Can Certain Foods Really Fight Cancer? 

1. Lemons: Lemon's potential anticancer effects were tested on animals and cells in a lab, and cannot be directly applied to humans. The limited amount of these compounds in lemon water is unlikely to have a significant impact. 

2. Garlic: Garlic contains compounds believed to have anticancer properties, like allicin.

However, research demonstrating these effects was conducted on animals and cells in a lab. The findings do not directly translate to humans and should only be considered as a reference. 

3. Sweet potatoes: Claims of sweet potatoes having anticancer properties stem from a Japanese study comparing the cancer-inhibiting effects of 20 vegetables, with sweet potatoes showing the strongest effect.

However, the study did not involve humans, and the extract used is different from direct consumption. Cancer is influenced by multiple factors and cannot be prevented solely by eating sweet potatoes.