How we rate
“Strong” = several concordant meta-analyses or systematic reviews. “Moderate” = one synthesis, or several controlled trials. “Limited” = early trials only. The rating is about the quality of the studies, not about how useful the supplement is.
Guar gum
Soluble fiber that lowers total cholesterol and LDL in meta-analysis and provides slight relief for irritable bowel syndrome in its hydrolyzed form. It does not cause weight loss.
Benefits
- Cholesterol: lowers total cholesterol by about 20 mg/dL and LDL by 14.52 mg/dL in type 2 diabetics (meta-analysis of 11 studies); same drop in total over 25 trials in people with cardiometabolic problems.
- Diabetic blood glucose: lowers HbA1c by 0.47 point in a meta-analysis of 14 trials; fasting blood glucose only drops in type 2 diabetics and above 15 g per day.
- Irritable bowel: in 188 adults, 5 g per day of hydrolyzed gum succeeded in 60% of patients against 40% with 30 g of wheat bran, and was better tolerated.
- Children: in 60 children aged 8 to 16 with functional abdominal pain, 5 g per day reduced symptoms in 43% of them against 5% under placebo; in 61 constipated children, as effective as lactulose, with fewer adverse effects.
- Too soft stools: in 44 healthy adults prone to diarrhea, 3 months of hydrolyzed gum normalized stool shape and increased bifidobacteria, without changing their frequency.
- Colds: in 96 healthy Japanese adults, 5.2 g per day for 12 weeks gave more days without cold symptoms, and less severe symptoms.
- Postprandial drop in pressure: in 22 elderly women prone to this discomfort, 9 g at mealtime made it drop from 72.7% of cases under placebo to 18.2%.
Precautions
Stomach: abdominal pain, flatulence, diarrhea, and cramps are the most frequent adverse effects; 3% of participants stopped because of them in weight trials. Toddlers: EFSA considers guar safe as an additive for the general population, but asks to monitor abdominal discomfort in infants and young children. Medications: taken with a meal, guar gum did not prevent the decrease in absorption of trimethoprim; the authors advise taking this antibiotic between meals. Limits: weight: no difference with placebo in a meta-analysis of 11 trials; the authors consider that risks outweigh benefits for weight loss. Satiety: in 25 obese dieting women, 20 g per day did not increase the feeling of satiety. Blood pressure: in 141 overweight hypertensives, six months of guar did not lower it, unlike psyllium. Constipation: in 52 elderly nursing home residents, neither stool frequency nor shape changed (only laxative use decreased); mixed with inulin, no advantage over placebo in 60 constipated women. Triglycerides and HDL: no effect on average; triglycerides only drop at 20 g per day or more in diabetics.
Recommended dosage
5 g per day of partially hydrolyzed gum (transit, irritable bowel); more than 15 g per day for fasting blood glucose in diabetics.
How to take it
- Two products: partially hydrolyzed gum (5 g per day) is the one from trials on transit, irritable bowel, and colds; classic guar gum is the one from trials on cholesterol and blood glucose.
- Cholesterol and blood glucose: in the pooled trials, from 100 mg to 30 g per day, from 1 to 24 months; one trial on 9 diabetics gave 5 g three times a day, with meals.
- Irritable bowel: 5 or 10 g per day for 12 weeks improve symptoms and quality of life; the benefit fades after stopping.
- Postprandial drop in pressure: 9 g with the meal, in two small trials in elderly people.
- With a medication: in 12 volunteers, the meal, with or without guar, reduced the absorption of an antibiotic, triméthoprime, by 22.2%; in 9 diabetics, guar did not change the absorption of glibenclamide.
- What does not work: weight loss, and the blood pressure of the hypertensive.
Did you know?
Added for 10 days to an antibiotic, 5 g per day of hydrolyzed guar gum increased the eradication of small intestinal bacterial overgrowth from 62.1% to 87.1% of patients.
What the studies say
This meta-analysis of 11 studies examined the impact of guar gum consumption on the lipid profile in patients with type 2 diabetes. The results showed a significant reduction in total cholesterol and LDL cholesterol. A dose of ≥20 g/day of guar gum also led to a noticeable decrease in triglycerides, with no effect on HDL cholesterol.
Li J, Chen R, Chen Y, Zhu D, Wu Z, Chen F, Huang X, Ali Khan B, Al Hennawi HE, Albazee E, Prabahar K, Hou K. — Critical reviews in food science and nutrition (2023) — View the source study
For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more