Do carrots improve your vision? Are oysters an aphrodisiac? Does an apple a day really keep the doctor away?
When it comes to food, there is some value in folk wisdom. Many traditional cultures have passed down their own medicinal methods for generations, whether there is evidence backing them up or not. Oftentimes, there is such a strong cultural implication there that these ‘remedies’ probably do have a benefit, even if it's just though a placebo effect.
So strong beliefs can have an impact. Whether that means there is scientific truth to any of these practices, is a different thing.