Crisp, crunchy celery is a staple in the diet, largely because it goes well with many other vegetables and is very low in calories. Celery is also a vegetable that is difficult to peel, and given its number 2 position on the contamination list, organic rather than conventionally grown celery is your healthier choice. Some 96 percent of all celery samples tested positive for pesticides, and nearly 90 percent of the celery samples had two or more pesticides. One celery sample was found to contain 13 different chemicals. But chemicals aside, celery is an excellent source of vitamin K and a very good source of vitamins A and C, folate, manganese, molybdenum, and potassium. Celery also contains phthalides, which may help lower cholesterol levels, and coumarins, which have antioxidant properties.