When eating grapes, most people enjoy the flesh and leave the seeds and sometimes the skin behind.
However, grape seeds contain a variety of naturally occurring plant compounds, including polyphenols.
One group of compounds commonly associated with grape seeds is proanthocyanidins, a type of polyphenol found in a variety of plant foods.
Grape seeds are used in several different ways. Oil can be extracted from the seeds to produce grape seed oil, while other extraction methods are used to produce grape seed extracts containing selected plant compounds.
In this article, we take a closer look at grape seed itself, including its naturally occurring compounds, the difference between grape seed extract and grape seed oil, proanthocyanidins and OPC, and some useful points to consider when choosing a grape seed supplement.
What Is Grape Seed?
Grape seed is simply the seed found inside a grape.
Large quantities of grapes are used to make products such as wine and grape juice. The seeds remaining from these processes can also be used for a variety of purposes.
Because grape seeds contain oil, they can be processed to produce grape seed oil.
On the other hand, extracts produced with a focus on plant compounds such as polyphenols are generally referred to as grape seed extract.
Although both products originate from grape seeds, grape seed oil and grape seed extract are different products with different compositions and characteristics.
Are Grape Seed Oil and Grape Seed Extract the Same?
When people hear the term “grape seed,” they may immediately think of grape seed oil used in cooking.
However, when learning about grape seed, it is useful to distinguish between grape seed oil and grape seed extract.
Grape Seed Oil
Grape seed oil is a vegetable oil obtained from grape seeds.
Its main fatty acids include linoleic acid and oleic acid. Depending on the product and manufacturing process, grape seed oil may also contain vitamin E and other naturally occurring components.
It is commonly used as a culinary oil and is known for its relatively mild flavour.
Grape Seed Extract
Grape seed extract is produced by extracting selected plant compounds naturally present in grape seeds.
One of the groups of compounds commonly associated with grape seed extract is proanthocyanidins.
For this reason, many grape seed supplements focus not on the oil itself, but on polyphenols derived from grape seeds.
What Are Polyphenols?
When researching grape seed, you will frequently encounter the term “polyphenols.”
Polyphenols are a broad group of compounds naturally produced by plants.
They are found in many foods and beverages we consume every day, including fruits, vegetables, legumes, tea, coffee and cacao.
Some familiar examples include:
- Anthocyanins found in grapes and berries
- Catechins found in green tea
- Isoflavones found in soybeans
- Quercetin found in foods such as onions
- Cocoa polyphenols found in cacao
- Proanthocyanidins found in grape seeds and other plant foods
In other words, “polyphenol” does not refer to one single substance. It is a general term covering a very large and diverse group of naturally occurring plant compounds.
Proanthocyanidins in Grape Seed
Among the compounds found in grape seeds, proanthocyanidins are among the most widely discussed and studied.
Proanthocyanidins are a type of polyphenol. They occur not only in grape seeds and grape skins but also in apples, cacao, berries and various other plant foods.
When reading about grape seed, you may also encounter the abbreviation “OPC.”
OPC is commonly used to refer to Oligomeric Proanthocyanidins.
The term is generally associated with relatively small oligomeric forms within the broader proanthocyanidin group.
Older health information and promotional materials sometimes describe OPC using claims such as “many times stronger than vitamin C” or “many times stronger than vitamin E.”
However, such numerical comparisons should not automatically be interpreted as showing how these compounds behave in the human body.
Antioxidant activity measured under laboratory conditions is not necessarily equivalent to what happens after a food or supplement is consumed, absorbed and metabolised.
For this reason, it is more appropriate to understand proanthocyanidins as one of the characteristic groups of polyphenols naturally present in grape seeds, rather than describing them using exaggerated comparisons.
What Does “Antioxidant” Mean?
Another term frequently associated with grape seed and polyphenols is “antioxidant.”
Our bodies naturally produce reactive oxygen species (ROS) as part of normal biological processes involving oxygen.
Reactive oxygen species are not simply substances that need to be eliminated. They also participate in various normal physiological processes.
