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Volume 13 - February 2004
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The Dietary Approaches to Stop Hypertension (DASH) diet not only benefits hypertension but also improves insulin sensitivity, according to the results of a study published in the February issue of Diabetes Care . This diet is high in fruits, vegetables, and low-fat dairy products but lower in total fat, saturated fat, and cholesterol. It is replete with nutrients associated with improved insulin sensitivity, including magnesium, calcium, and protein. The DASH diet also has been recommended for hypertension, and it consists of higher levels of potassium, magnesium, calcium, and fiber than the typical American diet. "As the DASH dietary pattern is implemented as a routine part of nonpharmacologic management of hypertension, it will be important to know the effects on insulin action of a comprehensive behavioral program that includes the DASH dietary pattern," write Jamy D. Ard, MD, from Duke University Medical Center in Durham, North Carolina, and colleagues. "If the addition of the DASH dietary pattern adds to a lifestyle intervention (i.e., weight loss, moderate sodium reduction, and increased physical activity) by increasing insulin sensitivity, such a finding would provide added evidence for the need to recommend the DASH dietary pattern as part of a comprehensive lifestyle intervention for treatment of hypertension and overall cardiovascular risk reduction." "Based on the results of this study, including the DASH dietary pattern as a basic part of a hypocaloric dietary plan can lead to significant improvements of up to 50% in insulin sensitivity," the authors write. "This combination of foods and nutrients may have an effect on a variety of different cellular targets that ultimately promotes changes in body composition during weight loss, resulting in a favorable impact on insulin action." Diabetes Care. 2004;27:340-347 |
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An obsession with "hydration" may have spawned an entire industry of water bottles, but most people get plenty of fluids, the Institute of Medicine panel said. However, nearly all U.S. and Canadian adults get far more salt than recommended, and too little potassium. The Institute, an independent body that advises the federal government on health matters, set general recommendations for water intake based on dozens of studies that show women need about 91 ounces (2.7 liters) of water a day on average, and men need 125 ounces (3.7 liters).Food, coffee or other drinks all contribute, so it is impossible to say how many glasses of plain water someone should drink, the panel said. Only those who are very physically active or who live in hot climates may need to drink more water, the researchers said. "While drinking water is a frequent choice for hydration, people also get water from juice, milk, coffee, tea, soda, fruits, vegetables, and other foods and beverages as well," Dr. Lawrence Appel, a professor of medicine at Johns Hopkins University in Baltimore and chairman of the panel, said in a statement. "Moreover, we concluded that on a daily basis, people get adequate amounts of water from normal drinking behavior -- consumption of beverages at meals and in other social situations -- and by letting their thirst guide them." The panel said most North Americans consume far too much salt, much of it in processed foods. Healthy 19- to 50-year-old adults should consume 3.8 grams of salt a day, and the most salt anyone should consume is 5.8 grams a day. Almost everyone gets more than this -- in the U.S., men's median intake of salt is between 7.8 and 11.8 grams per day, and women take in between 5.8 and 7.8 grams every day, the panel found. Canadian adults consume between 5.1 and 9.7 grams a day. "Older individuals, African Americans, and people with chronic diseases including hypertension, diabetes, and kidney disease are especially sensitive to the blood pressure-raising effects of salt and should consume less than the upper limit," the panel said in a statement. It said more than 95 percent of American men and 75 percent of American women get more than this. And Americans get far too little potassium every, the panel found. It said adults should consume 4.7 grams of potassium per day but most American women 31 to 50 years old consume no more than half this. Canadians typically get more potassium. "Research is needed to find ways to help people select better food choices to reduce their salt intake and boost their potassium consumption," Dr. Appel said. The panel recommended that researchers help food processors develop better ways of making food that is low in salt. The nation turns to the Institute of Medicine (IOM) of the National Academies for science-based advice on matters of biomedical science, medicine, and health. A nonprofit organization specifically created for this purpose as well as an honorific membership organization, the IOM was chartered in 1970 as a component of the National Academy of Sciences. As an independent, scientific adviser, the Institute of Medicine strives to provide advice that is unbiased, based on evidence, and grounded in science. The mission of the Institute of Medicine embraces the health of people everywhere |
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Research News: Maternal Smoking Reduces Iodine Transport Into Breast Milk Smoking reduces the transport of iodine into breast milk, according to the results of a study published in the January issue of the Journal of Clinical Endocrinology and Metabolism . The investigators suggest that women who breastfeed should not smoke, but if they do, they should have iodine supplementation. "Lack of iodine for thyroid hormone formation during the fetal stage and/or the first years of life may lead to developmental brain damage ," write Peter Laurberg, from Aalborg Hospital in Denmark, and colleagues. "During the period of breastfeeding, thyroid function of the infant depends on iodine in maternal milk." Worldwide, iodine deficiency is the main cause of preventable brain damage and mental retardation. Lack of thyroid hormone for more than a few weeks during brain development in utero or during the first years of life may permanently damage