We all know grapes are the world’s biggest and most valuable fruit crop — and are among the sweetest natural foods we can eat. But given their high sugar content, can grapes truly be part of a healthy diet? And what about wine, grape juice, and jelly?

Humans have been cultivating grapes for a long time — possibly as long as we’ve been living in civilizations. Babylonian ruler Hammurabi, famous for publishing the world’s first written code of laws, used his power to regulate the wine trade in the 18th century BCE.

The ancient Greeks and Romans worshiped the God of Wine (named Dionysus and Bacchus, respectively) with festivals, rituals, and, yes, drunken parties, too. When the Vikings first landed in North America, they found it so covered in wild grapes that they named it “Vinland.”

And the grape’s popularity hasn’t diminished with time. By edible weight, grapes are the world’s number one fruit crop, with about 74 million tons produced each year.

Grapes are grown for three purposes: eating fresh (as table grapes), eating dried (as raisins), and drinking (as wine and grape juice). But roughly half of all grapes grown around the world end up in wine bottles.

Given that grapes are high in naturally occurring sugars, and that they’re frequently fermented in alcoholic beverages, are grapes actually healthy? What about when that sweetness is concentrated in raisins? And how do we make sense of all the conflicting information about whether compounds in wine help us live longer, or cause disease?

Grapes of course are classified  as a small, round fruits — technically berries — that grow in clusters on deciduous vines of the flowering plant genus Vitis. They come in  number of  colors, ranging from yellow to green to red to crimson to purple to black (with even some dark blue and orange varieties thrown in for good measure). The darker grapes get their hue from differing kinds and concentrations of anthocyanins, a type of flavonoid that’s very interesting to health and antiaging researchers because of its unique antioxidant effects

While you could theoretically dehydrate any old grape into a raisin, cook it into jelly, or press and ferment it into wine, there are different varieties that are considered optimal for each of these culinary purposes.

Vitis vinifera is the dominant grape species for winemaking (in Latin, its name means “grapevine carrying wine”). You may be familiar with some of its more famous varieties, including Sauvignon Blanc, Syrah, Riesling, and Muscat Blanc. Vinifera grapes have a high sugar content and come in a wide range of berry sizes.

Table grape varieties include Thompson, Flame, Crimson seedless, Concord, Muscat, Niagra, and Red Globes.

Grapes are are nutritional powerhouses. According to the USDA, a serving of grapes is one cup or about 32 grapes.  In addition to a dose of hydration, a cup of grapes will provide, on average:

104 calories

27.3 grams of carbohydrates

23.4 grams of sugar

1.1 grams of protein

1.4 grams of fiber

18% of the daily value (DV) for vitamin K

6% DV for potassium

21% DV for copper

9% DV for thiamin

8% DV for riboflavin

8% DV for vitamin B6

Raisins also contain a decent amount of potassium, copper, and fiber. However, because the water content of the grapes has been removed, you’re mostly left with a concentrated sugar source. One small 1.5-oz box of raisins can contain a whopping 28g of sugar! However, as you’ll see below in the section on health benefits, raisins do share many of the health benefits of raw grapes.  

Pro Tip make sure to brush your teeth after, as dried fruit tends to stick to the teeth.

When it comes to antioxidants, the darker the grape, the higher the antioxidant concentration. And the red and purple grape varieties are highest in anthocyanins. Research shows that these compounds may help reduce the risk of heart disease, cognitive decline, and type 2 diabetes, as well as support healthy weight maintenance and a normal inflammatory response.

To get scientific Grapes also resveratrol, which has been associated with increased nitric oxide (NO) production. It is  a powerful neurotransmitter that helps blood vessels relax and also improves circulation, both of which are associated with heart health.

It also acts against tumors, and people are looking into using it to help prevent and treat several kinds of cancer. Green Grapes sure why not! They also deliver a wealth of phytonutrients and antioxidants, most of which belong to the flavanol family of polyphenols.

With all those antioxidants and polyphenols and anthocyanins and NO boosters, you’d expct grapes to provide oodles of health benefits. And luckily, they don’t disappoint.

Grapes and Type 2 Diabetes

Grapes can be very sweet. So you might be surprised to learn that both red and green grapes, as well as unsweetened grape juice, are considered to be low on the glycemic index and have a low glycemic load. Apparently, the fiber, water, and other cofactors in grapes help to create balance and to slow the absorption of the sugars they contain.

And might grapes also contain compounds that are helpful in the prevention of type 2 diabetes? Yes! The skin and seeds of the Vitis vinifera grape can reduce inflammation, prevent cell death, and encourage cell growth in people with type 2 diabetes. They can also reduce oxidative stress (which can damage cells) and improve the way your body metabolizes fats. Ironically, the skin and seeds of grapes, called grape pomace, are typically discarded in the wine-making process. But they are included in many fresh grape juices.

In 2021, researchers discovered that grape pomace can help treat type 2 diabetes. They chose a grape called Carménère (used in Chilean winemaking) and subjected its pomace to hot pressurized liquid extraction (which would make a great name for a spy thriller about a plot to smuggle hot water balloons out of the country).

Several of the polyphenols of interest in the resultant mixture were found to inhibit diabetes-related enzymes. A cluster of proanthocyanidins reduced the activity of two of the enzymes more effectively than the drug acarbose (you might know it as Precose or Prandase) that’s prescribed to accomplish the same thing.

Grapes and their Metabolic Benefits.

