Prebiotic Gut Goodness Powder

Hardly anyone asks us whether to take a prebiotic. They ask which one, and whether it'll make them gassy. These are the questions our naturopaths ask in store.

A good fit if

• Regularity is what you're after, and you can reach 10 g of fibre a day, where the trials found an effect
• You'd like to feed the bacteria you already have rather than swallow new ones
• You take an iron supplement. GOS and FOS taken with it greatly increased iron absorption
• You can give it four weeks, which is when the increase in bifidobacteria becomes clearly larger
• You'd rather start with food. Beans, leeks, onions, garlic and chicory all contain inulin

Check with us first if

• You follow a low FODMAP diet. Inulin, FOS and GOS are FODMAPs themselves, so a fermentable prebiotic works directly against the diet.
• You have medically diagnosed IBS. Two independent reviews found the prebiotic evidence limited or not significant, and we won't sell you one on an IBS promise.
• You're dairy-free or vegan. By law, galactooligosaccharides and 2'-fucosyllactose must contain lactose, so neither is dairy-free.
• You have coeliac disease. Wheat dextrin must contain gluten, and so does maltodextrin made from wheat, barley, rye or oats.
• You take medicine for blood sugar. Inulin lowered glucose tolerance test readings and improved insulin resistance in overweight adults, so it's worth mentioning to us.
• You already take a product containing GOS or 2'-FL. By law, their labels must say not to take them on the same day as another product containing the same ingredient.
• You're pregnant or breastfeeding. The research is reassuring, and any product with a regularity claim must still tell you to check with a health professional.
• You're buying for a child. GOS is capped at 8 g a day under three, 2'-FL isn't permitted under one month, psyllium needs medical advice, and fibre maltodextrin is for adults only.
• You take prescription medicine. Check with your doctor, pharmacist or our naturopaths before you start.

• Inulin (chicory root, long chain). Best known for: The name on most prebiotic labels, and the slowest of the fructans to ferment. Absorption: Bifidogenic across several trials; improved insulin resistance at 20 g a day in 12 overweight adults. Typical use: Powders and gut blends. Permitted as an active with no cap and no warnings.
• FOS / oligofructose (short chain). Best known for: Shorter, sweeter chains that ferment fast and early in the colon. Absorption: Bifidobacterium counts rose 0.579 across 8 trials, more in adults than infants. Raised iron absorption 51 per cent. Typical use: The likeliest of the common prebiotics to produce wind, and flagged for that in its own meta-analysis.
• GOS (galactooligosaccharides). Best known for: The closest commercial analogue to the oligosaccharides in human milk. Absorption: Improved bowel movements and stool form over 4 weeks in functional constipation; lowered GI symptom scores at 2.5 g a day in 427 students. Typical use: Made from lactose, so not dairy-free. Capped at 16.2 g a day, oral only, with a mandatory do-not-double-up warning.
• PHGG / guar galactomannan. Best known for: Partially hydrolysed guar. Low viscosity, slow even fermentation, the usual switch when nothing else is tolerated. Absorption: A 21-day trial in 61 adults increased complete spontaneous bowel motions; the same trial's microbiota analysis found species richness fell. Typical use: Capped at 25 g a day, with mandatory instructions to build the dose gradually and never take the powder alone.
• Acacia gum / gum arabic. Best known for: Non-viscous, mixes clear, and the slowest-fermenting of the common prebiotics. Absorption: 10 g a day improved stool frequency against placebo in 180 people; 40 g increased fullness acutely, and also bloating and rumbling. Typical use: Permitted as an active with no cap. The defensible pick for anyone gassy on inulin.
• Psyllium (Plantago ovata husk). Best known for: A bulking, gel-forming husk that is only partly fermented, so it bulks without much gas. Absorption: The only fibre rated moderate for chronic constipation in a graded review of 41 trials, and the only one that formed a gel in stool. Typical use: Labels must say it should only be used for children on medical advice whenever a children's dose is stated.
• Resistant starch (high amylose maize). Best known for: Starch your enzymes can't reach, fermented preferentially to butyrate. Absorption: Part of a diet that raised faecal short-chain fatty acids to 86.6 from 75.4 µmol/g and plasma propionate to 9.87 from 4.72 µM. Typical use: Permitted as an active with no cap. Added to a low-FODMAP diet it raised stool output about 50 per cent without worsening symptoms.
• 2'-FL and other human milk oligosaccharides. Best known for: The oligosaccharide of breast milk, now made by fermentation. Absorption: Shifted formula-fed infants toward a breastfed-like profile; in 89 older adults it raised bifidobacteria but missed its primary cytokine endpoint. Typical use: The most tightly conditioned form on this list. Lactose is a mandatory component, caps are tiered by age, and it isn't permitted under one month.

