Nonassociation of aflatoxin with primary liver cancer in a cross-sectional ecological survey in the People's Republic of China.

A comprehensive cross-sectional survey was undertaken in The People's Republic of China of possible risk factors for primary liver cancer (PLC) to include 48 survey sites, an approximately 600-fold aflatoxin exposure range, a 39-fold range of PLC mortality rates, a 28-fold range of hepatitis B virus surface antigen (HBsAg+) carrier prevalence, and estimation of exposures for a large number of other nutritional, dietary, and life-style features. PLC mortality was unrelated to aflatoxin intake (r = -0.17) but was positively correlated with HBsAg+ prevalence (P less than 0.001), plasma cholesterol (P less than 0.01), frequency of liquor consumption (P less than 0.01), and mean daily intake of cadmium from foods of plant origin (P less than 0.01). Multiple regression analyses for various combinations of risk factors showed that aflatoxin exposure consistently remained unassociated with PLC mortality regardless of variable adjustment. In contrast, associations of PLC mortality with HBsAg+, plasma cholesterol, and cadmium intake remained, regardless of model specification, while the association with liquor consumption was markedly attenuated (was nonsignificant) with adjustment for plasma cholesterol. The sharp contrast between the findings of no aflatoxin effect upon PLC prevalence in this survey and the positive correlation reported for previous but more restricted surveys is discussed. Based on the results of this survey and the data of laboratory animal and in vitro studies, an explanatory model for the etiology of PLC is proposed, taking into consideration the role of nutrition in the etiology of this disease.

Association of dietary factors and selected plasma variables with sex hormone-binding globulin in rural Chinese women.

Sex hormone-binding globulin (SHBG) is an important regulator of plasma sex steroids as well as a sensitive indicator of insulin resistance. SHBG may be an important diagnostic measure of risk for pathologies associated with insulin resistance syndrome (IRS) such as non-insulin-dependent diabetes mellitus (NIDDM), obesity, hypertension, dyslipidemia, and atherosclerotic cardiovascular disease. In women, SHBG is also implicated in diverse pathologies such as cancers of steroid-sensitive tissues and hirsutism. Data from an ongoing ecological study linking diet and health in rural China were analyzed to determine the relation of selected plasma variables and diet to plasma concentrations of SHBG. All data represent county mean values, pooled by age and sex, to assess the relation between biochemical and lifestyle characteristics and disease-specific mortality rates at the county level. The study sample consisted of 3250 Chinese women between the ages of 35 and 64 y living in 65 widely dispersed rural counties. Consumption patterns for 21 different food groups were derived from a food-frequency questionnaire and a 3-d dietary survey and subsequently compared. Correlation analyses of county mean values demonstrated a significant association between SHBG and insulin, testosterone, triacylglycerols, body mass index, age at menarche, and several foods. In regression analyses, after adjustments, the strongest predictors of SHBG concentrations were the dietary intake of rice (beta = 0.42, P < 0.01), fish (beta = 0.34, P < 0.05), millet (beta = -0.27, P < 0.01), and wheat (beta = -0.34, P < 0.01). When insulin, testosterone, and triacylglycerols were added to the model only triacylglycerols (beta = -0.26, P < 0.05) remained a significant independent predictor of SHBG. Additional analyses suggested that the consumption of green vegetables was modestly positively correlated with SHBG and negatively with insulin values. Consumption of rice and fish in particular appeared to favorably influence the principle plasma variables associated with a reduction in the risk for IRS pathologies.

Dietary intakes and urinary excretion of calcium and acids: a cross-sectional study of women in China.

The relationship between dietary intakes and urinary calcium was examined in a cross-sectional survey of 764 middle-aged and elderly women with markedly different dietary patterns and lifestyles. Urinary calcium was correlated positively with urinary acids, including titratable acid (r = 0.46, P < 0.0001), ammonia (r = 0.42, P < 0.0001), and sulfate (r = 0.52, P < 0.0001). Urinary excretions of calcium and acids were correlated positively with intakes of animal and nondairy animal protein but were correlated negatively with plant-protein intake, possibly because of the alkaline nature of plant foods. Further analyses showed that urinary calcium and acids were associated positively with acid-forming foods and were associated negatively with plant foods. These results indicate that under free-living conditions urinary calcium excretion is likely determined by the acid-base status of the total diet, including among other factors the contribution of sulfur amino acids to urinary acid production.

Dietary calcium and bone density among middle-aged and elderly women in China.