However, when the balance between their production and the body's protective mechanisms changes, this may contribute to what is commonly described as oxidative stress.
The human body has its own systems for responding to oxidative processes.
Compounds found in foods—including vitamin C, vitamin E, carotenoids and various polyphenols—have also been widely studied in relation to antioxidant activity.
It is important, however, not to interpret this as meaning that consuming larger quantities of antioxidant compounds automatically leads to better health.
Nutrition depends on the overall diet rather than one isolated compound.
A varied and balanced diet containing vegetables, fruits, whole grains, legumes and other nutritious foods should remain the foundation.
Different Parts of the Grape Contain Different Compounds
A grape is made up of several parts, and its flesh, skin and seeds do not have identical compositions.
While the flesh is the part most commonly eaten, the skin and seeds also contain a variety of naturally occurring plant compounds.
Grape seeds in particular have been studied as a source of proanthocyanidins and other polyphenols.
Eating significant quantities of grape seeds as part of an everyday diet, however, is not especially practical for most people.
For this reason, grape seed extracts have been developed as another way of using compounds obtained from the seeds.
Today, grape seed is available not only as a single-ingredient supplement but also in products combining grape seed with other ingredients such as propolis.
It is important to remember that supplements are still foods rather than medicines.
They should not be used with the expectation of preventing, treating or curing a disease, and they are not a replacement for a balanced diet.
Taking a Closer Look at the Compounds Found in Grape Seed
As we have seen, grape seed contains polyphenols including proanthocyanidins.
However, the presence of polyphenols alone should not be used to determine the overall value of a food or supplement.
Plants contain a large number of naturally occurring compounds, and even grapes can vary depending on factors such as variety, growing conditions, the part of the plant used and the extraction process.
There can also be important differences between consuming a plant as a food and consuming a concentrated extract in supplement form.
For this reason, when considering grape seed products, it is useful to look beyond a single highlighted compound and understand the ingredients and the form in which they are provided.
OPC Is a Term Related to Proanthocyanidins
The abbreviation OPC is frequently found on grape seed supplement information.
OPC generally stands for Oligomeric Proanthocyanidins.
Proanthocyanidins are a group of compounds made up of structural units such as catechin and epicatechin. Different forms can exist depending on how these units are linked and their degree of polymerisation.
OPC should therefore not be thought of as an entirely separate nutrient. It is a term used in relation to particular forms within the broader proanthocyanidin group.
When comparing products, it is better not to rely on the term “OPC” alone. Check the ingredient list, serving information and the amount or type of extract stated on the product label.
Antioxidant Activity and Health Effects Are Not the Same Thing
The term “antioxidant” is frequently used when discussing polyphenols and grape seed.
Scientific research investigates many different plant compounds, including their chemical properties, metabolism and behaviour under various experimental conditions.
However, demonstrating antioxidant activity in a laboratory experiment does not by itself demonstrate a particular health effect in humans.
It is important to consider whether research was conducted in a laboratory, in animals or in humans, as these types of studies provide different kinds of information.
For this reason, grape seed is best discussed as a plant-derived source of naturally occurring polyphenols rather than linking it directly to the prevention or treatment of specific health conditions.
Polyphenols Are Also Available from Everyday Foods
You do not need to take supplements in order to consume polyphenols.
They occur naturally in many everyday plant foods and beverages, including:
- Grapes and berries
- Apples and other fruits
- Soybeans and other legumes
- Vegetables such as onions
- Green tea and black tea
- Coffee
- Cacao-containing foods
Different foods contain different types and amounts of polyphenols.
Rather than relying heavily on one particular food, eating a variety of plant foods is a sensible way to approach everyday nutrition.
Grape seed can be considered one of many plant-derived sources of polyphenols.
What to Check When Choosing a Grape Seed Supplement
Grape seed extracts are widely used as ingredients in dietary supplements.
If you choose to use a supplement, it is worth looking beyond marketing messages and checking the information provided on the product label.
1. Check the Ingredients
Start by checking the ingredient list.
