4 Lactose intolerance & constipation

What is lactose intolerance an example of?

A disorder caused by impaired carbohydrate digestion

What causes lactose intolerance?

Lactase insufficiency, leading to inability to digest lactose properly

What genetic factor is linked to lactase persistence (LP)?

• Polymorphisms in the MCM6 gene

• This gene regulates lactase gene expression

Lactose intolerance can result from 3 reasons?

• • Primary lactase deficiency

• • Secondary lactase deficiency

• • Congenital lactase deficiency

What is the most common cause of lactose intolerance worldwide?

• Primary lactase deficiency

• Due to lack of the lactase persistence (LP) allele

What causes secondary lactase deficiency?

• Damage to or infection of the proximal small intestine

• Can temporarily reduce lactase levels

What is congenital lactase deficiency?

• A rare autosomal recessive disease

• Results in complete absence of lactase from birth

Does hypolactasia always cause symptoms?

• Hypolactasia means reduced levels of the lactase enzyme

• No

• Symptoms only occur when:

  • Lactose-containing food is consumed

  • And the remaining lactase enzyme activity is overwhelmed

What happens when undigested lactose reaches the colon?

• Colonic microflora ferment it and produce:

  • Short-chain fatty acids

  • Hydrogen

  • Carbon dioxide

  • Methane

How is lactose intolerance diagnosed using breath tests?

Hydrogen (H₂) produced by colonic bacteria appears in the breath

• Detected after a lactose challenge in lactase-deficient individuals

• (after drinking a lactose solution (the lactose challenge)

What are the main symptoms of lactose intolerance?

• Bloating

• Abdominal pain

• Diarrhoea

How is lactose intolerance diagnosed?

• Observation of symptoms after lactose consumption

• Hydrogen breath test

• Lactose or milk tolerance test

What are the dietary treatments for lactose intolerance?

• Reduce or eliminate lactose-containing foods (e.g. milk)

• Use milk products treated with lactase

• Use lactose-free milk

What is constipation?

Difficult or infrequent defecation

➢ Causes of constipation include:

• Neurogenic disorders

• Abdominal muscle weakness

• Low-fibre diet

• Sedentary lifestyle

• Ignoring the urge to defecate

• • Antidepressant drugs

• Opiates

• • Aging

What are neurogenic causes of constipation?

Disorders that reduce peristalsis in the large intestine:

• Hypothyroidism

• IBD with constipation

• Colon cancer

What dietary changes help relieve constipation?

• Increase water intake

• Reduce alcohol consumption

• Add wheat bran or other fibre to the diet

How can physical activity help with constipation?

Increase daily activity or exercise to stimulate bowel movement

What are recommended toilet habits for constipation relief? 4

• Keep a regular toilet routine

• Allow plenty of time on the toilet

• Don’t delay the urge to defecate

• Rest feet on a low stool to improve posture during defecation

constipation treatment - purgatives?

• Purgatives are medications used to stimulate bowel movements to relieve constipation.

• they help clear the intestines by softening stool, increasing water content, or directly stimulating the muscles of the gut to promote defecation.

exmaple of purgatives? bosf

• • Bulk laxatives

• • Osmotic laxatives

• • Faecal softeners

• • Stimulant laxatives (

What are bulk laxatives and give an example?

• Polysaccharide polymers that are not digestible

• Example: Methylcellulose

What are osmotic laxatives and give examples?

• Poorly absorbed solutes that draw water into the bowel

• Examples: Magnesium hydroxide

What are faecal softeners and examples?

• Soften stool to ease defecation

• Examples: Arachis oil, docusate sodium

• Often administered as enemas

What are stimulant laxatives and examples?

• Drugs that directly increase peristalsis

• Examples: Senna

What drugs increase GI motility without purgation?

• Antiemetics like domperidone, metoclopramide

• Increase gastrointestinal motility and gastric emptying

What is peristalsis?

• Wave-like muscle contractions in the GI tract

• Moves food and digestive contents forward through the digestive system

• Smooth, rhythmic squeezing motion