Which mineral deficiency, although found in numerous foods, is rare and can reduce internal absorption when supplemented?

The mineral in question is copper. Although copper is present in numerous foods such as shellfish, seeds, nuts, and whole grains, deficiencies are relatively rare. This is primarily because the body requires only a small amount of copper, and most individuals can obtain adequate amounts from a balanced diet.

When copper is supplemented, it can inhibit the absorption of other minerals, particularly zinc. This occurs because copper and zinc compete for absorption in the intestine. High levels of zinc can interfere with the intestine's ability to absorb copper, thereby potentially leading to a deficiency in copper even when it's consumed in sufficient dietary amounts.

Understanding this relationship highlights the importance of balancing micronutrient supplementation, as excessive intake of one can negatively impact the absorption of another, demonstrating the intricate interplay between different minerals in the body. This is a crucial concept in nutrition, especially in formulating dietary guidelines and recommending supplements.