What physicians can learn from consumers of dietary supplements.

BACKGROUND: Many Americans consume dietary supplements, including vitamins, minerals, herbs, and amino acids. Government regulation of dietary supplements is limited, and patients typically do not consult with their physicians regarding the use of supplements. METHODS: We conducted a qualitative study to describe patients' decisions about the use of dietary supplements and the communication they have with their physicians about such use. Four focus groups of customers from 3 local suburban health food stores were interviewed. RESULTS: The customers in the health food stores we investigated were motivated to pursue wellness and wanted to take responsibility for their health. They would welcome a partnership with their physicians, but generally believed that physicians are closed-minded and have little knowledge about dietary supplements. These consumers determined the effectiveness of dietary supplements through personal study and subjective experimentation. CONCLUSIONS: The health food store customers in our study were self-informed consumers who did not consult their physicians about their use of dietary supplements, because they did not believe that physicians were knowledgeable about or interested in supplements. An open-minded patient-centered approach would help physicians provide better care for patients who use dietary supplements.     

Vitamins--dietary intake and intake from dietary supplements in Germany

OBJECTIVE: To analyse the current vitamin intake and the contribution of dietary supplements to this intake of 4030 participants of the German Nutrition Survey (GeNuS) 1998, which was part of the representative German National Health Interview and Examination Survey (GNHIES), conducted from October 1997 until March 1999. DESIGN: In the GeNuS participants were interviewed comprehensively about their usual diet and supplementation patterns using a modified dietary history. SETTING: Population-based nutritional survey. SUBJECTS: A subsample of 4030 persons, aged 18-79 y, randomly selected from the GNHIES 1998. RESULTS: The contribution of dietary supplements to the vitamin intake reached 5% for vitamin E among men and 6% for vitamin C among women. Among the group of regular users, the contribution to the vitamin E intake is 36% among men and 43% among women. A substantial part of the population does not reach the current recommendations for some vitamins, especially for folate and vitamin E through their diet alone. Among regular supplement users, about one-third for folate and about half for the other vitamins reach the recommended intake only when supplemental intake is considered. Among the regular users of folate supplements, this proportion is about half. CONCLUSION: If reference values are used as preference intake, a substantial population part improves their vitamin intake by taking supplements regularly. Nevertheless, there are persons who stay below the reference values including supplemental intake or already consume more than 100% of recommendation excluding supplemental intake.     

Lead content in 70 brands of dietary calcium supplements.

OBJECTIVES. Elevated lead levels in calcium supplements may pose a health risk, particularly to children with milk intolerance who rely on these products to meet their calcium requirement. Earlier reports chiefly focused on the lead content in supplements derived from bonemeal and dolomite. This study undertook to determine the lead levels in the major forms of calcium supplements currently available. METHODS. The lead content was measured in 70 brands of calcium supplements grouped in the following five categories: dolomite, bonemeal, refined and natural source calcium carbonate, and calcium chelates. RESULTS. The lead levels measured in the supplements ranged from 0.03 microgram/g to 8.83 micrograms/g. Daily lead ingestion rates revealed that about 25% of the products exceeded the US Food and Drug Administration's "provisional" total tolerable daily intake of lead for children aged 6 years and under. Less than 20% of the supplements had "normalized" lead levels comparable to or lower than that reported for cow's milk. CONCLUSIONS. Children are the most sensitive to the low-level effects of lead. If calcium supplements are to provide an alternate source of calcium to some of these individuals, they should also deliver concomitant lead dosages no greater than those obtained from milk products themselves.     

Daily magnesium supplements improve glucose handling in elderly subjects.

