New research suggests that a short-term diet centered almost exclusively on a cheap, healthy breakfast staple can significantly lower cholesterol levels in just two days. 3 Millions of Americans have high cholesterol, though many are unaware of it because of a lack of symptoms. 3 A bowl of oatmeal for breakfast may help lower levels of LDL “bad” cholesterol. Among these participants, blood and stool samples showed that their LDL cholesterol levels had dropped by roughly 10% in just 48 hours. By contrast, those who ate almost nothing but oats for two days saw their lower cholesterol levels hold steady six weeks later.