Soluble fibre
Fibre that dissolves in water to form a gel, slowing digestion, regulating blood sugar and cholesterol, and feeding the gut microbiome.
Soluble fibres (pectin, inulin, beta-glucans, gums, mucilages) absorb water and form a viscous gel in the digestive tract. They are found in oats, pulses, apples, citrus fruit, psyllium and flax/chia seeds.
A fresh angle (the multi-purpose gel): this gelling power is behind all their benefits:
- Blood sugar: the gel slows glucose absorption → fewer blood sugar spikes (useful for diabetes and fullness)
- Cholesterol: the gel traps cholesterol and bile acids → lower LDL (oat beta-glucans have a recognised health claim for this)
- Fullness: the gel distends the stomach and slows emptying → a prolonged feeling of satiety
- Microbiome: highly fermentable, they feed the good bacteria → production of SCFAs (butyrate)
Psyllium, the champion soluble fibre: psyllium (the husks of plantain seeds) is a remarkable soluble fibre, used against both constipation (the gel softens and adds bulk) AND diarrhoea (it absorbs excess water). This two-way regulating effect makes it an ally for transit in both directions.
The downside (FODMAPs): some soluble fibres (inulin, FOS) are FODMAPs. Highly fermentable, they cause bloating and gas in sensitive people or if introduced too quickly. Psyllium is generally better tolerated (little fermentation).
In practice: increase gradually, drink enough water (the gel needs water), vary your sources. A mix of soluble and insoluble fibre is ideal.
Sources: oats, barley, pulses, apples, pears, citrus fruit, carrots, psyllium, flax/chia seeds, sweet potato.