A nutrient enema, also known as feeding per rectum, rectal alimentation, or rectal feeding, is an enema

Enema

An enema is the procedure of introducing liquids into the rectum and colon via the anus. The increasing volume of the liquid causes rapid expansion of the lower intestinal tract, often resulting in very uncomfortable bloating, cramping, powerful peristalsis, a feeling of extreme urgency and...

 administered with the intent of providing nutrition

Nutrition

Nutrition is the provision, to cells and organisms, of the materials necessary to support life. Many common health problems can be prevented or alleviated with a healthy diet....

 when normal eating

Eating

Eating is the ingestion of food to provide for all organisms their nutritional needs, particularly for energy and growth. Animals and other heterotrophs must eat in order to survive: carnivores eat other animals, herbivores eat plants, omnivores consume a mixture of both plant and animal matter,...

 is not possible. Although this treatment is ancient, dating back at least to Galen

Galen

Aelius Galenus or Claudius Galenus , better known as Galen of Pergamon , was a prominent Roman physician, surgeon and philosopher...

, and commonly used in the Middle Ages, and still a common technique in 19th century medicine, Nutrient enemas have been superseded in modern medical care by tube feeding and intravenous feeding.

A variety of different mixes have been used for nutrient enemas throughout history. A paper published in Nature in 1926 stated that because the rectum

Rectum

The rectum is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long...

 and lower digestive tract lack digestive enzyme

Digestive enzyme

'Digestive enzymes' are enzymes that break down polymeric macromolecules into their smaller building blocks, in order to facilitate their absorption by the body. Digestive enzymes are found in the digestive tract of animals where they aid in the digestion of food as well as inside the cells,...

s, it is likely that only the end-products of normal digestion such as sugars, amino acid

Amino acid

Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

s, salt

Salt

In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...

 and alcohol

Alcohol

In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....

, will be absorbed.

Notoriously, the treatment was given to U.S. President James A. Garfield after his shooting in 1881, and is asserted to have prolonged his life.