硒碘对大鼠谷胱甘肽过氧化物酶活力及甲状腺激素代谢的影响──Ⅱ．硒碘营养状态对大鼠甲状腺激素代谢的影响

用四种硒水平饲料和两种碘含量饮水饲养大鼠观察了其甲状腺激素（ＴＨ）代谢。硒组间肝脏、肾脏Ⅰ型脱碘酶（ＩＤⅠ）活力、血清Ｔａ含量差异显著；两碘组间甲状腺重量、甲状腺过氧化物酶（ＴＰＯ）活力。甲状腺碘含量、肾脏ＩＤⅠ及大脑Ⅱ型脱碘酶（ＩＤⅡ）活力差异明显；Ⅰ－（不加碘）组中甲状腺ＩＤⅠ活力与血清三碘甲腺原氨酸（Ｔａ）含量呈显著正相关。提示硒缺乏通过ＩＤⅠ影响ＴＨ代谢继而影响大脑ＩＤⅡ活力并可加重碘缺乏的效应；低碘时甲状腺ＩＤⅠ在维持循环Ｔａ含量中起重要作用；碘缺乏有可能增加硒缺乏的效应；硒、碘对ＴＨ代谢的影响可能在一定程度上取决于自身和对方的营养状态。     

Dietary selenium intake of preschool children

The results of this investigation indicate that the range of selenium intakes of the preschool children who were studied was in the acceptable range of adequate and safe as suggested by the Food and Nutrition Board. The majority of the selenium in the diets of the subjects came from grains. Although the amount of selenium consumed was within normal limits, the concentration in the diet was estimated to be 70% of the expected value for mixed diets, i.e., 0.1 microgram/gm.     

Dietary selenium and fecal mutagenicity in young men

Fecal mutagenicity, as a possible tool to evaluate risk for colon cancer, was measured in six healthy volunteers (24–33 yr) who consumed diets low in Se (19–24 μg/day) for 45 days followed by 24 days of a selenium repletion diet (203–224 μg/day). Samples were collected at the beginning of the dietary experiment, at the end of the Se-depletion period and at the end of the Se-repletion period. Mutagenic activity with S. typhimurium TA100 and TA98 did not vary significantly among samples taken after the two diet periods. Mutagenicity with TA98 was higher at the beginning of the dietary experiment than at the end of Se-depletion (p<0.01) and at the end of Se-repletion (p<0.1). This effect might be due to the change of the subjects from their habitual diet to the experimental liquid formula diet. Since fecal mutagenicity with both tester strains was the same after the Se-depletion and Se-repletion periods, Se does not appear to be a dominant factor for determining fecal mutagenicity under these experimental conditions.     

硒碘联合作用对机体甲状腺激素代谢的影响机制探讨

用克山病病区粮以及分别加 Se 或/和加 I 喂饲大鼠,并观察机体甲状腺激素的代谢变化。结果发现,缺 I 可显著降低循环和肝脏的 T_4水平,循环总 T_3受 Se、I 影响不十分明显,但 FT_3变化较大。缺 Se 使肝 I 型5′-脱碘酶活性下降,并使肝 T_3生成减少,但因此引起 T_4堆积的现象只能在缺 Se加 I 组中出现。甲状腺组织的甲状腺激素水平因缺 I 而减少,但缺 Se 并未使其进一步下降,反而有较大幅度的升高,且同时使甲状腺肿胀加剧。循环促甲状腺激素(TSH)有相对稳定循环T_3水平的作用。TSH 与 T_4负相关。研究提示,不同 Se、I 营养状况对循环和组织甲状腺激素代谢影响不同,肝组织内源性甲状腺激素受 Se 水平影响较大。     

过量碘对甲状腺激素代谢的损伤及硒的干预作用

目的研究过量碘性甲状腺激素代谢紊乱的机制并寻求合适的硒干预剂量。方法140只Balb/c小鼠分为7组:正常组、过量碘组(饮水含碘3000μg/L)和5个补硒组(饮水含碘3000μg/L,硒分别为0.1、0.2、0.3、0.4和0.5mg/L),共喂养16周。放射免疫法测定血清甲状腺激素水平,砷铈催化分光光度法测定尿碘和甲状腺碘水平,测定甲状腺谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)和甲状腺过氧化物酶(TPO)活性以及丙二醛(MDA)水平。结果0.1～0.5mg/L补硒组甲状腺激素水平与正常组比较差异无显著性,0.2mg/L补硒组甲状腺内碘含量较过量碘组显著下降(P<0.05),0.2～0.3mg/L补硒组甲状腺GSH-Px、SOD活性和MDA水平与正常组比较差异无显著性,0.1～0.3mg/L补硒组TPO活性与正常组比较差异无显著性。结论补充硒对过量碘导致的小鼠甲状腺氧化/抗氧化水平失衡、TPO活性水平下降都有有效的干预作用。     

