HbA1c

Nutrients connected to HbA1c

A link means the body needs the nutrient for this, or that low intake is linked to it. It does not mean extra supplements help if your intake is already adequate; each link shows how strong the evidence is.

• ChromiumPreliminary or mixed

  Both reviews of trials in type 2 diabetes found lower HbA1c with chromium than placebo, though the size varied widely between studies. This does not show fewer diabetes complications.

• CinnamonPreliminary or mixed

  A 2024 analysis of 24 trials found lower HbA1c with cinnamon in type 2 diabetes; results called inconclusive overall.

• FenugreekPreliminary or mixed

  HbA1c was lower in a 2023 meta-analysis of 10 trials; study quality varied.

• Bitter MelonPreliminary or mixed

  HbA1c fell by about 0.38 percentage points on average in the 2024 meta-analysis; further high-quality studies are needed.

• Black seedPreliminary or mixed

  Pooled trials in people with metabolic disease found HbA1c about 0.56 lower. Quality varied; authors urge caution.

• BarberryPreliminary or mixed

  HbA1c fell in the 2024 meta-analysis of type 2 diabetes trials but not in the 2020 one.

• GymnemaPreliminary or mixed

  A meta-analysis reported a lower HbA1c than at baseline in type 2 diabetes, with very high variation between studies and no control comparison.

• BerberinePreliminary or mixed

  HbA1c fell on average in pooled type 2 diabetes trials (about 0.6 percentage points in a 2022 analysis).

• Mulberry leafPreliminary or mixed

  The 2022 review found no significant HbA1c change; a 2025 analysis of 15 trials reported improvement. Evidence conflicts.

• Coptis (goldthread)Preliminary or mixed

  HbA1c fell on average (about 0.6 to 0.8 percentage points) in the pooled analyses read.

• CinnamonPreliminary or mixed

  Pooled trials report lower HbA1c with supplements; mixed.

• FenugreekPreliminary or mixed

  HbA1c was lower in a 2023 pooling of 10 trials of supplements; study quality varied.

• PomegranatePreliminary or mixed

  HbA1c fell by about 0.22 percentage points in a 2024 meta-analysis of 32 trials (small effect).

• SalaciaPreliminary or mixed

  A 3-month crossover trial of 51 people found a larger HbA1c fall with salacia tea than placebo; other trials were small or borderline.

• OkraPreliminary or mixed

  HbA1c fell in several meta-analyses of okra products in type 2 diabetes; certainty low.

• Dried fenugreek leaf (kasuri methi)Preliminary or mixed

  HbA1c was lower in a 2023 pooling of 10 trials of supplements; study quality varied. Based on seed studies, not dried leaf.

• Gynostemma (Jiaogulan) TeaPreliminary or mixed

  HbA1c fell by about 2 percentage points versus 0.2 on placebo in a 12-week trial of 24 people.

• MilletPreliminary or mixed

  HbA1c was lower in the pooled analysis.

• SorghumPreliminary or mixed

  HbA1c was lower in a pooled analysis with millets.

• Black Seed Oil (Nigella)Preliminary or mixed

  Lower HbA1c on average in pooled trials of black seed (mixed forms), with varied results.

• TaurinePreliminary or mixed

  A 2026 meta-analysis reported an average HbA1c drop of 0.21 percentage points with taurine supplements. A lab measure, not proof of better long-term outcomes.

• Alpha-lipoic acidPreliminary or mixed

  One meta-analysis of 41 articles found lower HbA1c; a dose-response analysis found oral effects below clinically important thresholds.

• BilberryPreliminary or mixed

  Pooled trials showed a borderline lower HbA1c (p=0.06 in the abstract).

• Olive leafPreliminary or mixed

  One 14-week trial found lower HbA1c with an extract; a 24-week pilot found no clear difference.

• American ginsengPreliminary or mixed

  HbA1c fell by 0.29% compared with placebo in one small crossover trial in adults with type 2 diabetes.

• MoringaPreliminary or mixed

  HbA1c fell in one prediabetes trial; the pooled 2025 result was not significant.

• Yerba matePreliminary or mixed

  Two prediabetes trials found lower HbA1c, which the authors say needs confirming.

