If older guys who exercise eat a small handful of walnuts every day for six weeks, it might help lower their stress hormone levels more than exercise alone.

What we've found so far suggests that eating walnuts daily may help lower cortisol levels in active older men, at least when combined with exercise. Our analysis of the available research shows that adding a small handful of walnuts to the daily routine of older men who exercise could lead to greater reductions in stress hormone levels compared to exercise alone [1]. We looked at one key assertion from the evidence, which is supported by 54.0 studies or data points, with no studies refuting it [1]. This means the current body of evidence we’ve reviewed leans toward a potential benefit of walnuts for managing cortisol in this group. We don’t yet know the exact mechanisms, but walnuts are rich in nutrients like omega-3 fatty acids and antioxidants, which may play a role in how the body handles stress. It’s important to note that our current analysis is based on limited assertions—just one so far—even though the supporting data points are numerous. We can’t say for sure how strong or consistent this effect is across different people or settings. Also, we’re not claiming walnuts directly “lower cortisol” in all cases—we’re only reporting what the reviewed evidence indicates for active older men over a six-week period. We also can’t say how much of the effect comes from walnuts specifically versus other lifestyle or dietary factors, since the evidence doesn’t clarify that. As we review more data over time, our understanding may change. For now, if you’re an older man who exercises and wants to support your body’s stress response, adding a small handful of walnuts to your daily diet might be a simple step worth considering—based on what we’ve found so far.