Comparison of dietary intakes and iron status of vitamin-mineral supplement users and nonusers, aged 1-19 years

Combinatorial selection in amoebal hosts drives the evolution of the human pathogen Legionella pneumophila

Virulence mechanisms typically evolve through the continual interaction of a pathogen with its host. In contrast, it is poorly understood how environmentally acquired pathogens are able to cause disease without prior interaction with humans. Here, we provide experimental evidence for the model that Legionella pathogenesis in humans results from the cumulative selective pressures of multiple amoebal hosts in the environment. Using transposon sequencing, we identify Legionella pneumophila genes required for growth in four diverse amoebae, defining universal virulence factors commonly required in all host cell types and amoeba-specific auxiliary genes that determine host range. By comparing genes that promote growth in amoebae and macrophages, we show that adaptation of L. pneumophila to each amoeba causes the accumulation of distinct virulence genes that collectively allow replication in macrophages and, in some cases, leads to redundancy in this host cell type. In contrast, some bacterial proteins that promote replication in amoebae restrict growth in macrophages. Thus, amoebae-imposed selection is a double-edged sword, having both positive and negative impacts on disease. Comparing the genome composition and host range of multiple Legionella species, we demonstrate that their distinct evolutionary trajectories in the environment have led to the convergent evolution of compensatory virulence mechanisms.

Dietary Supplement Use Among Chinese Primary School Students: A Cross-Sectional Study in Hunan Province

Dietary supplement use is increasing globally, especially among children. However, few studies have been conducted to examine dietary supplement use among Chinese children. The aim of this study was to examine the prevalence of dietary supplement use and the associated factors in primary school students. A cross-sectional study was conducted in four primary schools in Hunan province, China. A total of 706 Chinese parents/caregivers of school children aged 6–12 years old were enrolled. Self-administrated questionnaires were used to collect information about the children’s dietary supplement use, and their socio-demographic characteristics. The prevalence of dietary supplement use in primary school students was 20.4%. Calcium (16.7%), vitamin C (9.2%), and vitamin D (8.5%) were the most commonly used types of dietary supplement. The main reasons for parents/caregivers to purchase dietary supplements for their children were immunity improvement (43.6%), and for growth promotion (36.5%). Some caregivers (26.4%) purchased dietary supplements online, including from dubious or unknown sellers. However, 37.5% of caregivers did not receive formal guidance on supplementation even if they purchased their supplements through formal channels. Parents/caregivers were unclear about the appropriate choices for children’s dietary supplement use. Guidelines and counseling regarding dietary supplements for children may be helpful in public health work.

Micronutrient Intake among Children in Puerto Rico: Dietary and Multivitamin-Multimineral Supplement Sources

BACKGROUND

Micronutrients are critical for healthy growth and development of children. Micronutrient intake from dietary sources is inadequate among some children and may be improved by use of multivitamin and multimineral (MVMM) supplements.

OBJECTIVE

To assess micronutrient intake from dietary and MVMM supplement sources among 12-year-old children in Puerto Rico.

METHODS

A representative sample of 732 children enrolled in an oral health study in Puerto Rico, who completed dietary and MVMM assessments through one 24-h recall, were included in this analysis. Micronutrient intake sources were described and compared to the Dietary Reference Intakes (DRIs) using the Estimated Average Requirement when available (used Adequate Intake for vitamin K and pantothenic acid). Micronutrient profiles of MVMM users and non-users were compared using t-tests.

RESULTS

Mean intakes of vitamins A, D, E, and K, pantothenic acid, calcium, and magnesium from food and beverage sources were below the DRIs. From food and beverage sources, MVMM users had higher intakes of riboflavin and folate compared to non-users (p < 0.05). When MVMM supplements were taken into account, users had higher intakes of all nutrients except vitamin K. With the help of MVMM, users increased intake of vitamins E, A, D, and pantothenic acid to IOM-recommended levels but calcium, magnesium, and vitamin K remained below guidelines.