Reference values. There isn't one. The NHMRC reference values cover 25 vitamins and minerals and don't include a figure for prebiotics, because prebiotics aren't essential nutrients. You can live without them, so there's no recommended intake to quote.

Typical supplemental range. Trial doses ranged from 2.5 g to 30 g a day, which is more than most capsules provide: inulin and fructan blends at 9.2 to 30 g, GOS at 2.5 to 15 g, FOS at 15 g, and acacia at 10 to 40 g. The useful low-dose result is GOS at 2.5 g, which did better than 5 g on gut symptom scores in 427 students. Across 16 trials, more than 10 g a day was the point where fibre did better than the comparison for constipation. A blend with 500 mg a capsule isn't giving you a trial dose.

Upper level. Several prebiotics have a legal daily limit in listed medicines rather than a nutritional one: galactooligosaccharides 16.2 g for anyone four and over and 8 g for ages 0 to 3, guar galactomannan 25 g, larch arabinogalactan 15 g, hydrogenated polydextrose 15 g, fibre maltodextrin 50 g (adults only), 2'-fucosyllactose 12 g for ages 13 and over, and 3-fucosyllactose 5 g. Inulin, FOS, acacia, psyllium and resistant starch have no limit.

Worth knowing. Two tips matter more than the dose. Build up slowly over a week or two with plenty of water, because the discomfort, wind and loose stools depend on the dose and pass with time. And give it four weeks: the increase in bifidobacteria was clearly larger in trials that ran longer than four weeks, so a shorter try won't tell you much. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• Chicory root: inulin: the commercial source of nearly all inulin sold
• Leeks, onions, garlic, wheat and artichokes: inulin and oligofructose, as everyday dietary components
• Jerusalem artichoke: inulin: the source used in a six-month paediatric trial
• Beans, one cup daily: mixed fermentable fibre; raised gut diversity over eight weeks
• Milk: lactose, the substrate GOS is manufactured from
• Human breast milk: 2'-fucosyllactose, one of its most abundant oligosaccharides

This list is the part of the page we will not shorten. If any of it applies to you, talk to one of our naturopaths or your doctor before starting.

• Anyone with abdominal pain, nausea, vomiting or new diarrhoea. Mandatory do-not-use statement on every bowel-regularity product.
• Fibre powders taken dry. Mandatory instruction to mix with food or fluid; taking a swelling fibre alone is an obstruction risk.
• Anyone raising a fibre dose. Mandatory instruction to increase gradually and to increase fluid with it.
• Low-FODMAP diets and diagnosed IBS. Inulin, FOS and GOS are FODMAPs and can worsen symptoms.
• Dairy-free and vegan customers. Lactose is a mandatory component of galactooligosaccharides and of 2'-fucosyllactose.
• Coeliac customers. Gluten is a mandatory component of wheat dextrin and of maltodextrin from gluten grains.
• Infants under one month. 2'-fucosyllactose is not permitted for use in children under the age of 1 month.
• Children under three. Galactooligosaccharides capped at 8 g a day; psyllium requires medical advice whenever a children's dose is stated.
• Fibre maltodextrin. Must be indicated for use in adults only, and carries a low-blood-glucose warning.
• Doubling up. GOS and 2'-FL labels must say not to take them the same day as another product containing the same ingredient.
• People on blood-glucose-lowering medicines. Inulin lowered post-load glucose and improved insulin resistance in trials.
• Everyone, at higher intakes. Abdominal discomfort, flatus and diarrhoea are dose-related and common.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before starting.