We demonstrated similar plasma concentrations and urinary losses but lower erythrocyte magnesium concentrations (2.18 +/- 0.04 vs 1.86 +/- 0.03 mmol/L, P less than 0.01) in twelve aged (77.8 +/- 2.1 y) vs 25 young (36.1 +/- 0.4 y), nonobese subjects. Subsequently, aged subjects were enrolled in a double-blind, randomized, crossover study in which placebo (for 4 wk) and chronic magnesium administration (CMA) (4.5 g/d for 4 wk) were provided. At the end of each treatment period an intravenous glucose tolerance test (0.33 g/kg body wt) and a euglycemic glucose clamp with simultaneous [D-3H]glucose infusion and indirect calorimetry were performed. CMA vs placebo significantly increased erythrocyte magnesium concentration and improved insulin response and action. Net increase in erythrocyte magnesium significantly and positively correlated with the decrease in erythrocyte membrane microviscosity and with the net increase in both insulin secretion and action. In aged patients, correction of a low erythrocyte magnesium concentration may allow an improvement of glucose handling.     

Effect of dietary supplements and physical exercise on sensory perception, appetite, dietary intake and body weight in frail elderly subjects

This present study investigated the effect of a 17-week intervention programme with nutrient-dense foods (enriched with vitamins and minerals at 25-100% of the Dutch recommended dietary allowance) and/or physical exercise in 159 frail elderly subjects (forty-six men, 113 women, mean age 78.7 (SD 5.6) years). Subjects were randomized into four groups: (1) control, (2) nutrition intervention, (3) exercise or (4) both nutrition intervention and exercise. Main outcome variables were sensory perception (smell test and questionnaire), appetite (questionnaire), energy intake (3 d food record) and body weight (on a weighing scale and with dual energy X-ray absorptiometry measurements). At baseline, moderate but significant correlations were found between appetite and energy intake (r 0.30, P < 0.0001), between smell test and smell perception assessed by questionnaire (r 0.40, P < 0.0001) and between lean body weight and energy intake (r 0.50, P < 0.0001). Results after 17-weeks intervention revealed neither change in smell test scores (P = 0.19) nor in appetite (P = 0.17). A slight positive effect of exercise compared with non-exercising groups on energy intake (difference 0.5 MJ, P = 0.05) was shown next to a preserving effect of exercise on lean body mass (+0.08 kg) compared with a decrease (-0.4 kg) in non-exercisers (P < 0.02). The correlation between the change in lean body mass and change in energy intake was 0.18 (P = 0.05). In conclusion, an interesting preserving effect on lean body mass in frail elderly subjects due to 17 weeks of exercise was shown. Since a decline in lean body mass was observed in the non-exercisers, effects may be attributable to change in activity pattern. Changes in lean mass were also slightly, but significantly, correlated with changes in energy intake. In turn, energy intake was not related to a change in reported appetite or sensory perception. Nutrient-dense foods were not able to improve any of the outcome variables in this study.     

Assessing potential health risks from microcystin toxins in blue-green algae dietary supplements

The presence of blue-green algae (BGA) toxins in surface waters used for drinking water sources and recreation is receiving increasing attention around the world as a public health concern. However, potential risks from exposure to these toxins in contaminated health food products that contain BGA have been largely ignored. BGA products are commonly consumed in the United States, Canada, and Europe for their putative beneficial effects, including increased energy and elevated mood. Many of these products contain Aphanizomenon flos-aquae, a BGA that is harvested from Upper Klamath Lake (UKL) in southern Oregon, where the growth of a toxic BGA, Microcystis aeruginosa, is a regular occurrence. M. aeruginosa produces compounds called microcystins, which are potent hepatotoxins and probable tumor promoters. Because M. aeruginosa coexists with A. flos-aquae, it can be collected inadvertently during the harvesting process, resulting in microcystin contamination of BGA products. In fall 1996, the Oregon Health Division learned that UKL was experiencing an extensive M. aeruginosa bloom, and an advisory was issued recommending against water contact. The advisory prompted calls from consumers of BGA products, who expressed concern about possible contamination of these products with microcystins. In response, the Oregon Health Division and the Oregon Department of Agriculture established a regulatory limit of 1 microg/g for microcystins in BGA-containing products and tested BGA products for the presence of microcystins. Microcystins were detected in 85 of 87 samples tested, with 63 samples (72%) containing concentrations > 1 microg/g. HPLC and ELISA tentatively identified microcystin-LR, the most toxic microcystin variant, as the predominant congener.     