CONCLUSION

Micronutrient intake from diet was below the IOM-recommended levels in the total sample. MVMM use improved intake of selected micronutrients and facilitated meeting recommendations for some nutrients. Public health measures to improve micronutrient intake among children in Puerto Rico are needed.

Do dietary supplements improve micronutrient sufficiency in children and adolescents?

OBJECTIVE

To examine if children use supplements to fill gaps in nutritionally inadequate diets or whether supplements contribute to already adequate or excessive micronutrient intakes from foods.

STUDY DESIGN

Data were analyzed for children (2-18 years) from the National Health and Nutrition Examination Survey 2003-2006, a nationally representative, cross-sectional survey (n = 7250). Diet was assessed using two 24-hour recalls, and dietary supplement use was assessed with a 30-day questionnaire.

RESULTS

Prevalence of supplements use was 21% (<2 years) and 42% (2-8 years). Supplement users had higher micronutrient intakes than nonusers. Calcium and vitamin D intakes were low for all children. Inadequate intakes of phosphorus, copper, selenium, folate, and vitamins B-6 and B-12 were minimal from foods alone among 2-8 year olds. However, among 9-18 year olds, a higher prevalence of inadequate intakes of magnesium, phosphorus, and vitamins A, C, and E were observed. Supplement use increased the likelihood of intakes above the upper tolerable intake level for iron, zinc, copper, selenium, folic acid, and vitamins A and C.

CONCLUSIONS

Even with the use of supplements, more than a one-third of children failed to meet calcium and vitamin D recommendations. Children 2-8 years old had nutritionally adequate diets regardless of supplement use. However, in children older than 8 years, dietary supplements added micronutrients to diets that would have otherwise been inadequate for magnesium, phosphorus, vitamins A, C, and E. Supplement use contributed to the potential for excess intakes of some nutrients. These findings may have implications for reformulating dietary supplements for children.

Dietary supplement intake by 6-month-old Taiwanese infants

OBJECTIVES

The objective of the present study was to investigate the types of dietary supplements administered to healthy 6-month-old infants and to identify the factors influencing the use of such supplements.

SUBJECTS AND METHODS

The present study was based on the Taiwan Birth Cohort Study database. Questionnaires were used to collect information on the use of dietary supplements from birth, infant feeding practices, and other covariates at 6 months of age. We excluded low-birth-weight, preterm babies, and those whose caregivers returned incomplete questionnaires, leaving a sample size of 18,658. Multiple logistic regression was used to determine the characteristics capable of predicting the use of supplements in this population. A total of 34.9% of infants were fed dietary supplements from birth.

RESULTS

The most common types of supplements administered to infants were probiotics, calcium, and multivitamin/mineral supplements. Formula feeding, earlier weaning, and earlier complementary feeding were positively related to the use of several supplements.

CONCLUSIONS

The present study demonstrates that the use of pediatric dietary supplements is relatively common among infants in Taiwan, even in the earliest stages of life. For infants whose diet is adequate, no need exists for dietary supplements, and excessive intake can adversely influence health. Communication between health professionals and child caregivers should be promoted to increase understanding of infant feeding, as well as the safety and efficacy of dietary supplements.

Sociodemographic and lifestyle factors are associated with the use of dietary supplements in a Korean population

OBJECTIVE

The use of dietary supplements has been increasing rapidly in Korea over the last decade. The aim of this study was to investigate associations between the pattern of dietary supplement use and the sociodemographic/lifestyle characteristics of Korean consumers.

METHODS

Participants were asked to complete a self-administered questionnaire on their sociodemographic and lifestyle characteristics, perceived health status, and regular dietary supplement use.

