Minerals: What, Why and How: One of the Essential Nutrients for Good Health (#5 in series)
You need 7 nutrients in your diet to prevent disease and maintain good health. They are carbohydrates, proteins, fats, fiber, vitamins, minerals and water.
Minerals are your micronutrients and your body need them in small quantities. Vitamins are your other micronutrients. You learned about the importance of vitamins to good health last week in "Vitamins: What, Why and How: One of the Essential Nutrients for Good Health (#4 in series)"
If you missed any of the series on nutrients needed to maintain your health and prevent disease, you can get caught up -just follow the links below.. Knowing some basic scientific facts will go along way in helping you to make better decisions and not fall for the latest fad. Knowledge is power. They were:
MINERALS:
Minerals are categorized based on the amount you need per a day. Generally, if you require 100mg (1/50 of a teaspoon) or more per day of a mineral, it is considered a major (macro) mineral; otherwise, it is considered a trace (minor or micro) mineral. The classification does not imply importance.
Based on this criteria calcium, phosphorus, magnesium, sodium, potassium, chloride and sulfur are macro nutrients and iron, manganese, copper, chromium, iodine, zinc, cobalt, fluoride and selenium are some of the micronutrients.
Before going into induvial minerals, let’s consider some traits that are relevant to all minerals.
Minerals are present in all foods you eat. Minerals come from the ground and water. A fish swims in the water and consumes the minerals in the water. Then you eat the fish.
Not all minerals are absorbed the same. The term bioavailability refers to the degree that what you ingest is absorbed and made available to your body. Bioavailability depends on many factors (amount of acid in the stomach or what other vitamins or minerals are present in the meal) . Spinach, for example, contains plenty of calcium, but only about 5% of it can be absorbed because it contains oxalic acid, a calcium binder. Oxalic acid is found in rhubarb, sweet potatoes and other leafy green vegetables.
Fiber found in grains not leavened with yeast interferes with mineral absorption as well. Fiber contains phytic acid which can bind to some minerals. Yeast helps to breaks the bond between phytic acid and minerals.
Minerals compete with each other for absorption. This means that excess of one mineral influence the absorption and metabolism of other minerals. For example, the presence of large amounts zinc in the diet decreases copper, iron and calcium absorption.
Processes grains like foods made with flour will always have less mineral content. The enrichment process adds back only iron. Selenium, zinc, copper and other minerals are lost.
Excess mineral intake can also result in toxicities, especially with iron and copper.
For these reasons, you should avoid taking individual supplements of a mineral unless directed by a medical professional.
CALCIUM:
All cells in the body need calcium, but 99% of calcium in the body is used to strength bones and teeth. Calcium represents 40% of all minerals present in your body. That translates into about 2.5lbs (1200g) of calcium.
The body also needs calcium to moves muscles, transmit nerve impulses and maintain heart rhythm. Calcium helps release hormones and enzymes that affect almost every function in your body too.
Calcium absorption is increased in the presence of vitamin D and decreased in the presence of phytic acid (found in grains) and oxalic acid (found in plants). High amounts of sodium, caffeine, protein, phosphorus and alcohol in the diet can also decrease calcium absorption. In addition, as you age your ability to absorb calcium decreases. For this reason there are higher recommended intakes of calcium for people over the age of 50.
Your body maintains strict levels of calcium in your blood despite poor calcium intake. Your bones, however, pay the price. Calcium is taken from your bones to maintain blood levels of calcium. Over time, this can lead to osteopenia which if untreated can lead to osteoporosis- a condition where your bones become weaker and you are a greater risk they will break easier (discussed further under vitamin D).
Dairy products, such as milk, yogurt and cheese are the better sources of calcium. The exception is cottage cheese, because most calcium is lost during processing. Overall, nonfat milk is the most nutrient dense source of calcium.
Good plant based sources include kale, collard, turnip and mustard greens because they do not contain oxalic acid. Fortified foods follow as close competitors in supplying calcium. Check the label to make sure the product is fortified with calcium along with vitamin D.
Sodium (Na+), Chloride (Cl-) and Potassium (K+):
Unlike calcium, your body absorbs almost all the sodium you eat or drink. The primary source of sodium is sodium chloride or salt (NaCl).
Sodium (Na+), Chloride (Cl-) and Potassium (K+) all carry an electrical charge. This makes them electrolytes. Electrolytes facilitate heart and muscle contraction as well as nerve impulses.
Let’s say you want to move your arm. Sodium (Na+) stimulates your muscle cells to become active (known as depolarization), while potassium (K+) causes them to return to an inactive state or relax (known as repolarization). The whole process is called an action potential. For this reason you should look to balance these two nutrients (1).
Having too high sodium and too little potassium in your diet can increase your risk of CVD and stroke. The adequate intake (AI) for potassium is 4700mg for healthy adult men and woman. The upper limit (UL) for sodium is 2300mg with a suggested intake of 1500mg (2).
Currently less than 5% of Americans get adequate potassium while 97% of Americans exceed adequate intake for sodium. The best way to decrease your salt intake is to limit processed and packaged foods in your diet, because they contain the highest amounts of added salt.
