Home Ingredients Guava Fruit (Psidium guajava)

Guava Fruit (Psidium guajava)

Psidium guajava
Evidence Level
Limited
8 Clinical Trials
6 Documented Benefits
2/5 Evidence Score

Guava fruit is the edible fruit of the tropical tree Psidium guajava, eaten fresh, peeled or as juice. It is a separate product from guava leaf tea or leaf extract, which has its own page and its own research. According to USDA data, 100 g of raw pink-fleshed guava supplies about 228 mg of vitamin C, 5.4 g of fiber, 417 mg of potassium and 5,200 mcg of lycopene. Most human studies use the fruit as a vitamin C food: added to iron-containing meals, it raised hemoglobin in children. A single dose of a guava fruit extract blunted the blood sugar rise 30 minutes after a glucose drink, though not the overall response. Older trials reporting lower blood pressure and blood fats come from a research group whose data were later questioned, so they are not counted here. Guava is a food first; concentrated extracts are far less studied.

Studied Dose Whole fruit: 25 g/day with meals in preschoolers, 200 g/day in a gum study, 400 g/day for 6 weeks in young adults. Juice: 300 to 500 mL. Fruit extract: 2.5 mL of a supercritical CO2 extract in a 75 g glucose drink, single dose.
Active Compound Whole fruit nutrients: vitamin C (ascorbic acid), dietary fiber, potassium and, in pink-fleshed fruit, the carotenoid lycopene, plus polyphenols. This is the fruit, not the leaf extract.

Benefits

A food source of vitamin C, fiber, potassium and lycopene

Per 100 g, raw pink-fleshed guava provides about 228 mg of vitamin C, 5.4 g of total fiber, 417 mg of potassium and 5,200 mcg of lycopene for 68 kcal, according to USDA data. One fruit without refuse weighs about 55 g, so a single guava supplies roughly 125 mg of vitamin C.

Supported by Trial 7, Trial 6

Post-meal blood sugar response with a guava fruit extract

In a small double-blind randomized test in healthy young adults, 2.5 mL of a guava fruit extract added to a 75 g glucose drink led to a smaller blood glucose rise at 30 minutes than the glucose drink alone (10 versus 15 people in the main analysis). The rises at 60 and 90 minutes, the overall glucose area under the curve and insulin did not differ significantly, and this was one dose of an extract, not whole fruit.

Supported by Trial 1

Vitamin C from guava and iron status in children

Adding guava to iron-containing meals raised their vitamin C. In 399 preschoolers, 25 g of guava a day for 140 days raised hemoglobin, ferritin and plasma vitamin C more than banana or cucumber. In 200 schoolchildren, guava with a mungbean meal raised hemoglobin, but body iron stores, the main outcome, did not differ from the meal alone.

Supported by Trial 2

Gum tissue response during a short break from oral hygiene

In a randomized trial in young nonsmoking adults, eating 200 g of guava a day before and during 14 days without tooth brushing led to a smaller rise in a gum inflammation score than drinking water, similar to 200 mg/day of synthetic vitamin C. The guava group also built up less plaque than the water group.

Supported by Trial 3

Platelet response after one serving of guava juice

In 30 healthy volunteers randomized to 500 mL of fresh guava juice, yam bean juice or water, guava juice reduced collagen-triggered platelet clumping in blood samples compared with water. Blood pressure and heart rate fell from baseline, but versus water only systolic pressure at 5 hours was lower, and the guava group started with higher systolic pressure. This was a single-serving study with 10 people per group.

Supported by Trial 4

Blood pressure and cholesterol reports from early whole-fruit trials

Two early trials from one Indian group reported that eating guava lowered blood pressure, cholesterol and triglycerides versus usual diet. A later BMJ investigation raised serious doubts about this group's data, so they are not counted here. In a small trial in medical students, 400 g/day for 6 weeks gave no between-group comparison, and lipids rose with the peel.

