Larch Arabinogalactan

Also called arabinogalactan, larch arabinogalactan, larch tree extract, Larix arabinogalactan, ResistAid, larch fiber.

Best grade C across 7 graded outcomes Other Last checked Oct 21, 2026

We earn a commission if you buy through links on this page. It never changes our grades or rankings. How we make money →

The short answer

From 8 sources

Larch arabinogalactan is a soluble fibre from larch wood. Its best trial, in 199 cold-prone adults on 4.5 g a day, found fewer people caught a cold, though the main incidence result was borderline. Vaccine-response trials were partly positive and industry-funded, and 8.4 g a day for 6 months did not change cholesterol.

Quick pick

From a partner brand · paid link

Solaray Arabinogalactan, 60 vegetarian capsules

from HerbsPro

Label: 1 capsule: 300 mg larch (Larix spp.) extract with 255 mg arabinogalactan (85%).

Best for trying one bottle: $21.19 one-time (checked Oct 15, 2026).

Shop at HerbsPro

Partner links may earn us a commission. How partner links work

Every graded outcome on this page

7 rows · line = participants

Grade CCommon colds in adults who catch colds oftenColdsn 199
Grade CAntibody response to tetanus and flu vaccinesVaccine responsen 75
Grade CCholesterol, triglycerides, glucose and insulinBlood lipidsn 54
Grade CAntibody response to the pneumococcal vaccineVaccine responsen 45
Grade DImmune markers and quality of lifeImmune markersn 48
Grade DGut microbiome and digestive toleranceGut bacterian 30
Grade DGut bacteria and stool measuresGut bacterian 20
4 more graded outcomes, in the evidence chapter

Key facts

What it is: A non-digestible soluble fibre from larch wood that gut bacteria ferment⁶
Colds: 4.5 g/day for 12 weeks: fewer people with a cold (p = 0.038), but the main incidence result was borderline (p = 0.055) in 199 adults²
Vaccine response: Partial: higher antibodies to 2 of 7 pneumococcal types and to tetanus at 1.5 g/day, no change for flu vaccine^3,4
Cholesterol and glucose: No effect of 8.4 g/day for 6 months in 54 healthy adults⁵
Funding: The immune and 2021 microbiome trials tested one branded ingredient (ResistAid, made by Lonza); Lonza paid for the pneumococcal vaccine trial and a Lonza scientist was corresponding author of the microbiome trial^2,3,4,8

What it is

Larch arabinogalactan is a soluble, non-viscous fibre from larch (Larix) wood, sold as a powder or capsule for immune and gut support.

How it works

Proposed

Arabinogalactan reaches the colon undigested and is fermented by gut bacteria; at 15 to 30 g a day it raised faecal anaerobes and Lactobacillus and lowered faecal ammonia. Trial authors propose that it nudges immune responses to bacterial antigens, but the mechanism has not been shown in people.^2,6

Forms

Form

The form on this page
Form	Elemental %	Absorption (human data)	GI tolerance	Studied for
Larch arabinogalactan powder or capsules	Varies⁶Not applicable (fibre; no elemental fraction)	Not absorbed; fermented by bacteria in the colon.⁶	15 to 30 g/day was well tolerated in a 6-week study; tolerability matched placebo at 4.5 g/day for 12 weeks.^2,6	Colds, vaccine response, blood lipids and gut bacteria (1.5 to 30 g/day)

What the human research says

Human trials only, one row per outcome. The form line shows what each trial actually tested. Grades follow our evidence-grading policy.

Trial map

7 graded outcomes, largest study first

7 graded outcomes: 5 mixed, 2 no effect. The largest, a 2013 randomized trial of 199 people on common colds in adults who catch colds often, found mixed results.

By sizeTable

1Common colds in adults who catch colds often

Mixed · Grade C · RCT, 199 people, 2013

Healthy adults reporting about three colds in the previous 6 months

Dose, result and source

Every graded outcome on this page, largest study first
Outcome	Found	People	Study	Who was studied
Common colds in adults who catch colds often	Mixed	199	Grade C · RCT, 2013	Healthy adults reporting about three colds in the previous 6 months
Antibody response to tetanus and flu vaccines	Mixed	75	Grade C · RCT, 2013	Healthy adults aged 18 to 61 vaccinated against tetanus and influenza on day 30
Cholesterol, triglycerides, glucose and insulin	No effect	54	Grade C · RCT, 2004	Healthy adults aged 18 to 55 (larch n = 18, tamarack n = 19, placebo n = 17)
Immune markers and quality of life	No effect	48	Grade D · RCT, 2002	Healthy women aged 22 to 51 split across six groups (about 8 per group)
Antibody response to the pneumococcal vaccine	Mixed	45	Grade C · Pilot RCT, 2010	Healthy adults not previously vaccinated against Streptococcus pneumoniae
Gut microbiome and digestive tolerance	Mixed	30	Grade D · Crossover RCT, 2021	Healthy adults
Gut bacteria and stool measures	Mixed	20	Grade D · RCT, 2001	Healthy adults (11 men, 9 women)

Every graded row

7 rows

Form tested

Showing 7 of 7 outcomes. Human trials only.

