Seedless grapes

Seedless grapes: How much “nutritional information” are we losing in order to make it easier to eat?

Seedless grapes have become a common sight on supermarket shelves. They are sweet, crisp, convenient, and—above all—spare the consumer from dealing with those small seeds that many consider the fruit’s main drawback.
The breeding of seedless varieties has thus solved a very simple problem: it has made grapes easier to eat.
But does “easier to eat” necessarily mean nutritionally superior?
This is an interesting question because the grape seed—or *vinacciolo*—is not merely a small, extraneous element that gets in the way of eating the fruit. It is a biological component of the grape berry, possessing its own chemical composition that is particularly rich in phenolic compounds. Grape seeds contain catechins, epicatechins, and—above all—proanthocyanidins (and related procyanidins), as well as lipids, proteins, and carbohydrates [1].
And this is precisely where what we might call “nutritional information”—in a broad, accessible sense—comes into play.
By this term, we do not mean an official nutritional metric or a quantity that can be measured like calories or grams of protein. Rather, it describes the array of molecules, nutrients, and physical structures that a food makes available to the body when consumed in its natural state.
After all, a food is not simply the sum of its calories, sugars, fats, proteins, vitamins, and minerals. It is a complex matrix in which hundreds of molecules and structures interact with one another.
And the grape seed is part of this matrix.

The grape seed is small, yet chemically far from insignificant
When we look at a grape, the pulp naturally seems like the most important part. It is soft, sweet, high in water content, and readily available to the body. The seed, by contrast, is hard, bitter, and unappealing.
From a chemical standpoint, however, the picture is quite different. Grape seeds are particularly rich in polyphenols, including catechin, epicatechin, and proanthocyanidins. A classic review on grape seed composition details the presence of these molecules as well as more complex proanthocyanidin structures [1].
Direct comparisons between seeds and skins also demonstrate just how concentrated certain phenolic compounds are in the seed. Yilmaz and Toledo found that catechin and epicatechin concentrations in seeds were generally higher than in the skins analyzed, and they highlighted the contribution of proanthocyanidins to the seeds’ antioxidant capacity [2].
However, there is a study that is even more relevant to our discussion.
Baiano and Terracone analyzed seven table grape varieties grown in Puglia—Italia, Baresana, Pizzutello, Red Globe, Michele Palieri, Crimson Seedless, and Thompson Seedless—separating the seeds, skins, and pulp. The total phenolic content followed the hierarchy of seeds > skins > pulp, with the seeds showing high levels of proanthocyanidins [6].
This finding is particularly significant because it specifically concerns table grapes, including two seedless varieties.
Of course, this does not mean that every seeded grape is automatically superior to every seedless grape. The phenolic profile varies depending on the variety, ripeness, and growing conditions. It does mean, however, that the seed is a part of the grape berry with its own distinct biochemical composition—one that cannot simply be viewed as a hindrance to the eating experience.

What do we really know about the effects of substances found in grape seeds?
Proanthocyanidins and other polyphenols from grape seeds have sparked significant scientific interest due to their biological properties. Experimental studies have investigated, among other things, their antioxidant activity and potential interactions with vascular and metabolic processes [1,2].
However, when moving from biochemistry to human subjects, one must exercise much greater caution.
There are clinical studies involving the administration of standardized grape seed extracts—often containing polyphenol concentrations far higher than those obtained by simply eating a serving of grapes.
A 2016 meta-analysis comprising 16 clinical trials and 810 participants found an average reduction in systolic and diastolic blood pressure among subjects taking grape seed extract [3]. However, the authors themselves highlighted the heterogeneity of the studies and the need for larger, longer-term research.
Interesting data are also available regarding lipid profiles. A 2020 meta-analysis of 11 randomized trials involving 536 participants found a reduction in LDL and triglycerides, though it did not observe a significant overall effect on total cholesterol or HDL [4].
An earlier meta-analysis had examined various cardiovascular markers and found favorable results—particularly regarding certain blood pressure parameters—whereas the findings concerning lipids were less convincing [5].
These are interesting data, but they must be interpreted correctly.
This does not mean that eating grapes with their seeds is equivalent to taking a grape seed extract.
Rather, it means that certain molecules—highly concentrated in the seed—have demonstrated biological activities worthy of attention under specific experimental and clinical conditions.
This is a fundamental distinction.

And what about circulation?
There are interesting clinical data regarding venous function as well. A randomized study published in 2024 compared a *Vitis vinifera* (grape) seed extract with a purified micronized flavonoid fraction in patients with chronic venous disease. The grape seed extract was found to be non-inferior to the comparator treatment in improving venous symptoms and quality of life [7].
In this case, however, we are dealing with a standardized extract, not simply a portion of grapes.
It is therefore correct to state that grape seed compounds are being researched for potential vascular effects; conversely, it would be an overstatement to claim that eating grapes with their seeds “improves circulation” based on these studies.

And what about the prostate?
Research on grape seeds has also extended to prostate cancer, though even greater caution is warranted here.
A small Phase II study evaluated a daily dose of 300 mg of grape seed extract in men experiencing PSA progression following local treatment for prostate cancer. The results indicated a possible slowing of PSA dynamics in a subset of participants [8].
However, this was a small preliminary study—published only as a conference abstract—that lacked a placebo group. Consequently, it cannot demonstrate that grape seeds prevent or cure prostate cancer, and, above all, the findings cannot be automatically extrapolated to the consumption of grapes.
This serves as a prime example of a general rule in nutrition: the presence of a promising molecule in a food does not automatically mean that consuming that food will yield the therapeutic effect observed with a concentrated dose of the molecule or its extract.