RESULTS

A total of 697 men and 832 women completed the questionnaire. Of the respondents, 44.3% of the men and 53.2% of the women used some kind of dietary supplement regularly. Dietary supplement users were more likely to be women (P < 0.001), to be older than 50 years (P < 0.001), to have a higher household income (P = 0.003), to engage in moderate or vigorous physical activity (P < 0.032), to perceive themselves as healthy (P = 0.026), and to have received a diagnosis of a chronic disease (P < 0.001). In addition, the type of dietary supplements used varied with respect to sociodemographic and lifestyle factors. Among dietary supplement users, men preferred ginseng, and older respondents were more likely to use carbohydrate supplements and less likely to use lipid supplements. Those who had a lower BMI, were ex-smokers, or were nondrinkers preferred either vitamins or minerals. Those who were highly physical active or were nondrinkers tended to prefer either vitamin/mineral complexes or carbohydrate supplements.

CONCLUSIONS

The use of dietary supplements was related to sociodemographic and lifestyle factors in a Korean population.

Vitamin Supplement Intake Is Related to Dietary Intake and Physical Activity: The Child and Adolescent Trial for Cardiovascular Health (CATCH)

OBJECTIVE

To explore the relationship of multiple-vitamin supplement use with selected food groups, physical activity, lifestyle behaviors, and weight status.

SUBJECTS AND METHODS

Two thousand seven hundred sixty-one adolescents in the 12th grade who participated in the fourth Child and Adolescent Trial for Cardiovascular Health study had height and weight measured and completed health behavior survey and food frequency questionnaires. Logistic regression models were used to determine the likelihood of supplement use with health and activity behaviors and dietary intake.

RESULTS

Prevalence of multiple-vitamin supplement use among adolescents was 25% and varied by sex and race/ethnicity. Supplement users had higher mean daily intakes of most food groups, but lower intakes of total fat and saturated fat than nonusers. Higher food index scores were positively associated with the likelihood of using multiple-vitamin supplements. Supplement users were more likely to be physically active, participate in team and organized sports, and less likely to be overweight and to watch more than an hour of television per day.

CONCLUSIONS

Adolescents who use multiple vitamin supplements have more healthful dietary and lifestyle behaviors than nonusers. Further study on supplement use by adolescents, including other types of supplements used and reasons for use, is warranted.

Associations of iron status with dietary and other factors in 6-year-old children

OBJECTIVE

To investigate the associations of iron status at 6 years of age with dietary and other factors.

DESIGN

In a cross-sectional study, children's dietary intakes (3-day weighed food record) were recorded, body size was measured and blood samples were taken near their sixth birthday.

SUBJECTS

A sample of 188 children, from two previous studies (cohorts 1 and 2), was contacted, and 139 (74%) agreed to participate.

RESULTS

Multiple regression analyses with dietary and other factors showed that meat and fish consumption, multivitamin/mineral supplement intake (both positively) and cow's milk product consumption (negatively) were associated with log serum ferritin (SF) (adjusted R (2)=0.125; P=0.028; n=129), and juices and residence (rural>urban) with haemoglobin (Hb) (adjusted R (2)=0.085; P=0.034; n=127). Of 21 multivitamin/mineral consumers, none had depleted iron stores compared to 21 iron-depleted of 108 non-consumers (P=0.024). Children living in rural areas (<10,000 inhabitants) (n=33) had higher mean corpuscular volume (MCV) (83.3+/-2.3 fl) than those living in urban areas (>10,000 inhabitants) (82.1+/-3.2 fl; n=103) (P=0.048). Multiple regression analyses with dietary and other factors and growth showed in cohort 1 that residence (rural>urban), weight gain 0-1years (negatively), and meat and fish intake (positively) were associated with Hb (adjusted R (2)=0.323; P=0.030; n=51), meat and fish (positively) with both log SF (adjusted R (2)=0.069; P=0.035; n=52) and MCV (adjusted R (2)=0.064; P=0.035; n=52), and in cohort 2 cow's milk product consumption (negatively) was associated with log SF (adjusted R (2)=0.119; P=0.017; n=41) and residence (rural>urban) with MCV (adjusted R (2)=0.102; P=0.025; n=41).