Grade CCommon colds in adults who catch colds oftenColdsFewer people caught a cold; main incidence result borderlineRCT
n 199 · 2013

Mixed In the full analysis set, cold incidence tended to fall (p = 0.055) and fewer participants had a cold (p = 0.038); in the per-protocol set both were significant (p = 0.040 and p = 0.033). Symptom severity at the start of an episode was higher with arabinogalactan (p = 0.028). Tolerability did not differ from placebo.

Design: RCT, n = 199, 2013
Population: Healthy adults reporting about three colds in the previous 6 months
Form: ResistAid (proprietary larch arabinogalactan)
Dose: 4.5 g/day
Duration: 12 weeks
Source: Reference 2 · PubMed 23339578 (opens PubMed)

Grade CAntibody response to tetanus and flu vaccinesVaccine responseTetanus antibodies up at the lower dose only; no flu effectRCT
n 75 · 2013

Mixed At 1.5 g/day the rise in tetanus IgG at day 60 was greater than with placebo (p = 0.008); 4.5 g/day did not differ from placebo. Neither dose changed influenza antibodies compared with placebo. No serious adverse events.

Design: RCT, n = 75, 2013
Population: Healthy adults aged 18 to 61 vaccinated against tetanus and influenza on day 30
Form: ResistAid (proprietary larch arabinogalactan)
Dose: 1.5 g/day or 4.5 g/day
Duration: 60 days
Source: Reference 3 · PubMed 24219376 (opens PubMed)

Grade CCholesterol, triglycerides, glucose and insulinBlood lipidsNo change in lipids or glucoseRCT
n 54 · 2004

No effect Serum lipids seemed to dip at month 2, but there were no statistically significant differences among groups for any endpoint, including LDL cholesterol, apolipoproteins, glucose and insulin.

Design: RCT, n = 54, 2004
Population: Healthy adults aged 18 to 55 (larch n = 18, tamarack n = 19, placebo n = 17)
Form: Larch or tamarack arabinogalactan powder
Dose: 8.4 g/day
Duration: 6 months
Source: Reference 5 · PubMed 15054349 (opens PubMed)

Grade CAntibody response to the pneumococcal vaccineVaccine responseHigher antibodies to 2 of 7 vaccine typesPilot RCT
n 45 · 2010

Mixed IgG rose more than with placebo for 2 of 7 pneumococcal types (18C and 23F) at days 51 and 72; the other 5 types did not differ significantly. No effect on salivary IgA, white cell count, inflammatory cytokines or complement.

Design: Pilot RCT, n = 45, 2010
Population: Healthy adults not previously vaccinated against Streptococcus pneumoniae
Form: ResistAid (proprietary larch arabinogalactan)
Dose: 4.5 g/day
Duration: 72 days (vaccine given on day 30)
Source: Reference 4 · PubMed 20796315 (opens PubMed)

Grade DImmune markers and quality of lifeImmune markersNo change with larch aloneRCT
n 48 · 2002

No effect Complement properdin rose only in the two Echinacea-containing groups (21% and 18%); the abstract reports no significant change for the larch-only group.

Design: RCT, n = 48, 2002
Population: Healthy women aged 22 to 51 split across six groups (about 8 per group)
Form: Larch arabinogalactan (Larix occidentalis) alone or with Echinacea
Dose: Not stated in the abstract
Duration: 4 weeks
Source: Reference 7 · PubMed 11991793 (opens PubMed)

Grade DGut microbiome and digestive toleranceGut bacteriaMicrobiome shifts, no change in bowel habitsCrossover RCT
n 30 · 2021

Mixed Bacteroidetes rose and Firmicutes fell versus placebo, Bifidobacterium tended to rise, and microbiome diversity (alpha-diversity) fell. Bowel habit, stool consistency, GI symptoms, blood chemistry and vital signs did not change.

Design: Crossover RCT, n = 30, 2021
Population: Healthy adults
Form: ResistAid (proprietary larch arabinogalactan) versus maltodextrin
Dose: 15 g/day
Duration: 6 weeks per period
Source: Reference 8 · PubMed 34004416 (opens PubMed)

Grade DGut bacteria and stool measuresGut bacteriaMore gut anaerobes, no change in bowel habitsRCT
n 20 · 2001

Mixed Total faecal anaerobes rose at both doses and Lactobacillus rose over 6 weeks; faecal ammonia fell. No change in transit time, bowel frequency, stool weight, short-chain fatty acids, blood lipids or insulin.

