Grapes come in different colors and forms. There are red, green, and purple grapes, seedless grapes, grape jelly, grape jam and grape juice, raisins, currants, and sultanas, not to mention wine.
Up to 8,000 years ago, people first cultivated grapevines in what is now the Middle East.
Today, 72 million tons of grapes are grown each year worldwide, mostly to produce wine. Every year, 7.2 trillion gallons of wine are produced. Grapes are also a popular finger food.
The nutrients in grapes offer a number of possible health benefits. They have been associated with the prevention of cancer, heart disease, high blood pressure, and constipation.
Fast facts about grapes
- The nutrients in grapes may help protect against cancer, eye problems, cardiovascular disease, and other health conditions.
- Resveratrol is a key nutrient in grapes that may offer health benefits.
- Grapes are a good source of fiber, potassium, and a range of vitamins and other minerals.
- Grapes are suitable for people with diabetes, as long as they are accounted for in the diet plan.
A diet that is rich in fruits and vegetables has been linked to a reduced risk of various conditions, including heart disease, diabetes, cancer, and obesity.
Like other fruits and vegetables, grapes are a good source of fiber and water.
Antioxidants and other nutrients in grapes may make them particularly healthful, although more research is needed to confirm some of their benefits.
Here are some of the ways in which the nutrients in grapes may boost health.
Grapes contain powerful antioxidants known as polyphenols. These are thought to have anti-inflammatory and antioxidant properties. One of these is resveratrol. It is found in the skins of red grapes.
Laboratory studies have suggested that resveratrol may be able to slow or prevent the growth of tumors in lymph, liver, stomach, breast, colon, skin cancer, and leukemia.
Resveratrol is also present in red wine. Few studies have looked at the association between red wine and cancer risk in humans, but it has been shown that high intakes of alcohol on a consistent basis can increase the risk of cancer. Moderation is key.
A moderate intake of alcohol is defined by The Dietary Guidelines for Americans as up to one drink per day for women, and up to two drinks per day for men.
Another natural anti-inflammatory that occurs in grapes is the flavonoid quercetin. Studies have suggested that this, too, may help prevent or slow cancer growth.
2) Heart health
Animal studies have indicated that quercetin and resveratrol may reduce the risk of atherosclerosis and protect against the damage caused by low-density lipoprotein (LDL), or “bad” cholesterol.
These studies have mostly used doses of these flavonoids far higher than those usually consumed by humans.
The polyphenols in grapes, such as resveratrol, are thought to have antioxidant, lipid-lowering, and anti-inflammatory actions that may help reduce the risk of cardiovascular disease (CVD). They may achieve this by preventing platelet build-up and reducing blood pressure and the risk of irregular heart rhythms.
Grapes contain fiber and potassium, both of which support heart health. The American Heart Association (AHA) recommends increasing potassium intake while decreasing sodium consumption to improve blood pressure and cardiovascular health.
A study of data for 12,267 adults in the United States has shown that the more sodium people consume in relation to their potassium intake, the higher the risk of all-cause mortality.
High potassium intake has been associated with a reduced risk of stroke, protection against loss of muscle mass, and preservation of bone mineral density.
3) Blood pressure
Increasing potassium intake may help reduce the negative effects of too much sodium in the diet.
Grapes have a high potassium content. This suggests they can help reduce the effects of sodium in people with high blood pressure.
Fiber is important for maintaining a healthy cardiovascular system, including heart health and blood pressure. Grapes are a good source of fiber.
Grapes contain water and fiber. These can help people stay hydrated, keep bowel movements regular, and reduce the risk of constipation.
Because of the anti-inflammatory effects of quercetin, some suggest that consuming grapes may help to alleviate symptoms of allergies, including runny nose, watery eyes, and hives.
However, no human studies have been done to prove this theory.
In 2013, results of a study published in the BMJ suggested that certain fruits, but not juices, may reduce the risk of type 2 diabetes in adults.
During the study, which involved 187,382 participants and lasted 22 years, 6.5 percent of the participants developed diabetes.
However, those who consumed three servings a week of blueberries, grapes, raisins, apples, or pears had a 7-percent lower risk of type 2 diabetes compared with those who did not.
The relatively high level of sugar found in grapes leads some people to ask whether they are safe for people with diabetes to eat.