Supported by Trial 7, Trial 5

Mechanism of action

1

Vitamin C boosts non-heme iron absorption from a meal

In a stable-isotope study in 16 adolescents, adding 100 g of guava to a rice meal raised its vitamin C about 20-fold and more than doubled iron absorption (about 24% versus 10% in girls and 19% versus 9% in boys), while zinc absorption did not change. This is how guava helps iron status when eaten with iron-containing food.

2

Slows glucose transport across the gut lining in lab and animal studies

In human intestinal (Caco-2) cells and in mice, guava leaf and fruit extracts cut the transport of glucose from the gut into the body, acting more on the GLUT2 route than the SGLT1 route, and the effect held up after simulated digestion. In mice this was followed by a marked drop in blood glucose. These are laboratory and animal findings.

3

Whole-food vitamin C supply

With about 228 mg of vitamin C per 100 g (USDA), small servings of guava supply a meaningful amount of the vitamin. In the gum study, 200 g of guava a day performed about as well as 200 mg of synthetic vitamin C, which fits vitamin C as a main active nutrient, though the fruit also adds fiber, potassium and polyphenols.

Clinical trials

1
Guava Fruit Extract and Post-Glucose Blood Sugar: Double-Blind RCT
PubMed

Double-blind, randomized, parallel study of a supercritical CO2 guava fruit extract (2.5 mL) added to a 75 g oral glucose drink versus the glucose drink alone, single dose; one author's salary was paid by PM International AG (König et al. 2019, Nutrients)

31 healthy young adults randomized (15 control, 16 extract); the extract was given on three test days, and the main analysis compared the 10 tested in September with the 15 controls.

In the main analysis the glucose rise over fasting was smaller with the extract at 30 minutes (1.69 versus 2.60 mmol/L, p = 0.039) but not at 60 or 90 minutes, and the glucose area under the curve (p = 0.076) and insulin area under the curve (p = 0.435) did not differ significantly. The abstract also reports a smaller rise at 90 minutes (p = 0.023), a result not shown in the results section. The authors reported that storage and freeze-thawing appeared to weaken the extract.

2
Guava with a Preschool Meal and Iron Status: Cluster-Randomized Trial
PubMed

Three-arm, nonblinded, cluster-randomized trial adding 25 g of guava, banana or cucumber to a cereal and pulse supplementary meal for 140 days (Roy Choudhury et al. 2021, Ann N Y Acad Sci)

399 children aged 24 to 48 months at 28 preschools in 16 villages in Telangana, India.

Compared with the banana and cucumber groups, the guava group had higher hemoglobin (p = 0.002), serum ferritin (p < 0.001) and plasma vitamin C (p = 0.047), lower soluble transferrin receptor and less iron deficiency (p = 0.003). Fewer respiratory infections were also recorded (p = 0.035). There was no effect on cognitive development or growth.

3
Guava, Vitamin C and Gum Inflammation During No Brushing: RCT
PubMed

Randomized three-arm trial of 200 g guava a day, 200 mg synthetic vitamin C a day or water, given for 14 days before and during 14 days of experimental gingivitis (no oral hygiene) (Amaliya et al. 2018, J Clin Periodontol)

Young nonsmoking adults in Indonesia with minimal fruit and vegetable intake during the study.

Gingival Index rose by 0.10 with guava, 0.24 with vitamin C and 0.87 with water; both guava and vitamin C rises were significantly smaller than water. Plaque rose in all groups (1.30, 1.61 and 1.79) and was significantly lower with guava than water.

4
Guava Juice and Platelet Aggregation in Healthy Volunteers: RCT
PubMed

Randomized controlled trial of a single 500 mL serving of fresh guava fruit juice, yam bean root juice or water, with measurements over several hours; funded by the Thailand Research Fund (Thaptimthong et al. 2016, BMC Complement Altern Med)

30 healthy volunteers in Thailand, 10 per group.

