It depends on what kind of breast tenderness you're experiencing and the location of the breast tenderness.
1. If both breasts are tender, the most common cause is hormonal fluctuations, and this is most pronounced before a woman starts her period. This is normal, very common and nothing to be concerned about, although it can be particularly uncomfortable.
There are no miracle treatments for breast tenderness caused by hormonal fluctuations. However, there is some anecdotal evidence that supplements like Evening Primrose Oil and Vitamin E might help breast tenderness caused by hormonal fluctuations.
2. Breast pain that is localized to a specific part of the breast can be caused by trauma. Trauma includes being hit in the breast and also includes things like not wearing a supportive bra while exercising or wearing an ill-fitting underwire bra. Additionally, the weight of large, heavy breasts alone can cause some discomfort and pain.
3. Breast pain or worsening of breast pain can be associated with drinking a lot of caffeine and/or ingesting a lot of salt.
All of this being said, it is important to remember that although breast pain and tenderness can have a significant impact on women's quality of life, in the vast majority of cases it's not a sign of something bad, such as cancer.