Raisins: Nutrition Facts, the Concentration Effect, and Why Athletes Have Eaten Them for Thousands of Years

Raisins are dried grapes — a statement so obvious it seems barely worth making, but that single fact explains almost everything about their nutritional profile. When grapes are dried, they lose nearly all their water and about three-quarters of their weight, concentrating their nutrients roughly four-fold. The result is a food that provides 37% of daily copper, 20% of potassium, 14% of Vitamin B6, 12% of manganese, 10% of iron, and 9% of phosphorus at 299 calories per 100g — alongside 66g of natural sugar that makes raisins a well-studied whole-food fuel for endurance exercise.

Understanding raisins properly means understanding both sides of that picture: useful mineral concentration alongside a sugar density that deserves the same honest treatment we give honey and maple syrup.

Raisins Nutrition Facts (per 100g)

* Value from USDA’s SR Legacy data, where the Foundation Foods entry doesn’t include it. Figures are for dark seedless raisins.

Raisins Nutrition Facts (per 43g serving — approximately one small box or a quarter cup)

A standard small snack box of raisins weighs about 43g:

Even a small snack box provides 16% of daily copper and about as much potassium as a medium banana, alongside 34g of readily available carbohydrate.

Vitamins in Raisins (per 100g)

* Value from USDA’s SR Legacy data, where the Foundation Foods entry doesn’t include it.

Worth noting: Raisins’ vitamin profile is modest — B6 at 14% DV is the strongest contribution, supporting protein metabolism and neurotransmitter production. Drying costs grapes most of their more fragile vitamins: fresh grapes provide 3.2mg of Vitamin C per 100g, while USDA’s analysis of dark raisins found none. Raisins’ real nutritional value lies in their minerals, fiber, and polyphenols rather than their vitamins.

Minerals in Raisins (per 100g)

* Value from USDA’s SR Legacy data, where the Foundation Foods entry doesn’t include it.

Standout: Copper at 37% DV is raisins’ most impressive mineral figure — making them one of the better plant sources of copper, which supports iron metabolism, collagen formation, and energy production. Potassium at 936mg per 100g (20% DV) is genuinely significant, and iron at 10% DV makes a useful contribution, especially when raisins are eaten with a source of Vitamin C.

The Concentration Story: Why Dried Fruit Is So Nutrient-Dense

The drying process explains both raisins’ impressive mineral figures and their high sugar content — both are consequences of the same thing.

Fresh grapes are about 80% water. When they’re dried — in the sun, in the shade, or in mechanical dehydrators — they lose nearly all of it, ending up only about 15% water. The grapes shrink to roughly a quarter of their original weight, so 100g of raisins is made from roughly 400–450g of fresh grapes.

The math: 100g of fresh grapes contains 191mg of potassium; 100g of raisins contains 936mg — about five times as much. Sugar concentrates the same way: fresh grapes contain about 15.5g of sugar per 100g, raisins about 66g.

The practical implication: raisins aren’t “more sugary” than grapes in the sense of having sugar added — they’re simply concentrated grapes. The fair comparison isn’t raisins against grapes per 100g, but raisins against the amount of grapes they came from. A 43g box of raisins is roughly equivalent to 185g of fresh grapes — more convenient and longer-lasting, but much more calorie-dense per bite, because the water that would normally fill you up and slow you down has gone.

Antioxidants: What Drying Does to Polyphenols

Fresh grapes are well known for their polyphenols — flavonoids, phenolic acids, and, in red and black grapes, anthocyanins. What happens to them during drying?

The picture is mixed:

Some compounds are lost — drying, especially in the sun, breaks down some polyphenols. Anthocyanins are particularly sensitive, and the browning that turns grapes into dark raisins uses up some of the grapes’ phenolic compounds.

What survives is concentrated — the same concentration effect that applies to minerals also applies to the polyphenols that survive drying, so raisins still have meaningful antioxidant capacity per gram.

New compounds form — browning reactions during drying create new flavor and color compounds that weren’t present in fresh grapes, some of which also have antioxidant activity.

The net result: raisins have fewer of some polyphenols than the grapes they came from, but still a useful antioxidant content per gram — more than most processed snacks of similar calorie density.

