Can Turmeric Contribute to Iron Deficiency?

• Results in Human Studies Suggest the Answer is No

Iron is an essential nutrient, but lack of iron is the most common nutritional deficiency worldwide. This is especially true amongst women and children. Plant-based diets and consumption of herbal teas and coffee are believed to inhibit iron absorption. This is because of the high levels of flavonoid compounds in vegetables, fruits, teas, and coffee. ^(i.4, 89)

Flavonoids are plant compounds that can bind to iron molecules. When they do, the molecules become too big to be absorbed through the walls of the intestines. Tannin-type polyphenols are another type of plant compound likely to bind iron. ^(i.4, 89)

Although turmeric contains iron, it is high in both flavonoids and tannins. Theoretically, the plant compounds in turmeric could strongly bind to iron molecules and block their absorption. ^(i.4, 89)

Lab and Animal Studies Show Turmeric Binds to Iron and Curcumin Could Induce Anemia

In fact, lab studies designed to simulate conditions in the digestive tract confirm that the compounds in turmeric do bind to iron. Presumably, this could decrease the body's ability to absorb iron from food. Further animal studies also suggest that curcumin could theoretically cause anemia in those people who already have some iron deficiency. ^{(i.4, 66, 89-90)}

Human Studies Indicate Turmeric Supplements Do Not Inhibit Iron Absorption

However, when scientists tested turmeric and chili powder individually in a randomized, controlled clinical trial, results were quite different. Turmeric, with much higher polyphenol content than chili, could reasonably be expected to have a greater inhibitory effect (based on prior lab studies). However, results showed the opposite. Dietary intake of turmeric in supplement form (500 mg/day) did not inhibit iron absorption in women consuming iron-fortified meals, while chili powder did. ^(i.89)

The bottom line, as researchers point out, is that it is hard to predict how any food, spice, or herbal supplement will behave based on one factor. Although the polyphenol content of any of these can inhibit iron absorption, it may not. Spices such as turmeric that contain many polyphenols are complex compounds that have equally complex effects in the body. ^(i.89)