If older guys who already work out eat a small handful of walnuts every day for six weeks while keeping up their usual mix of strength and cardio workouts, their good cholesterol goes up and their bad cholesterol and fats in the blood go down—more than just exercise alone.

What we've found so far suggests that adding 15 grams of walnuts daily may improve cholesterol levels in trained elderly men who are already doing resistance and endurance training. The evidence we’ve reviewed leans toward this having a beneficial effect beyond exercise alone. Our analysis of the available research shows that when older men who regularly exercise include a small handful of walnuts in their daily diet for six weeks, their good cholesterol (HDL) tends to increase, while their bad cholesterol (LDL) and blood triglycerides tend to decrease [1]. This pattern was observed compared to a group that only exercised without adding walnuts. The evidence we’ve reviewed comes from one key assertion backed by 54.0 supporting findings and no studies or data that contradict it [1]. However, we note that only one distinct claim has been analyzed so far, which limits how strongly we can interpret these results. We emphasize that this is a narrow set of findings focused on a specific group: older men who are already physically active with a mix of strength and cardio training. We don’t yet know if the same effects would occur in women, younger individuals, or those who are not regularly exercising. Also, the exact mechanism—how walnuts might contribute—is not detailed in the evidence we’ve reviewed. Our current analysis shows a consistent signal that walnuts may support healthier cholesterol levels in this population, but more data would help strengthen our understanding. Practical takeaway: For older men already doing regular strength and cardio workouts, adding a small handful of walnuts to their daily routine might help improve their cholesterol profile—but this is based on limited evidence so far.