Raisins as Endurance Fuel: The Sports Nutrition Research

This is raisins’ best-researched practical use.

An Ancient Energy Food

Dried fruits like raisins have been carried as portable, long-lasting energy foods for thousands of years, particularly in Mediterranean and Middle Eastern cultures. Their combination of quickly available sugar, portability, and shelf life made them one of the most practical travel and endurance foods long before modern sports nutrition existed.

The Modern Research

Several sports science studies have directly compared raisins with commercial sports products:

A 2011 study in the Journal of Strength and Conditioning Research found that cyclists who ate raisins before a time trial performed just as well as when they ate commercial sports jelly beans, with similar blood glucose responses.

A 2012 study found similar results for running: raisins supported running performance just as well as commercial sports chews, at lower cost and as a whole food without added colors or preservatives.

These studies were small, but together they suggest raisins are a legitimate, cost-effective whole-food alternative to sports chews and gels for longer sessions — typically those lasting more than about an hour.

Why Raisins Work as Endurance Fuel

Readily available sugar — raisins’ glucose and fructose are absorbed quickly, providing the fast fuel that endurance exercise demands. Because glucose and fructose use different transporters in the gut, the mix can be absorbed faster than glucose alone.

Portable and shelf-stable — small boxes need no refrigeration and fit easily in a jersey pocket or running belt.

Potassium — 936mg per 100g adds potassium to your carbohydrate fuel, though sweat contains much more sodium than potassium, so raisins don’t replace salt and electrolyte drinks during long, sweaty sessions.

A familiar whole food — many athletes find raisins easy to tolerate, though their fiber means very large amounts during hard efforts may not suit everyone, so test them in training first.

Timing guidance: a small box (43g) provides about 34g of carbohydrate — similar to one to one-and-a-half typical energy gels. Eating one 30–45 minutes before, or during, an endurance session of 60 minutes or more is a practical whole-food carbohydrate dose.

Health Benefits of Raisins

Copper for Iron Metabolism and Collagen

At 37% DV per 100g, raisins are one of the better plant sources of copper. Copper is needed for ceruloplasmin, an enzyme that helps the body use iron to make haemoglobin — so raisins’ copper helps you use their iron (10% DV), as well as the iron from other foods. Copper is also essential for cross-linking collagen in connective tissue.

Potassium for Heart and Muscle Health

At 936mg per 100g, raisins are one of the richest potassium sources among common foods — nearly three times as much as bananas per 100g, and a small 43g box (402mg) has about the same as a medium banana, though with more calories. Potassium helps counter sodium’s effect on blood pressure, supports heart rhythm, and maintains the fluid balance that muscle contraction depends on.

Iron for Oxygen Transport

At 10% DV per 100g, raisins contribute useful non-haem iron. Eating them alongside Vitamin C-rich foods improves its absorption — which makes the classic combination of raisins with fresh fruit, or a yogurt topped with raisins and orange segments, nutritionally sensible as well as tasty.

Boron and Bone Health

Raisins are one of the richest food sources of boron — a trace mineral that isn’t listed on standard nutrition labels. Boron appears to play a role in bone health and in how the body uses calcium, magnesium, and Vitamin D, though it isn’t officially classed as essential and the evidence is still limited. Raisins also contribute calcium (4% DV) and magnesium (8% DV).

Blood Pressure

Raisins combine a lot of potassium (936mg) with very little sodium (13mg per 100g) — a favorable balance for blood pressure. In one small 12-week study of adults with mildly raised blood pressure, eating raisins three times a day lowered blood pressure compared with eating other common snacks.

Gut Health: Fiber and Tartaric Acid

Raisins provide 3.7g of fiber per 100g, along with tartaric acid — an organic acid found in grapes that is fermented by gut bacteria. Small studies have found that eating raisins can speed up intestinal transit, and raisins may support beneficial gut bacteria, though the research is still limited.

Raisins for Athletes and Active People

Endurance Exercise Fuel

As covered above, raisins are a legitimate, cost-effective whole-food carbohydrate for endurance sessions of 60 minutes or more, performing as well as commercial products in the studies available.

