Raisins (Vitis vinifera L.) are dried grapes. They are a convenient, shelf-stable snack and fresh fruit alternative enjoyed worldwide. Among dried fruits, raisins have the highest concentration of polyphenols—beneficial compounds with antioxidant and anti-inflammatory properties.

Most commonly made from Thompson Seedless grapes, raisins are naturally sweet because they contain more than 50% fructose and glucose (sugars). Despite their sweetness, raisins won’t necessarily raise your blood sugar. This is due to their high fiber content, which helps slow the digestion of sugars.

Raisins have promising gut health benefits and contain nutrients that support bone and heart health.

Raisins rank high among fruits with significant antioxidant potential due to their rich polyphenol content.

In the body, antioxidants offset harmful compounds called free radicals. When free radicals build up, it leads to oxidative stress, a state that causes cell damage and disease. By neutralizing free radicals, antioxidants help prevent oxidative stress and protect against disease. Resveratrol, a type of polyphenol and antioxidant, is especially notable for its heart-protective benefits.

When grapes are dried to make raisins, the concentration of beneficial phytonutrients increases because the same nutrients are now available in a smaller package.

Some nutrients and compounds can be lost during the drying process for raisins. Various pretreatment methods, such as coating with olive oil before drying, have been investigated to retain quality and prevent losses.

Dried fruits, including raisins, are excellent sources of dietary fiber. Raisins provide 4.5 grams (g) of fiber per 100-g serving, which is about 16% of the Daily Value (DV). Dietary fiber is essential for managing cholesterol and healthy blood sugars. It also supports gut health.

Raisins provide both soluble and insoluble fiber. Soluble fiber helps regulate blood sugar and cholesterol, while insoluble fiber (undigested fiber) adds bulk to stools and promotes regularity.

Raisins contain a particular fiber that may enhance a healthy gut microbiome—the community of bacteria and other microorganisms in the gastrointestinal tract. During the dehydration process, some of the grapes’ sugars are converted into fructans, a type of fiber with prebiotic properties. Prebiotics promote the growth of healthy gut bacteria. Raisins contain as much as 8% of these beneficial fructans.

A study involving healthy adults who consumed three servings of raisins daily showed an increase in beneficial gut bacteria, specifically Faecalibacterium prausnitzii, which is associated with improved colon health. More studies are needed to validate these findings.

Raisins contain a significant amount of fructose, a type of sugar with a low glycemic index (GI). Foods with a low GI are less likely to cause a spike in your blood sugar levels. Research suggests that moderate fructose consumption might help with blood sugar control.

Although raisins contain glucose, which can raise your blood sugar, they are also a good source of dietary fiber. Fiber is beneficial for blood sugar control because it helps slow the digestion of sugars, preventing a sharp rise in blood sugar.

Trials of people both with and without diabetes or other health conditions have shown that eating raisins can keep postprandial (after eating) blood sugar levels stable and prevent excessive insulin release into the blood. Long-term human studies are still needed to determine to what extent raisins affect blood sugar control.

Though research is limited, including raisins in your diet might help you lower your risk of heart disease. Their dietary fiber can reduce levels of low-density lipoprotein (LDL) cholesterol, also known as “bad cholesterol.” Raisins are also rich in polyphenols, which can influence cholesterol absorption and help maintain healthier cholesterol levels.

Research suggests that the polyphenols in raisins might also help lower blood pressure. Additionally, polyphenols like resveratrol possess antioxidant properties that may help reduce heart disease risk by decreasing inflammation and neutralizing harmful free radicals.

Raisins contain small amounts of calcium, magnesium, and vitamin K, which are nutrients that support bone health.

The dried fruit also contains a significant amount of the mineral boron: 2200 micrograms (mcg), or about 2.2 g, per 100-g serving. The recommended boron supplementation for people at risk for osteoporosis (a condition causing brittle bones) is 3 g.

Boron is essential for bone health as it influences certain hormones (chemical messengers) that affect your bones. It also enhances the metabolism of vitamin D and boosts the absorption of magnesium, both of which help support bone health.

Other nutrients in dried fruit that contribute to bone health include potassium and copper. A 1.5-ounce (oz) box of raisins provides 320 milligrams (mg) of potassium, about 6% of the DV, and 0.12 mg of copper, about 13% of the DV.

Both dark seedless raisins and sultanas, also called golden raisins, come from Thompson Seedless grapes, a light green–gold variety. However, sultanas are generally sweeter and softer than their darker counterparts. They are often coated with oil before drying.

