Coconut juice, more appropriately called coconut water, is the liquid inside the green, unripe coconut. It was traditionally used as a source of safe drinking water for Pacific Island natives, and sailors who visited the islands would stow green coconuts on the ship to drink on the return voyage.
Today, coconut water has enjoyed a resurgence as a sports drink and natural digestive remedy, and it is generally considered to be a healthy beverage. It is not, however, a miracle drink; there are certain aspects of coconut water that bear some consideration before indulging.
May Affect Sodium Levels
According to the U.S. Department of Agriculture, a cup of fresh coconut water contains 252 mg of sodium. This is not a problem for most people, but anyone with high blood pressure, heart disease or any other condition that requires them to follow a low-sodium diet should be aware that coconut water is not the same as pure water and should be factored into their daily sodium allowance. On the other hand, it is the sodium content in coconut water that proponents believe makes it an ideal sports drink.
May Not Rehydrate Completely
Besides the sodium content, which is considered the most important electrolyte after sports because it comes out in your sweat, a cup of coconut water contains 600 mg of potassium and 60 mg of magnesium. A 1993 study in the "Journal of the American College of Nutrition" found that the exact mineral content of coconut water depends directly upon the degree of ripeness.
Differences in sodium and glucose content were marked at various ages, so the only way to guarantee that you're getting the electrolytes you assume you're getting is to know the exact age of the coconut. The study noted that at no time in the maturation timeline was the sodium and glucose content high enough to be considered an effective rehydration drink.
May Cause a Reaction
Coconuts are technically seeds and were traditionally allowed for people with tree nut allergies. In 2006, the U.S. Food and Drug Administration reclassified the coconut as a tree nut, instantly sending allergy sufferers into confusion. The Food Allergy and Anaphylaxis Network notes that some allergic reactions have been reported, but they generally involved people who didn't have a tree nut allergy. A few of them did coincide with tree nut allergies, however, so it is best to talk to your doctor if you are concerned about a potential reaction.
High in Sugar
Many people drink coconut water as an alternative to other juices, believing the mild taste indicates a low sugar content. That isn't true. A cup of coconut water contains 6.26 g of sugar, or about 1.5 tsp. If you drank all of the juice in a green coconut, you would be drinking 16.4 g of sugar, or about 4 tsp. of sugar. This is the same amount of sugar found in half a can of cola. Diabetics and others watching their sugar intake should be aware that coconut water must be factored into their daily sugar allowance.