Benefits
Smaller blood sugar rise after a starch-containing meal
Eaten with a starchy meal, alpha-cyclodextrin lowers the after-meal blood sugar rise. In a dose-ranging meal test the 2-hour glucose curve shrank step by step as the dose went up and was significantly lower at 5 and 10 g. On this evidence the European Union authorizes a blood-glucose claim at a dose of at least 5 g per 50 g of starch eaten as part of the meal.
Lower blood triglycerides after a fat-containing meal
Taken right after a high-fat breakfast, 2 g of alpha-cyclodextrin made the rise in blood triglycerides over the next few hours significantly smaller than placebo in healthy adults, while blood glucose and cholesterol were unchanged. This is a short single-meal effect; the study did not measure blood fats over the longer term.
Body weight and blood lipids with daily use
Results are small and inconsistent. A 2-month crossover study in overweight adults saw about 0.4 kg more weight loss and roughly a 5 to 7% drop in total and LDL cholesterol versus the control phase, and a study in adults with type 2 diabetes reported weight maintenance. Both were industry-linked, and the largest independent 6-month trial found no cholesterol change.
Fullness and appetite at higher single doses
In the dose-ranging rice-meal test, larger doses left people feeling fuller, which is one rationale for using the fiber in weight management. The same higher doses were less pleasant to take and brought more minor digestive complaints such as stomach ache, nausea and bloating, so the appetite effect comes with a tolerability trade-off.
Binds dietary fat in laboratory and animal studies
In the test tube alpha-cyclodextrin forms complexes with fatty acids and can hold several times its weight in fat, and rodents fed it excreted more fat in their stool. This is the proposed basis for the lipid and weight marketing, but a controlled human study that measured stool fat found no increase, so the fat-binding route is not confirmed in people.
Mechanism of action
Resists digestion and acts as a soluble fiber
The ring of six alpha-1,4-linked glucose units is poorly broken down by human amylase and small-intestine enzymes, so much of it passes to the colon, where gut bacteria ferment it. This non-digestible, fermentable behavior is why the European Union treats it as a dietary fiber.
Slows starch and sugar uptake at the meal
In laboratory work alpha-cyclodextrin can inhibit pancreatic amylase and bind starch, and human meal tests show a smaller, dose-dependent glucose rise. A sucrose study, where amylase is not involved, found gastric emptying slightly slowed, so delayed carbohydrate absorption also contributes to the lower after-meal glucose.
Fat binding, shown mainly in the lab and animals
Alpha-cyclodextrin forms inclusion complexes with dietary fatty acids, which in vitro traps fat and in rodents raised fecal fat loss. In a controlled human study with radiolabeled fat, however, stool fat and post-meal blood fat were unchanged, so this route is not established in people despite being the usual explanation for the lipid claims.
Clinical trials
Double-blind, randomized crossover meal test adding 0, 2, 5 or 10 g of alpha-cyclodextrin to boiled white rice containing 50 g of digestible carbohydrate (Buckley et al. 2006, Ann Nutr Metab).
10 healthy adults.
The area under the 2-hour plasma glucose curve fell as the dose rose and was significantly lower at 5 and 10 g than with no alpha-cyclodextrin, while the insulin area did not change. Higher doses gave more fullness but also lower palatability and more minor stomach complaints. A small single-meal study.
Two-day randomized study of a 100 g sucrose drink taken with or without 10 g alpha-cyclodextrin, measuring gastric emptying, blood glucose and insulin (Gentilcore et al. 2011, Br J Nutr).
10 healthy older adults aged 68 to 76.
Alpha-cyclodextrin slightly slowed gastric emptying and lowered blood glucose at 60 minutes and insulin at 90 and 120 minutes, but the overall area under the glucose curve did not differ and the insulin area only trended lower. The effects were described as modest.
Double-blind, placebo-controlled crossover test of 2 g of alpha-cyclodextrin taken immediately after a commercially prepared high-fat breakfast (Jarosz et al. 2013, Metabolism).
Healthy adults.
The rise in blood triglycerides over the next 3 hours was significantly smaller with alpha-cyclodextrin than placebo (incremental area 0.30 vs 0.98 mmol/L/3 h). Blood glucose and cholesterol did not change. A single-meal study that did not measure longer-term blood fats.
Double-blind crossover trial of alpha-cyclodextrin (trade name FBCx) versus placebo over 2 months in overweight, non-diabetic adults (Comerford et al. 2011, Obesity).
41 healthy adults enrolled; 28 compliant (8 men, 20 women).
During the active phase, body weight fell by 0.4 kg, total cholesterol by about 5% and LDL cholesterol by about 7% versus the control phase; apolipoprotein B and insulin trended lower and glucose did not change. Small changes in a small group; two authors are linked to the ingredient.
Double-blind, placebo-controlled trial of 2 g FBCx (alpha-cyclodextrin) per fat-containing meal for 3 months, with participants told not to change their usual eating (Grunberger et al. 2007, Diabetes Metab Res Rev).
66 adults with type 2 diabetes and obesity.
The placebo group kept gaining weight while the alpha-cyclodextrin group held steady, and in participants with high triglycerides total cholesterol fell about 8% with alpha-cyclodextrin but rose with placebo; adiponectin rose. Some participants changed their diet, so weight data were adjusted. Two authors are linked to the ingredient.
Double-blind, placebo-controlled crossover study at the Mayo Clinic using radiolabeled dietary fat to measure stool fat over 72 hours with 2 g alpha-cyclodextrin per meal or placebo (Lytle et al. 2018, J Nutr).
8 healthy adults (5 women, 3 men) aged 23 to 54.
Total stool fat and the amount of labeled dietary fat recovered in stool did not differ between alpha-cyclodextrin and placebo, and the fat appearing in the blood after the meal was unchanged. The proposed fat-binding effect did not occur in people. One author worked for a supplement company.
Six-month, double-blind, placebo-controlled randomized trial with a 2x2 design testing alpha-cyclodextrin for cholesterol and hydrolyzed ginseng for glucose; all participants received weight-loss diet advice (Bessell et al. 2020, JAMA Netw Open).
401 adults with prediabetes and overweight or obesity in Sydney, Australia.
After 6 months, total cholesterol did not differ between the 200 people taking alpha-cyclodextrin and the 201 taking placebo (difference -1.5 mg/dL, not significant). Constipation and cough were reported more often with alpha-cyclodextrin. This large, independent trial found no cholesterol benefit.