Borage is normally grown as a flower and is common in companion planting schemes.
It is a bee magnet, attracts pollinators and some beneficial insects and repels some harmful ones such as tomato horn-worm. It also enhances some crops such as strawberries. It is less known as an edible crop.
Borage leaves are edible and taste similar to cucumber, the flowers are also edible and are used in salads and assorted delicacies. It has a mild laxative effect so should be used in moderation. It is refined and sold as borage oil, a supplement to treat arthritis. However, excessive use can lead to liver damage. It can also invoke premature labor, and should be avoided by pregnant and nursing women. . On the flip side it has shown promise as being beneficial to the heart and cardio system , has a positive effect on adrenal glands, kidneys and digestive system.
The flowers are sometimes added to salads, they have a slightly peppery taste. Eating borage leave raw - not a good idea, unless you relish the idea of picking prickles and spikes out of your toungue for the next few days. However when boiled the prickles and tiny thorns soften and dissipate. When fully cooked down it looks like a pale spinach and has a pleasant taste. The only thing I can think of comparing it to is a cross between spinach and cucumber with a tiny touch of pepper. I sometimes mix it with other greens such as collards or mustard greens.
Minus the pepper after taste that comes more from the flowers than the leaves, it is actually a cooling dish. Perhaps the cooling effect is relative to the alkaloids - I can't really say.
Borage's star-like edible edible flowers are preserved in sugary concoctions and used for cakes and candies see Bouquet Garni which has some nice Recipes and Serving Ideas for Borage.
References and Notes
1.Pyrrolizidine Alkaloids from Borage (Borago officinalis) Seeds and Flowers - Journal of Natural Products
2. Web MD - Borage is a plant. Its flowers and leaves, as well as the oil from its seeds are used as medicine.