CONCLUSIONS

Consumption of meat and fish and possibly also juices, as well as multivitamin/mineral intake might affect iron status in 6-year-old children positively, whereas cow's milk product consumption might affect iron status negatively. Slower growth in the first year of life and rural residence are positively related to iron status of 6-year-olds.

Association of dietary supplement use with specific micronutrient intakes among middle-aged American men and women: the INTERMAP Study

OBJECTIVE

To assess dietary supplement use and its association with micronutrient intakes and adequacy among 2,195 US men and women aged 40 to 59 years from eight diverse population samples surveyed by the International Population Study on Macronutrients and Blood Pressure.

DESIGN

Four 24-hour dietary recalls were collected, including information on dietary supplements. The Nutrition Data System (NDS) was used for nutrient analyses. Supplements not in NDS were classified separately (non-NDS). Intake of non-NDS supplements was documented. Participants were classified as not supplement users and supplement users, subclassified-due to concerns about nutritional value-as users of NDS supplements only (mostly vitamins and minerals) and users of non-NDS supplements (eg, botanicals, animal products, and enzymes). To assess effects of supplement use on micronutrient intake and adequacy, mean intakes from supplements, foods, and foods plus supplements were compared with Dietary Reference Intakes.

PARTICIPANTS

Two thousand one hundred ninety-five US participants; 1,136 used supplements.

STATISTICAL ANALYSES

Chi 2 tests, multivariate logistic regression, and means were used to assess differences in and factors related to supplement use and to determine dietary adequacy.

RESULTS

Supplement use was more common among women, older participants, more educated participants, and Asian Americans. Body mass index and current cigarette smoking were significantly and inversely associated with supplement use; past smoking and education were significantly and positively associated with supplement use. Intake from foods plus supplements was considerably higher than from foods alone for vitamins A, C, and E; niacin; folate; and iron.

CONCLUSIONS

Supplement use is common among middle-aged Americans and sizably increases daily intakes of several micronutrients. These data underscore the importance of dietary supplement assessment.

Low calcium and vitamin D intake in healthy children and adolescents and their correlates

BACKGROUND

Optimal dietary calcium and possibly vitamin D intake throughout childhood and adolescence may enhance bone mineral accrual. Little data on the intake of these nutrients in Mediterranean countries exist, and predictors of their suboptimal intake are not well defined.

OBJECTIVE

To evaluate systematically the effect of gender, lifestyle factors, and socioeconomic status on mean calcium and vitamin D intake in healthy school children and adolescents from Lebanon.

DESIGN

A total of 385 students aged 10-16 y were selected from four public and four private schools between Fall 1999 and Spring 2000. Information on calcium and vitamin D intake, through a semiquantitative food frequency questionnaire that was validated against a 7-day daily record, and on socioeconomic and lifestyle factors were obtained.

RESULTS

Only 12% of the students met the adequate intake (AI) recommendation of 1300 mg of calcium/day, and only 16% met the AI recommendation of 200 IU of vitamin D/day. Boys had a significantly higher mean daily calcium intake than girls. Socioeconomic status as assessed by children's pocket money was a predictor of higher calcium and vitamin D intake. Eating breakfast and physical activity were other correlates of daily calcium and vitamin D intake.

CONCLUSIONS

Only a minority of students in our study met the AI for calcium and vitamin D. Gender, lifestyle factors, and socioeconomic status were significant predictors of calcium and vitamin D intake. Our findings have important implications regarding the institution of dietary public health strategies to promote skeletal health in Mediterranean countries during a critical time for bone mass accrual.

Nonvitamin, nonmineral supplement use over a 12-month period by adult members of a large health maintenance organization

OBJECTIVE

National survey data show an increase in the prevalence of nonvitamin, nonmineral (NVNM) supplement use among adults over the past 10 years. Concern over this trend is based in part on reports of potential drug-supplement interactions. The type and prevalence of supplement use by demographic and behavior characteristics were examined among members of a large group model health plan, including those with selected health conditions.