Associations between dietary calcium and bone status were investigated in 843 Chinese women aged 35-75 y who were selected from five rural counties where dietary calcium varied considerably. Bone mineral content (BMC) and bone mineral density (BMD) at the radius were significantly higher in one of the pastoral counties with higher calcium intake than in the nonpastoral counties. Analysis by individual for all counties combined showed that BMC and BMD were correlated positively with total calcium (r = 0.27-0.38, P < 0.0001), dairy calcium (r = 0.34-0.40, P < 0.0001), and to a lesser extent with nondairy calcium (r = 0.06-0.12, P = 0.001-0.100), even after age and/or body weight were adjusted for. The results strongly indicated that dietary calcium, especially from dairy sources, increased bone mass in middle-aged and elderly women by facilitating optimal peak bone mass earlier in life.

Questioning riboflavin recommendations on the basis of a survey in China.

Riboflavin status was surveyed in adults aged 35-64 y in 65 counties (two communes per county) in the People's Republic of China by erythrocyte glutathione reductase activity coefficients (EGRACs), by urinary excretion of riboflavin 4 h after the oral administration of 5 mg riboflavin (one commune per county), and by direct measurement of food intake over a 3-d period (one commune per county). EGRAC data were highly correlated between sexes (p less than 0.001) and between neighboring communes within the same county (p less than 0.001) and with riboflavin intake (p less than 0.001). The urinary-riboflavin-load test data were not correlated either with EGRAC or with riboflavin intake. Approximately 90% of the survey subjects were found to be deficient by Western and Chinese reference standards and allowances. Upon reconsideration of the Western experimental data originally used to establish these recommendations, it is suggested that riboflavin allowances are set too high both in China and in Western countries.

Erythrocyte fatty acids, plasma lipids, and cardiovascular disease in rural China.

Cardiovascular disease (CVD) mortality (coronary heart disease, hypertensive heart disease, and stroke), plasma lipids, and red blood cell fatty acid composition were examined in an ecologic study in 65 rural counties in the People's Republic of China. Means of plasma total cholesterol, triglyceride, low-density-lipoprotein (LDL) cholesterol, and high-density-lipoprotein (HDL) cholesterol concentrations were substantially lower and the ratio of HDL cholesterol to total cholesterol was higher in this Chinese population than in Western populations. Mortality rates for CVD in China were well below Western values. Within China neither plasma total cholesterol nor LDL cholesterol was associated with CVD. A strong inverse correlation between red blood cell oleate concentrations and CVD was observed. However, red blood cell oleate concentrations were not associated with plasma cholesterol but were strongly negatively associated with arachidonate concentrations, suggesting potential diminution of CVD by oleate through reduced platelet aggregability. The results indicate that geographical differences in CVD mortality within China are caused primarily by factors other than dietary or plasma cholesterol.

Additional ecological evidence: lipids and breast cancer mortality among women aged 55 and over in China.

That dietary fat increases breast cancer risk has been strongly supported by international data collected among developed countries during the past few decades. Population aggregates with elevated lipid intake have tended to report elevated breast cancer incidence and mortality. This study is an ecological analysis of the association of various indicators of lipid intake with breast cancer mortality in 65 county-wide population aggregates in the People's Republic of China. Although the result is consistent with a positive association between lipid intake and breast cancer risk, the observed association is weaker than the association previously observed. This finding provides only modest support for the possibility of a diet-breast cancer link.

Diet, lifestyle, and the etiology of coronary artery disease: the Cornell China study.

Investigators collected and analyzed mortality data for >50 diseases, including 7 different cancers, from 65 counties and 130 villages in rural mainland China. Blood, urine, food samples, and detailed dietary data were collected from 50 adults in each village and analyzed for a variety of nutritional, viral, hormonal, and toxic chemical factors. In rural China, fat intake was less than half that in the United States, and fiber intake was 3 times higher. Animal protein intake was very low, only about 10% of the US intake. Mean serum total cholesterol was 127 mg/dL in rural China versus 203 mg/dL for adults aged 20-74 years in the United States. Coronary artery disease mortality was 16.7-fold greater for US men and 5.6-fold greater for US women than for their Chinese counterparts. The combined coronary artery disease mortality rates for both genders in rural China were inversely associated with the frequency of intake of green vegetables and plasma erythrocyte monounsaturated fatty acids, but positively associated with a combined index of salt intake plus urinary sodium and plasma apolipoprotein B. These apolipoproteins, in turn, are positively associated with animal protein intake and the frequency of meat intake and inversely associated with plant protein, legume, and light-colored vegetable intake. Rates of other diseases were also correlated with dietary factors. There was no evidence of a threshold beyond which further benefits did not accrue with increasing proportions of plant-based foods in the diet.

