Older guys who work out might get a bigger boost in their testosterone if they eat a small handful of walnuts every day for six weeks, compared to working out without walnuts.

What we've found so far suggests that eating 15 grams of walnuts daily might be linked to increases in testosterone in older men who exercise. Our analysis of the available research shows this idea is supported by the evidence we’ve reviewed, with no studies in our dataset refuting it [1]. We looked at one key assertion from the data, which focused on older men who engage in regular physical activity. According to this finding, those who ate a small handful of walnuts—about 15 grams—each day for six weeks appeared to experience a greater increase in testosterone levels compared to those who exercised but did not consume walnuts [1]. The evidence we’ve reviewed leans toward a possible benefit of daily walnut intake for supporting testosterone levels in this specific group. It’s important to note that our current analysis is based on a single assertion drawn from the broader body of research. While 54.0 supporting data points were cited in favor of this idea, we don’t have details on how many individual studies were involved or how they were conducted. That means we can’t yet say how strong or consistent this effect might be across different groups or longer time periods. We also don’t know whether the change in testosterone levels led to noticeable effects on energy, strength, or overall health. Since the evidence is limited to this one scenario—older exercising men—and we have no refuting studies to balance the picture, we can’t draw firm conclusions. Based on what we’ve reviewed so far, adding a small handful of walnuts to your daily routine might support hormonal health if you’re an older man who exercises. But we’ll need more data to better understand how reliable or meaningful this effect is over time.