Lifestyle and diet in people using dietary supplements

Summary Background The use of dietary supplements is often associated with a healthy lifestyle. Due to high variation in supplementation practice by country, these associations will be investigated in a large German cohort study. Aim of the study To describe the prevalence of dietary supplement use in the EPIC-Heidelberg cohort and to illuminate differences in health-relevant characteristics between regular users and non-users. Methods At cohort recruitment, 13,615 women aged 35–65 and 11,929 men aged 40–65 were asked for regular dietary supplementation over the past year. Results Regular use of any supplement was reported by 47% of the women and 41% of the men, vitamin or mineral supplements were taken by 40% and 33%, respectively. The use of vitamin and/or mineral supplements was significantly associated with higher age, being non- or ex-smoker, lower BMI, higher physical leisure time activity, and higher educational level. After adjustment for these factors, we observed positive associations between supplement use and the consumption of milk, milk products, and fish as well as the intake of vitamin C and β-carotene. In contrast, the supplement use was related to lower meat and meat product consumption, saturated fat intake, and n6/n3-fatty acid ratio in the diet, both in women and men. Except for Hemoccult^? testing in women, no association with participation in cancer screening was observed. Conclusions The high prevalence of supplement use in EPIC-Heidelberg was associated with several presumably healthier lifestyle and diet characteristics. This needs to be considered in further evaluations of the risk of chronic diseases.     

Botanicals and dietary supplements in diabetic peripheral neuropathy

BACKGROUND: Many persons use botanicals and dietary supplements for chronic conditions that do not respond to traditional Western medications. Tricyclic antidepressants, a common treatment option for diabetic neuropathy, can have many side effects and are a poor choice in certain populations (eg, the elderly). As such, patients might turn to botanicals and dietary supplements, not realizing that these products are not well regulated. METHODS: This article reviews botanicals and dietary supplements that have been involved in randomized controlled trials (RCTs) for diabetic neuropathy. We searched MEDLINE for English-language literature dating from 1966 to April 2001 using the following subject headings: (1) diabetes and botanical, herb, and supplement, (2) neuropathy and botanical, herb, and supplement, and (3) diabetic neuropathy and botanical, herb, and supplement. RESULTS: Our search found agents that might improve symptoms of neuropathy (eg, evening primrose oil, alpha-lipoic acid, capsaicin) without affecting glucose control. Botanicals and dietary supplements involved in only one RCT or associated with little clinical benefit were reviewed in brief. CONCLUSIONS: Evening primrose oil, alpha-lipoic acid, and capsaicin have received the greatest attention for their use in diabetic neuropathy, but further studies are needed to confirm their efficacy. Patients using these products need to be informed of potential drug interactions and side effects.     

Thermic effect of a meal. 3. Effect of dietary supplementation in chronically undernourished human subjects.

Five apparently healthy, chronically undernourished (UN) male volunteers aged between 18 and 30 years were studied before and after 12 weeks of dietary supplementation. The thermic effect of a meal (TEM) was measured over a period of 6 h using a ventilated-hood system. Results indicated a significant increase in body-weight after supplementation due to increases in body fat and fat-free mass (FFM) in the proportion of 69% and 31% respectively. The basal metabolic rates (BMR) measured post supplementation were significantly higher in absolute terms, with a trend towards higher values when adjusted for the changes in FFM. TEM responses measured after 12 weeks of supplementation were significantly lower when expressed either in absolute terms (presupplementation 227.0 kJ v. post supplementation 193.5 kJ), or as a percentage of the energy density of the meal (9.1% v. 7.7%). This lower TEM was reciprocal to the changes in the BMR (r -0.86). The post-meal total energy output (PMTEO) was, however, not significantly different after 12 weeks of dietary supplementation. The unchanged PMTEO would indicate an unaltered 'thermogenic capacity', following supplementation, in these chronically undernourished subjects. These results confirm our earlier conclusion that, in chronic undernutrition, the thermic response to a meal may not contribute to any energy saving.     