You can boost your potassium intake by including whole fruits, vegetables, whole grains, fresh or frozen meat, poultry and fish, and low-fat or non-fat milk products to your diet.
Electrolytes also regulate fluid balance in the body. There are three fluid compartments in your body that holds all your water. The largest is your intercellular compartment that is the fluid inside all your cells. Then outside your cells you have you extracellular compartment that includes a small interstitial space (the space between your cell and blood vessel) and plasma space (located in your blood vessels).
For your body to function property there must be a relatively stable balance within what is called your internal environment (that’s your plasma space).
Let’s say you consume a high salt diet. What will happen to plasma space?
Water from your other two spaces will go into your plasma space (to maintain balance or concentration) and pressure in your blood vessels will increase. To compensate for this increase in pressure the walls of your blood vessel needs to become stronger and thicker. Yet this only makes the space inside the arteries smaller and raises your blood pressure even higher.
Because your blood vessels are smaller, the oxygen and nutrients your blood carries for your brain, heart and other organs get there a little slower. Over time this can cause organ damage. This is why high blood pressure is called the silent killer.
Sometimes you may not even think of a food a being high in salt, because it does not taste salty. Again, it is your processed foods that have the most added salt.
Are you surprized with the amount of salt hidden in your food?
IRON (Fe):
Iron is an essential micro mineral. The primary reason you need it is to transport oxygen to every cell in your body. It also participates in DNA synthesis and supports energy metabolism in muscles. Iron is also necessary for growth, development, and synthesis of some hormones and connective tissue (3).
Your body keeps a tight regulation on iron, because in excessive amounts it can damage tissues.
Almost two-thirds of your iron used to make hemoglobin.
Hemoglobin is simply an iron molecule attached to four proteins. You have about 280 million hemoglobin molecules in one red blood cell (RBC).
Oxygen attaches to hemoglobin in the lungs and travels throughout your body to supply oxygen to all your cells and tissues. The high presence of carbon dioxide allows for the release of oxygen to your tissues. Hemoglobin then transports carbon dioxide back to the lungs that you release in expiration (4).
Closely related to hemoglobin is myoglobin. Myoglobin is found in cardiac and skeletal muscle. It functions as an oxygen storage unit, providing oxygen to the working muscles (your heart is a muscle too). It differs from hemoglobin in that it only binds to one protein group oppose to four. Myoglobin is why we can hold our breath and why whales can stay under water for long periods of time. A different storage unit for iron occurs in the liver (5).
Your body has the ability to recycle iron. Your spleen and other tissues break down old red blood cells about every 120 days. It separates the iron form the heme. The iron is then transported to the liver for storage or used again to make hemoglobin.
More than 90% of hemoglobin is recycled. For this reason you do not lose much iron and too much iron can lead to toxicity.
You can think of iron as having a circular path and there are only minor ways your body will lose iron. Healthy adult men may lose 1mg per day though the gastrointestinal tract (GI) and women may lose more due to menstruation.
Dietary iron has two main forms: heme and nonheme. Plants and iron-fortified foods contain nonheme iron only, whereas meat, seafood, and poultry contain both heme and nonheme iron.
Your ability to absorb and use each differs. In a healthy adult heme iron is highly bioavailable (15%-35%) and dietary factors have little effect on its absorption, whereas nonheme iron absorption is much lower (2%-20%) and is strongly influenced by the presence of other food components (6).
Vitamin C will enhance iron absorption form nonheme sources (plants and fortified foods). Vitamin C is the only absorption enhancer in vegetarian diets, and iron absorption from vegetarian and vegan meals can be best optimized by the inclusion of Vitamin C-containing vegetables. Cooking, industrial processing, and storage degrade vitamin C and remove its enhancing effect on iron absorption (7).
Phytates and polyphenols can inhibit iron absorption. Both are antioxidant compounds. Phytates are found in whole grains, legumes, nuts and seeds, while polyphenols are found in red cabbage, all assorted berries, red and purple grapes, and broccoli.
Animal proteins such as milk proteins, egg proteins, and albumin can also inhibit iron absorption as can the presence of other minerals such as lead, manganese, cobalt, and zinc (8).
If your diet or your body stores can’t supply enough iron to make hemoglobin, red blood production is reduced. Eventually, not enough oxygen will get to you cells and you will start to feel fatigue, tired and drained. You will look pale and could have brittle nails. These are classic symptoms of iron deficiency anemia.
Iron deficiency anemia is caused in several different ways.
There could be decrease in intake of iron. This is seen in infants 0-6 months old because breast milk contains almost no iron.
There could be an increased demand in iron. This is seen in growing children, adolescence and pregnant women because additional iron is needed to support the demands of growth.
There could be a problem with your body’s ability to absorb iron. This is common in people who take antacids because acid helps with iron absorption. A person who has had stomach surgery or has celiac disease can also have trouble absorbing iron.
There is an increase in blood loss in the body. When you bleed you lose red blood cells and hence iron and hemoglobin. This may be caused by heavy menstruation, peptic ulcers, colon cancer or polyps.
Your health care provider should be made aware of any symptoms you may have. It is important you do not ignore them.
Next week you will learn about food based guidelines. Are they making us fat? Are they good or bad? What do they look like around the world?