Guava juice attenuated collagen-induced, but not ADP-induced, platelet aggregation compared with water; the paper gives these values only in a figure. Heart rate and blood pressure fell from baseline after guava juice, but versus water only systolic pressure at 5 hours was significantly lower, and the guava group started with higher systolic pressure (116 versus 103 mm Hg). Dietary nitrate did not explain the guava effect.

5
Ripe Guava With or Without Peel, Blood Glucose and Lipids: Small RCT
PubMed

Randomized controlled study of 400 g/day of ripe guava with peel or without peel for 6 weeks versus no supplement, analyzed mainly with before and after paired tests; supported by an ICMR student research grant (Kumari et al. 2016, J Clin Diagn Res)

45 healthy medical students in India, 15 per group.

Without peel, total cholesterol, triglycerides and LDL fell and HDL rose within the group; fasting glucose did not change significantly. With peel, fasting glucose, total cholesterol, triglycerides and LDL rose and HDL fell. Both guava groups lost weight and had lower blood pressure from baseline. No clear between-group results versus the control group were reported.

6
Guava Fruit, Blood Pressure and Blood Lipids: 12-Week Trial (Data Questioned)
PubMed

Randomized, single-blind trial of guava fruit eaten before meals in a foods-to-eat approach for 12 weeks; this paper was among those whose results an outside statistician recalculated in a BMJ inquiry into the lead author's data (Singh et al. 1992, Am J Cardiol)

120 people with essential hypertension (61 guava group, 59 comparison group).

Reported net falls in total cholesterol (9.9%), triglycerides (7.7%) and blood pressure (9.0/8.0 mm Hg) and a net rise in HDL cholesterol (8.0%) with guava. PubMed lists no retraction or expression of concern, but because the data were later questioned these results are not used as evidence on this page.

7
Guava Fruit 0.5 to 1 kg a Day, Blood Pressure and Lipids: 4-Week Trial (Data Questioned)
PubMed

Randomized, single-blind controlled trial of a potassium-rich, high soluble fiber diet with 0.5 to 1.0 kg of guava daily versus usual diet, from the same research group (Singh et al. 1993, J Hum Hypertens)

145 people with essential hypertension (72 guava diet, 73 usual diet).

Reported a 7.5/8.5 mm Hg net fall in blood pressure, and falls in total cholesterol (7.9%) and triglycerides (7.0%), with no significant change in HDL. The reported soluble fiber intake of 47.8 g/day is hard to square with USDA data (5.4 g total fiber per 100 g, or 27 to 54 g total fiber in 0.5 to 1 kg), and this group's data were later questioned, so the results are not used as evidence here.

8
Guava Jelly Drink, Cognition and Mood: 8-Week Pilot RCT
PubMed

Pilot, double-blind, placebo-controlled, three-arm trial of 86 g/day of a jelly drink with a low or high share of guava juice plus mint syrup, versus a placebo jelly without guava; university-funded (Nguyen et al. 2026, Foods)

75 healthy adults aged 20 to 40 in Thailand, 25 per arm.

Brain-wave and memory measures improved on some tests: versus placebo at 8 weeks, P300 latency was shorter with the low dose and two memory test scores were better with the high dose, while most other tests did not differ. The low dose also improved an anxiety score versus placebo, while the high dose stress and total anxiety and depression score changes were reported against baseline. The active drinks contained mint syrup, so effects cannot be tied to guava alone.

Side effects and drug interactions

Common Potential side effects

Guava fruit is a common food, and the cited trials report little on side effects, so how well very large daily amounts (400 g to 1 kg) are tolerated is not well documented.
Each 100 g supplies about 5.4 g of fiber (USDA), so the amounts used in some trials add a large fiber load; increase intake gradually.
Guava is high in potassium (about 417 mg per 100 g, USDA); people told by a doctor to limit potassium should count it.
Concentrated guava fruit extracts have not been studied in pregnancy or breastfeeding; eating the fruit as food is a different matter from taking an extract.
Guava leaf tea and leaf extracts are a separate product with their own cautions; this page covers the fruit.