Metabolic effects of dietary fructose in healthy subjects.

To determine if dietary fructose causes adverse metabolic effects, we used a crossover design to compare a diet containing 20% of energy from fructose with an isoenergic high-starch diet that contained less than 3% fructose. Fourteen healthy subjects consumed each diet for 28 d. There were no significant differences between the diets in the mean values of hemoglobin A1C, serum glycosylated albumin, fasting plasma glucose, peak postprandial plasma glucose, integrated plasma glucose, fasting serum lactate, or fasting serum triglycerides. Peak postprandial serum lactate was significantly higher during the fructose diet at days 1, 7, and 14 but not at days 21 or 28. Peak postprandial serum triglycerides were significantly higher only at day 1 of the fructose diet. Day-28 fasting serum total and LDL cholesterol for the fructose diet were 9.0% and 11.0% higher, respectively, than the corresponding values for the starch diet. A high-fructose diet compared with a high-starch diet resulted in significantly higher fasting serum total and LDL cholesterol and also caused transient changes in postprandial serum lactate and triglycerides.     

Circulating triacylglycerol and apoE levels in response to EPA and docosahexaenoic acid supplementation in adult human subjects

High doses of n-3 PUFA found in fish oils can reduce the circulating concentration of triacylglycerol (TG), which may contribute to the positive impact of these fatty acids on the risk of CVD. The present study aimed to establish the differential impact of EPA and docosahexaenoic (DHA) on plasma lipids and apo in adults. Forty-two normolipidaemic adult subjects completed a double-blind placebo controlled parallel study, receiving an EPA-rich oil (4.8 g EPA/d), DHA-rich oil (4.9 g DHA/d) or olive oil as control, for a period of 4 weeks. No effects of treatment on total cholesterol, LDL-cholesterol or HDL-cholesterol were evident. There was a significant 22 % reduction in TG level relative to the control value following the DHA treatment (P=0.032), with the 15 % decrease in the EPA group failing to reach significance (P=0.258). There were no significant inter-group differences in response to treatment for plasma apoA1, -C3 or -E levels, although a significant 15 % within-group increase in apoE was evident in the EPA (P=0.006) and DHA (P=0.003) groups. In addition, a within-group decrease in the apoA1:HDL-cholesterol ratio was observed in the DHA group, suggesting a positive impact of DHA on HDL particle size. The DHA intervention resulted in a significant increase in the proportion of EPA P=0.000 and DHA P=0.000 in plasma phospholipids, whilst significant increases in EPA P=0.000 and docosapentaenoic acid P=0.002, but not DHA P=0.193, were evident following EPA supplementation (P<0.05). Our present results indicate that DHA may be more efficacious than EPA in improving the plasma lipid profile.     

Nonvitamin, nonmineral dietary supplements: issues and findings from NHANES III

The Commission on Dietary Supplement Labels encourages nutrition professionals to become knowledgeable about all dietary supplements. The Dietary Supplement Health and Education Act of 1995 (DSHEA) expanded the definition of dietary supplements beyond essential nutrients while distinguishing them from drugs or food additives. In order to give practical advice to consumers and policymakers, dietetics professionals need to understand the implications resulting from this less-restrictive regulatory environment for supplements. Dietetics professionals must also become familiar with claims made by manufacturers, retailers, and others regarding popular nonvitamin, nonmineral (NVNM) supplements, as well as usage prevalence and trends. However, NVNM supplements currently are classified inconsistently, and information on the prevalence of use is limited. Sales data suggest that total intake is increasing, and garlic and ginseng are consistently among the most popular supplements. Reported use of NVNM supplements in the third National Health and Nutrition Examination Survey was highest for garlic and lecithin. The data suggest associations of NVNM supplement use with age and more healthful lifestyles; however, there is also a reported link with higher alcohol consumption and obesity. Associations with education, income, region, and urbanization are not evident from the sales data. Standardized survey procedures regarding question phraseology, referent time period, and supplement categorization--along with use of representative samples--will improve our ability to assess supplement use, prevalence, and trends.     

