Idaho Dairy Council

Health Professionals - Nutrition News
Drinking milk improves folate availability in young women
- Another Reason for Women to Wear a Milk Mustache

Researchers at Penn State University suggest that drinking milk may increase the availability of folate contained in other foods. Folate may help prevent heart disease and stroke and is especially important for women of childbearing age to reduce the risk of birth defects. In this study, 31 women ages 19-33 were divided into two groups and consumed low-folate diets for eight weeks. One group drank three servings of fat free milk per day while the other group ate apple juice and egg whites, and researchers analyzed blood samples to determine the impact. Results suggest that consuming at least three servings of milk every day may help boost the body's ability to utilize folate.

The authors conclude, "The inclusion of cow milk in the diet enhanced the bioavailability of food folate as assessed by the changes in erythrocycte (red blood cells) folate and plasma homocysteine concentrations, but not in plasma folate concentrations." Further studies are needed to explore the mechanism of action by components in cow's milk that may account for increasing folate bioavailability. [Picciano MF, et al., Am J Clin Nutr, 80: 1565-1569, 2004]
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Family and Social Factors Influence Children's Eating Patterns

"The purpose of this paper," say the authors, "is to highlight some of the family and social factors that influence children's eating patterns and diet quality," providing health professionals with additional ways to combat childhood overweight. The paper discusses family and social factors such as food availability, preferences, accessibility, and portion size; modeling; mealtime structure; parent attitudes and behaviors regarding food; feeding styles; and socioeconomic and cultural factors.

Highlights:
  • Food acceptance patterns develop early in life; "children who are reluctant to try new foods generally have lower intakes of fruit and vegetables."
  • "Children choose to eat the foods that they are served most often, and they tend to prefer to eat foods that are readily available in the home."
  • "Research has demonstrated that in children as young as two years old, food preferences were associated with their mothers' food preferences."
  • "A growing body of research demonstrates similarities between parents' and children's food acceptance and preferences, intake, and willingness to try new foods."
  • Children and adolescents are influenced by what their friends eat.
  • "Children who eat meals with other family members consume more healthy foods and nutrients. "
  • "The availability of competitive foods from vending machines and a 1a carte programs challenges the nutritious selections available in school meals."
The authors say, "Promoting healthier eating patterns among children requires a multi-faceted approach targeting children, parents, families, and schools." As health professionals, it is important that we educate parents to not only providing healthy food choices in the home, but also to eat and thus model healthy eating themselves (www.MyPyramid.gov) [Patrick H and Nicklas TA, J Am College Nutr, 24(4): 83-92, 2005]
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Purdue study finds races react differently to dietary salt

WEST LAFAYETTE, Ind, May 2005. - African-American and Caucasian adolescent girls handle sodium and calcium differently, which may help explain why the races have different rates of hypertension and osteoporosis, according to research at Purdue University. In a study published in the April edition of the American Journal of Clinical Nutrition, nutrition researchers discovered Caucasian girls lose more calcium in their urine than African-American girls, but both races lose calcium at an accelerated rate when they consume a high-salt diet.

"While we found a racial difference in calcium retention in adolescents, we also confirmed that blacks retain more sodium on a high-salt diet than whites," said Connie Weaver, distinguished professor and head of Purdue's Department of Foods and Nutrition. "This proves that salt is processed differently in the races, but too much salt in the diet reduces bone density in both races."

One out of four Caucasians will be diagnosed with osteoporosis, a bone-loss disease that costs Americans $14 billion a year in health care. The disease strikes one out of 10 African-Americans, but studies show they are more susceptible to hypertension, Weaver said.

"Sodium causes water retention, which leads to high blood pressure, and that could be related to the high prevalence of hypertension in adult blacks," Weaver said. "So even though salt intake is less critical to blacks with respect to building bones, we still have to be concerned about how sodium affects heart health."

The research results were based on figures from Purdue's Camp Calcium. The summer camp, funded by the National Institutes of Health since 1990, is designed to investigate various aspects of calcium metabolism in adolescent girls and boys.

Thirty-five campers were selected to participate in two, 20-day summer camps separated by two weeks. While housed on campus, the girls ate a controlled diet that provided certain amounts of calcium and other nutrients under 24-hour supervision.

The camp participants included 22 African-American girls and 13 Caucasian girls between the ages of 10 and 15. Berdine Martin, research associate and Camp Calcium project director, said the age range was important because, as an earlier Camp Calcium study found, calcium absorption is highest just after a girl's first menstrual cycle.

"Hormones affect the way the body retains calcium," Martin said. "Almost 40 percent of adult peak bone mass is acquired during adolescence, so we can directly affect the way a body ages by regulating calcium at this age."

During the first session, half of the girls received a low-sodium diet and half received a high-sodium diet. The diet was reversed during the second session. Researchers found:
  • Adolescent girls need to have the equivalent of four cups of milk a day to take full advantage of the time when their bodies can develop peak bone mass.
  • Adolescent girls keep 25% of the net calcium they consume, but by the time they are young women, it drops to 5%.
  • Caucasian adolescent girls lose more calcium through their urine than African-American girls, resulting in lower bone density.
"Salt intake affects how the body uses calcium at a critical time of bone development in young girls, but in whites more than in blacks," Weaver said. "This is something that should be easy to monitor in order not only to ensure healthy bones in adults, but also to reduce health-care costs of our aging populations."