Important Drug interactions

Antiplatelet or anticoagulant medicines (aspirin, clopidogrel, warfarin and similar): a single 500 mL serving of guava juice reduced collagen-triggered platelet clumping in blood samples from healthy volunteers. The clinical relevance is unknown; if you take these medicines and plan to drink large amounts of guava juice, tell your doctor.
Medicines that raise potassium (potassium-sparing diuretics, ACE inhibitors, angiotensin receptor blockers): guava is a potassium-rich food, so large daily amounts add to potassium intake; ask your doctor if your potassium needs monitoring.
Diabetes medicines: a guava fruit extract blunted the blood sugar rise 30 minutes after a glucose drink in healthy adults. Effects with diabetes medicines have not been studied; monitor your readings if you use concentrated extracts.

Explore Other Ingredients

Metabolic Health
Berberine
Berberine is a yellow compound from plants such as barberry, goldenseal and Chinese goldth…
Metabolic Health
GlucoVantage® (Dihydroberberine)
GlucoVantage® is NNB Nutrition's branded dihydroberberine (DHB), a reduced form of berberi…
Metabolic Health
Inositol (Myo-Inositol)
Inositol is a sugar-like compound that the body makes from glucose and that takes part in…

Frequently asked questions about Guava Fruit (Psidium guajava)

Is guava fruit the same as guava leaf?

No. They come from the same tree but are used differently. The fruit is eaten as food and is high in vitamin C. The leaf is brewed as a tea or taken as an extract, mainly for blood-sugar support, and it carries a different set of compounds. The blood-sugar tea trials are about the leaf, not the fruit.

How much vitamin C is in a guava?

USDA data list about 228 mg of vitamin C per 100 g of raw guava. One fruit without refuse weighs about 55 g, so a single guava supplies roughly 125 mg, and a cup (165 g) roughly 375 mg. Vitamin C content varies between fruits.

Does eating guava lower blood pressure or cholesterol?

This is not established. The trials that reported large drops came from one research group whose data were later questioned in a BMJ inquiry. A small trial in healthy students found lipid changes that went in opposite directions depending on whether the peel was eaten, without a clear comparison against the control group.

Does pink guava contain lycopene?

Yes. The USDA entry for raw common guava, footnoted as pink fleshed, lists about 5,200 mcg of lycopene per 100 g, along with about 374 mcg of beta-carotene. No human trial has tested guava lycopene for a health outcome.

Is a guava fruit extract the same as eating the fruit?

No. The only guava fruit trial with a between-group blood sugar result used 2.5 mL of a supercritical CO2 extract taken once with a glucose drink, not whole fruit. Whole guava supplies vitamin C, fiber and potassium, while an extract's makeup depends on how it is made, and extracts have far less research behind them.

What is Guava Fruit?

Guava fruit is the edible fruit of the tropical tree Psidium guajava, eaten fresh, peeled or as juice. It is a separate product from guava leaf tea or leaf extract, which has its own page and its own research. According to USDA data, 100 g of raw pink-fleshed guava supplies about 228 mg of vitamin C, 5.

What is Guava Fruit used for?

NutraSmarts does not list Guava Fruit under a health category. What the research covers: Per 100 g, raw pink-fleshed guava provides about 228 mg of vitamin C, 5.4 g of total fiber, 417 mg of potassium and 5,200 mcg of lycopene for 68 kcal, according to USDA data.

What is the recommended dosage of Guava Fruit?

The clinically studied dose is Whole fruit: 25 g/day with meals in preschoolers, 200 g/day in a gum study, 400 g/day for 6 weeks in young adults. Juice: 300 to 500 mL. Fruit extract: 2.5 mL of a supercritical CO2 extract in a 75 g glucose drink, single dose. Always follow the product label and check with a healthcare provider for personal advice.