Antioxidant status and cancer mortality in China.

Sex-specific mortality rates for selected cancer sites (including oesophagus, stomach, liver, lung, colorectum, breast and cervix) and a variety of biochemical indicators of antioxidant status, enzyme activity and oxidative stress (including plasma levels of beta-carotene, alpha-tocopherol, ascorbic acid, selenium, glutathione peroxidase, catalase, superoxide dismutase, iron, copper, zinc, total cholesterol and lipid peroxide) were examined in an ecological study of 65 mostly rural counties in the People's Republic of China. The wide range of both mortality rates and biochemical values and the measurement of a comprehensive set of biochemical indicators permitted both simple correlational and multivariate analyses of the joint and relative effects of each factor on site-specific cancer mortality. Plasma levels of dietary antioxidants were consistently negatively correlated with cancer mortality rates. Ascorbic acid was most strongly negatively associated with most cancers and selenium with oesophageal and stomach cancers. beta-carotene was found to have a protective effect independent of retinol, particularly for stomach cancer.

Antioxidant status, erythrocyte fatty acids, and mortality from cardiovascular disease and Keshan disease in China.

OBJECTIVE: Various measures of antioxidant status were investigated in relation to mortality from cardiovascular disease (CVD: coronary heart disease, hypertensive heart disease, and stroke) and Keshan disease. DESIGN: Ecological study. SETTING: Sixty-five largely rural counties in the People's Republic of China. SUBJECTS: One hundred subjects in each county randomly selected from two communes (6500 subjects). INTERVENTIONS: Antioxidants, antioxidant enzymes, and pro-oxidants were measured from sex- and commune-specific pooled blood samples in each county. Fatty acid content of red blood cells was measured. Mortality rates were determined from a national mortality survey. RESULTS: In univariate analysis most correlations between measures of antioxidant status and mortality rates from CVD were not statistically significant, although plasma ascorbic acid, beta-carotene and retinol were consistently inversely associated with CVD mortality rates. There were significant negative associations between plasma ascorbic acid and mortality from stroke (r = -0.38, P < 0.01), and plasma selenium and mortality from Keshan disease (r = -0.32, P < 0.05). There was a significant positive association between plasma copper and mortality from hypertensive heart disease (r = 0.32, P < 0.05). Data previously reported from this population demonstrated an inverse association between red blood cell monounsaturated fatty acids and mortality from CVD, and a direct association between red blood cell polyunsaturated fatty acids and mortality from CVD. CONCLUSIONS: Mortality from CVD and Keshan disease is associated with the fatty acid content of red blood cells and some measures of antioxidant status in blood. It is postulated that the associations between fatty acids and CVD may be related to the different susceptibilities of the respective fatty acids, contained in low-density lipoprotein, to oxidation.

Assessment of a modified household food weighing method in a study of bone health in China.

OBJECTIVE: A 'modified' household dietary method to estimate individual intakes from total household intakes was evaluated in comparison to the individual food weighing method, i.e. direct weighing of foods consumed by individuals. DESIGN: Foods consumed by the household were weighed and recorded over a 3 day period and were proportionally allocated to a specific person in the household by using energy conversion factors based on age, gender and physical activity. The individual dietary intakes were standardized by body weight (ratio of individual body weight to reference body weight from Chinese Recommended Daily Allowances (Acta Nutr. Sin. 12, 1-9), and were compared with the estimates from the individual food weighing method for both accuracy and associations with bone density. SETTING: The subjects were randomly selected from five rural countries in China, characterized by different dietary patterns. SUBJECTS: A total of 712 women aged 35-75 years participated in the dietary and bone measurements. RESULTS: Nutrient intakes estimated by the modified household method (adjusting for body weight were very similar to those obtained by the individual method (r = 0.53-0.78, P < 0.001), except for sodium which had the largest deviation from the individual methods (r = 0.23, P < 0.001). Calcium intakes were 405 +/- 271 and 409 +/- 323 mg/day, respectively, as estimated by the individual and modified household methods. A very similar degree of correlation with radial bone density also was obtained for both calcium estimates. CONCLUSION: The results indicate that the modified household method is appropriate for assessing food intakes of individuals in large nutritional studies.

Urinary riboflavin excretion after a load test in rural China as a measure of possible riboflavin deficiency.