Weaver says the strength of this research is the fact that the diets were strictly controlled and monitored in a clinical setting. While a longer study would reveal even more information, it would be difficult to control a diet as tightly as is possible at Camp Calcium, she said.

Research will continue to examine racial differences in how bodies handle calcium during this year's camp, when the focus will be on Asian adolescents. Girls between 12 and 14 and boys between 13 and 15 will attend the six-week camp in two three-week periods and participate in science classes, arts and crafts, sports, nutrition classes, and field trips.

Weaver is an internationally recognized expert on calcium metabolism and bone health. She was a member of the Dietary Guidelines Advisory Committee, which gave recommendations to the U.S. Department of Agriculture to produce the most recent "Dietary Guidelines for Americans." She is director of the National Institutes of Health Botanicals Research Center for Age Related Diseases and past president of the American Society for Nutritional Sciences.
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Fat excretion may contribute to calcium/dairy's weight loss benefits

This randomized, crossover study in 10 moderately overweight subjects examined whether high and low calcium intakes primarily from low-fat dairy products, in diets high and normal in protein content, influence daily energy expenditure and substrate oxidation (utilization of fat, carbohydrates, and protein), fat and energy excreted in feces, and concentrations of hormones involved in metabolism and appetite. All 10 participants were instructed to follow all 3 of the following 1-week diets (not energy restricted) in randomly assigned order: 1) Low calcium/normal protein - 500 mg calcium and 15% of calories from protein; 2) High calcium/normal protein - 1800 mg calcium and 15% of calories from protein; 3) High calcium/high protein - 1800 mg calcium and 23% of calories from protein. Results showed that calcium intake had no effect on 24-hour energy expenditure or fat oxidation. However, fecal fat excretion significantly increased ~2.5-fold and fecal energy excretion increased by 55% during the high calcium/normal protein diet when compared to the other two diets. The authors estimate that this would translate into a weight loss of about 7.7 pounds per year. They say that calcium interacts with fatty acids in the gut, forming insoluble salts, and reducing fat absorption. The researchers found no effects of the diets on blood cholesterol, free fatty acids, triglyceride, insulin, or leptin concentrations, or thyroid hormone levels. The researchers also noted a "minor but important" decrease in blood pressure when participants were following the two high-calcium diets. The authors acknowledge previous studies that demonstrate in mice how dietary calcium can regulate fat metabolism, but show in this study how fat excretion on a high calcium diet may also contribute to weight loss. [Jacobsen R, et al., International J Obesity, January 18: 1-10, 2005]
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Overweight postmenopausal women need extra calcium during weight loss

Several studies have shown that a 5% to 10% weight loss is associated with a decrease in bone mass in obese postmenopausal women. This study is the first to assess the influence of caloric restriction on bone mineral density (BMD) and bone mineral content (BMC) at two levels of calcium intake in 66 overweight (BMI of 27) postmenopausal women - a group that is increasingly encouraged to lose weight. Participants were randomly assigned to follow an energy-restricted diet (1200-1500 kcals/day) or to maintain their weight over a 6-month period. Those in the weight loss group were randomly assigned to either a normal (1,000 mg/day) or high (1,700 mg/day) calcium intake from diet (~600 mg/day) plus calcium supplements (calcium citrate). In total, 47 women successfully completed the weight loss program (lost ~ 9.3% of original body weight) and 19 women maintained their body weight. Results showed that during normal calcium intake, women in the weight loss group lost significantly more BMD and BMC in the hip (trochanter) and BMD in the spine than did the women who maintained their weight. Those in the weight loss group with a normal calcium intake (1,000 mg/day) lost significantly more BMD and BMC in the hip (trochanter) than did those in the high-calcium group (1,700 mg/day). Weight loss on a normal calcium diet did not affect bone at other sites (i.e., total body, spine, femur, radius). The authors report that the observed reduction in circulating estradiol (estrogen) as a result of fat loss and/or the rise in parathyroid hormone and cortisol most likely explain the bone loss seen in this study. They say, "Postmenopausal women with a low BMD who undergo moderate weight loss and consume 1,000 mg of calcium per day will be at greater risk for hip fracture." They say that current calcium recommendations are not adequate for postmenopausal women who are on a calorie restricted diet. [Reidt CS, et al., J Bone Min Res, 20(3): 455-463, 2005]
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Low mineral intakes associated with high systolic blood pressure

This analysis, supported by a grant from the National Dairy Council, evaluated blood pressure and nutrient intake data from 10,033 adult participants of the third National Health and Nutrition Examination Survey (NHANES III, 1989-91 and 1991-94) and 2,311 participants in NHANES IV (1999-2000). The findings demonstrated - as had an earlier analysis of NHANES I (1984) - that inadequate mineral consumption (i.e., calcium, potassium, magnesium) is associated with higher blood pressure - a relationship that has "persisted over two decades." After separating those with untreated hypertension by type (systolic, diastolic, or both), "the blood pressure effect of low mineral intake was most pronounced in those with only systolic hypertension." Those with isolated systolic hypertension also exhibited significantly lower intakes of energy, protein, carbohydrate, fat and fiber in NHANES III, and lower intakes of energy and carbohydrate in NHANES IV - which is consistent with a dietary pattern of deficiency rather than excess. "This observation," say the authors, "is clearly not simply a fleeting trend in the United States." Rather, it is a "consistent pattern of dietary intake characterized by low intakes of dairy products, fruits, and vegetables."