Some products primarily contain grape seed, while others combine grape seed with additional botanical or nutritional ingredients.
Checking the ingredients helps you understand exactly what you are consuming.
2. Understand What the Stated Amount Means
Supplement labels often prominently display amounts such as “XX,000 mg.”
It is important to understand that the actual weight of a concentrated extract and its stated equivalent amount of original plant material are not necessarily the same thing.
For example, a relatively small quantity of concentrated botanical extract may be described as being equivalent to a much larger quantity of the original raw material.
Rather than comparing products based only on the largest number printed on the label, check whether the figure refers to the actual extract amount, a dry-herb equivalent or another form of equivalence.
3. Check the Recommended Daily Intake
Supplements generally provide instructions or a suggested daily intake.
Taking more than the recommended amount does not necessarily provide additional benefit, so follow the directions provided with the individual product.
4. Check for Overlapping Ingredients
If you use several supplements at the same time, some ingredients may overlap.
It can therefore be useful to review the ingredient and nutritional information across all the supplements you regularly use rather than considering each product in isolation.
Single-Ingredient and Combination Grape Seed Supplements
Grape seed supplements are available in different formulations.
Some products focus primarily on grape seed extract, providing a relatively straightforward formulation centred on grape seed-derived compounds.
Others combine grape seed with additional ingredients such as propolis or other botanical materials.
Neither approach is automatically better than the other.
The important point is to check the ingredients and product information and choose a formulation that suits your individual dietary preferences and needs.
Supplements Are Intended to Complement the Diet
One of the most important things to understand about grape seed—and supplements in general—is their role within the diet.
Supplements provide certain ingredients in a convenient and concentrated form.
They are not, however, a substitute for everyday food.
A varied diet should remain the foundation for obtaining protein, fats, carbohydrates, vitamins, minerals, fibre and the many other compounds naturally present in food.
People who take medicines, are receiving medical treatment, are pregnant or breastfeeding, or have concerns about their health should consider speaking with a doctor, pharmacist or other qualified healthcare professional before using supplements.
Start by Understanding Grape Seed
Although grape seeds are easy to overlook, they contain naturally occurring plant compounds including proanthocyanidins and other polyphenols.
At the same time, information about grape seed sometimes uses the word “antioxidant” in ways that may imply very broad health benefits.
Rather than placing too much emphasis on a single compound, it is more useful to understand what the ingredient is, where it comes from and how it fits into the overall diet.
Grape seed extract supplements are simply one of the available ways in which grape seed-derived ingredients can be consumed.
When choosing a product, check its ingredients, the meaning of the stated amounts, and the recommended intake rather than relying solely on large numbers or promotional terminology.
Summary
Grape seed is a plant-derived ingredient obtained from the seeds of grapes.
Grape seeds contain polyphenols including proanthocyanidins, and these compounds continue to be studied for their chemical and nutritional characteristics.
Here are the main points covered in this article:
- Grape seed simply means the seed of the grape.
- Grape seed oil and grape seed extract are different products.
- Grape seeds contain polyphenols including proanthocyanidins.
- OPC is a term commonly used in relation to oligomeric proanthocyanidins.
- Polyphenols are also naturally present in many other plant foods.
- The word “antioxidant” alone should not be interpreted as proof of a specific health benefit.
- When choosing supplements, check the ingredients, serving information and the meaning of stated amounts.
- Supplements are not a replacement for a varied and balanced diet.
Rather than relying on one particular food, supplement or compound, consider grape seed as one of many plant-derived ingredients that can form part of a broader approach to everyday nutrition.
Important Information
This article is intended to provide general educational information about grape seed, polyphenols and proanthocyanidins.
It is not intended to diagnose, treat, cure or prevent any disease, nor does it claim that any particular food or dietary supplement provides such effects.
Dietary supplements are not substitutes for medicines or medical treatment. If you have concerns about your health, take medication, are undergoing medical treatment, or are pregnant or breastfeeding, consult a doctor, pharmacist or other qualified healthcare professional when appropriate.
