Red wine contains measurable amounts of iron. However, it is generally not considered a high-iron food source and contributes only a small fraction to an average person’s daily intake. The concentration of iron in any given bottle can vary widely based on the entire process from vineyard to cellar.
Iron Content and Variability in Red Wine
The iron concentration in red wine typically ranges from 1 to 10 milligrams per liter (mg/L), though some analyses report an average closer to 5 mg/L. A standard 5-ounce serving (150-milliliter) provides around 0.7 milligrams of iron. This amount is small compared to the Recommended Dietary Allowance (RDA), which is 8 mg per day for adult men and postmenopausal women, and 18 mg per day for premenopausal women.
Red wine’s iron content is significantly higher than white wine, where levels are often below 1 mg/L. This difference occurs because red wine is fermented with the grape skins, which are a primary source of the element. The final concentration is influenced by factors like the specific grape varietal, the mineral composition of the vineyard’s soil, and the vintage. A serving of red wine offers less iron than common high-iron foods, such as spinach or red meat.
Sources of Iron During Wine Production
Iron enters the wine through two primary pathways: natural absorption and processing contamination. Grapevines absorb trace minerals, including iron, from the soil, which are concentrated in the grape skins and pulp. This naturally occurring iron is the foundational source in the finished product.
The concentration can increase during winemaking due to contact with various materials. While modern wineries predominantly use non-reactive stainless steel equipment, older iron machinery, pipes, or grape bins can introduce the element. Certain winemaking aids, such as fining agents like bentonite clay or filter pads, may also contribute trace amounts of iron. Excessive iron from contamination can lead to an undesirable reaction called “iron casse,” resulting in cloudiness or sediment.
Biological Impact and Health Considerations
The iron found in red wine is non-heme, which is less readily absorbed by the body than the heme iron found in animal products. The high concentration of polyphenols, such as resveratrol, present in red wine significantly impacts its bioavailability. These compounds bind to the non-heme iron in the gut, actively inhibiting its absorption into the bloodstream. Studies show that the percentage of iron absorbed from red wine is much lower compared to white wine, which contains fewer polyphenols.
The combination of iron and alcohol consumption presents a specific risk for individuals with hereditary hemochromatosis, an iron overload disorder. This genetic condition causes the body to absorb too much iron from the diet due to a defect in the iron-regulating hormone hepcidin. Alcohol suppresses hepcidin production, which can further increase iron absorption and accelerate iron accumulation in the liver and other organs. For those with hemochromatosis, the iron in red wine, coupled with the systemic effects of alcohol, necessitates careful moderation or avoidance.