According to new research, eating walnuts daily protects you from heart disease in a profound way. Just four hours after eating nuts, doctors observe a significant improvement in blood cholesterol levels as well as blood vessel flexibility.

“Only by consuming a handful of walnuts or walnut oil for four days in a week you can significantly reduce the risk of heart disease,” says Dr. Penny Kris Etherton.

Of course, this isn’t the first documented observation of the superfood benefits of nuts. Ancient Romans believed that walnuts were a sexual enhancer among other things. They used to scatter them on newlywed couples. Walnuts were also used by the ancient British to treat mental illness, thinking the shape of the nut meant it was healthy for the brain.

If you don’t like the taste of walnuts, they’re easy to sneak into your food. You can put them on salads, in smoothies, in your oatmeal, and you can even make walnut energy bars. Walnuts are loaded with vitamin E, folate, melatonin, omega 3 fats, and antioxidants.