Raised thyroid stimulating hormone associated with kelp intake in British vegan men

To explore the hypothesis that the iodine intake of vegans might be inadequate, thyroid stimulating hormone concentrations were measured in plasma samples from 101 British men, of whom 48 were vegans and 53 were omnivores. The geometric mean thyroid stimulating hormone concentration, adjusted for age and body mass index, was 47% higher in the vegans than in the omnivores (P= 0.001). Five vegans but none of the omnivores had a thyroid stimulating hormone concentration above the reference upper limit of 5 mU/1 (P=0.022). High concentrations of thyroid stimulating hormone are usually indicative of marginal iodine status, but can also result from excessive iodine intake. The three vegans with the highest values of thyroid stimulating hormone reported regular use of kelp tablets or kelp powder. None of the other vegans, and none of the omnivores, reported taking kelp. After exclusion of the three vegans who took kelp, the remaining vegans had an adjusted geometric mean thyroid stimulating hormone concentration 29% higher than that of the omnivores (P=0.012). It was concluded that use of kelp can be associated with raised thyroid stimulating hormone, and that the iodine status of vegans who do not use kelp requires further investigation.     

Effect of oral iodized oil on thyroid size and thyroid hormone metabolism in children with concurrent selenium and iodine deficiency

OBJECTIVES: To determine the efficacy of oral iodized oil in goitrous children who are both selenium (Se) and iodine deficient; to investigate if Se status modifies the response of iodine deficient, goitrous children to oral supplementation with iodized oil. DESIGN: A longitudinal intervention trial. SETTING: Two rural villages in the western C?te d'Ivoire. SUBJECTS: 51 goitrous non-anemic schoolchildren with both iodine and Se deficiency. INTERVENTION: Each child received an oral dose of 0.4 ml iodized poppyseed oil containing 200 mg of iodine. They were followed for 1 y with measurements of urinary iodine (UI), thyrotropin (TSH), thyroxine (T4), and thyroid volume by ultrasound. RESULTS: At baseline all children were goitrous and Se deficient; median UI was 29 microg/l and mean serum Se (s.d.) was 14.8 (10.7) microg/l. After receiving iodized oil, thyroid volume decreased significantly vs baseline at 10, 15, 30 and 50 weeks (P<0.001). At 50 weeks mean percentage change in thyroid volume from baseline was-46.6% and only five children remained goitrous. Median TSH values at 5, 10, 15, 30 and 50 weeks were reduced significantly (P<0.001) compared to baseline. Among individual children the severity of Se deficiency predicted the degree of response to iodized oil. Baseline serum Se and percentage change in thyroid volume from baseline at 50 weeks were strongly correlated (r2=0.554). Baseline Se and percentage decrease in TSH from baseline at 30 weeks were also well-correlated (r2=0.467). CONCLUSION: Although more severe Se deficiency partially blunts the thyroid response to iodine supplementation, oral iodized oil is an effective method for iodine repletion in goitrous children who are Se deficient. SPONSORSHIP: The Swiss Federal Institute of Technology, Zürich, the Foundation for Micronutrients in Medicine, Rapperswil, Switzerland, and the Thrasher Research Fund, Salt Lake City, USA.     

Dietary variety within food groups: association with energy intake and body fatness in men and women

BACKGROUND: Short-term experimental studies suggest that dietary variety may influence body fatness but no long-term human studies have been reported. OBJECTIVE: The purpose of this study was to determine whether dietary variety within food groups influences energy intake and body fatness. DESIGN: Seventy-one healthy men and women (aged 20-80 y), who provided accurate reports of dietary intake and completed a body-composition assessment, were studied. RESULTS: Dietary variety was positively associated with energy intake within each of 10 food groups (r = 0.27-0.56, P < 0.05). In multiple regression analysis with age and sex controlled for, dietary variety of sweets, snacks, condiments, entrées, and carbohydrates (as a group) was positively associated with body fatness (partial r = 0.38, P = 0.001) whereas variety from vegetables was negatively associated (partial r = -0.31, P = 0.01) (R2 = 0.46, P < 0.0001). In separate models, both a variety ratio (variety of vegetables/variety of sweets, snacks, condiments, entrées, and carbohydrates) and percentage dietary fat were significant predictors of body fatness (controlled for age and sex, partial r = -0.39 and 0.31, respectively, P < 0.01). However, dietary fat was no longer significantly associated with body fatness when the variety ratio and dietary fat were included in the same model. CONCLUSIONS: Our data, coupled with those of previous short-term studies, suggest that a high variety of sweets, snacks, condiments, entrées, and carbohydrates coupled with a low variety of vegetables promotes long-term increases in energy intake and body fatness. These findings may help explain the rising prevalence of obesity.     