Metabolic syndrome is a group of conditions, often caused or worsened by diet, that can lead to serious problems like high blood pressure, type 2 diabetes, and heart disease. The polyphenols found in grapes may protect the body from some of the health problems that are often associated with a high-fat, highly processed diet: high LDL cholesterol, high blood sugar, and high blood pressure. The polyphenols also appear to protect the stomach and liver and can help prevent obesity.

A 2017 study found that a compound extracted from the skin of grapes also improved metabolic markers in rats fed a high-fat diet. Protection included lower cholesterol, decreased insulin resistance, protection against oxidative damage, and reduced inflammation. (Our view on the use of animals in medical research is here.)

Grapes are good for the liver as well. In 2012, researchers studied the effects of extracts from the Suosuo grape variety, which is popular in China, on mice whose livers had been damaged by an overactive immune response. They discovered that two substances from the grapes, triterpenoids and flavonoids, seemed to calm this response down. They also reduced the concentrations of harmful chemicals in the liver, helped restore its enzyme activity, and balanced out proteins that control cell death, as well as regulated immune system messengers in the liver.

Eight years later, scientists were able to more or less replicate these findings in humans. A 2020 study found that the flesh and skin of seedless black grapes protected people’s livers from chemical damage more effectively than the standard-of-care drug, silymarin. A particular class of polyphenols known as phenolics decreased stress and inflammation in the liver, which in turn helped to reduce damage and prevent liver scarring.

Grapes and Inflammation is a good thing — until it’s not. Acute inflammation helps with wound healing, but chronic inflammation can cause damage to tissues and organs, lead to diseases like heart disease, type 2 diabetes, and inflammatory bowel disease, and lead to premature aging. IL-8, also known as Interleukin-8, is a type of protein in the body that plays a major role in the inflammation process. It’s needed to fight infections and heal wounds, but too much IL-8 can also lead to excessive inflammation and potentially contribute to disease. And many people in the modern world suffer from ongoing and excessive chronic inflammation.

A 2016 study found that a Turkish variety of raisins had a significant effect in reducing the release of IL-8. It was discovered that this was mainly because these raisins have seeds, unlike many other types.

In 2020, Romanian researchers tested fresh and fermented extracts of the pomace of a local grape variety, Fetească neagră, as well as pomace from Pinot Noir grapes, to compare their effects on inflammation, oxidative stress, and cancer cell growth in test tubes and in rats with inflammation. Both fresh and fermented pomace extracts reduced oxidative stress caused by inflammation, while the fermented Fetească neagră extracts most powerfully inhibited cancer cell growth.

 

Then a  2023 review article noted that grape extracts’ antioxidant and anti-inflammatory properties make them ideal ingredients in skin care products, due to their potential to improve skin condition and reduce signs of aging. Grape extracts can also do a number on potentially harmful microbial pathogens. Compounds from grape pomace may help control gum inflammation caused by harmful bacteria, suggesting that you might start seeing grapes in the ingredient list of some brands of toothpaste.

What about Grapes and Grape Products. Are they good for you?  Fresh grapes check a lot of nutritional boxes. They contain antioxidants and flavonoids that can help to reduce inflammation and lower heart disease risk. They’re high in fiber, which can promote healthy digestion. And thanks in part to their fiber, which is especially high in grape skins and seeds, grapes’ high sugar content doesn’t appear to be a problem for most people. But what about other grape products, like wine, raisins, jams, juices, and jellies? Do the benefits of consuming those foods outweigh the negatives?

And Finally Wine! As many already are aware, There’s a lot of evidence that drinking alcohol, even in moderation, can increase your risk of certain cancers and cardiovascular diseases. But recent research has found what appears to be an exception for wine. A 2023 review determined that wine differs from other alcoholic beverages in how it interacts with our cells. Drinking wine in moderation not only does not increase the risk of chronic degenerative diseases, the researchers concluded, but it may actually be associated with health benefits.

One reason could be wine’s high polyphenol content, including but not limited to resveratrol, anthocyanins, catechins, and tannins. Polyphenol content and composition vary from grape to grape and wine to wine, but red wines tend to contain more polyphenols than whites.

Variations in winemaking techniques matter as well when it comes to potential wine health benefits. Fermentation, maceration (grinding up the grapes), aging, clarification (fining and filtering), and the use of preservatives can impact what polyphenols make it into the bottle and how long they remain active. And there are other well-known catches related to alcohol to consider, too, including its negative effects on mental health and its well-known propensity for addiction.

Grape Juice provides many benefits without fermentation. Maybe  the best way to get all these awesome polyphenols is to drink the juice of the grape before it’s fermented into alcohol. It’s certainly a common way to consume grapes: Grape juice is one of the most popular fruit juice flavors in the US. And it has a similar biochemical makeup as wine, so it could potentially deliver similar health benefits minus the alcoholic toxicity and danger of dependence.

But, downside here is that many brands of grape juice contain added sugar. If you want to drink grape juice, you may want to consider making your own, so you can be sure the final product is 100% juice. But — even if you find a brand with zero added sugar, or make your own, the juice still may deliver large concentrations of sugar to your body all at once. That’s because it’s missing the fiber that can act to slow down absorption, meaning it could trigger an unhealthy blood sugar spike in some people.

Make your own! Grape jams and jellies are another popular way to consume grapes. And for a fruit that’s already so sweet on its own, you might be shocked to discover how much refined sweetener is often added to the final product. Many brands of grape jam and jelly use high-fructose corn syrup manufactured from bioengineered (GMO) corn. They may also contain other harmful additives, such as artificial colors, flavors, and preservatives.

The bottom line here? If you want to derive the maximum health benefits from grapes, the safest way is to consume them in their whole food form. Enjoy!