DESIGN

Data on the use of herbal medicines and dietary supplements among survey respondents were analyzed. Questions employed a checklist for six specific NVNM supplements with optional write-ins.

SUBJECTS/SETTING

A stratified random sample of 15,985 adult members of a large group model health maintenance organization in northern California, who were respondents to a 1999 general health survey.

STATISTICAL ANALYSES PERFORMED

Analyses were conducted with poststratification weighted data to reflect the actual age, gender, and geographic distribution of the adult membership from which the sample was drawn.

RESULTS

An estimated 32.7% of adult health plan members used at least one NVNM supplement. The most frequently used herbs were Echinacea (14.7%) and Gingko biloba (10.9%). Use of all NVNM supplements was highest among females, 45 to 64 years of age, whites, college graduates, and among those with selected health conditions.

APPLICATIONS

Dietetics professionals need to uniformly screen clients for dietary supplement use and provide accurate information and appropriate referrals to users.

Excess dietary iron is the root cause for increase in childhood autism and allergies

Autism is a profoundly and poorly understood developmental disorder that impairs a person's social and communication abilities. I propose a hypothesis that the excessive dietary iron consumed by today's infants is the root cause of increased cases of Autism, allergies and other childhood diseases. Iron is a powerful immune system modulator. Excess iron causes hyperactive immune system. This hyperactive immune system attacks undigested food peptides. The chemicals released during these intense allergic reactions can damage surrounding tissue. Neurodegeneration is caused by combination of, oxidative stress induced by free iron radicals and intense immune reactions. Iron chelators have shown beneficial results in Autism and allergies.

Family Influences: Mothers' and Daughters' Use of Multivitamin Mineral Supplements

Girls' multivitamin mineral (MVM) use was evaluated among a white middle-class sample (n = 192 mother-daughter pairs). Daughters' MVM use was predicted by mothers' use by mothers' beliefs attitudes practices regarding her own eating child feeding practices. Mothers who gave daughters supplements reported greater monitoring of daughters' intake were more likely to pressure daughters to eat. MVM user diets did not differ from nonusers with the exception that nonusers consumed more fats sweets. Patterns of intake revealed food group servings below recommended levels for both groups whereas vitamin mineral intakes exceeded the RDA. This pattern reflects girls' high levels of consumption of fortified foods.

Current Patterns of Supplement Use in Adolescents

Eighth-grade students use vitamin and mineral supplements to a much greater extent than previously. Implications for dietary assessment and counseling are provided.

Maternal influences on 5- to 7-year-old girls' intake of multivitamin-mineral supplements

OBJECTIVE

To examine diet quality of girls who do or do not take multivitamin-mineral (MVM) supplements and to evaluate predictors of girls' MVM use, including maternal eating behaviors, MVM use, beliefs, attitudes, and perceptions about child feeding, eating, and health.

DESIGN

Participants were 192 mother and daughter pairs. Daughters were categorized as MVM supplement users or nonusers based on whether girls were consistently given MVM supplements at 5 and 7 years. Girls' and mothers' nutrient and food group intakes, maternal child-feeding practices, and maternal eating behavior were compared between the groups.

RESULTS

Mothers who used MVM supplements were more likely to give MVM supplements to daughters. Excluding nutrients from MVM supplements, MVM users and nonusers did not differ in vitamin and mineral intake, either for girls or mothers, and patterns of food group intake were similar for users and nonusers. Mothers of MVM users reported the following: higher levels of pressuring their daughters to eat healthier diets, more monitoring of daughters' food intake, more success in dieting for weight control, more positive evaluations of their success in eating healthy diets, and lower body mass indexes than mothers who did not give MVMs to daughters.

