Guava: very high in vitamin C, thin everywhere else

Guava carries more vitamin C than almost anything else in the fruit aisle. Our USDA record puts 228.3 mg in 100 g of the common raw fruit, and a cup of it weighs 165 g. That vitamin C does something measurable for iron, in children who are short of it. Added to a daily mungbean meal in Indian schoolchildren for seven months, guava raised haemoglobin by 3.7 g/L. Body iron stores in the same trial moved by 0.65 mg/kg with a confidence interval crossing zero, so that part did not hold. Every iron trial on this page was run in children with anaemia or iron deficiency eating high-phytate plant meals. In adults whose iron is already normal it has not been measured. The blood pressure results people quote come from one research group in the early 1990s, and both of their trials were in patients already diagnosed with essential hypertension. Their four week trial fed people 0.5 to 1.0 kg of guava a day, several cups of fruit, and their twelve week trial reported a fall of 9.0/8.0 mm Hg against usual diet without saying how much guava people ate. Nobody has repeated either one. In the one place a Cochrane review put guava head to head with a drug, period pain, the drug won by 1.19 points on a ten point scale in a trial of 155 women.

The numbers, per 100 g

What your body absorbs

• The vitamin C in guava was not enough to move body iron stores: the same 7-month trial found a treatment effect of 0.65 mg/kg body weight, with a confidence interval crossing zero. — 200 school children aged 6-10 years, 71% iron-deficient at baseline, 7 months (n = 200) Evidence B source
  +0.65 mg/kg body iron (95% CI -0.34 to 1.63; P = 0.197), not significant
• Adding 25 g of guava to a preschool meal shifted the iron to vitamin C molar ratio from 1:1.4 to 1:12, while the ratio did not move in the banana and cucumber groups. — 399 preschoolers aged 24-48 months, 28 preschools in Telangana, India, 140 days (n = 399) Evidence B source
  Iron to vitamin C molar ratio 1:1.4 to 1:12; higher haemoglobin (P = 0.002) and ferritin (P < 0.001)
• Guava juice carrying about 200 mg of vitamin C with the main meal raised haemoglobin by 0.64 g/dL over 10 weeks, but ferritin moved by only 2.47 ng/mL and that change was not significant. — 95 anaemic boarding school children aged 6-9 years, Tarahumara, northern Mexico, high-phytate diet, 10 weeks (n = 95) Evidence B source
  +0.64 g/dL haemoglobin (95% CI 0.18 to 1.11; p = 0.01); ferritin +2.47 ng/mL (95% CI -1.04 to 5.98; p = 0.12)

What cooking and storage change

• The form matters: guava eaten in bite-size pieces had a glycemic index of 29, while the same fruit as puree scored 47. — 19 healthy adults in Singapore, 9 older and 10 young, crossover (n = 19) Evidence B source
  Glycemic index 29 (bites) vs 47 (puree); difference between treatments P = 0.003

What it does to your health

• 200 g of guava a day held the rise in gingival inflammation to 0.10 index points over 14 days of stopped brushing, against 0.87 points with water. — young non-smoking adults, three arms: 200 g guava, 200 mg synthetic vitamin C, or water, 14 days of experimental gingivitis (n = group sizes not reported in the abstract) Evidence B source
  Change in Gingival Index 0.10 (guava) vs 0.24 (vitamin C) vs 0.87 (control)
• In patients with essential hypertension, substituting guava into the usual diet for 12 weeks cut total cholesterol by 9.9% and blood pressure by 9.0/8.0 mm Hg against usual diet. The abstract does not say how much guava that was. — 120 patients with essential hypertension, 61 in the guava arm and 59 controls, 12 weeks (n = 120) Evidence B source
  Total cholesterol -9.9%, triglycerides -7.7%, blood pressure -9.0/8.0 mm Hg, HDL cholesterol +8.0%
• An earlier trial of the same group fed 0.5 to 1.0 kg of guava a day for four weeks and reported a net fall of 7.5/8.5 mm Hg in blood pressure, on a dose far above any normal portion. — 145 patients with essential hypertension, 72 on a guava-rich diet and 73 on usual diet, 4 weeks (n = 145) Evidence B source
  Net decrease 7.5/8.5 mm Hg in systolic and diastolic pressure; soluble fibre intake 47.8 vs 9.5 g/day

