Iron rich nuts
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Iron-Rich Nuts: Nutritional Insights and Bioavailability
Iron Content in Nuts and Oilseeds
Nuts and oilseeds are often considered for their nutritional benefits, including their iron content. A study assessing sixteen varieties of nuts and oilseeds found significant variations in their total and ionisable iron content. Nigre seeds had the highest total iron content, while linseed seeds had the lowest. However, the bioavailability of iron, which is crucial for its absorption in the human body, was notably high in pistachio nuts and almonds but markedly low in groundnuts.
Inhibitory Effects on Iron Absorption
Despite the presence of iron, many nuts contain compounds that inhibit iron absorption. A study involving 137 Indian women demonstrated that the absorption of iron from meals containing walnuts, almonds, peanuts, and hazelnuts was significantly lower compared to bread meals. This reduction in absorption is attributed to the high levels of phytates and polyphenols in these nuts, which are known inhibitors of iron absorption. Interestingly, coconut did not significantly reduce iron absorption due to its lower content of these inhibitors. Additionally, the inhibitory effects of Brazil nuts and peanuts could be mitigated by the presence of ascorbic acid (vitamin C).
Baru Nuts and Iron-Induced Oxidative Stress
Baru nuts, native to the Brazilian savanna, have been studied for their high mineral content, including iron, and their potential health benefits. Research on rats supplemented with iron showed that consumption of baru nuts reduced iron-induced oxidative stress in the liver, heart, and spleen. This protective effect is partly attributed to the high levels of phenolic compounds and phytic acid in baru nuts, which exhibit significant antioxidant activity.
Impact of Iron Fertilization on Hazelnuts
Iron fertilization can enhance the nutritional quality of nuts. An orchard experiment on the 'Tombul' hazelnut variety revealed that iron fertilization improved several nut traits and increased the mineral content, including iron. Specifically, fertilization with 8 kg ha⁻¹ iron significantly boosted the iron content in hazelnuts, making them a valuable source of this essential mineral. A 100-gram serving of these hazelnuts could provide approximately 50.88% of the recommended daily allowance for iron, highlighting their potential contribution to human nutrition.
Conclusion
While many nuts are rich in iron, their bioavailability can be limited by the presence of inhibitors like phytates and polyphenols. However, certain nuts like pistachios, almonds, and iron-fertilized hazelnuts show promise as good sources of bioavailable iron. Additionally, the consumption of nuts like baru can offer protective health benefits against iron-induced oxidative stress. Therefore, incorporating a variety of nuts into the diet, along with strategies to enhance iron absorption, can be beneficial for meeting nutritional iron requirements.
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