Do nuts have iron
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Some studies suggest that nuts contain iron but have low bioavailability and can inhibit iron absorption, while other studies indicate that certain nuts may reduce iron-induced oxidative stress.
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Iron Content and Bioavailability in Nuts
Iron Content in Various Nuts
Nuts are often considered a nutritious snack, but their iron content and bioavailability can vary significantly. Research has shown that different varieties of nuts contain varying levels of total and ionisable iron. For instance, nigre seeds have the highest total iron content, while linseed seeds have the lowest. However, the presence of iron alone does not determine its nutritional value; bioavailability is a crucial factor.
Bioavailability of Iron in Nuts
The bioavailability of iron from nuts is generally low. Most nuts and oilseeds have less than 10% bioavailability of iron, making them less effective as iron sources compared to other plant foods. Among the nuts studied, pistachio nuts and almonds showed relatively higher bioavailability, whereas groundnuts had markedly low bioavailability.
Inhibitors of Iron Absorption in Nuts
Nuts contain significant amounts of phytates and polyphenols, which are known inhibitors of iron absorption. A study involving 137 Indian women found that the absorption of iron from meals containing nuts (such as walnuts, almonds, peanuts, and hazelnuts) was significantly lower compared to meals without nuts. The overall geometric mean absorption from nut meals was only 1.8%, compared to 6.6% from bread meals alone. Interestingly, coconut did not significantly reduce iron absorption, likely due to its lower levels of these inhibitors.
Overcoming Inhibitory Effects
The inhibitory effects of nuts on iron absorption can be mitigated by the presence of ascorbic acid (vitamin C). For example, the addition of 50 milligrams of ascorbic acid was found to overcome the inhibitory effects of Brazil nuts and peanuts on iron absorption. This suggests that combining nuts with vitamin C-rich foods could enhance iron absorption.
Protective Effects of Specific Nuts
Some nuts, like the baru nut (Dipteryx alata Vog.), not only contain iron but also offer protective health benefits. The baru nut is rich in minerals, tannins, and phytic acid, and has demonstrated antioxidant activity. In a study on rats, consumption of baru nuts reduced iron-induced oxidative stress in various tissues, suggesting that the nut's bioactive compounds, including phenols and phytic acid, contribute to this protective effect.
Conclusion
While nuts do contain iron, their bioavailability is generally low due to the presence of inhibitors like phytates and polyphenols. However, the negative impact on iron absorption can be mitigated by consuming vitamin C-rich foods alongside nuts. Additionally, certain nuts like the baru nut offer additional health benefits by protecting against iron-induced oxidative stress. Therefore, while nuts can be a part of a balanced diet, relying on them as a primary source of iron may not be effective.
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