Garlic has been used since ancient times to treat and prevent disease. According to an article published in the 2001 "Journal of Nutrition," ancient medical texts in India, Egypt, Rome, China and Greece prescribed garlic treatments for various ailments. It has also flavored and garnished food since ancient times. Garlic powder consists of garlic reduced to a powder texture that dissolves well in liquids. One teaspoon of chopped, raw garlic is equivalent to 1/8 teaspoon of garlic powder.

Raw garlic and garlic power vary in their nutritional values, according to the USDA National Nutrient Database. A 1 teaspoon serving of raw garlic contains 4 calories, while 1/8 teaspoon serving of garlic powder contains 1.25 calories. There are 0.93 grams of carbohydrates in a 1 teaspoon serving of raw garlic. A 1/8 teaspoon serving of garlic powder contains 0.28125 grams carbohydrates. Fiber is also a carbohydrate. A 1 teaspoon serving of raw garlic provides 0.1 gram dietary fiber, while 1/8 teaspoon of garlic contains 0.0375 gram of dietary fiber.

The protein contained in 1 teaspoon of raw garlic is 0.18 gram, while the protein contained in 1/8 tsp of garlic powder is 0.06375, according to the USDA National Nutrient Database. One teaspoon of raw garlic contains 0.10 gram of dietary fiber, while 1/8 teaspoon of garlic powder contains 0.0375 gram of dietary fiber. Both forms of garlic contain a negligible amount of fat.

Raw garlic and garlic powder also contain minerals, according to the USDA National Nutrient Database. One teaspoon of raw garlic contains 5 milligrams calcium, while 1/8 teaspoon of garlic powder contains 0.25 milligrams calcium. The amount of phosphorous in 1 teaspoon of raw garlic is 2 milligrams; 1/8 teaspoon of garlic powder contains 0.25 milligram phosphorous. Potassium content in 1 teaspoon of raw garlic is 11 milligrams, while 1/8 teaspoon of garlic powder contains 4.625 milligrams potassium.

Trace amounts of vitamins are also found in raw garlic and garlic powder, according to the USDA National Nutrient Database. One teaspoon of raw garlic provides 0.9 milligram vitamin C; 1/8 teaspoon of garlic powder does not contain any vitamin C. One teaspoon of raw garlic contains 0.035 milligram vitamin B-6, while 1/8 teaspoon of garlic powder contains 0.006375 milligram vitamin B-6. Choline content for 1 teaspoon of raw garlic is 0.6 milligram; choline content for 1/8 teaspoon of garlic powder is 0.2625.