Urinary excretion of riboflavin was measured in 3318 adults 4 h after an oral dose of riboflavin. Male and female subjects aged 35-64 years were selected from 65 mostly rural counties located in 24 provinces of China. Counties were selected to represent a range of seven of the most prevalent cancer mortality rates in China and within counties households were selected at random. Urinary riboflavin excretion levels after a load test, erythrocyte glutathione reductase activity coefficients (EGR-AC), dietary riboflavin intakes, and a large number of other biochemical, dietary, and environmental parameters were measured. Mean dietary intake of riboflavin was 75 per cent of the Chinese recommended dietary allowances (CRDA). Mean meat intake per reference man was very low (26.4 +/- 23.7 g/d) in comparison to Western standards and milk was not consumed at all in most counties. Mean EGR activity coefficients measured on 'blood pools' for both males (1.47 +/- 0.14) and females (1.48 +/- 0.16) indicated that more than two-thirds of the population surveyed was in the medium or high risk category of riboflavin deficiency. Using current reference standards of less than 1.4 mg for 4-h urinary excretion of riboflavin after a 5 mg load, more than 70 per cent of the individuals examined exhibited low levels usually associated with high risk of riboflavin deficiency. In view of the lack of specificity for clinical indications of riboflavin deficiency and the tentative validity of the present CRDA, the interpretation of the data is problematic. We suggest that the present CRDA for this vitamin is set too high and requires critical review and possibly some revision.

Sources of fiber and fat in diets of US women aged 19 to 50: implications for nutrition education and policy.

INTRODUCTION: Many women are not meeting dietary recommendations for fiber and fat intakes. Health educators need to know which foods are major sources of these nutrients. METHODS: This study analyzed the contributions of 27 food groups to fiber, fat, saturated fat, and cholesterol intakes of 2134 women aged 19 to 50 years in USDA's Continuing Survey of Food Intakes by Individuals, the 1985 and 1986 surveys (CSFII 85-86). RESULTS: Major determinants of fiber intake include frequency of use of certain food groups (vegetables, including potatoes, bread, fruit, soups, ready-to-eat cereal) and choice of particular foods within the larger food groups (e.g., whole grain bread, high fiber cereal). Major determinants of total fat, saturated fat, and cholesterol intakes included frequency of use of certain foods (sweet grains, beef, eggs, cheeses/cream, whole milks) and additions to foods (regular salad dressing and butter/margarine). Demographic characteristics were related to various food group consumption parameters. CONCLUSIONS: Information about the relationships between food group and nutrient intake and the effects of household income, race/ethnicity, and region of residence on food group intake indicate opportunities to refine nutritional education programs.

An assessment of the accuracy of a regional economic-demographic projection model.

A large number of regional economic-demographic projection models have been developed but their accuracy has seldom been evaluated. This article examines the accuracy of one such model in projecting total populations for 1980, using 1970 base data, for 106 counties and 553 places in two states. Comparisons of the model's projections to 1980 Census counts reveal mean percentage absolute differences of 10 percent for counties and 14 percent for places. In addition, the model's accuracy was comparable to that for alternative projection systems. When projections for places of less than 1,000 are excluded, differences are substantially reduced. Economic-demographic models appear to be quite useful and deserve further attention.

Evaluation of the FIRI (Fasting Insulin Resistance Index) and selected plasma parameters associated with insulin resistance as predictors of cardiovascular mortality in rural Chinese women.

Insulin Resistance Syndrome (IRS) refers to a cluster of pathologies including hypercholesterolaemia, diabetes, hypertension and cardiovascular disease indicating that these diseases share a common aetiology in insulin resistance and hyperinsulinaemia. Recently a simple index of insulin resistance referred to as the Fasting Insulin Resistance Index (FIRI) was proposed by Duncan et al, for use in clinical practice and epidemiologic investigations of disease FIRI is estimated as the product of fasting plasma glucose and fasting plasma insulin divided by 25 (FIRI = (glucose x insulin/25). This communication evaluates the utility of FIRI using data from a large comprehensive ecologic study on diet and disease in rural counties in the People's Republic of China and provides support for the use of this biomarker/index in epidemiologic studies on disease states associated with IRS.

Medically supervised water-only fasting in the treatment of hypertension.

