Joan Benson

Trans-fatty acids and colon cancer

Trans-fatty acids have been hypothesized to be carcinogenic, although there are limited data in humans testing this hypothesis. In this study, we examine the association between trans-fatty acids and colon cancer using data from a case (n = 1,993)-control (n = 2,410) study conducted in Utah, Northern California, and Minnesota. Dietary data were collected using a detailed diet history questionnaire, and nutrient values were generated from the Nutrition Coordinating Center nutrient database. After adjustment for other variables, including age at diagnosis, body size, physical activity, aspirin and/or nonsteroidal anti-inflammatory drug (referred to collectively as NSAIDs) use, energy intake, and dietary fiber and calcium, we found a weak association in women [odds ratio (OR) = 1.5, 95% confidence interval (CI) = 1.1-2.0] but not in men (OR = 1.2, 95% CI = 0.9-1.7); no increased risk was observed for the cis form of the fatty acids. For men and women, slightly stronger associations were observed in those ≥67 years of age (OR = 1.4, 95% CI = 0.9-2.1 for men; OR = 1.6, 95% CI = 1.0-2.4 for women). Those who did not use NSAIDs were at a 50% greater risk of developing colon cancer when they consumed high levels of trans-fatty acids. Women who were estrogen negative, i.e., postmenopausal not taking hormone replace therapy, had a twofold increase in risk from high levels of trans-fatty acids in the diet, while women who were estrogen positive did not experience an increased risk of colon cancer, regardless of level of trans-fatty acids consumed. We believe that these data have important public health implications. It seems prudent to avoid consuming partially hydrogenated fats, since no increased risk was observed for the cis form of fatty acids, while suggestions of increased risk from trans-fatty acids exist for subsets of the population.

Energy Balance and Rectal Cancer: An Evaluation of Energy Intake, Energy Expenditure, and Body Mass Index

Lack of energy balance, or greater energy intake than expenditure as indicated by a large body mass index (BMI), has been associated with colon cancer, although less is known about its association with rectal cancer. In this study, we examined the association between BMI, energy intake, and energy expenditure and their combined effect on rectal cancer risk. A population-based case-control study was conducted in Utah and Northern California. Incident cases (n = 952) of rectal cancer and population-based controls (n = 1205) were interviewed between 1997 and 2002 to obtain detailed information on body size, dietary intake, and physical activity patterns. BMI (kg/m2) was not associated with rectal cancer in either men or women. Participation in vigorous leisure-time physical activity over the past 20 yr was associated with a significant 40% reduction in rectal cancer risk. Energy intake was associated significantly with increased risk of rectal cancer, especially among people whose diagnosis was prior to age 60 yr (odds ratio [OR] = 3.9; 95% confidence interval [CI] = 1.7-9.1 for men; OR = 2.8; 95% CI = 1.1-7.2 for women). There was a significant interaction between energy intake and energy expenditure, although not between BMI and either energy intake or energy expenditure. These data suggest that large BMI, an indicator of lack of energy balance, is not an important component of the etiology of rectal cancer. However, both physical activity and energy intake were significantly associated with rectal cancer risk. These data suggest that energy expenditure and energy intake alter rectal cancer risk through mechanisms other than energy balance.

Effect of antioxidant supplementation on urine and blood markers of oxidative stress during extended moderate-altitude training

OBJECTIVE To investigate the increase in oxidative stress during work at moderate altitudes due to additional energy expenditure, tissue anoxia, and UV light exposure. METHODS Thirty US Marine Corps volunteers were divided into placebo (P) and antioxidant supplement (S) groups and tested for markers of oxidative stress before (t0), at the midpoint of (t1), and after (t2) 14 days of winter training at a moderate altitude (approximately 2700 m). The antioxidant supplement consisted of a daily dose of 20,000 IU beta-carotene, 400 IU vitamin E, 500 mg vitamin C, 100 micrograms selenium, and 30 mg zinc. The following markers of oxidative stress were measured: urine thiobarbituric acid reactive substances (TBARSs), urine hydroxynonenal (HNE), urine 8-hydrodeoxyguanosine (8-OHdG), plasma total peroxyl radical trapping potential (TRAP), and plasma lipid hydroperoxides (LPOs). Urine was collected on a 24-hr basis at t0, t1, and t2; blood samples were collected at t0 and t2. RESULTS P group LPOs increased 30% (p < 0.05) between t0 and t2, whereas S group LPOs did not increase. Both groups exhibited significant increases in urine TBARSs, HNE, and 8-OHdG by t2. Urine TBARSs, HNE, and 8-OHdG increased between t0 and t1 in both groups, with the greater increase in the S group. The conflicting results between the plasma and urine markers of oxidative stress may be due to a time-phase relationship. CONCLUSIONS The results of this study suggest that work in a moderate-altitude cold-weather environment is accompanied by increased oxidative stress, despite relatively high intakes of dietary and supplemental antioxidants.

