In affluent countries such as the U.S., it is difficult to believe that vitamin and mineral deficiencies exist. Most of the U.S. population suffers from over-nutrition rather than under-nutrition, says Nelda Mercer, R.D., consultant and spokesperson for the American Dietetic Association.
With approximately half of the U.S. population categorized as overweight, one would think that people are consuming more than the recommended amounts of essential nutrients. But the reality is that "due to factors such as lifestyle, age and underlying disease" some people are deficient in essential nutrients. Recent studies have pointed to some specific cases of micro-deficiencies in select groups of people.
The B Vitamins
The "tea and toast generation" is at higher risk for vitamin B deficiencies, says Mercer. "Some reside in nursing homes, senior citizen-assisted living residences or alone. The majority have limited intakes of food and they don't cook everyday or they just don't have a desire to eat." ? Low levels of B vitamins, particularly B6, B12 and folic acid, may increase the risk of heart disease. Recent work has focused on the link between vitamin B deficient individuals and heart disease.
Research by Kilmer McCully M.D., clinical associate professor of pathology at Brown University, Providence, R.I., focused on how vitamin B6, B12 and folic acid deficiencies can elevate homocysteine levels and lead to arteriosclerosis. According to McCully, when homocysteine levels rise, they begin to damage the cells and tissues of healthy arteries and stimulate growth of arteriosclerotic plaques, which can lead to heart disease.
Studies have already established the link between insufficient folic acid and fetal neural tube defects. Another study focused on the relationship between repeat miscarriages and vitamin B12 deficiency.1 Vitamin B12 is essential to the nervous system and to the development of new tissue and, therefore, is critical to fetal growth. Michael Bennett M.D., of Ha'Emek Medical Center in Afula, Israel, conducted a study that examined infertility and recurrent fetal loss in patients who were B12 deficient. Researchers found that increased homocysteine levels causing hypercoagulability led to fetal loss at the onset of a vitamin B12 deficiency. Additionally, a prolonged deficiency resulted in infertility.
Essential for bone health, vitamin D aids in the absorption of calcium. A recent study from Harvard Medical School and Massachusetts General Hospital found that 30 to 40% of people in the U.S. might be vitamin D deficient.2 Low levels of vitamin D are detected frequently in elderly and housebound people, but this study found that hypovitaminosis D is common in general medical inpatients, including those with vitamin D intakes exceeding the recommended daily amount and those without apparent risk factors for vitamin D deficiency. Several studies have linked vitamin D levels to the occurrence of multiple sclerosis (MS). A study conducted by researchers at Penn State and Helen Hayes Hospital in New York City has shown that a daily dose of vitamin D causes changes in blood chemistry that indicate positive effects for multiple sclerosis patients. Blood samples drawn after just 6 months of vitamin D supplementation show an increase in transforming growth factor b-1, which is associated with the remission and suppression of the immune response that produces symptoms in MS patients. In addition, the researchers found a decrease in interleuken-2, which is associated with the cells that induce MS.
Dr. Margherita Cantorna, assistant professor of nutrition involved in the study, and others hypothesize that one crucial environmental factor involved in the development of the disease is the amount of sunlight a person receives. Exposure to sunlight catalyzes the production of vitamin D in the skin. In support of a connection to MS, Cantorna points out that the incidence of the disease is nearly zero near the equator and increases with latitude in both hemispheres. In addition, Switzerland has high MS rates at low altitudes and low MS rates at high altitudes. Ultraviolet light is more intense at higher altitudes, resulting in the skin manufacturing more vitamin D.
According to the National Osteoporosis Foundation, the typical American gets only about 600 mg of calcium a day in his diet, about half of what is needed. A deficiency in calcium intake can ultimately lead to osteoporosis later in life. It already has been established that low levels of vitamin D affect calcium absorption. Other factors also influence calcium intake.
For example, a high sodium diet increases the loss of calcium and other minerals through the kidneys into the urine. Every two extra grams of dietary sodium decreases the amount of calcium absorbed by 30 to 40 mg.3 Various medications, including immuno-suppresive medications, non-steroidal anti-inflammatory drugs and some antibiotics may interfere with calcium absorption, as well.
