On the blog last week, we talked about Minerals and the major minerals which consist of sodium, potassium, chloride, calcium, phosphorus, magnesium and sulfur.
Today we shall be talking about trace minerals. Trace minerals or microminerals which consist of iron, zinc, iodine, selenium, copper, manganese, fluoride, chromium and molybdenum.
The body needs trace minerals in very small amounts. The amounts needed in the body however is not an indication of their importance. For example iron is considered to be a trace mineral, but the amount needed is somewhat more than for other microminerals.
Let’s now take a look into some of these microminerals (iron, zinc, iodine, and fluoride), their importance to the body and food sources that they can be found.
- Iron is an important mineral that helps maintain healthy blood. It is a part of a molecule (hemoglobin) found in red blood cells that carries oxygen in the body. Without enough iron, there aren’t enough red blood cells to transport oxygen, which leads to fatigue. Iron is also part of myoglobin, a protein that carries and stores oxygen specifically in muscle tissues. Iron is important for healthy brain development and growth in children, and for the normal production and function of various cells and hormones.
Iron from food comes in two forms: heme and non-heme. Heme is found only in animal flesh like meat, poultry, and seafood. Non-heme iron is found in plant foods like whole grains, nuts, seeds, legumes, and leafy greens. Non-heme iron is also found in animal flesh (as animals consume plant foods with non-heme iron) and fortified foods.
Heme iron is better absorbed by the body than non-heme iron. Certain factors can improve or inhibit the absorption of non-heme iron. Vitamin C and heme iron taken at the same meal can improve the absorption of non-heme iron. Bran fiber, large amounts of calcium particularly from supplements, and plant substances like phytates and tannins can inhibit the absorption of non-heme iron.
The Recommended Dietary Allowance (RDA) for adults 19–50 years is 8 mg daily for men, 18 mg for women, 27 mg for pregnancy, and 9 mg for lactation. The higher amounts in women and pregnancy are due to blood loss through menstruation and because of the rapid growth of the fetus requiring extra blood circulation during pregnancy.
Meats, poultry, and seafood are richest in heme iron. Fortified grains, nuts, seeds, legumes, and vegetables contain non-heme iron.
2. Zinc is a trace mineral, meaning that the body only needs small amounts, and yet it is necessary for almost 100 enzymes to carry out vital chemical reactions. It is a major player in the creation of DNA, growth of cells, building proteins, healing damaged tissue, and supporting a healthy immune system.
Because it helps cells to grow and multiply, adequate zinc is required during times of rapid growth, such as childhood, adolescence, and pregnancy. Zinc is also involved with the senses of taste and smell. The Recommended Dietary Allowance (RDA) for adults 19+ years is 11 mg a day for men and 8 mg for women. Pregnancy and lactation require slightly more at 11 mg and 12 mg, respectively.
The Tolerable Upper Intake Level is the maximum daily intake unlikely to cause harmful effects on health. The UL for zinc is 40 mg daily for all males and females ages 19+ years.
Meats, poultry, and seafood are rich in zinc. Some plant foods like legumes and whole grains are also good sources of zinc, but they also contain phytates that can bind to the mineral, lowering its absorption.
3. Iodine; Iodine is an essential trace mineral not made by the body so must be obtained by food or supplements. It is found naturally in some foods and is added to supplements and some salt seasonings.
Iodine is needed to make the thyroid hormones thyroxine and triiodothyronine, which assist with the creation of proteins and enzyme activity, as well as regulating normal metabolism. Without enough iodine, these thyroid hormones do not work properly and can lead to an under-active or overactive thyroid gland, causing the medical conditions of hypothyroidism and hyperthyroidism with various negative side effects in the body.
The Recommended Dietary Allowance for iodine is 150 micrograms (mcg) daily for adult men and women 19+ years, and 220 and 290 mcg daily for pregnant and lactating women, respectively.
The Upper Intake Level (UL) for iodine for adults 19+ years and pregnant and lactating women is 1,100 mcg daily.
Iodine is found in soil and the ocean, which varies in amount and will affect how much of the mineral is contained in a food. Iodine is found mainly in animal protein foods and sea vegetables, and to a lesser extent in fortified foods like breads, cereals, and milk.
4. Fluoride; Fluoride is naturally present in many foods and available as a dietary supplement. Fluoride is the ionic form of the element fluorine, and it inhibits or reverses the initiation and progression of dental caries (tooth decay) and stimulates new bone formation.
Soil, water, plants, and foods contain trace amounts of fluoride. Most of the fluoride that people consume comes from fluoridated water, foods and beverages prepared with fluoridated water, and toothpaste and other dental products containing fluoride.
Brewed tea typically contains higher levels of fluoride than most foods, depending on the type of tea and its source, because tea plants take up fluoride from soil. Fluoride levels can range from 0.3 to 6.5 mg/L (0.07 to 1.5 mg/cup) in brewed tea made with distilled water.
Fluoride concentrations in cow’s milk are also very low, ranging from 0.007 to 0.086 mg/L
Only trace amounts of fluoride are naturally present in most foods, and most foods not prepared with fluoridated water provide less than 0.05 mg/100 g.
A mineral deficiency occurs when your body doesn’t obtain or absorb the required amount of a mineral. The human body requires different amounts of each mineral to stay healthy. Specific needs are outlined in recommended daily allowances (RDA).
A deficiency often happens slowly over time and can be caused by a number of reasons. An increased need for the mineral, lack of the mineral in the diet, or difficulty absorbing the mineral from food are some of the more common reasons.
Mineral deficiencies can lead to a variety of health problems, such as weak bones, fatigue, or a decreased immune system. There are five main categories of mineral deficiency: calcium, iron, magnesium, potassium, and zinc.
The symptoms of a mineral deficiency depend upon which nutrient the body lacks but possible symptoms include:
- constipation, bloating, or abdominal pain
- decreased immune system
- irregular heart beat
- loss of appetite
- muscle cramping
- nausea and vomiting
- slow social or mental development in children
- weakness or tiredness
Certain mineral deficiencies cannot be treated with diet alone. You may be required to take a multivitamin or mineral supplement. These may be taken alone or with other supplements that help the body absorb or use the mineral. Vitamin D, for example, is usually taken along with calcium. It is best to seek the advice of your healthcare provider to determine how much and how often you should take supplements if needed.
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