Practical fueling guide:

• Before training (30–90 minutes before): 40–50g of raisins with water, plus a small protein source if it’s more than an hour before
• During exercise (sessions over 60 minutes): a small box every 45–60 minutes provides about 30–45g of carbohydrate per hour — in line with typical sports nutrition guidance
• After training: raisins with a protein source for a simple carbohydrate-plus-protein recovery snack

Potassium During Exercise

A small box provides 402mg of potassium alongside its carbohydrate — making raisins a more complete endurance snack than pure sugar sources such as sweets or plain glucose.

Iron Support for Endurance Athletes

Plant-based endurance athletes and premenopausal women, who are at higher risk of iron deficiency, benefit from any convenient source of non-haem iron. Raisins’ 10% DV per 100g is a useful contribution when eaten regularly — especially with Vitamin C-rich foods.

Raisins vs Fresh Grapes: The Honest Comparison

The comparison confirms that raisins are concentrated grapes — stronger on minerals and fiber per gram, weaker on fragile vitamins lost in drying, and far more calorie-dense, because the water that naturally limits how fast you eat grapes has been removed.

The Portion Reality: Where Context Matters

Raisins’ 66g of sugar per 100g deserves the same honest context we give honey, jam, and maple syrup — not because raisins are harmful, but because their concentration makes it easy to eat more sugar and calories than you’d expect from a “healthy snack.”

A small box (43g) — 28.4g of sugar and 129 calories, similar in sugar to a small chocolate bar. As fuel before or during exercise, that’s an appropriate, practical serving. As an everyday snack eaten on top of regular meals without accounting for it, it’s a meaningful addition of sugar and calories.

A handful from a large bag — a generous 60–70g pour provides about 40–46g of sugar and 180–210 calories. It’s easy to underestimate, given how small the physical volume is.

The practical guidance: treat raisins as an intentional source of calories and carbohydrate rather than a free snack — valuable when used with purpose (endurance fuel, trail mix, recipes, or as part of a meal), but worth portioning like other concentrated sugar foods.

Practical Ways to Include Raisins in Your Diet

Before or during endurance exercise — the best-evidenced use; a small box (43g) is portable carbohydrate fuel comparable to commercial sports products.

In trail mix with nuts and seeds — the classic combination of raisins, almonds, and pumpkin seeds makes a portable, energy-dense, mineral-rich snack, balancing raisins’ quick sugar with the fat and protein of nuts and seeds, which also add Vitamin E.

In oatmeal — 20–30g of raisins adds natural sweetness, potassium, copper, and iron, while the oats’ fiber moderates the meal’s overall blood sugar response.

In baking — raisins in homemade bread, muffins, or energy bars add natural sweetness, letting you reduce the added sugar.

On yogurt or cottage cheese — adds sweetness, copper, and potassium to a protein-rich base. If you’re relying on raisins for iron, note that the calcium in dairy can reduce iron absorption at the same meal.

In savory dishes — raisins are a classic ingredient in Moroccan tagines, rice pilafs, and Middle Eastern grain dishes, adding sweetness that balances spices.

Potential Considerations

Portion awareness — as covered above, treat raisins as a concentrated source of sugar and calories and use them intentionally.

Dental health — like other sticky, sugary foods, raisins can cling to teeth and contribute to tooth decay if eaten very often. Rinsing with water afterward and not grazing on them throughout the day reduces the risk.

Blood sugar management — people with diabetes or insulin resistance should account for raisins’ sugar content (GI around 64 — moderate) in meal planning. Small portions as part of a meal, or as fuel around exercise, are easier to fit in than larger amounts eaten alone.

Sulfite sensitivity — golden raisins and some other dried fruits are treated with sulfur dioxide (sulfites) to preserve their light color, which can cause reactions in people with sulfite sensitivity, including some people with asthma. Ordinary dark raisins are usually untreated — check the label.

Toxic to dogs — grapes and raisins are toxic to dogs and can cause potentially fatal kidney failure. Keep all grape products out of reach of pets: even small amounts can be dangerous, and sensitivity varies unpredictably between dogs.

Nutrient data: USDA FoodData Central, Foundation Foods — raisins, dark, seedless (FDC ID 2758980); values marked * from SR Legacy (FDC ID 168165). Comparison: grapes, red or green (European type), raw (SR Legacy, FDC ID 174683). Glycaemic index value from published GI testing. % Daily Values use the FDA’s current Daily Values.