Grapefruit is a low-calorie food with a high content of vitamin C, fiber, potassium, and other nutrients. 

For example, just one-half of a grapefruit supplies the entire RDA for vitamin C. 

I think getting vitamins from food rather than from supplements is better because of all the co-factors found in foods that aid the body in utilizing the nutrients.

Grapefruit has also been used to aid weight loss.

Besides using grapefruit as a low glycemic food to help you lose weight (and control your blood sugar), studies suggest that eating grapefruit lowers your risk of cancer and heart disease. 

This is probably because it’s a good source of antioxidants. Grapefruit also helps boost the immune system to help fight off viral infections.

One caution about grapefruit, it interferes with certain metabolic pathways in the liver that detoxify certain compounds. 

For instance, it appears to interfere with the breakdown of estrogens, which may be a good thing for women going through menopause because it enhances the action of estrogen. 

It isn't a good thing for men suffering from low testosterone, erectile dysfunction, or BPH.

The Food and Drug Administration requires some medications to list whether it's unsafe to consume grapefruit while taking them. 

It’s probably a good idea not to eat a lot of grapefruit if you have abnormal heart rhythm, have symptoms of estrogen dominance, or are taking estrogen hormone replacement therapy.

The peels and seeds of grapefruit appear to have disinfectant, antioxidant, and wound-healing properties. However, avoid extracts that are made using chemical extraction methods, something that applies to many commercial grapefruit seed extract products.

You can use the seeds, pith, and peels as a medicine provided the grapefruits are organic so you aren’t getting any pesticides or chemicals on the peels. 

You can always eat a little bit of the bitter white pith when eating the grapefruit and you can include a little pith and some seeds when juicing the fruit to get this immune-boosting effect. 

You can also dry the peels and use them in herbal formulas in a similar manner to using lemon peel or other citrus peels.