A grape is a berry, and the grapes on a plate mostly belong to the same species as wine grapes, Vitis vinifera. A 2023 genetic study of 3,525 vines estimated that domestication happened about 11,000 years ago, in Western Asia and the Caucasus at about the same time, and produced both table and wine grapevines. Wine still takes most of the crop: about 71% of the world’s grapes in 2023, against 27% eaten fresh and 2% dried.
“White” grapes are really pale green. Red and black skins get their color from anthocyanin pigments, and white grapes lack them because of mutations in two neighboring genes. In a study of 55 white varieties, every one carried the same white version, which suggests that all of them share a common origin. Grapes also have a famous party trick: cut halves throw sparks in a microwave oven. Researchers explained it in 2019 as microwaves concentrating into hotspots where two water-filled, grape-sized spheres touch.
Many of the human trials below did not use fresh grapes. They used a freeze-dried grape powder made under the California Table Grape Commission, an industry group, and the Commission funded several of them. In two trials, 46 g of powder stood in for 252 g of fresh grapes. Resveratrol, a compound grapes contain, has also been tested as pills, and the trials below label those plainly.
Health benefits of grapes
The top findings from 28 studies, strongest evidence first
What the stars mean
- Strong. Several randomized trials, pooled in a meta-analysis, point the same way, or regulators (FDA or EFSA) have approved the claim.
- Moderate. Good randomized trials support it, but there are fewer of them, or their results vary.
- Limited. Small, short or single trials, or mixed results. Promising, but it needs confirmation.
Population and lab studies get no stars: they show a link or a mechanism, not proof.
How we rate evidence →- ★★Slightly lower “bad” LDL cholesterolGrape products in any form, not only fresh grapes, lowered LDL by about 5 mg/dL across 48 trials. Total cholesterol fell 6.2 mg/dL, and HDL did not change.
- ★★Slightly lower blood pressureThe top number fell by about 3 points (3.17 mm Hg systolic) across 30 trials, though the certainty was low. Raisins and powder worked, grape juice did not.
- ★★Less insulin resistance, no change in HbA1cGrape products made the body respond better to insulin (insulin resistance fell by 0.54 on the HOMA-IR scale). HbA1c, average blood sugar, did not change, and fasting blood sugar came out slightly higher (1.19 mg/dL).
- ★★No clear effect on body weightGrapes and grape products did not change body weight, waist size or body fat. BMI fell by 0.14, which the authors say to ignore given the low quality of the studies.
- ★★Lower blood pressure with grape seed extractGrape seed extract, a supplement made from the seeds and not the fruit, lowered the top number by about 6 mm Hg systolic. The bottom number fell 2.8 mm Hg.
All 28 studies, strongest evidence first
Grape products in any form lowered LDL cholesterol by about 5 mg/dL in a meta-analysis of randomized trials
Meta-analysis of 48 randomized trials (59 study arms) of grape products in any form, not only fresh grapes. Total cholesterol fell 6.2 mg/dL and triglycerides 7.6 mg/dL, while HDL did not change. The effect on HDL and LDL varied with the dose of polyphenols.
Grape products lowered systolic blood pressure by 3.17 mm Hg, but the certainty of the evidence was low
Meta-analysis of 30 randomized trials of grape products, including juice, raisins and grape powder. Whole grape products (raisins and powder) lowered systolic pressure by 2.69 mm Hg, while grape juice did not. Diastolic pressure, blood vessel function and heart rate did not change, and results varied between trials.
Grapes and grape products lowered insulin resistance (HOMA-IR) by 0.54, but not HbA1c, and fasting blood sugar came out slightly higher
Meta-analysis of 29 trials (1,297 people) of grapes or grape products. Fasting insulin and HbA1c did not change, and fasting blood glucose was 1.19 mg/dL higher than in the control groups. The authors ask for larger, longer trials.
Grape products lowered one liver enzyme, ALP, but not ALT or AST, in a meta-analysis of 11 trials
Adults in trials lasting at least 2 weeks. All three enzymes fell in trials of 12 weeks or longer and in trials of grape seed extract, which is a supplement. The authors say the effects were small and may not matter in practice.