Safety, limits and interactions

• Guava belongs to the cross-reacting fruit group: in one patient with anaphylaxis to peach, IgE antibodies bound extracts of guava as well as banana, mandarin and strawberry. — one adult patient with allergic reactions to several fruits (n = 1) Evidence D source
  IgE binding to a 30 kd protein shared by peach, guava, banana, mandarin and strawberry

What people believe that the data does not support

• For period pain a Cochrane review found guava no better than anti-inflammatory drugs, and the single trial of 155 women pointed the other way (MD 1.19, 95% CI 0.42 to 1.96). — women with primary dysmenorrhoea; guava compared with NSAIDs in one trial of 155 women, within a review of 27 trials and 3101 women (n = 155) Evidence A source
  Mean difference 1.19 points on a 0 to 10 pain scale (95% CI 0.42 to 1.96), favouring NSAIDs
• The European Union register holds 4 health claims for guava and has authorised none of them: the antioxidant claim POL-HC-7236 is listed as non-authorised. — regulatory decision, European Union, register snapshot of 2026-09-21 (n = -) Evidence E source
  0 authorised claims, 4 non-authorised claims for guava

Who this works differently for

• In Indian schoolchildren, adding fresh guava to a daily mungbean meal for 7 months raised haemoglobin by 3.7 g/L compared with the same meal without guava. — 200 school children aged 6-10 years in rural Haryana, India, 46% anaemic at baseline, 7 months (n = 200) Evidence B source
  +3.7 g/L haemoglobin (95% CI 1.6 to 5.6; P = 0.001)
• Among 350 older Thai adults, those who ate guava had about half the odds of frailty (OR 0.52, 95% CI 0.28 to 0.96). — 350 older adults in northern Thailand, cross-sectional, frailty by Fried phenotype (n = 350) Evidence C source
  Odds ratio 0.52 (95% CI 0.28 to 0.96, p = 0.037), adjusted for confounders

What is still unknown

• Across 27 trials and 3101 women, the same Cochrane review found no high quality evidence for any dietary supplement in period pain, guava included, and safety data were missing. — 27 randomised trials, 3101 women, mostly students with primary dysmenorrhoea (n = 3101) Evidence A source
  No high quality evidence of benefit; only 4 of 27 trials reported adverse effects in both arms

The bottom line

Eat it whole. In a crossover in 19 adults, guava in bite-size pieces scored 29 on the glycemic index and the same fruit as puree scored 47, with the gap between the two reaching P = 0.003. That is the most practical instruction on this page. Two other findings sit at trial level. Two hundred grams of guava a day held the rise in gum inflammation to 0.10 index points over 14 days of stopped brushing, against 0.87 points with water, and a 200 mg synthetic vitamin C arm landed between them at 0.24. Among 350 older adults in northern Thailand, people who ate guava had about half the odds of frailty, an odds ratio of 0.52. That one is cross-sectional, so it describes who eats guava as well as what guava does, and the two cannot be separated in that design. Regulators have already read the marketing. The European Union register holds four health claims for guava and has authorised none of them, the antioxidant claim included. What we cannot tell you is bigger than what we can, and you should know the shape of it. On safety our whole file is one paper from 1990: a single patient with anaphylaxis to peach whose antibodies also bound guava, banana, mandarin and strawberry. One person. We have no upper intake limit for guava in our file, no study of it alongside any medication, no safety data in children, and nothing on pregnancy or kidney disease. If you react to peach or other stone fruit, guava is worth raising with whoever treats your allergy, and you should know that we are reasoning from that one case. The Cochrane reviewers who went through 27 trials and 3101 women for period pain found no high quality evidence for any dietary supplement, guava among them, and only 4 of those 27 trials reported side effects in both arms. We also have nothing on how the vitamin C figure moves with variety, ripeness or storage, and nothing on what a normal portion of guava looks like in anybody's week. Our table carries two guavas, common and strawberry, and every number quoted here is the common one.

