Highlights of Tufts University nutrition research: January 2004

01/30/04

Men and Women Respond Differently to Low Fat, Low Cholesterol Diets

It is well known that a diet high in cholesterol is associated with increased risk for coronary heart disease – a major cause of death and disability and the recommended therapeutic approach is to follow a diet low in saturated fat and cholesterol. Until recently, the effect of this therapeutic diet on cholesterol response in men and women has not been well understood. Jose Ordovas, PhD, a professor at the Friedman School of Nutrition Science and Policy, and his colleagues recently examined the difference in cholesterol response by gender. The results of this study were published in The Journal of Nutrition.

Ordovas and his colleagues at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts studied a small group of men over the age of 40 and postmenopausal women with moderately elevated cholesterol levels. For an initial six-week period, the study participants consumed an average American diet (AAD) that was relatively high in total fat, saturated fat and cholesterol – similar to diets consumed in the US. This was followed by another six-week period during which participants consumed a Therapeutic Lifestyle Changes (TLC) diet that restricts total fat, saturated fat and cholesterol intake – similar to the National Cholesterol Education Program Adult Treatment Panel II and III. A period of two to seven weeks separated the AAD and TLC diet phases, during which the participants' habitual diets were resumed.

The researchers observed a difference in how men and women reacted to the diets. They found that middle aged men had a more favorable cholesterol response to the TLC diet than post-menopausal women, with a 19 percent drop in men's cholesterol compared to a 12 percent drop in women's. Although the change in cholesterol level was smaller in women than for men, both differences were significant. The researchers are unclear as to why men responded more strongly than women did, but as the results indicate, both genders can benefit from following a heart-healthy diet low in saturated fat and cholesterol.

Iron Helps Build Strong Bones

Calcium is the first nutrient many people think of when trying to build strong bones. But another nutrient not usually associated with bone health may also play an important role. According to the January edition of the Tufts University Health & Nutrition Letter, the mineral iron helps produce an integral component of bone called collagen.

There is a complicated relationship at work because iron and calcium compete for absorption in the body. Research has shown that iron's role in bone building is effective only if the recommended 800-1200 milligrams of calcium are consumed. According to the article, "too much or too little can throw things off." A recent study on more than 250 post-menopausal women found that those who consumed about 18 milligrams of iron, along with adequate calcium, had the greatest bone mineral density. This amount is higher than the Recommended Daily Allowance of eight milligrams set for women of this age group.

Iron-rich foods include beef, poultry, shellfish, beans, liver, wheat germ and prune juice. In addition to iron and calcium, the newsletter advises people not to forget the other bone building nutrients such as vitamin D and vitamin K, which are also part of a well-balanced diet.

Loss of Familiar Fruits and Vegetables May Increase Obesity Risk for Some Elderly Hispanics

Immigrants to the US often acquire new eating patterns as they become accustomed to American products and fast food culture, a phenomenon that researchers call "acculturation." These new eating patterns can sometimes result in lower nutritional value and a subsequent rise in obesity and associated chronic conditions. A recent study conducted by Katherine Tucker, PhD, associate professor at the Friedman School of Nutrition Science and Policy, and her colleagues found that while elderly Hispanics in Massachusetts follow dietary patterns that have not been strongly adapted to general US patterns, they also have a high prevalence of obesity and associated chronic conditions. Unlike some other groups, where reports have shown that acculturation to American eating habits leads to poorer diets, Tucker explains, "less dietary acculturation was associated with obesity in this group of mainly Carribean origin Hispanics."

Tucker and colleagues Odilia Bermudez, PhD, and Hai Lin, PhD, MPH, at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University examined major dietary patterns of Puerto Rican and Dominican immigrants, the two most common Hispanic groups in Massachusetts.

The researchers identified the association between acculturation and dietary patterns as well as the association among those dietary patterns with total and central obesity (around the torso). Study participants consisted of 449 Puerto Rican and 133 Dominican elders, and a neighborhood-based comparison group of 243 non-Hispanic white elders, all aged 60 to 92 years. Dietary patterns were defined by five clusters of food groups: fruit and cereal; starchy vegetables; rice; whole milk; and sweets. They discovered that Hispanics were more likely to consume the starchy vegetables and milk dietary pattern more than their non-Hispanic white counterparts. Furthermore, only Hispanics followed the rice pattern, which correlated with two measures of obesity and was not correlated with adaptation to the American diet.

The study provides insight into the effects of acculturation on dietary patterns in this population subgroup. Tucker and colleagues believe that consumption of highly refined grains combined with an overall lack of fruit and vegetables may contribute to weight gain and associated chronic conditions. According to Dr. Tucker, "based on our experience, tropical fruits and a variety of root crops are readily available in Puerto Rico while here, if available, they are quite expensive, and therefore may be less consumed."

Source: Eurekalert & others

Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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