Conditions & Artificial Nutrition

Artificial nutrition describes the delivery of nutrients to a person who cannot meet their nutritional needs through normal eating and drinking. It is sometimes called clinical nutrition or nutritional support. There are two main types:

• Enteral nutrition (EN) — nutrients are delivered directly into the gastrointestinal (GI) tract via a feeding tube (NG tube, PEG, RIG, NJ tube, etc.). The gut is still used for digestion and absorption. Also called tube feeding.
• Parenteral nutrition (PN) — nutrients are delivered directly into the bloodstream via a central venous catheter (PICC, Hickman, Portacath, etc.), bypassing the gut entirely. When given at home long-term, this is called Home Parenteral Nutrition (HPN).

The decision about which type of nutrition support to use — and whether to proceed at all — is based on the nature and severity of the underlying condition, the expected duration of nutritional need, and the patient's overall clinical condition. This is guided by BAPEN (British Association for Parenteral and Enteral Nutrition) and NICE guideline CG32 (Nutrition support for adults).

Intestinal Failure occurs when the gut cannot absorb sufficient nutrients, fluid, and electrolytes to sustain life. It is classified into three types:

• Type I — short-term, self-limiting (e.g. post-operative ileus, acute illness). Often resolves with a period of PN support.
• Type II — prolonged, often in metabolically unstable patients requiring specialist centre care (e.g. high-output fistula, sepsis, multiple surgeries). Can last weeks to months.
• Type III — chronic, irreversible. The patient requires long-term or permanent HPN. Examples include permanent short bowel syndrome, radiation enteritis, and chronic dysmotility.

Type III IF is the primary indication for long-term home parenteral nutrition. Patients are managed by specialist intestinal failure units (IFUs) — a small number of centres in the UK that coordinate with home care companies to deliver PN at home.

SBS occurs when the small intestine is significantly shortened — typically less than 200cm of functional small bowel remains — reducing its ability to absorb nutrients, fluids, and electrolytes. Common causes include:

• Extensive surgical bowel resection due to Crohn's disease
• Mesenteric ischaemia (loss of blood supply to the bowel)
• Volvulus (bowel twisting)
• Trauma or injury
• Radiation damage
• In infants: necrotising enterocolitis (NEC) or congenital defects

Whether PN is required depends on the length of remaining bowel, which segments remain (the ileum is particularly important for B12 and bile salt absorption), whether the colon is intact, and the degree of intestinal adaptation over time. Some patients with SBS can eventually wean off PN as the remaining bowel adapts.

Crohn's disease is a type of inflammatory bowel disease (IBD) that can affect any part of the GI tract from mouth to anus, causing chronic inflammation, strictures, abscesses, and fistulae. It is one of the most common causes of intestinal failure in the UK.

Artificial nutrition may be needed in Crohn's disease when:

• Active disease causes severe malnutrition or malabsorption
• Multiple bowel resections over time result in short bowel syndrome
• Enteric fistulae prevent normal absorption
• As primary therapy in children with active Crohn's (exclusive enteral nutrition / EEN)
• As a bridge to surgery to improve nutritional status

In children with Crohn's, exclusive enteral nutrition (EEN) — taking all nutrition as liquid formula via tube or orally — is a first-line treatment for active disease, as effective as steroids for inducing remission. In adults, enteral nutrition is used as nutritional support rather than primary therapy.

Gastroparesis is a condition in which the stomach empties abnormally slowly, despite no mechanical obstruction. This causes nausea, vomiting, bloating, early satiety, and often severe malnutrition.

Common causes include:

• Diabetic gastroparesis — autonomic neuropathy affecting the vagus nerve
• Post-surgical — following upper GI surgery (e.g. oesophagectomy, gastrectomy, bariatric surgery)
• Idiopathic — no identifiable cause; often follows a viral illness
• Connective tissue disorders (e.g. systemic sclerosis)
• Neurological conditions

Nutritional support aims to bypass the stomach. Options include nasojejunal (NJ) tube feeding or a surgical jejunostomy (feeding tube placed directly into the jejunum). If the small intestine is also affected or jejunal feeding is not tolerated, parenteral nutrition may be required.

Intestinal motility disorders affect the ability of the gut to move food and waste through the GI tract in a coordinated way. The most severe form is Chronic Intestinal Pseudo-Obstruction (CIPO), which causes the bowel to behave as if it is obstructed when no physical blockage exists.

Other motility conditions that may require nutritional support include:

• Generalised dysmotility affecting multiple GI segments
• Opioid-induced bowel dysfunction (severe cases)
• Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) — a rare genetic condition
• Systemic sclerosis / scleroderma affecting the GI tract

Management is complex and multidisciplinary. Enteral nutrition may be tried first; PN is required when the gut cannot tolerate or absorb enteral feeds. Some patients require cyclical or supplemental PN alongside oral or enteral intake.