The American Diabetes Association encourages people to consume grapes and other fruits, as long as the carbohydrate amount is counted as part of their meal plan.The vitamins, minerals, and fiber in grapes make them a healthful way to satisfy a sweet tooth.
7) Diabetic neuropathy and retinopathy
Some studies have indicated that resveratrol may protect against diabetic neuropathy, which affects nerve function. Scientists believe this may be due to the neuroprotective effects of this compound.
Animal studies have indicated that resveratrol may also protect against retinopathy, which can severely affect vision.
Diabetic neuropathy and retinopathy can result when diabetes is poorly controlled.
8) Eye health
Grapes contain the antioxidants lutein and zeaxanthin, which can help maintain eye health. They are thought to neutralize unstable molecules known as free radicals. In this way, they may reduce oxidative stress and damage to the retina, and help prevent cataracts and other conditions.
Laboratory tests have suggested that resveratrol may protect against various eye problems, including age-related macular degeneration, glaucoma, cataract, and others.
However, it remains unclear exactly how it works, and how it might be beneficial to humans.
Results of an in vitro study published in the journal Dermatology and Therapy claims that resveratrol could help treat acne, especially if used with benzoyl peroxide as a topical treatment.
10) Other conditions
Other health issues that resveratrol may help with include:
- Alzheimer’s disease
- blood glucose control
- boosting the immune system
However, some studies have questioned whether resveratrol can benefit humans in these ways. More evidence is needed.
According to the U.S. Department of Agriculture (USDA), one cup of red or green grapes weighing around 151 grams (g) contains:
- 104 kilocalories
- 1.09 g of protein
- 0.24 g of fat
- 27.33 g of carbohydrate, of which 23.37 g is sugars
- 1.4 g of fiber
- 288 mg of potassium
- 15 milligrams (mg) of calcium
- 0.54 mg of iron
- 11 mg of magnesium
- 30 mg of phosphorus
- 3 mg of sodium
- 0.11 mg of zinc
- 4.8 mg of vitamin C
- 22 micrograms (mcg) of vitamin K
- 3 mcg of folate
Grapes also contain vitamins B and A, and they are high in water content. A cup of grapes contains over 121 g of water.
They are also high in antioxidants, such as lutein and zeaxanthin. The skins of red grapes contain the phytochemical resveratrol, which appears to protect against several chronic diseases and conditions.
The flavonoids myricetin and quercetin are also found in grapes. These help the body to counteract harmful free radical formation.
Grapes are available year-round. Select grapes that are tight to the touch and free of wrinkles. They are best stored in the refrigerator and should be washed before eaten.
The best way to eat grapes is as fresh fruit. Most grape jellies or spreads and juices have added sugars, and they can be high in calories.
Here are some handy tips for incorporating more grapes into the diet:
- Slice grapes in half and add them to a chicken salad.
- Make a fruit cocktail with fresh grapes, pineapple, sliced peaches, and strawberries.
- Freeze grapes and eat them as a snack or dessert on a hot day.
- Have a cup of fresh grapes for a quick, 100-calorie snack
A group known as the Environmental Working Group (EWG) produces a list each year of fruits and vegetables with the highest levels of pesticide residue, known as the Dirty Dozen. Grapes are currently number 8 on this list. Buying organic grapes can reduce the risk of pesticide exposure.
Beta-blockers are commonly prescribed for heart disease. They can cause potassium levels to increase in the blood. People who use beta-blockers should consume foods that are high in potassium in moderation.
People who use blood-thinning drugs should speak to their doctor before consuming large quantities of grapes, as resveratrol may increase the anticoagulant action of these drugs, in a similar way to Vitamin K. Warfarin, or Coumadin is a popular blood thinner.
Consuming too much potassium can be harmful to those whose kidneys are not fully functional. If the kidneys cannot remove excess potassium from the blood, this can be fatal.
When drinking wine, women are advised to drink no more than one drink a day, and men no more than two.
A final word
Both red and green grapes contain resveratrol, but red grapes, and specifically their skins, contain more. It is better to get the benefits of resveratrol from eating grapes rather than drinking wine.
Resveratrol is available in supplement form, but the benefits of grapes include fiber and a range of minerals and vitamins. Dietary sources of nutrients are more beneficial than supplements because they supply fiber and other nutrients.