Is Guava Fruit safe, and does it have side effects?

Side effects and cautions reported for Guava Fruit include: Guava fruit is a common food, and the cited trials report little on side effects, so how well very large daily amounts (400 g to 1 kg) are tolerated is not well documented. Each 100 g supplies about 5. It may also interact with some medications. Guava Fruit is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Guava Fruit interact with any medications?

Possible interactions include: Antiplatelet or anticoagulant medicines (aspirin, clopidogrel, warfarin and similar): a single 500 mL serving of guava juice reduced collagen-triggered platelet clumping in blood samples from healthy volunteers. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Guava Fruit?

NutraSmarts rates the evidence for Guava Fruit as Limited (2 out of 5). It is backed by 8 study summaries and 15 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(15 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. U.S. Department of Agriculture, Agricultural Research Service. FoodData Central: Guavas, common, raw (SR Legacy, FDC ID 173044). USDA FoodData Central. 2019;SR Legacy food 173044..SourceUsed to support: Not PubMed-indexed. Nutrient values per 100 g of raw common guava (entry footnoted as pink fleshed): 228 mg vitamin C, 5.4 g total dietary fiber, 417 mg potassium, 5,200 mcg lycopene, 374 mcg beta-carotene, 14.3 g carbohydrate, 68 kcal. One fruit without refuse is listed as 55 g and one cup as 165 g.
  2. König A, Schwarzinger B, Stadlbauer V, Lanzerstorfer P, Iken M, Schwarzinger C, Kolb P, Schwarzinger S, Mörwald K, Brunner S, Höglinger O, Weghuber D, Weghuber J. Guava (Psidium guajava) Fruit Extract Prepared by Supercritical CO(2) Extraction Inhibits Intestinal Glucose Resorption in a Double-Blind, Randomized Clinical Study. Nutrients. 2019;11(7):1512. doi: 10.3390/nu11071512.PubMedUsed to support: Double-blind randomized study in 31 healthy young adults: 2.5 mL of a supercritical CO2 guava fruit extract in a 75 g glucose drink gave a smaller glucose rise than the glucose drink alone at 30 minutes (p = 0.039) in the main analysis of 10 extract versus 15 control subjects, while the rises at 60 and 90 minutes, the glucose area under the curve (p = 0.076) and the insulin area under the curve did not differ significantly; the abstract's additional 90 minute result is not shown in the results section. Single dose. Funded by Austrian public research bodies; one author's salary was paid by PM International AG.
  3. Roy Choudhury D, Nair Krishnapillai M, Nagalla B, Vijaya Kankipati R, Ghosh S, Buwade J, Fernandez-Rao S. Guava with an institutional supplementary meal improves iron status of preschoolers: a cluster-randomized controlled trial. Ann N Y Acad Sci. 2021;1492(1):82-95. doi: 10.1111/nyas.14556.PubMedUsed to support: Nonblinded cluster-randomized trial in 399 preschoolers: 25 g of guava with a cereal and pulse meal for 140 days raised hemoglobin, serum ferritin and plasma vitamin C and lowered iron deficiency compared with banana or cucumber, with fewer recorded respiratory infections; no effect on cognitive development or growth.
  4. Rani V, Moretti D, Khetarpaul N, Thankachan P, Zimmermann MB, Melse-Boonstra A, Brouwer ID. Vitamin C-Rich Guava Consumed with Mungbean Dal Reduces Anemia and Increases Hemoglobin but not Iron Stores: A Randomized Controlled Trial of Food-to-Food Fortification in Indian Children. J Nutr. 2024;154(12):3740-3748. doi: 10.1016/j.tjnut.2024.10.042.PubMedUsed to support: Seven-month randomized trial in 200 children aged 6 to 10: fresh guava (about 170 mg vitamin C) with a mungbean meal did not raise body iron stores, the primary outcome (p = 0.197), but raised hemoglobin by 3.7 g/L more than the meal alone (p = 0.001) and lowered anemia prevalence (p = 0.022).