Results provided a "critical new insight" regarding the relationship between sodium intake and blood pressure. They found that sodium intake was significantly lower in those with isolated systolic hypertension (those most at risk for cardiovascular disease) compared with those with normal blood pressure. Dietary patterns differed significantly between blood pressure categories. The authors say, "The nutritional pattern of lower intakes of all minerals including sodium and of macronutrients is unique to persons with isolated systolic hypertension" - which comprised 60% of the hypertensive persons in the study sample. In contrast, persons with isolated diastolic hypertension were more likely to be overweight and to have a higher sodium intake. The authors conclude, "Our data indicate that effects of sodium on blood pressure are limited to those individuals with isolated diastolic hypertension with its accompanying higher BMI." In this group, who are likely salt sensitive, restricting sodium intake along with calories may be the most effective dietary intervention. Individuals with the greatest cardiovascular risk - older persons with systolic hypertension - will most benefit from a dietary pattern, regardless of sodium level, such as the DASH (Dietary Approaches to Stop Hypertension) diet, which is rich in minerals from low-fat dairy foods, fruits, and vegetables.

The authors say the results of this analysis likely explain why previous randomized controlled trials of diet modification for blood pressure management have had such widely varying results. Future interventions should address the substantial differences in nutritional intakes between categories of hypertension. [Townsend MS, et al., Am J Hypertens, 18: 261-269, 2005]
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Omitting breakfast impairs insulin sensitivity and could lead to weight gain

This randomized crossover trial in 10 healthy, normal weight women tested whether eating or omitting breakfast affects total daily energy intake, energy expenditure, or blood levels of glucose, insulin, or lipids. Each subject participated in two 14-day interventions, separated by a 2-week interval. During the breakfast period, the women consumed breakfast cereal with 2% milk before 8 a.m., then a chocolate-covered cookie between 10:30 and 11:30 a.m. During the omitting breakfast period, participants ate the cookie between 10:30 and 11:30 a.m. and ate cereal and milk between noon and 3:30 p.m. The average calorie intake recorded over 3 days was significantly lower when the women ate breakfast compared to when they omitted breakfast. Omitting breakfast was associated with significantly higher fasting total and LDL-cholesterol than was eating breakfast. In addition, the insulin response to the test meal was significantly lower in the group eating breakfast than in those omitting breakfast. The authors conclude, "Omitting breakfast impairs fasting lipids and postprandial (after a meal) insulin sensitivity and could lead to weight gain if the observed higher energy intake was sustained." [Farshchi HR, Taylor, and Macdonald IA, Am J Clin Nutr, 81: 388-396, 2005]
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International experts agree: Diets higher in dairy associated with lower weight

A recent compilation of international studies and abstracts published mainly in The International Journal of Obesity further support the role of calcium, specifically calcium from dairy foods, in weight management. While several American studies have established the link between 3 servings of dairy each day and effective weight management, these were the first studies to examine populations in a variety of countries such as Italy, Iran and Denmark.

An Italian study (1) explored the association between dairy and body mass in children, finding that as children increased milk consumption their body mass decreased. Furthermore, the children in this study who drank whole milk daily had lower incidence of overweight compared to those who drank milk less frequently. The study from Iran (2) found that people who ate more dairy foods including milk, yogurt and cheese were less likely to be overweight or obese than those who consumed less dairy.

"These international study results further affirm the connection between high calcium intake through dairy foods and protection from obesity and weight gain," said Angelo Tremblay, PhD, Department of Preventive Medicine, Laval University, Quebec, Canada. "While dairy's role in weight management has proven beneficial in American research, it's promising to see a similar effect on other cultures."

One additional study from Denmark (3) found a diet high in calcium that also included a normal level of protein resulted in less absorption of dietary fat and may partly explain why a high-calcium diet produces weight loss. Researchers presented much of the data at the 13th European Congress on Obesity in 2004.

(1) Barbara G. et al. Inverse association between body mass and frequency of milk consumption in children. British Journal of Nutrition. 2005; 93(1):15-9.
(2) Mirmiran P, et al. Dairy consumption and body mass index: An inverse relationship. International Journal of Obesity. 2005; 29:115-121.
(3) Jacobsen, R. Effect of short-term high dietary calcium intake on 24-h energy expenditure, fat oxidation, and fecal fat excretion. International Journal of Obesity (2005) 29, 301. 292
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