Celery seed is not well-known in Western herbal medicine, although it has been used medicinally for thousands of years in other parts of the world. During ancient times, Ayurvedic medicine used celery seed to treat colds, flu, water retention, poor digestion, various types of arthritis, and certain diseases of the liver and spleen.
Today, celery seed is used primarily as a diuretic (increasing urine output to help the body get rid of excess water). Celery seed is also suggested for treating arthritis and gout, and to help reduce muscle spasms, calm the nerves, and reduce inflammation. However, there are no scientific studies in humans that show whether celery seed is effective for these conditions or any others. Studies do show that celery seeds act as a mosquito repellent.
A few animal studies suggest that celery seed extracts may help lower blood pressure and cholesterol, as well as protect the liver from damaging substances such as the pain reliever acetaminophen (Tylenol).
Preliminary animal studies also show that celery seed may help prevent the formation of cancerous tumors in mice. In humans, researchers have found that people who eat a diet rich in lutein (from celery, spinach, broccoli, lettuce, tomatoes, oranges, carrots, and greens) were significantly less likely to develop colorectal cancer. However, celery was just one part of their diet, and no one knows whether the effect is due to celery, another food, or some combination of foods.