  5. Monárrez-Espino J, López-Alarcón M, Greiner T. Randomized placebo-controlled trial of guava juice as a source of ascorbic acid to reduce iron deficiency in Tarahumara indigenous schoolchildren of northern Mexico. J Am Coll Nutr. 2011;30(3):191-200. doi: 10.1080/07315724.2011.10719960.PubMedUsed to support: Randomized placebo-controlled trial in 95 anemic children aged 6 to 9: 300 mL of natural guava juice (about 200 mg vitamin C) with the main meal on school days for 10 weeks gave 0.64 g/dL higher hemoglobin than a vitamin C-free guava-flavored drink (p = 0.01) in the iron-deficient subsample, with no significant difference in ferritin; the authors called the effect marginal.
  6. Nair KM, Brahmam GN, Radhika MS, Dripta RC, Ravinder P, Balakrishna N, Chen Z, Hawthorne KM, Abrams SA. Inclusion of guava enhances non-heme iron bioavailability but not fractional zinc absorption from a rice-based meal in adolescents. J Nutr. 2013;143(6):852-8. doi: 10.3945/jn.112.171702.PubMedUsed to support: Stable-isotope study in 16 adolescents: adding 100 g of guava to a rice meal gave the meal 20 times more vitamin C and raised iron absorption (23.9% versus 9.7% in girls, 19.2% versus 8.6% in boys, P < 0.05), while fractional zinc absorption did not change.
  7. Amaliya A, Risdiana AS, Van der Velden U. Effect of guava and vitamin C supplementation on experimental gingivitis: A randomized clinical trial. J Clin Periodontol. 2018;45(8):959-967. doi: 10.1111/jcpe.12922.PubMedUsed to support: Randomized trial in young nonsmoking adults: 200 g guava a day or 200 mg synthetic vitamin C a day, taken before and during 14 days without oral hygiene, led to significantly smaller Gingival Index rises (0.10 and 0.24) than water (0.87); plaque was significantly lower with guava than water.
  8. Thaptimthong T, Kasemsuk T, Sibmooh N, Unchern S. Platelet inhibitory effects of juices from Pachyrhizus erosus L. root and Psidium guajava L. fruit: a randomized controlled trial in healthy volunteers. BMC Complement Altern Med. 2016;16:269. doi: 10.1186/s12906-016-1255-1.PubMedUsed to support: Randomized trial in 30 healthy volunteers (10 per group): a single 500 mL serving of fresh guava juice attenuated collagen-induced, but not ADP-induced, ex vivo platelet aggregation compared with water. Heart rate and blood pressure fell from baseline after guava juice, but versus water only systolic pressure at 5 hours was significantly lower, from a higher starting value. Funded by the Thailand Research Fund.
  9. Kumari S, Rakavi R, Mangaraj M. Effect of Guava in Blood Glucose and Lipid Profile in Healthy Human Subjects: A Randomized Controlled Study. J Clin Diagn Res. 2016;10(9):BC04-BC07. doi: 10.7860/JCDR/2016/21291.8425.PubMedUsed to support: Randomized study in 45 healthy medical students: 400 g/day of ripe guava without peel for 6 weeks lowered total cholesterol, triglycerides and LDL within the group, with no significant change in fasting glucose; guava with peel raised fasting glucose and lipids. Results were reported as before and after changes within each group, without clear between-group comparisons against the control group.