brain function. In 2001, 50 million children were born in areas without protection against iodine deficiency according to a report in a 2002 issue of the Bulletin of the World Health Organization by de Benoist and Clugston. Thyroid hormones required for fetal brain development are of maternal origin. Fetal thyroid hormones increase from the second trimester to after birth to account for brain development in infancy. Maternal milk concentrates iodide to allow for adequate iodine use by the infant. It is postulated that the chemical thiocyanate accumulates in the blood of smoking mothers and competitively inhibits iodide transport in the mammary gland and ultimately into the infant thyroid gland. This can lead to iodine deficiency in the infants. The investigators used cotinine levels in urine and serum to identify whether healthy pregnant women who were admitted for delivery were smokers or nonsmokers. Both groups had identical urinary iodine on the fifth postpartum day, but smoking was associated with reduced iodine content in breast milk and in the infants' urine. In smokers, iodine transfer into breast milk was inversely related to urinary cotinine concentration. Smoking mothers had significantly higher serum levels of thiocyanate, which may interfere with iodide transport in the lactating mammary gland by competitive inhibition of the sodium-iodide symporter. "Smoking during the period of breastfeeding increases the risk of iodine deficiency-induced brain damage in the child," the authors write. "Women who breastfeed should not smoke, but if they do, an extra iodine supplement should be considered." J Clin Endocrinol Metab. 2004;89:181-187 |
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Debunking Carbohydrates MythsWhat an athlete eats and drinks can affect their exercise performance. Much the same, what you eat and drink affects how you run. Many of the athletes today get confused about the role of carbohydrates versus proteins in their diets. So what are carbohydrates and proteins? Simply, carbohydrates are nutrients that mainly act as your fuel. Just like a car if there is no gas it will not run. Proteins are nutrients that are the building blocks for making hormones, enzymes and blood cells. Three common myths are:
All of these beliefs are strengthened by articles and advertisements in popular health & fitness magazines pushing "carb-free" energy drinks & "zero-carb" energy bars. Myth #1: Carbohydrates are bad It is tempting to label nutrients as either good or bad, but both carbohydrates and proteins are critical to good health and exercise performance. The key is that they perform different roles and so you cannot substitute one for the other. Carbohydrate is the preferred fuel for working the muscle. It:
The fact is carbohydrates in whole grains (whole wheat, pumpernickel, cracked wheat breads, whole wheat pasta, brown rice, quinoa, oatmeal), vegetables and whole and dried fruits are good for the body. They provide us with:
Myth #2: Carbohydrates make you fat Carbohydrates do indeed stimulate insulin released from the pancreas, but insulin is a very important hormone. On the contrary, insulin unlocks the key to cells so fuel can enter the muscles. As an anabolic hormone, it also helps facilitate the entry of amino acids into muscles so they can be built, maintained or repaired. While insulin, which is stimulated by both carbohydrates and protein, does facilitate the storage of excess calories into fat cells, it does not promote weight gain. And, insulin will not convert carbohydrate into fat when the carbohydrate is needed for fuel or as an energy reserve in muscle. Excess calories, whether from carbohydrate, protein or fat, cause weight gain. Myth #3: Carbohydrates are not the key to fueling muscle mass However, protein is not critical for fueling working muscles. When carbohydrate is in short supply, protein can be used as a fuel. But then it gets diverted from its more important roles. For that reason, carbohydrate intake should be adequate enough to do its job—provide athletes with the energy they need for the occasion. Athletes, as compared to couch potatoes need more protein but when carbohydrate intake is adequate; their protein needs are only modestly elevated. These needs are easily fulfilled through a diet containing foods like eggs, beef, chicken, turkey, fish, cheese, milk, yogurt, nuts, soy and protein-rich alternatives like lentils, baked beans, black beans and kidney beans. This all goes to show that carbohydrates, consumed from the right sources and in the right amounts, provide athletes with the energy they need to perform at their best. Some key points to remember. First, it is important to consume enough calories. Low energy intake can result in loss of muscle mass, loss in bone density, increased risk of fatigue, injury and illness. Optimal needs are individualized. They are based on sex, age, bone structure, genes and the sport itself. Second, grains, fruits and vegetables, and milk products are important to maintain the blood sugar levels during exercise. Athletes have only slightly increased protein requirements which can generally be met through diet alone. Fat is also important because it provides energy, fat soluble vitamins and essential fatty acids. Third, adequate fluid intake before, during and after exercise is necessary because dehydration decreases one's exercise performance. Try drinking a cup of water two hours before the run. As well your pre workout snack or meal should provide sufficient fluid to maintain hydration. Make sure its low in fat and fibre . For example, try 1% yogurt because it has little fat, no fibre, a little protein and mainly carbohydrates. This snack is also beneficial since it does increase your blood sugar levels too quickly. Most athletes find it difficult to consume a shake before hand since it feels like they have liquid in their stomach. However, snacks or meals are by trial and error because some people have a higher metabolism and need more food. I know some people who eat pancakes and juice before hand. In conclusion, without a proper meal plan your exercise performance could be jeopardized. So if any of you do not have a great run today at least you know why. For further information please contact: Ali J. Chernoff, B.Sc., R.D.N. |
