Thursday, October 29th 2009

By unknown

By Stephanie O’Neill

As a child, most of us were confused by Popeye’s affection for spinach, that green, mushy vegetable that was forced down our throats. Now that we are older, though, we understand that iron is good for us and consider buying burgers or maybe even spinach when we are at the grocery store. But, what exactly does iron do for our bodies?

Iron is a metal that is essential to us in small quantities. The suggested intake of iron is 8 to 18 mg/day, but this dose varies depending on age, medical condition, and lifestyle. In the body, iron is found in hemoglobin, a protein in red blood cells that delivers oxygen to tissues, in myoglobin, a protein that delivers oxygen to muscle tissues, and in storage proteins in bone marrow and the liver. Iron is essential for cell growth, health and immunity.

According to the World Health Organization, iron deficiency is the most common nutrition disorder in the world and is the only one that is widespread in the developed world. Approximately 80 per cent of people are estimated to have it, while 30 percent of people are thought to have anemia, a condition usually caused by iron deficiency in which levels of healthy red blood cells are abnormally low due to a lack of hemoglobin.

Most people know that iron is an important part of a diet, but there are several factors that can affect the degree to which iron is absorbed by the body, regardless of how much iron is actually ingested. There are different types of dietary iron: heme iron and non-heme iron. Heme iron is derived from hemoglobin and is found in animal products like meats (beef, turkey, chicken, tuna, shrimp). The body metabolizes this type of iron very efficiently with 15 per cent to 35 per cent being absorbed.

Non-heme iron, on the other hand, can come from iron-rich plant foods (lentils, soy, spinach, oatmeal, tofu, kidney beans, lima beans, chick peas), but the body can only absorb two per cent to 20 per cent of this type of iron. Since healthy people need to absorb about 10 per cent to 15 per cent of dietary iron, maximizing absorption in addition to healthy consumption is something that should be taken into consideration.

Other aspects of diet can affect iron absorption. For example, a lack of vitamin A will prevent iron from being released from stores. This problem is more common, however, in underdeveloped countries. Vitamin C increases iron absorption and is essential in all diets, but especially in a vegetarian one. Foods that are high in calories but low in vitamins and minerals negatively affect iron intake (such as junk foods). Unfortunately, so can other foods typically thought of as healthy such calcium, tannins (found in tea), oxalates (ironically found in spinach), fiber, phytates (found in whole grains) and polyphenols.

Because some foods, such as soybeans, contain both non-heme iron and iron absorption inhibitors, eating meat or other iron absorption enhancers at the same time can counterbalance this problem. Less iron will be absorbed, however, if storage levels in the body are already high. Getting what we need is not always straightforward, so becoming more educated about food nutrition and food properties is worthwhile.

People who lose a lot of blood (for example, menstruating women) are at risk of iron deficiency. Additionally, intense exercise can increase the turnover of red blood cells, increasing the need for the replacement of stored iron. Those who do not eat meat regularly will also be at an increased risk of iron deficiency because of the inefficient absorption rates of non-heme iron.

These factors mean that attention to iron intake is especially important for females who are pregnant, females of child-bearing age, distance runners, female athletes, women with heavy menstrual flow and vegetarians. Since iron is mostly absorbed in the small intestine, people with gastrointestinal problems, such as those with Crohn’s disease, may also be at an increased risk of iron deficiency. Women who are on oral contraceptives will usually not be at risk, whereas women who use an intrauterine device (IUD) may have heavier menstrual flow and might consequently be at greater risk.

Adult men and post-menopausal women are not typically iron deficient; however, iron toxicity is a concern. Iron is normally not excreted, so if there is too much of it in storage, it will accumulate in organs and tissues; this can result in hemochromatosis and organ damage, cirrhosis of the liver, and heart failure. Iron supplementation is therefore only suggested when diet cannot provide the needed dose of iron, and only if recommended by a doctor.

If you find yourself in one of the groups of people that are at risk of iron deficiency or iron deficiency anemia, be sure to be on the lookout for signs and symptoms, such as weakness, fatigue, decreased immune function, body temperature fluctuations, inflammation of the tongue, changes in appetite and headaches. University-age men should be getting between eight and 11 mg/day of iron, while women of the same age group should be getting between 15 and 18 mg/day. So next time you make your weekly trip to the grocery store, remember Popeye and grab that spinach, or other iron-rich food.

Tags: anemia, heme iron, hemoglobin, iron, meat, metal, myoglobin, non-heme iron, popeye, spinach