• FlaxseedPreliminary or mixed

  The same 7-trial meta-analysis found lower HbA1c; evidence is limited and MSK reports conflicting data.

• CuminPreliminary or mixed

  One 2021 review reported lower HbA1c; not measured in the others we read.

• Black seed (nigella)Preliminary or mixed

  HbA1c was about 0.56 lower on average in the 31-trial review of supplements.

• SumacPreliminary or mixed

  The 2024 pooling reported HbA1c about 0.5 percentage points lower; the 2021 pooling did not find a significant change.

• Guava leafPreliminary or mixed

  HbA1c fell only in some subgroups of small 8 to 12 week studies; a 2026 meta-analysis of related plants found no clear HbA1c change.

• Japanese knotweed (hu zhang)Preliminary or mixed

  An umbrella review found a favourable short-term HbA1c result for isolated resveratrol in type 2 diabetes but concluded the evidence does not support using it; this is not shown for knotweed root.

• MangoPreliminary or mixed

  HbA1c fell more with mango than with bread in an 8-week trial of 35 adults with type 2 diabetes; in another trial it stayed stable in the mango group.

• JackfruitPreliminary or mixed

  HbA1c fell by 0.25% in 40 adults with type 2 diabetes who ate green jackfruit flour in place of grain flour for 12 weeks, versus no change with placebo.

• KalePreliminary or mixed

  HbA1c fell in one 12-week trial using a freeze-dried kale bar.

• Vijaysar (Indian kino)Preliminary or mixed

  Average HbA1c fell from 9.8% to 9.4% in the 1998 open trial with no comparison group, a small change.

• Sesame seedPreliminary or mixed

  HbA1c fell in two pooled analyses of sesame products; small trials, form not stated.

• PistachiosPreliminary or mixed

  One 11-trial meta-analysis found HbA1c lower by 0.14 on average.

• FlaxseedPreliminary or mixed

  Lower HbA1c in the same meta-analysis.

• Sesame Seeds & TahiniPreliminary or mixed

  Lower HbA1c in two meta-analyses of sesame products.

• Yerba MatePreliminary or mixed

  Two prediabetes trials in a 2025 review found lower HbA1c; needs confirming.

• Chamomile TeaPreliminary or mixed

  HbA1c was lower after 8 weeks of the tea than with water in 64 adults with type 2 diabetes.

• Black Seed Oil (Nigella)Preliminary or mixed

  HbA1c was lower on average (about 0.56 points) in the same meta-analysis; study quality varied.

• QuinoaPreliminary or mixed

  Reduced in the one-year trial in impaired glucose tolerance (one trial).

• Navy BeansPreliminary or mixed

  Pooled trials found lower HbA1c or fructosamine with pulse-containing diets.

• White Beans (Cannellini & Great Northern)Preliminary or mixed

  Pooled trials found lower HbA1c or fructosamine with pulse-containing diets.

• Lima BeansPreliminary or mixed

  Pooled trials found lower HbA1c or fructosamine with pulse-containing diets.

• Mung BeansPreliminary or mixed

  Pooled trials found lower HbA1c or fructosamine with pulse-containing diets.

• Adzuki BeansPreliminary or mixed

  Pooled trials found lower HbA1c or fructosamine with pulse-containing diets.

• Canned Beans (Drained, Rinsed)Preliminary or mixed

  HbA1c-type markers fell with pulses in a 2009 pooled analysis; a 2020 review of trials rated the evidence in type 2 diabetes very low quality.

• CarobPreliminary or mixed

  A 90-day trial in prediabetes with a carob liquid concentrate found better HbA1c than placebo.

• Safflower OilPreliminary or mixed

  HbA1c fell by 0.64 points with 8 g a day in one crossover trial of women with type 2 diabetes.

• Walnut & Other Nut OilsPreliminary or mixed

  HbA1c fell from 7.00 to 6.37 in one trial of walnut oil in type 2 diabetes.

• Pomegranate JuicePreliminary or mixed

  HbA1c about 0.22 percentage points lower in a 2024 pooled analysis of pomegranate in many forms.

• HoneyPreliminary or mixed

  The umbrella review said 10 g of honey a day may lower HbA1c; certainty and population limits apply.

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