Cheerios are probably the biggest and do the most advertising, and also are the first to lay claim to that. General Mills can launch a campaign solely highlighting that, while other companies probably just push to be noticed. Are there lesser known cereals, ones that are probably better for you, that has the same ingredients that lower cholesterol?
It might just be the whole oats/grains in the product. Quaker Oats makes the same claim with their products (though I don't think instant oatmeal is too healthy, though I'll eat it in a pinch), as does Kellogg's Heart Smart cereal. (Although Heart Smart has several listings of sugar, including corn syrup and high fructose corn syrup and partially hydrogenated oils and listings of preservatives that I don't consider healthy and will not buy a product if any of these are even listed once.) I shop at Trader Joe's, which is a chain of low cost health food stores. They have a Cheerios equivalent, Joe's O's that have the same comment about cholesterols on them.
In my opinion, it just helps to eat a good, healthy diet. My mother-in-law told me last month that her doctor put her on a new pill for her high cholesterol. Now, this woman eats plenty of stuff I don't even consider food. That day, I noticed she put creamy, fatty dressing on he salad (to me, those types of dressings ruin the salad), and had a nice chunk of red meat for dinner. Typical of her. I had made the diet comment, too. On the other hand, I eat real, whole, good foods and my cholesterol (as of the test I took in late spring/early summer) is low.
Other than the American Heart Association site, I'm sure there are sites that offer information on lowering and maintaining good cholesterol levels, but I just can't think of any good search phrases now.