Grapes and grape products did not change body weight in a meta-analysis of randomized trials
BMI fell by a trivial 0.14, which the authors say should be ignored given the low quality of the studies. Waist circumference, body fat, waist-to-hip ratio, leptin and adiponectin did not change. Weight fell 0.68 kg in 3 trials in women and 0.62 kg in 3 trials in people with metabolic syndrome.
Grape seed extract, a supplement, lowered systolic blood pressure by about 6 mm Hg in a meta-analysis
Meta-analysis of 16 trials in 810 people. Diastolic pressure fell 2.8 mm Hg. The drops were larger in obese people and in people with metabolic syndrome. The extract comes from the seeds, not the fruit, and the authors call for larger, longer trials.
Resveratrol pills, a compound grapes contain, did not lower CRP, cholesterol, blood sugar or blood pressure across 10 trials
Meta-analysis of 10 randomized trials (11 treatment arms) of resveratrol supplements. HDL cholesterol was slightly lower, by 4.18 mg/dL. These were pills, not grapes, so they say little about eating the fruit.
Eating 500 g of red grapes a day for 8 weeks lowered LDL cholesterol in people with high cholesterol
Randomized trial in 69 people with high cholesterol, who ate 500 g of red or white whole grapes a day or nothing extra. The drop in total and LDL cholesterol against the control group was reported for red grapes, and both colors raised antioxidant capacity, with red grapes cutting a marker of fat damage (TBARS) more. Blood sugar, triglycerides and HDL did not change. That is a large daily amount.
36 g a day of grape powder for 4 weeks lowered triglycerides by 15% in premenopausal and 6% in postmenopausal women
Double-blind crossover trial in 24 premenopausal and 20 postmenopausal women, who took freeze-dried grape powder or a placebo with matching calories for 4 weeks each. LDL cholesterol, a urine marker of whole-body oxidative stress and TNF-alpha also fell, while LDL oxidation did not change.
Freeze-dried grape polyphenol powder for 30 days lowered systolic blood pressure and improved blood vessel dilation in men with metabolic syndrome
Double-blind crossover trial in 24 men aged 30 to 70, who took the powder or a placebo with a 3-week break between. A vessel adhesion marker (sICAM-1) was lower on the powder, and other metabolic syndrome measures did not differ. The abstract gives p-values, not the size of the drop.
46 g a day of grape powder for 4 weeks raised adiponectin and IL-10, but only in men without dyslipidemia
Double-blind crossover trial in 24 men with metabolic syndrome. The powder equals 252 g of fresh grapes. Compared with placebo, the two anti-inflammatory markers rose only in the 13 men with no dyslipidemia, not in the 11 with high triglycerides and low HDL. The California Table Grape Commission funded the study.
60 g a day of grape powder for 4 weeks lowered fasting triglycerides but did not improve HDL function in adults with metabolic syndrome
Randomized double-blind crossover pilot study in 20 adults aged 32 to 70, using freeze-dried grape powder or a placebo with a 3-week break. The main goal, a marker of how well HDL protects (PON1 activity), did not change, and neither did other blood fats or metabolic measures.
Grape powder for 3 weeks lowered large LDL particles in obese adults
Double-blind crossover trial in 24 obese adults aged 20 to 60, who took grape powder or a placebo powder for 3 weeks each. Large LDL cholesterol also fell. Immune cells made more IL-1β and IL-6 when stimulated after the grape period, which the authors read as a more sensitive response to infection risk.
A single 46 g dose of grape powder did not change blood sugar or blood fats after meals in obese adults
Double-blind crossover trial in 25 obese adults who got the powder (equal to 252 g of fresh grapes) or a placebo with breakfast, with lunch 5 hours later. Insulin, triglycerides, uric acid and antioxidant capacity did not change either. The authors suspect the polyphenol dose was too low. The California Table Grape Commission is listed among its funders.
Eating fresh table grapes for 21 days did not change blood sugar, liver enzymes or triglycerides in healthy adults
Randomized trial in 40 healthy adults, who ate 5 g of fresh table grapes per kg of body weight a day or got diet advice only. Cholesterol fell in both groups. Four weeks after the grapes stopped, the omega-3 index was higher (8.23 against 6.09), as was adiponectin, and FGF21, a marker linked to fatty liver, was lower.
