A handful of mixed nuts can be good for the heart. But people with rheumatoid arthritis (RA), who have twice the risk of heart disease as healthy adults, might want to pick out the walnuts for themselves.

Almonds, hazelnuts, peanuts, pecans, pistachios and walnuts are backed by enough scientific evidence to garner recognition from the U.S. Food and Drug Administration for their heart-protective qualities. Most nuts are good sources of fiber, antioxidants and unsaturated fat.

Walnuts, however, “are unusual because, unlike other nuts, they are high in omega-3 fatty acids,” says Pennsylvania State University nutrition scientist Sheila West, PhD. Omega-3s lower many cardiovascular risks, and West’s recent work reveals they also can relax blood vessels, which helps counter stress on the heart. “A daily diet including walnuts or walnut oil lowered resting blood pressure and blood pressure response to stress,” she says. In addition, study participants who added both walnuts and flax oil to their diet had significantly reduced levels of C-reactive protein, a marker of inflammation linked to arthritis and heart disease.

Other investigators have found omega-3s in fish oils lessen joint pain in RA, but it’s not as clear that omega-3s in nuts or flax oil have the same benefits. “Early studies suggest joint damage would be dampened by plant-based omega-3s, but this hasn’t been tested in humans,” West says. “Adding walnuts and flax oil is safe – as long as you cut other calories and fat – and may be worth a try for individuals with inflammatory conditions.”