Dietary selenium intake controls rat plasma selenoprotein P concentration

The purpose of this study was to determine the effect of dietary selenium on selenoprotein P concentration. Selenoprotein P was quantitated in plasma by radioimmunoassay. Selenium-dependent glutathione peroxidase activity in plasma and liver 105,000 x g supernatant was measured for comparison. Weanling male rats were fed a selenium-deficient diet or a control diet that contained 0.5 mg selenium/kg as Na2SeO4. The concentration of selenoprotein P fell at approximately the same rate in the rats fed the selenium-deficient diet as did plasma glutathione peroxidase activity. Groups of weanling rats were fed different levels of selenium for 8 wk. Selenoprotein P concentration was proportional to dietary selenium level up to 0.1 mg/kg and was a greater percentage of control values than was glutathione peroxidase activity. No increment in selenoprotein P concentration occurred between 0.1 and 0.5 mg selenium/kg diet. These results indicate that the concentration of selenoprotein P in the plasma is directly dependent on selenium supply in the diet up to 0.1 mg/kg. There is overlap between the dietary selenium ranges in which selenoprotein P concentration and glutathione peroxidase activity increase, but the selenoprotein P range is lower than the glutathione peroxidase range.     

Dietary energy shortage and ethanol intake in golden hamsters

Adult male golden hamsters, which are avid consumers of ethanol solutions, were maintained on powdered Purina chow and tap water, and they were permitted continuous access to either a 15% or a 30% ethanol solution (v/v). In two experiments, the effect of chronic dietary energy shortage on ethanol consumption was examined. Energy shortage was produced either by food restriction (Experiment 1) or by dilution of the diet with nonnutritive cellulose (Experiment 2). Dietary energy shortage caused increases of up to 50% in ethanol consumption, and the energy derived from ethanol offset the short-fall in food-derived energy by up to 50%. When normal feeding conditions were reinstated, hamsters maintained their enhanced intake of ethanol solutions, consuming up to 15.4 g/kg/day of ethanol. Possible factors underlying the enhanced intake of ethanol solution both during and after dietary energy shortage are discussed.     

Dietary habits and selenium intake of residents in mountain and coastal communities in Japan

We used a Simple Food Frequency Questionnaire (SFFQ) in combination with other dietary approaches to estimate the selenium intake from different food groups based on the average long-term diet, in two rural communities in Japan, one in a mountain area and the other in a coastal area. The intake frequencies of rice and wheat products were significantly different in the two districts. The intake frequencies of fish, meat, and eggs, which are rich in selenium, were not significantly different. The mean dietary selenium intake, estimated from the SFFQ and the 24-h recall method, was 82.7 microg/d (n=234) (range 19.2-180.1 microg/d) in the mountain community. The mean dietary selenium intake estimated from the SFFQ and average value of the normal portion size was 118.0 microg/d (n=123) (range 22.6-255.3 microg/d) in the coastal community. These estimated mean values exceeded the Japanese RDA, although the range of daily selenium intake was large. In the mountain community, fish made the largest contribution to dietary selenium intake (48.2% of daily total), followed by eggs (24.3%), and meat (17.0%). In the coastal community, fish accounted for 57.7% of daily total selenium intake, followed by meat (17.5%), and eggs (16.1%). In both districts, the total contribution of rice and wheat products was around 10%. It was found that the contribution of fish to dietary selenium intake was high and the contribution of cereals was low among Japanese.     

Dietary pattern classifications with nutrient intake and health-risk factors in Korean men

Objective

This study was performed to identify dietary patterns in Korean men and to determine the associations among dietary patterns, nutrient intake, and health-risk factors.

Methods

Using baseline data from the Korean Health and Genome Study, dietary patterns were identified using factor analysis of data from a validated food-frequency questionnaire, and associations between these dietary patterns and health-risk factors were analyzed.

Results

Three dietary patterns were identified: 1) the “animal-food” pattern (greater intake of meats, fish, and dairy products), 2) the “rice-vegetable” pattern (greater intake of rice, tofu, kimchi, soybean paste, vegetables, and seaweed), and 3) the “noodle-bread” pattern (greater intake of instant noodles, Chinese noodles, and bread). The animal-food pattern (preferred by younger people with higher income and education levels) had a positive correlation with obesity and hypercholesterolemia, whereas the rice-vegetable pattern (preferred by older people with lower income and educational levels) was positively associated with hypertension. The noodle-bread pattern (also preferred by younger people with higher income and education levels) had a positive association with abdominal obesity and hypercholesterolemia.

