They can lower your cholesterol. About a handful of walnuts, or 2 ounces, was linked to lowering total cholesterol numbers and LDL or "bad" cholesterol as well as improved blood vessel cell wall function in a recent study of 112 people between the ages of 25 and 75. The people randomized in the study to enjoy that daily snack saw improvements to their overall diets, compared with those randomized to go without walnuts. Added bonus: When they also were given a little dietary counseling, their waistlines shrank. Walnuts are loaded with monounsaturated fats, including known heart protectors omega-3 fatty acids. (Try one of these top 10 cholesterol-fighting foods.)

They can improve your memory. A 2012 Journal of Alzheimer's Disease report found that eating walnuts as part of a Mediterranean diet was associated with better memory and brain function. The antioxidants in walnuts may help counteract age-related cognitive decline and even reduce the risk of neurodegenerative diseases, including Alzheimer's.

They can reduce inflammation. You've likely heard of the inflammation-fighting powers of those all-mighty omega-3s. And while the most powerful of them all—docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA)—come from fish, the plant variety, alpha-linolenic acid or ALA, shouldn't be totally written off. Walnuts are one of the richest sources of ALA, which may not carry all the health effects of its fishy compatriots but does still seem to fight inflammation. Experts think a diet higher in omega-3s may simply mean we're not eating as many inflammation-provoking omega-6 fatty acids.

They can lower blood pressure. In studies of how people respond to stressful situations—like plunging your foot into an ice bath or delivering a speech in front of your peers—those who eat walnuts seem to have lower blood pressure, both in response to that stress and when not under stress. Since walnut oil, as well as flax oil, produced similar results, researchers believe the perks may be due to that same ALA that reduces inflammation, this time exerting its do-good properties on BP.