Design: RCT, n = 20, 2001
Population: Healthy adults (11 men, 9 women)
Form: Western larch arabinogalactan in a drink
Dose: 15 g/day and 30 g/day
Duration: Two 3-week periods without washout
Source: Reference 6 · PubMed 11506055 (opens PubMed)

What the numbers add up to

Each point is worked out from the data and the sources numbered on this page, with the arithmetic shown under it. It adds no new data and is not medical advice.

One ingredient, one sponsor

All three immune trials used Lonza's ResistAid, and Lonza paid for at least one of them; no independent group has repeated the cold result.^2,3,4

A fibre that does not lower cholesterol

Unlike viscous fibres, 8.4 g a day for 6 months did not change blood lipids or glucose.⁵

Studied doses

Doses used in research, shown against the official limits. They describe the studies, not a recommendation for you.

Studied doses in research, not advice. These are amounts used in research, not personal advice. Your clinician or pharmacist can say what fits you.

Doses studied in human trials

Doses studied in human trials ranged from 1.5 g/day for 60 days in a vaccine-response study to 30 g/day for 3 weeks in a gut study; the cold trial used 4.5 g/day for 12 weeks, a microbiome trial 15 g/day for 6 weeks and the cholesterol trial 8.4 g/day for 6 months.^2,3,5,6,8

Interactions and safety

Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.

What Larch Arabinogalactan meets

0 cited rows 1 tested together

Medicines 0

No medicine rows in our sources.

Larch Arabinogalactan0 medicines · 1 supplement

Supplements and foods 1

Tested together in a graded trial

Also cited: 1 tested together

EchinaceaEchinacea page
- Tested together
  Immune markers and quality of life. Graded on the Larch Arabinogalactan page; tested together is not a claim that they work better together.

Interactions

0 agents

None found in our sources.

Check with what you take

Kept on this device only

Add what you take. We list every interaction our evidence profiles cite between Larch Arabinogalactan and your picks, and between your picks.

Add a supplement or medicine

Most cited:

Add a supplement or medicine you take to check it against Larch Arabinogalactan.

Starting from one medicine? The interaction checker rates how serious each pair is, on a curated list of 19 entries for 11 medicines. This cabinet has no severity rating: it lists every interaction row our supplement pages cite.

Who should be careful

3 groups

Pregnancy, breastfeeding and children: None of the trials in our sources studied these groups, and NCCIH notes that many supplements have not been tested in pregnant women, nursing mothers or children.¹
People on medicines: No drug interaction studies were found, and NCCIH’s general guidance applies: tell your health care providers about any supplement you use, as some supplements interact with medicines.¹
Expecting cold protection: The one cold trial was borderline on its main measure and has not been repeated by an independent group.²

How to read the label

What to check on the Supplement Facts panel.

How to read the label

3 checks

Count the grams

Immune trials used 1.5 to 4.5 g of arabinogalactan a day, far more than a single capsule of a few hundred milligrams.^2,3,4

Branded vs generic

The cold and vaccine trials all tested one proprietary ingredient, ResistAid; results may not carry over to other larch extracts.^2,3,4

Gut-study doses are powder-sized

Microbiome and gut trials used 15 to 30 g a day, an amount that is practical only as a powder, not as capsules.^6,8

Have the bottle? Photograph its Supplement Facts panel and see each line, larch arabinogalactan included, beside the doses and forms the trials used in Label X-Ray.

Where to buy Larch Arabinogalactan

Products from brands we partner with that contain Larch Arabinogalactan. Check the amount per serving against the doses studied above, and the label for other ingredients.

Larch Arabinogalactan products from partner brands

1 product Paid links · we earn a commission

Quick pickHerbsProSolaray Arabinogalactan, 60 vegetarian capsules
1 capsule: 300 mg larch (Larix spp.) extract with 255 mg arabinogalactan (85%)
$21.19one-timeChecked Oct 15, 2026
Shop at HerbsPro (paid link, opens in new tab)

Frequently asked questions

Short answers to common questions; the numbers link to the sources below.

Common questions

7 answers

Does larch arabinogalactan help with colds?

Possibly, but the evidence is thin. In one trial of 199 cold-prone adults, 4.5 g a day for 12 weeks meant fewer people caught a cold, yet the main incidence result was borderline (p = 0.055) and the trial has not been repeated independently.²

Does it boost vaccine responses?