46 g a day of table grape powder for 16 weeks raised macular pigment density in older adults
Double-blind placebo-controlled trial in 34 older adults in Singapore. Macular pigment optical density rose from 0.56 to 0.61 on the powder, and a skin marker of sugar damage (AGEs) rose only in the placebo group. Blood lutein and skin carotenoids did not differ. The California Table Grape Commission is listed as its funder.
46 g a day of grape powder for 4 weeks increased gut bacteria diversity and lowered total cholesterol by 6.1% in healthy adults
Pilot study that compared 4 weeks on the powder, equal to two servings of California table grapes, with a baseline period on a low-polyphenol diet. There was no placebo group. Akkermansia bacteria rose and HDL fell 7.6%, while LDL (5.9%) and bile acid (40.9%) drops were only trends. The California Table Grape Commission funded the study.
Two weeks of grape powder made 9 of 29 volunteers more resistant to UV skin redness
Each of 29 volunteers took a powder equal to three servings of grapes a day and had their skin tested before and after. The other 20 did not respond. Gut bacteria and urine markers differed between the two groups, but the authors say it is uncertain whether the gut explains the effect. The California Table Grape Commission supported the work, and one author serves on its scientific advisory committee.
Six weeks of grape powder raised hand grip strength and sped up a walking test in postmenopausal women
Pilot double-blind trial in 15 healthy postmenopausal women who took freeze-dried grape powder or a control powder. A 14.4% rise in the muscle hormone irisin was not statistically significant. The California Table Grape Commission is listed among its funders.
Eating 0.15 to 0.45 kg of grapes a day for 2 weeks lowered markers of cell growth in the colon lining
Study of 30 people who ate that amount of grapes (1/3 to 1 lb) after a low-resveratrol diet, with no placebo group. Colon biopsies before and after showed lower Ki67 and cyclin D1, and people lost 1.2 kg on average. The changes were largest in people over 50. These are tissue markers, not cancer rates.
Fresh table grape intake for 21 days changed 20 circulating microRNAs in healthy adults
Randomized trial in 40 healthy adults, using the same 5 g per kg of body weight a day of Autumn Royal grapes: 18 of the 20 microRNAs went down and 2 went up. Some of them relate to gastrointestinal cancer pathways, but the trial measured small RNA molecules in blood, not disease.
A grape drink with a high-fat meal lowered a urine marker of oxidative stress compared with placebo
Randomized trial in 32 healthy adults, who had a grape or placebo drink with a high-fat meal in the morning or the evening. The F2-isoprostane effect was borderline (p = 0.05), and the marker was highest after the morning placebo. Tartaric acid and resveratrol in urine were higher after the grape drink.
Grape powder for 5 weeks raised an antioxidant enzyme in people on hemodialysis
Double-blind trial in non-diabetic hemodialysis patients, 16 per group, with a powder providing 500 mg of polyphenols a day. CRP, an inflammation marker, rose in the placebo group but not in the grape group. The trial was small and short.
Grape and raisin eaters had a 12% lower risk of type 2 diabetes for every 3 servings a week
Three US cohorts of health professionals, with 12,198 cases of type 2 diabetes over 3,464,641 person-years. The hazard ratio was 0.88 (range 0.83 to 0.93) for grapes and raisins together, and fruit juice went with a higher risk. Diet came from questionnaires, and a link is not proof of cause.
Farm workers who ate large amounts of grapes had more tooth decay than a grain-farm comparison group, but healthier gums
Small 1989 study of farm workers in low-fluoride areas. Decay scores were 17.4 for the grape group, 24.2 for apples and 9.9 for the grain group. Advanced gum disease was lowest in the fruit groups. It was observational and old, and the groups were defined by the farm people worked on.
Mice fed table grapes in a high-fat diet for 11 weeks carried less body fat
Study in mice, not people. Mice ate a butter-rich high-fat diet with 3% or 5% grapes. The 5% group had lighter livers with less triglyceride, and 3% grapes shifted gut bacteria. Grape feeding also helped keep a gut-lining protein in place. Inflammation markers in fat tissue and the gut changed little.
A polyphenol-rich fraction of table grapes lowered body fat and improved glucose tolerance in high-fat-fed mice
Study in mice, not people. Mice ate a high-fat diet for 16 weeks with 5% whole grape powder or its polyphenol-rich or polyphenol-poor fraction. The polyphenol-rich fraction did the work, and gut bacteria changed too.