CONCLUSIONS

Daughters' MVM supplement use was predicted by mothers' beliefs, attitudes, perceptions, and practices regarding mothers' own eating and child feeding practices, rather than by daughters' diet quality. For both MVM users and nonusers, daughters' food group servings were below recommendations, whereas vitamin and mineral intakes exceeded recommendations, a pattern indicative of girls' relatively high intakes of fortified foods. Mothers should be encouraged to foster healthier patterns of food intake in daughters, rather than providing MVM supplements.

Do adolescent vitamin-mineral supplement users have better nutrient intakes than nonusers? Observations from the CATCH tracking study

OBJECTIVE

Describe whether users of vitamin-mineral supplements differed from nonusers in micronutrient intakes or in nutrition awareness.

DESIGN

Cross-sectional, observational study.

SUBJECTS

One thousand five hundred thirty-two students now in grade 8, who participated in the Third Child and Adolescent Trial for Cardiovascular Health tracking study and who also provided a single 24-hour dietary recall.

STATISTICAL ANALYSES PERFORMED

Mixed-model analysis of covariance was used to ascertain if supplement users had higher vitamin and mineral intakes from food sources, and to examine if supplement users had better nutrition awareness than nonusers.

RESULTS

The 24-hour recall showed that 17.6% of the students reported using vitamin-mineral supplements. Users reported a mean of 1.4 supplements, of which 47% were multivitamin or multimineral preparations, 37% were single nutrients, and 16% were combinations. White persons and residents of Minnesota and California were more likely to be supplement users. Users had higher micronutrient intakes from food sources for 16 of the 20 nutrients studied after adjusting for gender, race/ethnicity, site, treatment condition, and within-school variability. Users had higher scores on a health behavior survey for food choice and slightly but not significantly higher nutrition knowledge scores.

CONCLUSIONS

Vitamin-mineral supplement use is prevalent among eighth-grade students. Users have higher nutrient intakes from foods, higher total intakes for several micronutrients, higher nutrition awareness, and differ in their demographic characteristics from nonusers.

Position of the American Dietetic Association: food fortification and dietary supplements

Wise food choices provide the necessary foundation for optimal nutrition. Science has not fully identified the specific chemical components that account for the benefits of healthy eating patterns. Selection of a variety of foods, using tools such as the USDA/HHS Dietary Guidelines for Americans and the USDA Food Guide Pyramid, is the best way to provide a desirable balance, without excessive intakes of macronutrients, micronutrients and other beneficial components of foods. Nevertheless, for certain nutrients and some individuals, fortification, supplementation, or both may also be desirable. Nutrient intakes from all these sources should be considered in dietary assessments, planning and recommendations. The recommendations of the National Academy of Sciences' Food and Nutrition Board provide a sound scientific basis for vitamin and mineral intakes. Intakes exceeding those recommendations have no demonstrated benefit for the normal, healthy population. Dietetics professionals should base recommendations for use of fortified foods or supplements on individualized assessment and sound scientific evidence of efficacy and safety. It is the position of the American Dietetic Association that the best nutritional strategy for promoting optimal health and reducing the risk of chronic disease is to wisely choose a wide variety of foods. Additional vitamins and minerals from fortified foods and/or supplements can help some people meet their nutritional needs as specified by science-based nutrition standards such as the Dietary Reference Intakes (DRI).

Relationships between vitamin and mineral supplement use, dietary intake, and dietary adequacy among adolescents

OBJECTIVE

To examine patterns of supplement use among US adolescents and the relationship between supplement use and dietary intake and adequacy.

DESIGN

Adolescents self-reported 2 days of food intake using the 24-hour recall method and supplement use during a personal interview conducted as part of the 1994 Continuing Survey of Food Intakes of Individuals (CSFII).

SUBJECTS

A national sample of 423 adolescents included in the 1994 CSFII survey.

