokines. We have reported that Avns suppressed endothelial expression of chemokines (MCP‐1, IL‐8), pro‐inflammatory cytokines (IL‐1 and IL‐6) and several adhesion molecules, all of which suggest oats’ potential anti‐inflammatory and anti‐atherogenic properties. In agreement with our in vitro observations, supplementing a high fat diet of LDLr−/− mice with feed containing 27% or 40% oats significantly reduced aortic lesion development. However, this effect of an oat‐based diet cannot be attributed only to its cholesterol lowering effect; rather, it is due to the additive/synergistic anti‐inflammatory interaction with oat Avns. To elucidate Avns’ contribution to the inhibition of atherogenesis, we supplemented a high fat diet of LDLr−/− mice with regular oats or false‐malted oats for 16 wks. Avns’ concentration as measured by LC/MS‐MS in the regular oat diet was 10 ppm; in the false‐malted oat diet, it was 451 ppm. Food intake was not different between the groups, but high fat‐fed mice gained body weight significantly (p<0.05). Both oat‐based diets (malted or false‐malted) significantly (p<0.05) reduced high fat diet‐induced atheroma lesions in the aortic tricuspid valve, but there was no difference in the extent of lesions between these two groups. However, LDLr−/− mice fed a high fat diet containing false‐malted oats with high levels of Avns had significantly (p<0.05) lower numbers of lesions in the descending aorta than mice fed a low fat diet, a high fat diet, or a high fat diet supplemented with regular oats. A non‐significant trend toward reduction of expression of VCAM‐1 in the lesions of aortic valves of mice fed high fat diet containing high levels of Avns was observed. Importantly, reduction of blood total cholesterol levels was the same in both oat‐supplemented groups, suggesting that false‐malted oats, with their higher concentrations of Avns, contributed more to the reduction of aortic lesions. These preliminary in vivo data suggest that consuming oats, especially false‐malted oats, may be beneficial in the prevention of cardiovascular disease.Support or Funding InformationSupported by USDA‐ARS agreement #58‐1950‐0‐014