Mice fed grape powder kept their light-sensing retinal cells after an oxidative eye injury
Study in mice, not people. Freeze-dried grape powder equal to three daily human servings was fed for 5 weeks before a chemical injury to the retina. Retinal thickness, photoreceptor numbers and retinal function held up, unlike in mice on a sugar-matched control diet.
Who should be careful with grapes
Most people can eat grapes freely. Take a little care if one of these applies:
- Babies and young children. Whole grapes can block a small airway. The NHS advises cutting small, round foods like grapes into quarters (4 small pieces) and staying with a child while they eat. Hospital doctors report that whole grapes are well suited to block a child’s airway and that many people do not know it. The fix is simple: cut them.
- Irritable bowel syndrome. Grapes contain fructose, and Monash University found more of it when it retested grapes, so people who react to fructose may tolerate only small servings. Check the Monash FODMAP app for the current serving.
- Diabetes or blood sugar problems. A cup has 23.4 g of sugars. A large cohort linked grapes to a lower diabetes risk, but trials found a small rise in fasting glucose, so count grapes as carbohydrate and ask your care team about portions.
How to choose, store and eat grapes
- Red or black: the colored skins hold anthocyanins, and in the one head-to-head trial 500 g a day of red grapes lowered LDL cholesterol, a drop the trial reported for red grapes only.
- Green: the “white” grapes lack skin anthocyanins, but in the same trial they also raised antioxidant capacity against the control group.
- Raisins, powder or juice: in a meta-analysis of 30 trials, raisins and grape powder lowered systolic blood pressure by 2.69 mm Hg, while grape juice did not.
Pick plump grapes still attached to their stems, and keep them in the fridge, unwashed, rinsing gently right before you eat them and discarding any moldy ones. Residues are no reason to skip them: in USDA tests of 709 grape samples in 2023, 9 had a residue above the legal limit.
Sources
- Your baby’s first solid foods. NHS.
- Lumsden AJ, Cooper JG. The choking hazard of grapes: a plea for awareness. Arch Dis Child. 2017.
- Feltbower S, McCormack J, Theilen U. Fatal and near-fatal grape aspiration in children. Pediatr Emerg Care. 2015.
- Why FODMAP content in foods changes: retested foods. Monash University FODMAP blog.
- Muraki I, Imamura F, Manson JE, et al. Fruit consumption and risk of type 2 diabetes: results from three prospective longitudinal cohort studies. BMJ. 2013.
- Moodi V, Abedi S, Esmaeilpour M, et al. The effect of grapes/grape products on glycemic response: a systematic review and meta-analysis of randomized controlled trials. Phytother Res. 2021.
- Ashoori M, Soltani S, Kolahdouz-Mohammadi R, et al. The effect of whole grape products on blood pressure and vascular function: a systematic review and meta-analysis of randomized controlled trials. Nutr Metab Cardiovasc Dis. 2023.
- Rahbar AR, Mahmoudabadi MM, Islam MS. Comparative effects of red and white grapes on oxidative markers and lipidemic parameters in adult hypercholesterolemic humans. Food Funct. 2015.
- Guide to handling fresh produce. Colorado State University Extension.
- Pesticide Data Program annual summary, calendar year 2023. USDA Agricultural Marketing Service.
History of grapes
Grapes were farmed early. A 2023 study of the genomes of 3,525 wild and cultivated grapevines estimated that domestication happened about 11,000 years ago in Western Asia and the Caucasus, producing both table and wine grapevines. An earlier study put the split between wild and cultivated lines at about 22,000 years ago, and its authors say the long gap may reflect light management by people before true domestication. Wikipedia dates cultivation to 6,000 to 8,000 years ago, so the answer depends on whether you ask genes or archaeology.
The vines then traveled. According to the 2023 study, the Western Asia grapes spread into Europe with early farmers, mixed with wild western grapes and later split into muscat and wine types. Egyptian hieroglyphs record purple grapes, and Greeks, Cypriots, Phoenicians and Romans grew them for both eating and wine.
Seedless grapes are an old idea. The Sultana, also called Thompson Seedless, is thought to come from Asia Minor, and the Ottomans took it to Crete in the 19th century. It is named in the United States after William Thompson, an early California grower. It is the most widely planted variety there, covering about a third of California’s grape area, and in 2000 it made about 97% of the state’s raisins. Seedless vines are grown from cuttings, so having no seeds is no problem for the plant, only for breeders.