Smoking also contributes to less efficient calcium absorption. In addition to calcium, smoking also affects levels of antioxidants. Researchers from the Johns Hopkins School of Public Health have found that non-smokers living with smokers tended to have lower serum concentrations of a- and b-carotene.4 Iron deficiencies are especially common among women, says Mercer. "Weight-conscious women shy away from eating red meat, even the leaner varieties that are important sources of iron, zinc and other essential trace minerals." ? Iron forms part of hemoglobin in red blood cells and myoglobin in muscle cells. It is used to synthesize some enzymes and is needed for immune function.
Deficiencies compromise immune function and contribute to poor growth and development among children. Deficiency can progress to anemia, which impairs work performance andâ€”in pregnant womenâ€”increases the risk of pregnancy complications and pre-term births.
A study from the Instituto Venezolano de Investigaciones Cientificas in Caracas, Venezuela, looked at the effects of both vitamin A and b-carotene on absorption of non-heme iron.5 It found that the addition of either vitamin A or b-carotene to test meals significantly increased iron absorption from rice, corn and wheat sources.
Daily intakes of magnesium often are lower than the recommended average of 320 mg per day. Over 300 enzymes use magnesium as an activator. Without it, many enzymes would function less efficiently. Proper nerve function and cardiac function require magnesium.
In humans, deficiency can cause an irregular heartbeat, which is sometimes accompanied by weakness, muscle pain, disorientation and seizures. A link between magnesium deficiency and sudden heart attacks also has been observed.
Deficiency is possible if one uses thiazide diuretics, because they increase magnesium loss in the urine. In addition, heavy perspiration for weeks in hot climates and long-standing diarrhea or vomiting can cause significant loss. Alcoholism also increases the risk of deficiency.
Again, it is important to note that, overall, the general American population suffers from over-nutrition. Vitamin and mineral deficiencies will most likely occur in people with any kind of disease that impairs nutrient absorption, people on diets that eliminate certain foods and the elderly.
On the Web: Nutrition
- www.nutrition.gov - Government nutrition site
- www.nlm.nih.gov/medlineplus - A service of the National Library of Medicine
- www.nutrition.org - American Society for Nutritional Sciences
- www.nal.usda.gov/fnic - Food and Nutrition Information Center
- www.healthfinder.gov - Consumer health information from the Federal Government
- www.faseb.org/ascn - American Society for Clinical Nutrition
- www.eatright.org - American Dietetic Association
Sidebar: Carnitine, Going Beyond a Sport Supplement
Carnitine in cells shuttles long chain fatty acids from the cytosol into the mitochondria so that fatty acids can be burned to provide energy. In the sports industry, carnitine supplementation claims to help produce more energy, increase stamina, stimulate fat burning and promote weight loss. More research is needed to show whether these claims hold true.
Carnitine, however, may be gaining more recognition in the medical field. In a study of 51 pediatric patients with carnitine deficiency at the Valley Children's Hospital and the Veteran's Administration Hospital in Madison, Wis., Dr. Susan Winter discussed a clinical profile of secondary carnitine deficiency, an analysis of potential causes and the demonstration that treatment of carnitine deficiency helps to alleviate the symptoms of the primary disorder or disease. Dr. Winter has treated more than 1,000 carnitine deficient children and her experience leads her to believe that, rather than a rare condition, "secondary plasma carnitine deficiency is a common pediatric finding."
In his book, The Carnitine Defense, Dr. Stephen DeFelice discusses carnitine's ability to prevent fatty buildup in the heart, liver and muscles, and to reduce the health risks posed by poor metabolism, especially for those suffering from heart disease and diabetes.
In addition, carnitine may help in the treatment of cancer when taken with adriamycin, a chemotherapeutic agent. It may be possible that a cancer patient can take carnitine supplementation to protect his heart while the dose of adriamycin, which is cardiotoxic, is increased to much higher levels than normal, resulting in the death of more cancer cells.