Seeds contain more than just polyphenols
There is another point worth noting: the grape seed is not merely a small vessel for phytochemicals.
It is also a physical structure.
Its matrix is ​​resilient and contains components that are not necessarily fully digested. When the seed is chewed, some of its components may be released and made available; However, when ingested almost whole, part of its structure can pass through the gastrointestinal tract without being fully broken down.
In this respect, the grape seed can contribute—albeit modestly—to the bulk of intestinal contents through its incompletely digestible structural component.
It is important, however, not to overstate this point. There is no solid clinical evidence to support the idea that consuming grape seeds serves as a genuine remedy for constipation or as a “natural laxative.”
Any contribution they may make to bowel function should therefore be viewed as a result of the food’s overall physical structure, rather than as a proven therapeutic effect.

So, what changes with seedless grapes?
At this point, we can return to the initial question.
Seedless grapes are not a poor-quality food, nor are they something to be avoided. The flesh and skin continue to provide water, sugars, fiber, and numerous phenolic compounds. Furthermore, the phytochemical profile can vary considerably among different cultivars [6].
The point, therefore, is not to establish that seeded grapes are “healthy” while seedless ones are “unhealthy.”
That would be a simplistic conclusion, unsupported by available evidence.
The issue is different. When we remove the seed, we eliminate a part of the berry that possesses its own distinct chemical identity.
Specifically, we eliminate a fraction that can be rich in proanthocyanidins, catechins, epicatechins, and other phenolic compounds [1,2,6].
We cannot quantify the total “benefits” lost, because there is no specific “health percentage” attributable to the seed. Moreover, there are no long-term clinical studies directly comparing the habitual consumption of seeded versus seedless grapes.
However, we can state something much simpler and scientifically sound:
by eliminating a part of the fruit, we also eliminate the molecules characteristic of that part.
And this is precisely the meaning of the term “nutritional information.”

Greater edibility does not necessarily mean greater completeness
The breeding of seedless grapes solved a practical problem: it eliminated something many consumers perceive as a nuisance.
The result is a fruit that is easier to eat.
But dietary convenience and biological completeness are not necessarily the same thing.
A food can become more convenient precisely because it has been modified, selectively bred, or stripped of certain components. This does not automatically mean it becomes inferior; it simply means it changes. In the case of grapes, the change is particularly striking because the seed is not merely a residue devoid of biological function; it is the plant’s seed—a structure containing its own specific array of molecules, including significant amounts of phenolic compounds [1,6].
Therefore, when we choose a bunch of seedless grapes, we are not necessarily choosing a “less healthy” food.
We are choosing a different kind of food.
A food in which a biologically distinct component has been removed to make consumption easier.
And perhaps this is the most interesting question to ask ourselves regarding many modern foods: how much of their complexity are we willing to sacrifice for the sake of convenience?
For when we remove that tiny seed that bothers us so much, we are not simply eliminating an obstacle.
We are removing a small—yet biologically rich—part of the fruit.
And that part, too, was an integral part of its nutritional profile.

Guido Bissanti

Recommended reading
Shi J, Yu J, Pohorly JE, Kakuda Y. Polyphenolics in grape seeds—biochemistry and functionality. Journal of Medicinal Food. 2003;6(4):291–299. doi:10.1089/109662003772519831.

Yilmaz Y, Toledo RT. Major flavonoids in grape seeds and skins: antioxidant capacity of catechin, epicatechin, and gallic acid. Journal of Agricultural and Food Chemistry. 2004;52(2):255–260. doi:10.1021/jf030117h.

Zhang H, Liu S, Li L, Liu S, Liu S, Mi J, Tian G. The impact of grape seed extract treatment on blood pressure changes: a meta-analysis of 16 randomized controlled trials. Medicine (Baltimore). 2016;95(33):e4247. doi:10.1097/MD.0000000000004247.

Anjom-Shoae J, Milajerdi A, Larijani B, Esmaillzadeh A. Effects of grape seed extract on dyslipidaemia: a systematic review and dose-response meta-analysis of randomised controlled trials. British Journal of Nutrition. 2020;124(2):121–134. doi:10.1017/S0007114520000902.

Feringa HHH, Laskey DA, Dickson JE, Coleman CI. The effect of grape seed extract on cardiovascular risk markers: a meta-analysis of randomized controlled trials. Journal of the American Dietetic Association. 2011;111(8):1173–1181. doi:10.1016/j.jada.2011.05.015.

Baiano A, Terracone C. Varietal differences among the phenolic profiles and antioxidant activities of seven table grape cultivars grown in the south of Italy based on chemometrics. Journal of Agricultural and Food Chemistry. 2011;59(18):9815–9826. doi:10.1021/jf203003c.

Kim SM, Joh JH, Jung IM, Kim MJ, Lee SS, Hwang HP, Kang JM, Jung HJ, Yang SS, Min SK, Yoo YS, Gwon JG, Park HS, Lee T. Vitis vinifera seed extract versus micronized purified flavonoid fraction for patients with chronic venous disease: a randomized noninferiority trial. Annals of Vascular Surgery. 2024;109:177–186. doi:10.1016/j.avsg.2024.06.011.

Maroni P, Kessler ER, Rodrigues-Pessoa R, Nicklawsky A, Flaig T, Lam E, Bernard B, Moore J, Anderson K, Gao D, Raina K, Agarwal R. A phase II trial using grape seed extract for prostate cancer patients with non-metastatic PSA progression after local therapy [abstract]. Cancer Research. 2020;80(16 Suppl):CT207. doi:10.1158/1538-7445.AM2020-CT207.