Nutrition Habits and Knowledge in Competitive Adolescent Female Gymnasts

In brief: Diet quality and nutrition knowledge were evaluated in 97 competitive female adolescent gymnasts. Each gymnast kept a three-day diet record and completed a questionnaire. The gymnasts averaged only 1,838 kcal per day, which is 300 kcal less than the recommended energy intake for 13-year-old girls 60 in. tall. More than 40% consumed diets that provided less than two thirds of the recommended dietary allowance for calcium, folate, vitamin B6, iron, and zinc. Their nutrition knowledge was poor; thus, a nutrition education program would be valuable for these athletes.

Nutritional Intake in Adolescent Athletes

Nutrition plays a critical role in the success of the competitive adolescent athlete. Some groups have stricter nutrition requirements than others. The authors summarize nutrition intake data on serious female gymnasts, ballet dancers, and high-school cross-country runners. This article also discusses the nutritional needs of young male wrestlers and weightlifters.

Dietary antioxidants and plasma lipids: The CARDIA study

OBJECTIVE To determine if dietary antioxidants play a role in preventing coronary heart disease (CHD) by having an impact on lipid levels. METHODS Data from the Coronary Artery Risk Development in Young Adults (CARDIA) Study were used to assess the associations of reported intake of vitamins A, C, E and beta carotene, and their use in supplements, with lipid levels in a black and white, healthy adult (18 to 30 years of age at the baseline examination) population. RESULTS After adjusting for age, education level, physical activity, body size, alcohol consumption and caloric intake, vitamin A, beta carotene, and vitamin C (white women) intake were directly associated with HDL-cholesterol levels among women who smoked cigarettes, with the strongest associations being observed for white women. Black men who took supplements of vitamins A and C and did not smoke cigarettes had significantly higher HDL-cholesterol levels compared to those in the lowest levels of dietary intake. Although vitamin E was associated with higher levels of HDL-cholesterol, the association was only of borderline significance among white men who smoked cigarettes (p = 0.06). We did not observe any consistent associations between antioxidants and other plasma lipids, including total cholesterol, LDL-cholesterol, or triglycerides. CONCLUSIONS We conclude that dietary antioxidants are associated with HDL-cholesterol levels in some subsets of the population, although these associations may be operating in conjunction with other lifestyle behaviors.

A comparison of subjective and objective measures of physical exertion

Abstract Better methods are needed to improve validity and reliability of physical activity (PA) assessment instruments. The purpose of this study was to compare individuals Borgs Rate of Perceived Exertion (RPE) scores to GT1M ActiGraph accelerometer output, with the aim to better understand estimates of perceived exertion for exercise prescription. Adults were recruited (n = 117) from Utah, with 43.1% males (n = 50), and most (53.1%) self-reporting regular exercise. Participants performed three indoor laps of increasing intensity, ranging from walking to running, and immediately completed a RPE form. A subsample was mailed the same RPE survey 6–8 weeks later to compare differences from their initial responses. Individual accelerometer data was compared to RPE levels from validated metabolic equivalents (METs). There were significant differences between the RPE ratings and the accelerometer output overall for gender (χ2 = 10.9, P = 0.004), and exercise status (χ2 = 15.5, P < 0.001). The odds of underestimating RPE for an exerciser were 3.67 times greater than a non-exerciser (95% CI = 1.48, 9.11). The subsample also underestimated RPE after the time lapse (Z = −2.324, P = 0.020). Overall, the RPE proved to be a useful tool for most individuals and could be used in individualised exercise prescription, although women may overestimate, and regular exercisers may underestimate exertion.

The Polyp Prevention Trial

Abstract The Polyp Prevention Trial (PPT) is a randomized clinical trial sponsored by the National Cancer Institute. National Institutes of Health, that tests the relationship between diet and the formation of large bowel adenomatous polyps, the precursor lesion for most large bowel cancers. Approximately 2000 participants from 8 Clinical Centers have been randomized into the trial. Half were assigned to the intervention group and asked to adopt a low-fat (20% of calories from fat), high-fiber (18grams/1000kcal), high fruit and vegetable (5 to 8 daily servings) eating plan. Numerous epidemiological studies suggest that these dietary factors may be protective for large bowel cancer. The remaining participants were assigned to the control group, maintaining their usual diet. Registered dietitians play a central and critical role in the PPT. The 4-year intervention program is delivered solely by RDs. The success of the intervention depends to a great degree on the abilities of these nutritionists to deliver the program effectively as well as to help participants sustain a high level of motivation for making long-term dietary changes. In addition, RDs at both the Coordinating Center and at the Clinical Centers play a vital role in ensuring standardization of the delivery and documentation of the intervention program. RDs also have the primary responsibility for administering the baseline and annual dietary assessments and for assuring quality and standardization of dietary assessment activities. The Polyp Prevention Trial provides opportunities not available to RDs working in typical clinical settings. For example, the study design allows for approximately 50 hours of in-person counseling for each participant along with resources to assist participants in making long-term changes. The PPT also presents unique challenges to nutritionists in their multiple roles of providing nutrition education and behavioral counseling; administering dietary assessments; maintaining objectivity and standardization; and performing administrative, organizational, and managerial activities.