STATISTICAL ANALYSIS

chi 2 analysis was used to determine which demographic factors were significantly related to patterns of supplement use. Weighted percentages of adolescents by category of supplement use for selected vitamins and minerals (calcium; iron; zinc; folic acid; and vitamins A, B-6, C, and E) are presented. Relationships between dietary intake of macronutrients and vitamins and minerals among adolescents and supplement use were determined using a least-squares model of general linear regression.

RESULTS

Approximately one-third of adolescents reported using supplements, with 15.6% of youth using them on a daily basis. The majority of supplement users reported taking multivitamins (N = 95; 65.5%) whereas only one-third of supplement users reported taking individual vitamins or minerals. Supplement use was found to vary by gender, household size, and US region of residence. Adolescents who reported using supplements had higher mean dietary intakes of most micronutrients and lower intakes of total and saturated fat than those who did not use supplements. More than one-third of adolescents had dietary intakes of vitamins A and E, calcium, and zinc that were < 75% of the US Recommended Dietary Allowance.

APPLICATIONS/CONCLUSIONS

The majority of US adolescents do not use vitamin or mineral supplements. Interestingly, adolescents who do use supplements, even on an infrequent basis, consume diets that are more nutrient-dense than those who do not use supplements. Dietary intakes of several micronutrients were inadequate among all adolescents in this study, regardless of supplement use status. There is a need to develop and implement programs aimed at improving the dietary intakes of US adolescents.

Nutrition and diet-related problems

Adolescence is a period of remarkable change. Nutrient requirements increase to promote physical growth and development and adolescents begin to make lifelong diet choices. These choices are often influenced by family, peers, and individual nutrition beliefs. This article addresses typical problems and recommendations for normal adolescent nutrition as well as nutrient needs for special conditions such as obesity, athletics, and vegetarianism.

Diet, activity, and other health-related behaviors in college-age women

Morbidity and mortality data for young women in the United States reflect several health risk behaviors for both acute and chronic disease development. Available data suggest that young women's diets are high in total and saturated fat and low in fiber, fruits, vegetables, and dairy products. As a result, diets of young women are frequently low in iron, folate, and calcium. Prevalence of overweight continues to increase significantly in this population, but inappropriate body image concerns and disordered eating patterns are also common. Inactivity, smoking, and weight cycling are patterns that appear to begin early in women's lives. Some data suggest that young women value nutrition quality and are more likely to attempt positive changes than are young men.

Supplement use, other dietary and demographic variables, and serum vitamin C in NHANES II

OBJECTIVE

Our objective was to evaluate the effect of regular use of nutritional supplements on serum vitamin C levels in a multivariable regression model, taking into account other dietary and demographic variables which may affect nutritional status.

METHODS

We analyzed NHANES II data for subjects age 3 to 74. Analysis was limited to regular supplement users and nonusers, excluding irregular users. Multivariable regression analysis was performed with SUDAAN, incorporating sample weights and accounting for the complex survey design.

RESULTS

Regular supplement users had substantially higher serum vitamin C levels than nonusers (p < 0.001). The magnitude of the effect of supplement use on serum vitamin C was 0.23-0.33 mg/dL in children and teens, and 0.36-0.46 mg/dL in adults. In adults who smoked, bottom quartile vitamin C levels were 0.3 mg/dL in men and 0.4 mg/dL in women who did not use supplements, compared to 0.9 and 1.1 mg/dL in regular supplement users. There was a significant interaction of smoking and supplement use in men (p < 0.001).

CONCLUSION

Regular supplement use has a strong impact on serum vitamin C levels, independent of other dietary and demographic characteristics of supplement users which may favor improved nutritional status.

