Are nuts high in iron

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Are Nuts High in Iron?

Iron Content in Nuts and Oilseeds

Nuts and oilseeds exhibit a wide range of iron content. A study assessing sixteen varieties of nuts and oilseeds found significant variations in both total and ionisable iron content. Among the tested varieties, nigre seeds had the highest total iron content, while linseed seeds had the lowest. However, the bioavailability of iron, which is the proportion of iron that is absorbable by the body, varied significantly among different nuts. Pistachio nuts and almonds showed relatively high bioavailability, whereas groundnuts had markedly low bioavailability.

Inhibitory Effects on Iron Absorption

Despite the presence of iron in nuts, their overall contribution to dietary iron can be limited due to the presence of iron absorption inhibitors. Nuts such as walnuts, almonds, peanuts, and hazelnuts contain significant amounts of phytates and polyphenols, which are known to inhibit iron absorption. A study involving 137 Indian women demonstrated that the absorption of iron from meals containing these nuts was significantly lower compared to meals without nuts. Specifically, the geometric mean absorption from nut meals was 1.8%, compared to 6.6% from bread meals alone. Interestingly, coconut did not significantly reduce iron absorption, likely due to its lower content of these inhibitors.

Bioactive Compounds and Iron-Induced Oxidative Stress

Some nuts, like the baru nut from the Brazilian savanna, contain high levels of minerals, tannins, and phytic acid, which contribute to their antioxidant properties. Research on rats supplemented with iron showed that consumption of baru nuts reduced iron-induced oxidative stress in various tissues, suggesting a protective effect. The study indicated that the phenolic compounds and phytic acid in baru nuts might play a role in mitigating oxidative damage caused by excess iron.

Conclusion

While nuts do contain iron, their effectiveness as a dietary iron source is limited by the presence of absorption inhibitors such as phytates and polyphenols. The bioavailability of iron from nuts is generally low, with some exceptions like pistachio nuts and almonds. Additionally, certain nuts like the baru nut may offer protective benefits against iron-induced oxidative stress due to their bioactive compounds. Therefore, while nuts can contribute to iron intake, they are not considered the best sources of bioavailable iron among plant foods.