The Relationship Among Diet, Exercise, and Perimenstrual Symptoms

Abstract Research has shown that 30-90% of women suffer from mild to moderate perimenstrual symptoms while 2-10% experience severe symptoms. Yet, after decades of study, neither a definite etiology for symptom development, nor an encompassing and effective treatment has been found. To reduce symptom severity and prevalence researchers are currently suggesting a combination of lifestyle modifications including, moderate exercise, stress management, education and a balanced diet high in complex carbohydrates and low in fat, refined products, alcohol, caffeine and sodium rich foods. This study evaluated the impact of diet and exercise on perimenstrual symptom prevalence and severity. Forty-nine volunteer women completed an exercise questionnaire, one 3-day food record, and a prospective menstrual symptom calendar of 27 symptoms for one cycle. Mean daily dietary intake was as follows: (% of kcals) % CHO=55 +/-9.5%, % fat=28 +/-8.6%, % protein=15 +/- 3.2%, alcohol=6 +/- 12.9 gm, caffeine=102.5 +/- 112.7mg, sodium=2854 +/- 1074mg. Mean weekly exercise times included: 241 +/- 288 mins. for light exercise, 150 +/- 140.5 mins. for moderate exercise, 101 +/- 146 mins. for vigorous exercise, and 25 +/- 44.7 mins. for weight lifting. Symptom prevalence ranged from 6.1% for dizziness to 61.2% for cramps arid back ache. Multiple regression analysis was used to evaluate the relationship between dietary and exercise factors and pre-established symptom groups. Results showed that lifestyle variables played the strongest role in development of the premenstrual tension symptom group (PMTD) which includes the symptoms depression, confusion, crying, forgetfulness and insomnia. In this analysis (R 2 =.497) the factors most strongly associated with exacerbating symptoms were weight lifting (p=.002), moderate exercise (p=.02) and protein (p =.008). High CHO intake was associated with less severe symptoms (p=.036). Thus, it appears that a low carbohydrate, high protein diet may play a significant role in development of the PMTD symptoms. However, the impact of exercise remains in question. While exercise is expected to reduce symptoms, this study showed the opposite. Limitations of this study prevent determining whether the significant relationship between moderate exercise, weight lifting and symptoms exists because exercise exacerbates symptoms or women with symptoms are already implementing exercise for self-treatment. The results of this study support the proposition that dietary and exercise factors can influence perimenstrual symptoms. Further research involving monitored behavior and dietary changes will help clarify the importance of independent factors in perimenstrual symptom occurrence and the direction of cause and effect

Time-Efficient Methods of Measuring the Impact of Targeted Dietary Intervention Campaigns: The Polyp Prevention Trial Experience

Abstract LEARNING OUTCOME: To describe assessment tools that measure the impact of targeted campaigns within a dietary intervention trial. Dietary intervention trials face the challenge of maintaining changes over long periods of time. In addition to supporting behavior change, interventions need timely ways to assess the impact of both short- and long-term strategies in order to efficiently address problems. These considerations were pertinent in the Polyp Prevention Trial (PPT), a randomized trial that tests the effect of a low-fat (20% kcal from fat), high-fiber (18 gms fiber/1000 kcal), high fruit/vegetable (5-8 daily servings based on caloric intake) eating plan on the recurrence of large bowel adenomatous polyps, the precursor lesion for most colorectal cancers. Half of the 2079 PPT participants were randomized to the intervention group and provided with ongoing nutrition/behavioral counseling to help them maintain the eating plan for 4 years. Participants complete Food Frequency Questionnaires (FFQ) and 4-Day Food Records annually to measure dietary changes, but to prevent study bias, only trial averages are shared with participants and staff. At the end of Year 1, participants made marked progress toward goals, but plateaued in Year 2 with respect to fruits/vegetables(F/V) and showed a slight drift upward in fat percent. To encourage participants to reach and maintain goals, 3 targeted campaigns (each lasting 6 to 8 months) were launched sequentially: first a fat campaign (to lower fat); then the Fruit & Veg-a-thon (to increase F/V intake); and finally the PPT On My Mind campaign (to support progress toward all 3 goals). Campaign messages were delivered via phone, in-person sessions, and mail using a variety of print and non-print materials. While post-fat campaign FFQ data showed slight reductions in fat, it was difficult to attribute this decrease directly to the campaign. Furthermore, there was no way to give participants feedback about individual progress. Therefore, time-efficient methods to evaluate campaign impact were incorporated into the second and third campaigns. First, FFQ data were used to identify food group sources that differentiated goal achievers from those not reaching goals. On routine campaign contacts, previous days intake information related only to these specific foods was collected and tracked and a simple impact analysis was performed monthly. This focused data collection provided information about the short-term impact of targeted intervention efforts (e.g., monthly changes in mean F/V intake during the Fruit & Veg-a-thon varied from +1.5 to 2 servings over pre-campaign levels) while taking less than 10minutes/participant on average (vs. 60 to 90minutes for an FFQ). These measures also offered a way to provide frequent feedback to participants to encourage further behavior changes.