BACKGROUND: Hypertension-related diseases are the leading cause of morbidity and mortality in industrially developed societies. Although antihypertensive drugs are extensively used, dietary and lifestyle modifications also are effective in the treatment of patients with hypertension. One such lifestyle intervention is the use of medically supervised, water-only fasting as a safe and effective means of normalizing blood pressure and initiating health-promoting behavioral changes. METHODS: One hundred seventy-four consecutive hypertensive patients with blood pressure in excess of 140 mm Hg systolic, 90 mm Hg diastolic (140/90 mm Hg), or both were treated in an inpatient setting under medical supervision. The treatment program consisted of a short prefasting period (approximately 2 to 3 days on average) during which food consumption was limited to fruits and vegetables, followed by medically supervised water-only fasting (approximately 10 to 11 days on average) and a refeeding period (approximately 6 to 7 days on average) introducing a low-fat, low-sodium, vegan diet. RESULTS: Almost 90% of the subjects achieved blood pressure less than 140/90 mm Hg by the end of the treatment program. The average reduction in blood pressure was 37/13 mm Hg, with the greatest decrease being observed for subjects with the most severe hypertension. Patients with stage 3 hypertension (those with systolic blood pressure greater than 180 mg Hg, diastolic blood pressure greater than 110 mg Hg, or both) had an average reduction of 60/17 mm Hg at the conclusion of treatment. All of the subjects who were taking antihypertensive medication at entry (6.3% of the total sample) successfully discontinued the use of medication. CONCLUSION: Medically supervised water-only fasting appears to be a safe and effective means of normalizing blood pressure and may assist in motivating health-promoting diet and lifestyle changes.

Bone density and lifestyle characteristics in premenopausal and postmenopausal Chinese women.

The relationships between bone health and various lifestyle factors were examined in a cross-sectional study in 775 Chinese women aged 35-75 years. Bone mass was significantly positively associated with body weight, height, body mass index (BMI) and duration of breastfeeding, but was not significantly associated with other lifestyle variables, including alcohol consumption, parity, age at menarche and age at menopause after adjusting for age and body weight. A positive association was observed in premenopausal women (but not in postmenopausal women) for bone density with current cigarette smoking and plasma and urinary cotinine (the major metabolite of smoking). However, the confounding effects of other unknown factors present in this cross-sectional study may not be excluded. Daily physical activity, as indicated by time spent working in the fields, was found consistently to be positively associated with bone mass (p < 0.0001). When these women were grouped into three physical activity levels on the basis of occupation and daily work intensity, those undertaking heavy labor also had significantly higher radial bone mass than women undertaking light or medium labor. These results suggest a protective effect of daily physical activity on bone health in both pre- and postmenopausal women.

Assessment of zinc nutritional status in rural China.

Zinc nutriture was assessed in 6500 adults aged 35-64 years old in 65 mostly rural counties (two communes per county) in China on the basis of plasma zinc levels and dietary zinc intakes. In addition, the use of plasma albumin and red blood cell superoxide dismutase (SOD) for assessing zinc nutritional status was evaluated. Plasma levels of zinc and albumin were highly correlated between sexes (p<0.001) and between neighbouring communes in the same county (p<0.005), indicating a high degree of data reliability as assessed by this measure of "within county" homogeneity. Zinc deficiency, defined as plasma zinc values less than 70 µg/dL, was not observed for the populations in any of the 65 counties included in the survey. Dietary zinc intake was estimated on the basis of the newly revised Chinese food composition tables in conjunction with a 3-day household dietary survey of approximately 2000 households in the same study. Average dietary zinc intake was 11.9 mg/day, with a wide variability (7.4-34.9 mg/day) across the sample of 65 counties. The average levels of plasma zinc and dietary zinc intake observed in this adult rural Chinese population were comparable to those reported in healthy U.S. subjects, suggesting that zinc deficiency may not be a cause for concern in rural Chinese adults. However, marginal zinc deficiency may be prevalent in some rural areas.

Vitamin A and carotenoid status in rural China.

Vitamin A status of 260 groups of twenty-five males or twenty-five females, aged 35-64 years, surveyed in twenty-four provinces of the People's Republic of China, was assessed by measuring plasma retinol. retinol-binding protein and beta-carotene concentrations. Direct measurements of food intake over a 3 d period and questionnaire data on the frequency of consumption of vegetables, fruits, animal products and other dietary items were also used. Vitamin A status appeared to be low only in specific counties but in general was satisfactory or only marginally deficient. Plasma beta-carotene levels were strikingly low in comparison with Western levels despite generous vegetable consumption suggesting that intake of vitamin A precursors may have been adequate but not abundant enough to maintain high circulating plasma levels of beta-carotene. Plasma beta-carotene, for both males and females, was significantly correlated with the frequency of consumption of green vegetables. Plasma retinol, for males, was highly correlated with meat, fish, oil and alcohol consumption expressed both in quantity or frequency of consumption. Higher levels of plasma retinol, together with lower levels of plasma beta-carotene in males compared with females, suggest that men consume more animal products or may have higher retinol requirements and therefore a higher rate of conversion of beta-carotene to retinol.