  10. Singh RB, Rastogi SS, Singh R, Ghosh S, Niaz MA. Effects of guava intake on serum total and high-density lipoprotein cholesterol levels and on systemic blood pressure. Am J Cardiol. 1992;70(15):1287-91. doi: 10.1016/0002-9149(92)90763-o.PubMedUsed to support: Randomized, single-blind 12-week trial in 120 people with essential hypertension reporting net falls in total cholesterol (9.9%), triglycerides (7.7%) and blood pressure (9.0/8.0 mm Hg) and a rise in HDL (8.0%) with guava fruit. PubMed lists no retraction or expression of concern, but the paper was among those recalculated in a BMJ inquiry into the lead author's data, so its results are not used as evidence here.
  11. Singh RB, Rastogi SS, Singh NK, Ghosh S, Gupta S, Niaz MA. Can guava fruit intake decrease blood pressure and blood lipids? J Hum Hypertens. 1993;7(1):33-8..PubMedUsed to support: Randomized, single-blind 4-week trial in 145 people with essential hypertension: a diet with 0.5 to 1.0 kg of guava daily reportedly lowered blood pressure by 7.5/8.5 mm Hg, total cholesterol by 7.9% and triglycerides by 7.0% versus usual diet. The reported soluble fiber intake (47.8 g/day) is hard to reconcile with guava's total fiber content, and the group's data were later questioned, so the results are not used as evidence here.
  12. White C. Suspected research fraud: difficulties of getting at the truth. BMJ. 2005;331(7511):281-8. doi: 10.1136/bmj.331.7511.281.PubMedUsed to support: Not a guava study. BMJ article describing concerns about data from the Moradabad research group of the lead author of the guava trials. A statistical reviewer recalculated results from several manuscripts and published papers, including the 1992 guava trial, and found that P values recalculated from the reported means and standard deviations consistently failed to agree with those reported. No official body reached a formal finding of misconduct.
  13. Nguyen HH, Wattanathorn J, Thukham-Mee W, Muchimapura S, Paholpak P. A Pilot Randomized, Double-Blind, Placebo-Controlled Parallel Group Trial Evaluating the Effect of 8 Week-Consumption of Guava Jelly Drink in Improving Cognition and Mental Well-Being in Working-Age Adults. Foods. 2026;15(14):2461. doi: 10.3390/foods15142461.PubMedUsed to support: Pilot double-blind trial in 75 adults aged 20 to 40: 86 g/day of a guava juice and mint syrup jelly drink for 8 weeks versus placebo jelly. Versus placebo at 8 weeks, P300 latency was shorter with the low dose and two memory test scores were better with the high dose; most other measures did not differ, the low dose improved an anxiety score versus placebo, and the high dose stress and total anxiety and depression score changes were reported against baseline. The placebo lacked mint, so effects cannot be attributed to guava alone. University-funded.
  14. Müller U, Stübl F, Schwarzinger B, Sandner G, Iken M, Himmelsbach M, Schwarzinger C, Ollinger N, Stadlbauer V, Höglinger O, Kühne T, Lanzerstorfer P, Weghuber J. In Vitro and In Vivo Inhibition of Intestinal Glucose Transport by Guava (Psidium Guajava) Extracts. Mol Nutr Food Res. 2018;62(11):e1701012. doi: 10.1002/mnfr.201701012.PubMedUsed to support: Laboratory and animal study: guava leaf and fruit extracts inhibited glucose transport by up to about 80% in human intestinal Caco-2 cells, with a greater effect on GLUT2 than SGLT1, and the activity survived treatment with digestive juices. In C57BL/6N mice the extracts significantly lowered blood glucose. No human participants.
  15. Deguchi Y, Miyazaki K. Anti-hyperglycemic and anti-hyperlipidemic effects of guava leaf extract. Nutr Metab (Lond). 2010;7:9. doi: 10.1186/1743-7075-7-9.PubMedUsed to support: Leaf, not fruit. Review from the leaf tea's manufacturer summarizing small Japanese trials of an aqueous guava leaf extract tea for post-meal and fasting blood sugar and blood fats. Cited only to show that the blood sugar research on guava leaf is a separate body of evidence from the fruit.