To keep their golden color, sultanas are treated with sulfur dioxide, a bleaching preservative that prevents them from oxidizing (turning brown) and retains their quality and uniform color.

Per 100-g serving, raisins and sultanas are similar in calories, protein, and sugars. Dark seedless raisins, however, are higher in fiber (4.5 g compared to sultanas’ 3.3 g) and contain 80% more iron.

Currants, also known as Zante currants or Corinthian raisins, are derived from the Black Corinth grape. They have existed for centuries in Mediterranean cultures. Compared to raisins, they are smaller in size.

Overall, currants and raisins have a similar nutritional profile (calories, fiber, sugars, etc.). Per 100-g serving, they both deliver around 4.5 g of fiber and over 60 g of sugar. However, because currants are much smaller than raisins, you’ll get more currants than raisins for the same volume portion.

A 100-g serving of dark, seedless raisins provides:

• Calories: 299
• Fat: 0.25 g 
• Sodium: 26 mg
• Carbohydrates: 79.3 g
• Fiber: 4.5 g
• Sugar: 65.2 g
• Protein: 3.3 g
• Copper: 0.27 mg, or 30% of the DV
• Potassium: 744 mg, or 16% of the DV
• Magnesium: 36 mg, or 8.5% of the DV

Packed with fiber, potassium, and antioxidants, raisins can be a heart-healthy snack option. Plus, they are very low in fat and sodium. The dried fruit also contains smaller amounts of calcium and vitamin K, which can help support bone health.

Grape and raisin allergies are uncommon but possible. Anaphylaxis related to the consumption of grapes or their products is rare.

However, some raisins are processed with preservatives like sulfur dioxide. People with sulfite allergies may have severe or life-threatening reactions due to these preservatives. Raisins can also incur some mold during the drying process, which means raisins may not be suitable for individuals with mold allergies.

Food allergies can present as hives, itching or swelling in and around the mouth, and abdominal cramping. If you experience these symptoms after eating raisins, seek medical help and don’t eat raisins again until consulting a healthcare provider.

It’s always a good idea for people with specific allergies to consult with their healthcare provider to avoid eating any potentially harmful foods.

While eating raisins straight out of the box can be a satisfying snack, there are several other ways to include them in your diet:

• Enjoy them in oatmeal: Stirring raisins into your oatmeal while it cooks allows them to become plump and juicy, adding a natural sweetness to your porridge.
• Sprinkle on a parfait: A sprinkling of raisins adds a delightful texture and a touch of sweetness that pairs perfectly with fresh fruit and nuts.
• Use as a salad topper: Raisins’ dense chewiness complements a variety of textures in a salad and adds a burst of sweetness.
• Create muesli: Mix raw oats with sliced almonds, raisins, and a dash of cinnamon for a nutritious, fiber-rich breakfast. Serve with a dairy or plant-based milk of your choice.
• Swap out chocolate chips: Replace chocolate chips with raisins in cookies, muffins, and other baked treats to maintain sweetness while increasing fiber content.
• Make trail mix: Combine raisins with a mix of nuts and seeds for a convenient, energy-boosting snack.
• Enhance a savory dish: Add raisins to savory dishes like couscous. Their sweet flavor can balance the richness of stewed meats and earthy spices and add a unique twist to your meal.

Though raisins are often sun-dried, the process can take several days. You can make raisins at home using your oven instead. Here’s how to make them:

1. Wash and dry a couple of bunches (or two pounds) of grapes.
2. Pierce each grape to allow moisture to escape as they dry out.
3. Place the grapes onto a baking sheet and lightly spray with cooking oil.
4. Bake at 145 degrees Fahrenheit (63 degrees Celcius) for eight hours or more until they are wrinkled and chewy, as desired.
5. Remove the dried grapes from the oven and let cool completely. This will reduce any moisture buildup that can turn into mold.
6. Store the raisins in an airtight container for up to a few weeks.

Raisins are a dried fruit snack commonly enjoyed around the world. Fiber-rich and packed with antioxidant polyphenols, they have heart-protective and gut-friendly potential. Despite being naturally sweet, raisins might also aid in blood sugar control.

While raisin allergies are rare, preservatives in the processing and too much moisture retention during the drying process may cause reactions in people with sulfite or mold allergies.

You can enjoy raisins as a snack or serve them in oatmeal, trail mix, or savory dish. If you have a few bunches of grapes, you can also make your own raisins at home.