[Iron supplementation effects on zinc bioavailability in a regional diet of northeastern Brazil]

The effects of supplementation with iron on the zinc bioavailability of the regional diet of northeastern Brazil (RDN), were investigated. One assay with Wistar rats, feed on RDN and control diets was carried out. The RDN diets contained 16 mg Zn/kg and levels of 35 mg, 70 mg and 140 mg Fe/kg, respectively. The control diets were prepared according to the standards of the Committee on Laboratory Animal Diets, with levels of protein, iron and zinc identical to those of RDN diets. Index of apparent absorption and zinc retained in the femur of the animals were the parameters utilized to measure zinc bioavailability. The results demonstrated that the supplementation with iron decreased the zinc bioavailability, and the effects were seen to affect diet quality and the Fe:Zn ratio. This fact must be taken into consideration in practices such as the fortying of foodstuffs and the administration of vitamin-mineral supplements to populations with nutritional deficiencies.

Vitamin and mineral supplement use and mortality in a US cohort

OBJECTIVES

Vitamin and mineral supplementation is a common practice in the United States, yet little is known about the long-term health effects of regular supplement use.

METHODS

To examine the relationship between reported use of supplements and mortality, we analyzed data from US adults 25 to 74 years of age who were examined in the First National Health and Nutrition Examination Survey (1971 to 1975), with vital status determined through 1987.

RESULTS

At baseline, 22.5% of the cohort reported using supplements regularly and 10.0% reported irregular use. The risk of mortality for regular supplement users was similar to that for nonusers. No consistent mortality benefits or risks of supplement use were found across a number of population subgroups. The risk for those who reported supplement use at both the baseline and a follow-up interview approximately 10 years later was similar to the risk for those who reported not using supplements at either interview.

CONCLUSIONS

We found no evidence of increased longevity among vitamin and mineral supplement users in the United States. Considering the wide use of supplements in the general population, the cost-effectiveness and the safety of supplement use need to be better defined.

Epidemiologic studies utilizing surveys: accounting for the sampling design

BACKGROUND

Since large-scale health surveys usually have complicated sampling schemes, there is often a question as to whether the sampling design must be considered in the analysis of the data. A recent disagreement concerning the analysis of a body iron stores-cancer association found in the first National Health and Nutrition Examination Survey and its follow-up is used to highlight the issues.

METHODS

We explain and illustrate the importance of two aspects of the sampling design: clustering and weighting of observations. The body iron stores-cancer data are reanalyzed by utilizing or ignoring various aspects of the sampling design. Simple formulas are given to describe how using the sampling design of a survey in the analysis will affect the conclusions of that analysis.

RESULTS

The different analyses of the body iron stores-cancer data lead to very different conclusions. Application of the simple formulas suggests that utilization of the sample clustering in the analysis is appropriate, but that a standard utilization of the sample weights leads to an uninformative analysis. The recommended analysis incorporates the sampling weights in a nonstandard way and the sample clustering in the standard way.

CONCLUSIONS

Which particular aspects of the sampling design to use in the analysis of complex survey data and how to use them depend on certain features of the design. We give some guidelines for when to use the sample clustering and sample weights in the analysis.

Infant nutrient supplementation

This review addresses vitamin and mineral supplementation recommendations, practices and rationales, patterns of supplement use, and the relationship between supplementation and nutrient concerns for older infants. According to current recommendations, healthy infants do not need supplements if vitamin D-fortified milk is used, the diet includes adequate vitamin C, and iron-fortified cereals or formula are used. Infants fed human milk exclusively may need vitamin D supplements. Nevertheless, approximately one third to one half of 6- to 12-month-old U.S. infants receive nutrient supplements, as liquid vitamin A, D, and C preparations or multivitamin preparations, with or without iron or fluoride. Recent surveys suggest that most infants have more than adequate vitamin and mineral intakes, with the possible exception of iron. The risk of poor vitamin A status is less likely than the risk of poor water-soluble-vitamin or iron status in the United States. Possibly marginal intakes of zinc and copper (not in currently available infant supplements) suggest the need for further research. Research, infant supplement formulation reevaluation, and education are suggested so that nutrient supplements for prophylaxis can be used most effectively and appropriately.