Sources

1. guav-r1-02 · randomised controlled trial
   Daily consumption of mungbean dal along with guava did not result in an overall improvement of body iron stores [mean treatment effect: 0.65 mg/kg body weight; 95% confidence interval (CI): -0.34, 1.63; P = 0.197]
   J Nutr, 2024 · checked 2026-09-23
2. guav-r1-03 · cluster-randomised controlled trial
   The iron to vitamin C molar ratio improved in the GG from 1:1.4 to 1:12 but remained unaltered in control groups.
   Ann N Y Acad Sci, 2021 · checked 2026-09-23
3. guav-r1-06 · randomised placebo-controlled trial
   the guava group had 0.64 g/dL higher Hb (CI(95), 0.18-1.11; p = 0.01) and 2.47 ng/mL higher PF (CI(95), -1.04 to 5.98; p = 0.12) compared with the placebo group
   J Am Coll Nutr, 2011 · checked 2026-09-23
4. guav-r1-05 · randomised crossover trial
   All fruit forms and types studied were low glycemic index (GI) (guava bites: 29; papaya bites: 38; papaya puree: 42; guava puree: 47), albeit a significant difference in GI between the treatments was found (P = 0.003).
   J Nutr Health Aging, 2017 · checked 2026-09-23
5. guav-r1-04 · randomised controlled trial
   The GI increase in both guava and vitamin C group was significantly less than the increase in the control group (ΔGI: 0.10, 0.24 and 0.87, respectively).
   J Clin Periodontol, 2018 · checked 2026-09-23
6. guav-r1-10 · randomised single-blind trial
   There was a significant net decrease in serum total cholesterol (9.9%), triglycerides (7.7%) and blood pressures (9.0/8.0 mm Hg) with a significant net increase in high-density lipoprotein cholesterol (8.0%) after 12 weeks of guava fruit substitution in group A than in group B.
   Am J Cardiol, 1992 · checked 2026-09-23
7. guav-r1-11 · randomised single-blind trial
   group A patients were associated with 7.5/8.5 mmHg net decrease in mean systolic and diastolic pressures compared with group B
   J Hum Hypertens, 1993 · checked 2026-09-23
8. guav-r1-12 · case report
   The patient's serum, but not control sera, contained IgE antibodies reactive to extracts from peaches, guavas, bananas, mandarins, and strawberries in an ELISA.
   J Allergy Clin Immunol, 1990 · checked 2026-09-23
9. guav-r1-07 · systematic review and meta-analysis
   There was no evidence of any difference between NSAIDs and dill (MD 0.13 points, 95% CI -1.01 to 1.27; one RCT, 47 women), fennel (MD -0.70 points, 95% CI -1.81 to 0.41; one RCT, 59 women), guava (MD 1.19, 95% CI 0.42 to 1.96; one RCT, 155 women)
   Cochrane Database Syst Rev, 2016 · checked 2026-09-23
10. guav-r1-13 · regulatory register entry
    POL-HC-7236 Guava Guava is a major dietary source of antioxidants Antioxidants from dietary sources contribute to the protection against free radicals which cause cell damage contributes to the protection of cells and tissues from oxidative damage help strengthen our body's natural defences against oxidative stress Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-7236, snapshot 2026-09-21 · checked 2026-09-23
11. guav-r1-01 · randomised controlled trial
    children in the guava group showed a larger increase in hemoglobin concentration (3.7 g/L; 95% CI: 1.6, 5.6; P = 0.001)
    J Nutr, 2024 · checked 2026-09-23
12. guav-r1-09 · cross-sectional study
    Guava fruit and Acacia pennata vegetable consumption had lower odds of frailty, which were 0.52 times (95% CI 0.28−0.96, p = 0.037)
    Nutrients, 2022 · checked 2026-09-23
13. guav-r1-08 · systematic review and meta-analysis
    There is no high quality evidence to support the effectiveness of any dietary supplement for dysmenorrhoea, and evidence of safety is lacking.
    Cochrane Database Syst Rev, 2016 · checked 2026-09-23