Red grape juice inhibits iron availability.




Journal of Agriculture and Food Chemistry

Related Monographs

Consumer Data: Iron
Professional Data: Iron


Iron is essential for the transport of oxygen through the body via red blood cells. Iron is also involved in the conversion of blood sugar to energy. It provides a crucial building block for the production of enzymes that are involved with making new cells, amino acids, hormones and neurotransmitters. Other important activities requiring iron include liver detoxification, the metabolism of fatty acids, and the synthesis of carnitine and the neurotransmitters serotonin and dopamine. Iron is essential for the production of collagen and elastin, which provide structural integrity and elasticity for organs and tissues.

Liver is by far the richest iron-containing food. Other good sources of iron-rich foods include organ meats, fish and poultry. Dried beans and vegetables are the best plant sources, followed by dried fruits, nuts, and whole grain breads and cereals. Fortification of cereals, flours and bread with iron has contributed significantly to daily dietary iron consumption.

A study published in the Journal of Agriculture and Food Chemistry examined the bioavailability of iron in an in vitro setting after the digestion of certain fruit juices. Juices bought from the local grocery store were combined with infant cereal with iron or FeCl(3) (an iron compound) and then digestion was simulated. The juices used were apple, orange, prune, pear, white and red grape juice, and grapefruit. The results showed that the pear, apple, grapefruit, and white grape juices increased iron bioavailability. In contrast, the prune and red grape juices strongly inhibited iron bioavailability. This is thought to be due to polyphenolic compounds found in these juices that bind to iron. The authors concluded that those who need optimal nutritional absorption of iron should avoid these types of juices, although stating “compounds that inhibit Fe availability are also linked to anticancer benefits; thus, a dietary balance of the above juices may be optimal.”1


1. Boato F, et al. Red grape juice inhibits iron availability: application of an in vitro digestion/caco-2 cell model. J Agric Food Chem. Nov 2002;50(23):6935-8.