Conclusion

This study identifies three unique dietary patterns in Korean men, which are independently associated with certain health-risk factors. The rice-vegetable dietary pattern, modified for a low sodium intake, might be a healthy dietary pattern for Korean men.     

Dietary fat and the regulation of energy intake in human subjects

The role of dietary fat in the regulation of energy intake was assessed by manipulating a conventional diet and measuring spontaneous food consumption. Twenty-four women each consumed a sequence of three 2-wk dietary treatments in which 15-20%, 30-35%, or 45-50% of the energy was derived from fat. These diets consisted of foods that were similar in appearance and palatability but differed in the amount of high-fat ingredients used. Relative to their energy consumption on the medium-fat diet, the subjects spontaneously consumed an 11.3% deficit on the low-fat diet and a 15.4% surfeit on the high-fat diet (p less than 0.0001), resulting in significant changes in body weight (p less than 0.001). A small amount of caloric compensation did occur (p less than 0.02), which was greatest in the leanest subjects (p less than 0.03). These results suggest that habitual, unrestricted consumption of low-fat diets may be an effective approach to weight control.     

Carnitine metabolism in thyroid hormone treated rats and mice

This study was undertaken to investigate the changes in carnitine metabolism in rats and mice injected with T4 for 3 days and 10 days, respectively, and in rats fed a T3 and T4-supplemented diet for 6 weeks. Thyroid hormone administration brought about a significant increase in urinary excretion of total carnitine. In T3 + T4-treated rats urinary esterified-carnitine to free-carnitine ratio increased significantly in the later phase of administration. Carnitine pool size in the body was significantly decreased in both T4-injected mice and T3 + T4-fed rats. In the latter animals, this decrease was due to the reduced carnitine contents in organs other than the liver, especially in skeletal muscle. The amount of carnitine synthesized by control and T3 + T4-treated rats was calculated from the data on carnitine intake, urinary carnitine excretion and carnitine pool size in the body over the 6-week period. Values obtained were 66.2 +/- 3.2 (mean +/- SEM) mumol/rat and 28.5 +/- 4.9 mumol/rat, respectively, and the difference was significant (p less than 0.05). These results indicate that carnitine synthesis is depressed by thyroid hormone, however, some possibilities that thyroid hormone may increase carnitine synthesis were also discussed.     

Dietary energy density is associated with energy intake and weight status in US adults

BACKGROUND: Laboratory-based investigations indicate that the consumption of foods with a low energy density (kcal/g) decreases energy intake. Although low-energy-dense diets are recommended for weight management, relations between energy density, energy intake, and weight status have not been clearly shown in free-living persons. OBJECTIVES: A representative US sample was used to determine whether dietary energy density is associated with energy intake, the weight of food consumed, and body weight and to explore the influence of food choices (fruit, vegetable, and fat consumption) on energy density and body weight. DESIGN: A cross-sectional survey of adults (n = 7356) from the 1994-1996 Continuing Survey of Food Intakes by Individuals and two 24-h dietary recalls were used. RESULTS: Men and women with a low-energy-dense diet had lower energy intakes (approximately 425 and 275 kcal/d less, respectively) than did those with a high-energy-dense diet, even though they consumed more food (approximately 400 and 300 g/d more, respectively). Normal-weight persons had diets with a lower energy density than did obese persons. Persons with a high fruit and vegetable intake had the lowest energy density values and the lowest obesity prevalence. CONCLUSIONS: Adults consuming a low-energy-dense diet are likely to consume more food (by weight) but to have a lower energy intake than do those consuming a higher-energy-dense diet. The energy density of a variety of dietary patterns, including higher-fat diets, can be lowered by adding fruit and vegetables. Our findings support the hypothesis that a relation exists between the consumption of an energy-dense diet and obesity and provide evidence of the importance of fruit and vegetable consumption for weight management.     

Dietary intake and major sources of plant lignans in Latvian men and women

Higher intake of lignans, diphenolic plant compounds, may reduce the risk of certain types of cancer and cardiovascular diseases. We assessed the dietary intake of four lignans: matairesinol, secoisolariciresinol, lariciresinol and pinoresinol. Furthermore, for the breads we supplemented the data with two more lignans: syringaresinol and medioresinol. Study subjects were 172 men and 97 women aged 40–75 years, residing in Riga, the capital of Latvia, all living at home, eating habitual food. Median total lignan intake was 2259 (range 1169–5759) μg/day. Secoisolariciresinol contributed 58% and syringaresinol 22% of lignan intake. Bread was the major food source of lignans in men (86%), whereas in women it was bread (57%) and flaxseed (35%).