Food iron absorption in human subjects. V. Effects of the major dietary constituents of semisynthetic meal.

Studies were performed in adult volunteer subjects to determine the effect on nonheme iron absorption of protein, carbohydrate, and fat. These constituents were administered as egg albumin, dextrimaltose, and corn oil, respectively, in a semisynthetic meal containing 700 kcal and 4.1 mg iron. Because any one of these ingredients are unpalatable when administered alone, their effect was determined by serially deleting or doubling their content in the basal semisynthetic meal. With both approaches, carbohydrate and fat had little influence whereas egg albumin had a significant inhibitory effect on the absorption of nonheme iron.     

The assessment of vascular function during dietary intervention trials in human subjects

The potential to reduce cardiovascular morbidity through dietary modification remains an area of intense clinical and scientific interest. Any putatively beneficial intervention should be tested within a randomised controlled trial which records appropriate endpoints, ideally incident CVD and death. However, the large sample sizes required for these endpoints and associated high costs mean that the majority of dietary intervention research is conducted over short periods among either healthy volunteers or those at only slightly increased risk, with investigators using a diverse range of surrogate measures to estimate arterial health in these studies. The present review identifies commonly employed techniques, discusses the relative merits of each and highlights emerging approaches.     

The effect of dietary supplements on the nPCR in stable hemodialysis patients.

OBJECTIVE: To investigate whether (1) dietary supplements raise the normalized protein catabolic rate (nPCR) and/or further improve the nutritional status of stable hemodialysis patients who have both a low nPCR and a low dietary protein intake, <1.2 g/kg body weight/day; and if (2) protein intake measured by nPCR reflects protein intake measured by estimated food diaries in stable patients. DESIGN: Prospective experimental study with a single intervention group. SETTING: Hospital outpatient hemodialysis unit. SUBJECTS: Seventeen stable chronic hemodialysis patients (10 men, 7 women) were studied over 8 months. INTERVENTION: Subjects with both a low nPCR and dietary protein intake <1.2 g/kg body weight/day received dietary supplements for the first 2 months. Measurements to assess protein intake and nutritional status were taken at baseline and repeated at the end of 2 months, and at 6 months postintervention. MAIN OUTCOME MEASURE: nPCR, dietary protein intake using 7-day estimated food diaries, serum urea, serum albumin, serum creatinine, serum bicarbonate, dialysis adequacy (Kt/V), and body mass index (BMI). RESULTS: Dietary supplements significantly increased both the nPCR and the total protein intake at 2 months (1.21 +/- 0.26, 1.10 +/- 0.12, respectively) compared with baseline (0.95 +/- 0.18, 0.75 +/- 0.19, respectively) and 8 months (0.99 +/- 0.12, 0.78 +/- 0.21, respectively), P <.0001, respectively. There was no change in the nutritional status of the subjects. There was a significant difference between the nPCR and the dietary protein intake at baseline, P <.004; at 2 months, P <.047; and at 8 months, P <.001. CONCLUSION: Dietary supplements can significantly increase the nPCR and dietary protein intake in stable hemodialysis patients with a low nPCR and dietary protein intake. Because a low nPCR is associated with a high morbidity and mortality rate, it may be prudent to supplement such patients. The use of the nPCR to quantify dietary protein intake in stable hemodialysis patients should be used with caution.