Only partly. One trial found higher antibodies to 2 of 7 pneumococcal types; another found a stronger tetanus response at 1.5 g a day but not at 4.5 g, and no change in flu antibodies.^3,4

Does it lower cholesterol?

No. In a 6-month trial, 8.4 g a day did not change cholesterol, triglycerides, glucose or insulin compared with placebo.⁵

Does it cause gas or bloating?

In a 6-week crossover trial, 15 g a day did not change bowel habits, stool consistency or digestive symptoms compared with maltodextrin, and 15 to 30 g a day was well tolerated in an earlier gut study.^8,6

Is it safe in pregnancy or while breastfeeding?

It has not been studied in these groups. NCCIH notes that many supplements have not been tested in pregnant women, nursing mothers or children, and no LactMed record covers larch arabinogalactan.¹

Is it a prebiotic fibre?

It is a fermentable soluble fibre. At 15 to 30 g a day it raised faecal anaerobes and Lactobacillus in 20 adults, without changing bowel habits.⁶

Who funded the research?

The immune trials tested Lonza’s branded ResistAid ingredient, Lonza paid for the pneumococcal vaccine study, and a Lonza scientist was corresponding author of the 2021 microbiome trial; the other abstracts do not name a funder.^2,3,4,8

Sources

8 sources: trial abstracts, NIH fact sheets and reference databases. Numbers in the text link here.

Sources cited on this page

8 sources

1Using Dietary Supplements WiselyFact sheet National Center for Complementary and Integrative Health (NCCIH), 2019 · nccih.nih.gov
2Larch arabinogalactan effects on reducing incidence of upper respiratory infections.RCT Curr Med Res Opin, 2013 · PMID 23339578
3Immunomodulatory effects of ResistAid™: A randomized, double-blind, placebo-controlled, multidose study.RCT J Am Coll Nutr, 2013 · PMID 24219376
4Proprietary arabinogalactan extract increases antibody response to the pneumonia vaccine: a randomized, double-blind, placebo-controlled, pilot study in healthy volunteers.Pilot RCT Nutr J, 2010 · PMID 20796315
5No long-term benefits of supplementation with arabinogalactan on serum lipids and glucose.RCT J Am Diet Assoc, 2004 · PMID 15054349
6Effects of dietary arabinogalactan on gastrointestinal and blood parameters in healthy human subjects.RCT J Am Coll Nutr, 2001 · PMID 11506055
7Immunological activity of larch arabinogalactan and Echinacea: a preliminary, randomized, double-blind, placebo-controlled trial.RCT Altern Med Rev, 2002 · PMID 11991793
8Effect of arabinogalactan on the gut microbiome: A randomized, double-blind, placebo-controlled, crossover trial in healthy adults.Crossover RCT Nutrition, 2021 · PMID 34004416

What changed

Every dated change to this page: what changed, who made it and why.

Change log

2 entries

Dated changes to this page
Date	Change	Who and why
Oct 21, 2026definition, key facts, evidence, studied doses, safety, label guide, FAQ	Added PMID 34004416 (2021 ResistAid microbiome crossover RCT, 30 adults; D). Regraded two small null trials to match the grading rules: lipids-glucose-2004 from no-effect to C and immune-markers-2002 from no-effect to D (not adequately powered). Added a label step, two FAQs (tolerance; pregnancy and breastfeeding) and a note that interaction data are lacking. Definition shortened to 140 characters. Fact-checked against the sources; corrected: the funding key fact now says a Lonza scientist was corresponding author of the microbiome trial, not that Lonza led it.	Writer: Kymata Health EditorialTrigger: A–Z page audit
Oct 15, 2026all	Initial editorial evidence review. Every PMID checked against NCBI E-utilities esummary (title, year, journal; none retracted) and each cited abstract read; numbers taken from the abstracts. Funding: Lonza paid for the 2010 pneumococcal trial (full-text acknowledgement); the 2013 trials name no funder and test Lonza's ResistAid; the Minnesota trials list non-government support without naming it. Safety from NCCIH's Using Dietary Supplements Wisely (no ODS, LiverTox, LactMed, Health Canada or EMA entry found). Where to buy: Solaray Arabinogalactan (label checked 2026-10-15).	Writer: Kymata Health EditorialTrigger: new page

Supplement & Nutrient Encyclopedia. Educational information only; it is not medical advice and does not replace a clinician. Dietary supplements are not intended to diagnose, treat, cure or prevent any disease. Statements about supplements have not been evaluated by the FDA.

Larch Arabinogalactan

Solaray Arabinogalactan, 60 vegetarian capsules

Medicines 0

Supplements and foods 1

EchinaceaEchinacea page