Many neurological conditions affect the ability to swallow safely (dysphagia), which can lead to aspiration (food or liquid entering the airway), malnutrition, and dehydration. Enteral nutrition via a feeding tube allows safe nutrition delivery when swallowing is unsafe or insufficient.

Conditions commonly leading to enteral tube feeding include:

• Stroke — both temporary (NG tube) and long-term (PEG) feeding may be needed
• Motor Neurone Disease (MND/ALS) — PEG or RIG placed before respiratory function declines too far
• Multiple Sclerosis (MS) — in advanced disease affecting swallowing
• Parkinson's disease — in late-stage disease
• Acquired Brain Injury — trauma, hypoxia
• Cerebral Palsy — depending on severity
• Dementia — complex ethical considerations; best interest decisions

The decision to proceed with tube feeding in neurological conditions requires careful multidisciplinary discussion including the patient (or their legal proxy) and a speech and language therapist (SALT).

Cancer and its treatment can significantly affect nutrition through multiple mechanisms. Nutritional support may be required when oral intake is insufficient to meet nutritional needs.

• Head and neck cancers — tumours or treatment (radiotherapy, surgery) affecting swallowing; NG tube or PEG used during treatment
• Oesophageal cancer — obstruction to swallowing; jejunostomy or PN
• Upper GI cancers (stomach, pancreas) — malabsorption, surgical resection
• Cancer-related cachexia — severe muscle and weight loss driven by the tumour's metabolic effects
• Chemotherapy and radiotherapy side effects — nausea, mucositis, enteritis reducing oral intake
• Radiation enteritis — damage to the small bowel from abdominal/pelvic radiotherapy, causing malabsorption

In palliative settings, nutritional support decisions are guided by quality of life, prognosis, and the patient's own wishes. Artificial nutrition does not always prolong life in end-stage cancer; decisions are made with careful compassionate discussion.

The pancreas plays a crucial role in digestion through its production of digestive enzymes. Disease affecting the pancreas can impair digestion and lead to malnutrition.

• Acute severe pancreatitis — a medical emergency often requiring ICU care. Early enteral nutrition via nasojejunal tube is now preferred over PN, as it maintains gut integrity and reduces infectious complications. PN is reserved for cases where enteral feeding is not possible or tolerated.
• Chronic pancreatitis — repeated inflammation leads to exocrine pancreatic insufficiency (EPI), causing malabsorption of fat, fat-soluble vitamins, and protein. Managed with pancreatic enzyme replacement therapy (PERT) and dietary modification; enteral nutrition may be needed in severe cases.
• Post-pancreatectomy — surgical removal of part or all of the pancreas for cancer or chronic pancreatitis may require nutritional support during recovery and long-term enzyme replacement.

• Radiation enteritis — damage to the bowel from radiotherapy to the abdomen or pelvis, causing chronic malabsorption. Can develop months or years after treatment.
• Enteric fistulae — abnormal connections between segments of bowel or to the skin, causing bypass of absorptive bowel. Often requires PN to allow the gut to rest.
• ARFID (Avoidant Restrictive Food Intake Disorder) — a recognised eating disorder without body image disturbance; severe cases may require enteral supplementation.
• Anorexia nervosa — severe cases requiring hospital admission may need nasogastric refeeding under careful supervision with refeeding syndrome monitoring.
• Critical illness — patients in ICU often require enteral or parenteral nutrition when oral intake is impossible.
• Rare metabolic and genetic conditions — some conditions (e.g. mitochondrial disorders, rare enzyme deficiencies) may require specialised nutritional support.
• HIV/AIDS — in advanced disease with severe malabsorption or wasting.
• Congenital GI malformations — in neonates and children: gastroschisis, intestinal atresia, Hirschsprung's disease.

If you or someone you care for is struggling to eat adequately due to a medical condition, the first step is to speak to your GP. A referral to a dietitian, gastroenterologist, or specialist nutrition team can be requested.

• GP — request a referral to a dietitian or gastroenterologist; ask about a nutritional assessment
• Dietitian — NHS or private; can assess nutritional needs and recommend oral supplements, enteral nutrition, or refer on to specialist teams
• Gastroenterology / specialist intestinal failure unit — for complex conditions; the UK has a small number of designated IFUs that manage long-term PN
• BAPEN (bapen.org.uk) — professional association; patient resources and information about nutritional support
• PINNT (pinnt.com) — charity supporting patients on home artificial nutrition; peer support, helpline, travel advice
• NHS Choices (nhs.uk) — condition-specific information and service finder