Open Source Apothecary At Home / The twelve-month course

Unit 2 (February): The digestive system, carminatives and bitters

The physiology of digestion, and the two herb actions — carminative and bitter — that have real mechanisms behind them.

guide

The physiology, plainly. Digestion is mechanical and enzymatic. The stomach acidifies and begins protein breakdown; the small intestine absorbs, with the pancreas and liver supplying enzymes and bile; the colon absorbs water and hosts the microbiome. Motility is the variable that matters most for common complaints — too fast gives urgency and diarrhoea, too slow gives bloating and constipation, and uncoordinated gives cramping and IBS.

The two herb actions with real mechanisms.

Carminatives — fennel, peppermint, chamomile, ginger — relax smooth muscle in the gut wall, which relieves spasm and helps trapped gas move. This is a plausible, demonstrable mechanism, and it is why carminative herbs are the ones with actual trial evidence for bloating and spasm.

Bitters — dandelion root, gentian, artichoke — stimulate taste receptors that trigger a reflex increase in digestive secretions, including stomach acid and bile. This is a genuine physiological reflex, not folklore, and it is the reason bitters must be tasted to work: a bitter in a capsule bypasses the receptor.

Where the evidence actually sits. Peppermint oil has meta-analytic support for IBS, and the enteric coating is what makes it work in the gut rather than the oesophagus. Psyllium has trial evidence for constipation. Fennel has trial evidence in dyspepsia and infant colic. Everything sold for "detox" and most of what is sold for bloating has none.

The red flags for this system are the point of the month. Difficulty swallowing, vomiting blood, black stool, unexplained weight loss, a new change in bowel habit over 40, or anaemia are all reasons to stop treating a gut problem at home.

What the studies found

Growing it

In season this month: dried material from last year, plus the first planning

• Fennel — sow in spring; seed harvest late summer. Buy the seed this year.
• Peppermint and spearmint — order plants or divisions for spring planting
• Ginger — start rhizome pieces indoors now in warmth; they need a long season
• Chamomile — surface-sow indoors in late winter for planting out later

Garden work

• Lime the beds if the pH test said to
• Plan the mint containment: a sunken pot or a dedicated permanent bed
• Nothing goes into wet ground yet — check drainage after thaw

Preparation

Project: a carminative blend and a bitter

Carminative blend (equal parts, dried)

• Fennel seed (crush before use), peppermint leaf, chamomile flower, and a little ginger
• 1 heaped teaspoon per cup, covered, 5-10 minutes
• Drink after meals for bloating and spasm

A bitter

• Dandelion root, roasted and ground, or a slice of fresh ginger chewed before a meal
• It must be tasted — the reflex depends on the bitter receptors, not on absorption
• Take 10-15 minutes before eating

Ginger tea (for nausea)

• 2-3 slices fresh, or about 1 g dried powder, steeped 10 minutes
• Before the nausea starts, not after

Cautions and interactions

• Peppermint worsens reflux — it relaxes the lower oesophageal sphincter.
• Do not give fennel to a colicky infant without discussing it with a clinician first.
• Bitters are avoided in active ulcers and in reflux — they increase acid.
• Ginger and dandelion interact with anticoagulants and blood-pressure medication respectively.
• Most products sold for bloating and detox have no evidence.

When this is not a self-care problem — get help

• Difficulty swallowing, vomiting blood, or black tarry stool — urgent care.
• Unexplained weight loss, or a new persistent change in bowel habit over 40 — medical assessment.
• Severe abdominal pain with a rigid, tender abdomen — emergency care.
• Anaemia with gut symptoms — assessment; do not treat with nettle tea.

Related

• The twelve-month course
• Indigestion without an ulcer (functional dyspepsia)
• Irritable bowel syndrome: the diet has the strongest evidence
• Constipation: fibre, water, and when a laxative is the wrong tool
• Reflux and heartburn
• Fennel

Sources

1. Menthacarin, a Proprietary Peppermint Oil and Caraway Oil Combination, Improves Multiple Complaints in Patients with Functional Gastrointestinal Disorders: A Systematic Review and Meta-Analysis. Digestive diseases (Basel, Switzerland) 2023; doi:10.1159/000528553 PubMed 36502789
2. Systematic review and meta-analysis: efficacy of peppermint oil in irritable bowel syndrome. Alimentary pharmacology & therapeutics 2022; doi:10.1111/apt.17179 PubMed 35942669
3. Dietary modifications for infantile colic. The Cochrane database of systematic reviews 2018; doi:10.1002/14651858.CD011029 PubMed 30306546
4. Peppermint oil for the treatment of irritable bowel syndrome: a systematic review and meta-analysis. Journal of clinical gastroenterology 2014; doi:10.1097/MCG.0b013e3182a88357 PubMed 24100754
5. Therapy options in irritable bowel syndrome. European journal of gastroenterology & hepatology 2010; doi:10.1097/MEG.0b013e3283405a17 PubMed 21389791
6. Peppermint oil for irritable bowel syndrome: a critical review and metaanalysis. The American journal of gastroenterology 1998; doi:10.1111/j.1572-0241.1998.00343.x PubMed 9672344