North America had its own grapes. Native Vitis species grew wild and were part of many Native Americans’ diets, but early European colonists found them unsuitable for wine. In 1849 Ephraim Bull of Concord, Massachusetts, planted seeds from wild Vitis labrusca and tested over 22,000 seedlings to find the Concord grape. Thomas Welch made the first Concord grape juice in 1869.
Today the world grows about 72.5 million tonnes of grapes a year (2023 figure), led by China, with about 19%, followed by Italy, France and the United States. Peru and Chile are the leading exporters. Most grapes still become wine, but the 27% eaten fresh is what fills the supermarket bunch.
Sources
- Dong Y, Duan S, Xia Q, et al. Dual domestications and origin of traits in grapevine evolution. Science. 2023.
- Zhou Y, Massonnet M, Sanjak JS, Cantu D, Gaut BS. Evolutionary genomics of grape (Vitis vinifera ssp. vinifera) domestication. Proc Natl Acad Sci U S A. 2017.
- Walker AR, Lee E, Bogs J, et al. White grapes arose through the mutation of two similar and adjacent regulatory genes. Plant J. 2007.
- Khattak HK, Bianucci P, Slepkov AD. Linking plasma formation in grapes to microwave resonances of aqueous dimers. Proc Natl Acad Sci U S A. 2019.
- Grape. Wikipedia.
- Sultana (grape). Wikipedia.
- Concord grape. Wikipedia.
Frequently asked questions about grapes
Are grapes good for you?
For most people, yes, in moderation. Grapes have 69 calories and 0.9 g of fiber per 100 g, and a cup (151 g) gives 18% of the daily value for vitamin K and 21% for copper. In trials, grape products lowered systolic blood pressure by 3.17 mm Hg and LDL cholesterol by about 5 mg/dL, but the certainty was low and many trials used powder, not fresh grapes.
Are red or green grapes healthier?
Red may have a small edge, but only one trial here compared them. In 69 people with high cholesterol, 500 g a day of red grapes for 8 weeks lowered total and LDL cholesterol against a control group, a drop reported for red grapes only. Both colors raised antioxidant capacity. Red and black skins get their color from anthocyanins, which green grapes lack.
How many grapes can you eat a day?
No study here sets an ideal amount. Trials used 500 g of whole grapes a day for 8 weeks, 5 g per kg of body weight for 21 days, and 0.15 to 0.45 kg for 2 weeks. A cup (151 g) has 104 calories and 23.4 g of sugars, so the amount that suits you depends on the rest of your diet.
Are grapes good for people with diabetes?
They can fit, but count them as carbohydrate. A cup has 23.4 g of sugars (15.5 g per 100 g) and the glycemic index is 54. In three US cohorts, people who ate grapes and raisins had a 12% lower risk of type 2 diabetes for every 3 servings a week, which is a link, not proof. In trials, insulin resistance fell but fasting glucose was 1.19 mg/dL higher, so ask your care team about portions.
Are grapes good for weight loss?
No study here shows that. In a meta-analysis of randomized trials, grapes and grape products did not change body weight, waist circumference or body fat. Grapes have 69 calories per 100 g and 0.9 g of fiber, so any effect would come from what they replace in your diet.
Do grapes lower blood pressure and cholesterol?
A little, in trials. Across 30 trials, grape products lowered systolic blood pressure by 3.17 mm Hg, and whole forms such as raisins and powder did so by 2.69 mm Hg while juice did not. Across 48 trials, LDL cholesterol fell by about 5 mg/dL. The certainty of the blood pressure evidence was low, and the trials included juice and seed extracts.
Can toddlers eat grapes?
Only cut up. The NHS advises cutting small, round foods like grapes into quarters (4 small pieces) when feeding babies and staying with a child while they eat. Hospital doctors report that whole grapes are well suited to block a child’s airway, and that this is not widely known. Cutting them as the NHS advises is the simple fix.
Is resveratrol in grapes good for you?
Grape powder in one trial contained resveratrol alongside flavans, anthocyanins and quercetin, but resveratrol pills did not help in 10 trials: CRP, cholesterol, blood sugar and blood pressure did not change. No trial here measured the resveratrol from eating grapes, so the benefits seen in grape trials should not be credited to it alone.