Optimizing Mineral Intake

By Marie Spano, M.S., R.D., Contributing Editor

Research indicates essential minerals should be consumed in their correct mineral balance to optimize health, including for better bone health, improved blood pressure and more.

Bone-building minerals

Bone is a storage depot for calcium. Though this mineral plays a critical role in bone health, it plays an even more-important role in vascular contraction, vasodilation, muscle function, nerve transmission, intracellular signaling and hormone secretion. Therefore, when dietary intake of calcium falls below a persons needs to maintain these vital functions, calcium is pulled out of bone to maintain blood-calcium concentrations. A consistently low dietary intake will steadily decrease calcium content in bone, leading to a decline in bone-mineral density and bone strength (Food and Nutrition Board, Institute of Medicine, Washington, D.C.).

Some green vegetables contain calcium, but large quantities are required to meet dietary needs, and the calcium from spinach, kale, broccoli and other vegetables isnt as bioavailable as the calcium from dairy foods. Manufacturers can rely on dairy ingredients rich in calciumfrom milk powders, whey minerals and various types of whey ingredientsto provide adequate fortification with a highly bioavailable calcium content," notes Mary Higgins, vice president, U.S. Ingredients Trade Services, U.S. Dairy Export Council, Arlington, VA. In addition, milk contains several other bone-building minerals, including phosphorus, magnesium, potassium and zinc.

Though calcium is vital for bone health, too much could be harmful. A longitudinal study that followed more than 61,000 women for 19 years found a dietary intake of more than 1,100 mg calcium per day was associated with a higher rate of hip fracture (British Medical Journal, 2011; 342:d1,473). The ideal ratio of calcium to phosphorus for optimal bone structure and absorption of calcium is 1.2:1," notes Ram Chaudhari, Ph.D., FACN, CNS, senior executive vice president and chief scientific officer, Fortitech, Schenectady, NY.

Additionally, a person can consume all of the calcium in the world, but they will not have strong bones unless they consume a sufficient amount of magnesium and phosphorus," says Barbara Bufe Heidolph, principal, food phosphates, ICL Performance Products LP, St. Louis. Calcium, magnesium and phosphorus together make up a complex called carbonated hydroxyapatite, the key component of bone and teeth."

According to NHANES 2005 to 2006 data, most Americans are consuming the estimated average requirement for phosphorus, but below the estimated average requirement for magnesium, a mineral involved in over 300 chemical reactions in the body (USDA, Agricultural Research Service, 2009). Magnesium is a forgotten nutrient. And, though some companies are adding more magnesium to foods, it is tough to add more than 25% to 35% of the Daily Value because of the changes in taste and texture," says Chaudhari. Other minerals important for bone health include copper, fluoride, manganese, zinc and boron.

According to NHANES 2007 to 2008 data, the average adult is consuming adequate amounts of zinc and copper to meet the Dietary Reference Intakes for these minerals. However, some individuals are at risk of developing deficiencies in these minerals, notably those with malabsorption syndromes (American Journal of Clinical Nutrition, 1998; 67:952S-959S). In addition, individuals who consume excess zinc for an extended period of time could increase their risk for copper deficiency (Modern Nutrition in Health and Disease," 10th ed., 2006: 286-299). Large intakes of supplemental iron may decrease zinc absorption (American Journal of Clinical Nutrition, 1998; 68:422S-426S).

Minerals for healthy blood pressure

Sodium is critical for muscle and nerve functioning, as well as blood-pressure regulation. We need sodium in our diet; however, the level in our body impacts our body fluids and how hard our kidneys must work," notes Heidolph. And U.S. adults consume considerably more sodium than they need. Males and females 20 years of age and over consume an average of 4,043 mg and 2,884 mg sodium per day, respectively (USDA, Agricultural Research Service, 2010). When individuals consume too much sodium, water retention increases, which translates to an increase in blood volume, a subsequent increase in blood pressure and a decrease in potassiuma vicious cycle," she says. This is a very complex biological process which involves the lungs, heart, liver, kidneys, adrenal glands, the blood and arteries, along with several enzymes and hormones." Therefore, Americans should consume less than 2,300 mg or 1,500 mg sodium per day, with the latter recommended for African Americans, individuals with hypertension, diabetes or chronic kidney disease, and individuals ages 51 and older (2010 Dietary Guidelines for Americans).

However, decreasing sodium in the diet does not necessarily translate to a decrease in blood pressure," notes Heidolph. On the other hand, research has found a positive correlation between an increase in intake of potassium-rich foods and, in turn, a difference in blood pressure."

Potassium blunts the effects of sodium on blood pressure, and a diet rich in magnesium may also play an important role in blood pressure (Institute of Medicine, Food and Nutrition Board, 2010; Clinical Cardiology, 1999; 22:1,111-1,115). However, potassium balance depends, in part, on the amount of sodium and magnesium in the blood. A high-sodium diet may increase the need for potassium, while magnesium deficiency is associated with low levels of potassium (Mineral and Electrolyte Metabolism, 1997; 23:105-112).

Despite the fact that many Americans should focus on consuming less sodium, like all electrolytes, it is critical that blood-sodium levels remain within a healthy range. Very low blood sodium, hyponatremia, can be dangerous and results from prolonged, heavy sweating without replacing sodium or excessive water intake, or a combination of the two. In fact, many endurance athletes or athletes training intensely for long periods will require more than 2,300 mg sodium per day. Other causes of hyponatremia include congestive heart failure, kidney disease, those on diuretics, burn victims, vomiting or diarrhea (American Journal of Physiology, 1997; 273:E268-725).

A balanced intake of minerals is vital for good health. Because minerals interact with each other, a deficiency or excess of certain minerals could cause an acute problem, contribute to a chronic disease or disrupt the balance of other minerals in the body.

Marie Spano, M.S., R.D., CSCS, is a nutrition communications expert whose work has appeared in popular press magazines, e-zines and nutrition-industry trade publications. She has been an expert guest on NBC, ABC and CBS affiliates on the East Coast. For more information, visit mariespano.com.