News and studies on grape juice

The 2025 grape harvest was one of the best of the decade in southern Brazil

Published 08/13/2026 · source from March 2025

Brazil's 2025 grape harvest in Rio Grande do Sul exceeded expectations: estimates from Consevitis-RS and Embrapa Uva e Vinho (Brazil's grape and wine research agency) pointed to about 750 million kilograms of grapes harvested in the state, a 38.5% increase over 2024's 541.52 million kg; the Serra Gaúcha region, the country's main grape-juice belt, accounted for 80% of that volume.[1]

Weather cooperated: a spring and summer with enough cold hours, no late frosts, and a dry harvest window, conditions that favored more even ripening. Growers interviewed for the report described grapes with more intense flavor and aroma and higher sugar concentration, which tends to translate into juice with deeper color and fuller taste.[1]

Worth noting: more natural sugar in the grape doesn't change the per-age serving recommendations already covered elsewhere on this site; it's good news for product quality, not a reason to drink more.

Grapes, resveratrol, and memory: what science has confirmed (and what's still a promise)

Published 08/13/2026 · systematic review from January 2025

We already mention on the Older adults page that a small pilot study linked grape juice to improved verbal memory. A systematic review and meta-analysis published in Frontiers in Aging Neuroscience in January 2025 helps put that kind of finding in perspective.[2]

The review pooled randomized controlled trials on natural compounds and cognitive performance, including two studies on Vitis vinifera (grapevine) supplementation: a 12-week trial showed improvement on cognitive screening tests (MMSE and RBANS); a 26-week trial found no direct cognitive improvement, but observed that brain metabolism declined less in specific regions than in the control group.[2]

A separate trial on isolated resveratrol, in people with mild-to-moderate Alzheimer's disease, found no statistically significant effect on biomarkers or cognition over a year of follow-up.[2]

The reviewers' own conclusion: the evidence base is still mixed, and not strong enough to recommend any single natural compound, grape-derived or otherwise, as a substitute for established medical treatment.[2] In short: it's a promising research area worth watching, but grape juice does not treat or prevent cognitive decline on its own. Anyone concerned about this should talk to a doctor.

Video: what Dr. Michael Greger found reviewing 5 studies on grapes and the brain

Published 08/13/2026 · video from February 2020

Michael Greger is a physician, a New York Times bestselling author, and the founder of NutritionFacts.org, a nonprofit known for videos that summarize scientific research with full citations. In "Benefits of Grapes for Brain Health," he reviews five studies on grapes (juice or whole fruit) and brain function, landing on a more cautious conclusion than usually makes it into headlines on the topic.[3]

The studies, in the order he presents them: a 2010 trial with Concord grape juice showed improved verbal learning in older adults with mild cognitive impairment (but not memory, which wasn't statistically significant); a 2012 repeat, using the same tests, found no benefit for verbal learning, the opposite of the first study; a 2016 study in middle-aged mothers improved one memory measure and driving-simulator performance, but not most of the cognitive measures tested; and a 2017 study in young adults had only 2 of 7 cognitive measures reach statistical significance.[3]

The point Greger emphasizes most: several of these studies were funded by Welch's, a grape juice manufacturer: a relevant conflict of interest when interpreting results that favor the product.[3]

One detail worth flagging for readers of this site: in the only study that used brain imaging (PET) to directly measure metabolism, the group that benefited was the one given freeze-dried grape powder (the whole fruit, dehydrated), not juice: the placebo group declined in regions associated with early Alzheimer's, while the grape group did not.[3] It echoes something we say elsewhere on this site: whole fruit tends to have the edge over juice when it comes to more consistent evidence.

Watch: Benefits of Grapes for Brain Health — Dr. Michael Greger, NutritionFacts.org (YouTube)

Red or white grape juice: which has more polyphenols?

Published 08/13/2026 · source from 2005 (Food Science and Technology)

One of the most common questions on this topic. Short answer: if the goal is maximizing polyphenols and resveratrol, red wins, and the reason is the production process, not something magical about the color. Red juice is made with more contact with the grape skin (where these compounds concentrate), while white juice gets much less of that contact.[4]

A Brazilian study published in the journal Food Science and Technology measured trans-resveratrol between 0.19 and 0.90 mg/L in domestic grape juices, levels that make whole red grape juice a reasonable alternative source of resveratrol for people who don't drink wine, though well below the concentration found in red wine (0.82 to 5.75 mg/L).[4]

That doesn't mean white juice "isn't worth it": it keeps most of the vitamins and minerals grapes offer, it's just lower in these specific dark-skin-linked antioxidants. If you already prefer white's milder flavor, there's no need to switch over this; it's more a matter of priority than "right or wrong."

Source: Determinação de resveratrol em sucos de uva no Brasil (in Portuguese) — Sautter et al., Food Science and Technology (2005)

"Does grape juice make you gain weight?" — one of the most-searched questions, answered

Published 08/13/2026

It's one of the most typed questions on this topic, so it's worth a direct summary. According to Brazil's official food composition table (TACO/Unicamp), 100 ml of bottled concentrated grape juice has 58 kcal and 14.7 g of carbohydrates; for comparison, that's a calorie-per-milliliter close to a regular soda.[5]

According to registered dietitian Renata Mayer (CRN 41459), grape juice doesn't "make you gain" or "help you lose" weight on its own: what determines that is your overall daily calorie balance. The catch is that juice has little fiber, protein, or fat (the nutrients that create satiety), so it's digested quickly and doesn't sustain fullness the way whole fruit would.[6]

In practice, this lines up with what we say elsewhere on this site: grape juice can fit into a balanced diet, but whole fruit, with its fiber intact, tends to be the better pick when the goal includes weight or blood sugar control.

Sources: TACO table — Uva, suco concentrado, envasado (in Portuguese) · Suco de uva engorda? Especialista responde (in Portuguese) — Renata Mayer/Vitat

Video: how Proteste tests which whole grape juice is best

Published 08/13/2026 · video with 90,000 views

We already cite Proteste's written test on the Favorites page, with the ranking of all 15 brands evaluated. Proteste also published a video showing the process behind that test: analyst Eugênio walks through the criteria used to judge flavor, acidity, and quality across whole grape juice brands sold in Brazil.[7]

The video has over 90,000 views and nearly 300 comments, many from viewers naming their favorite brand, which gives a sense of how much personal opinion this topic stirs up in Brazil (and how much individual taste varies beyond what any ranking can capture).

Watch: Qual será o melhor suco de uva integral? (in Portuguese) — Proteste channel, YouTube

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