If you're an adult with mild obesity, swapping out saturated fats (like butter) for healthier fats from walnuts or vegetable oils for six weeks might lower your blood pressure by about 5 or 6 points — and how your body processes food could affect how much it drops.

If you're at risk for heart disease, swapping some fatty foods for whole walnuts every day for six weeks might lower an important type of blood pressure by a small but meaningful amount — even if your top blood pressure number doesn't change.

If you're at risk for heart disease, swapping some unhealthy fats in your diet for a handful of walnuts every day for six weeks might lower a key type of blood pressure by a small but meaningful amount — and the nuts themselves may do more good than just their fats alone.

If you're an adult with extra weight and a higher risk for heart problems, eating a special diet with less saturated fat and more healthy fats—like those in walnuts or vegetable oils—for 6 weeks can lower your bad cholesterol by about 10 to 15 points, no matter if the healthy fats come from whole walnuts or oils.

If you're at risk for heart disease, swapping out saturated fats for healthier fats like walnuts or olive oil for six weeks might help your blood pressure and cholesterol, but it won’t make your arteries more flexible in the short term.

If you're an obese adult with metabolic syndrome, eating a handful of walnuts or cashews every day for two months won't noticeably improve your cholesterol, blood pressure, or inflammation—if you don't gain or lose weight.