Contribution of dietary protein and inorganic sulfur to urinary sulfate: toward a biomarker of inorganic sulfur intake

BACKGROUND: Sulfiting agents are widely used as food additives. Limits are set on their use in foods because they may adversely affect health. Sulfiting agents are excreted in urine as sulfate, which is indistinguishable from sulfate derived from sulfur amino acids. OBJECTIVE: The objective was to assess the contribution of inorganic sulfur to urinary sulfate excretion and of dietary protein to urinary sulfate and nitrogen excretion with the aim of developing a urinary biomarker of inorganic sulfur intake. DESIGN: Nine healthy men were fed a sequence of 3 diets for 15 d (n = 7), 5 diets for 10 d (n = 6), or both. The diets contained 51-212 g protein/d (0.43-1.71 g S/d) and 0.17-0.27 g inorganic S/d; p-aminobenzoic acid-validated 24-h urine samples (n = 47) were analyzed for sulfate and nitrogen. RESULTS: Dietary inorganic sulfur was efficiently excreted as sulfate in urine. Urinary sulfate derived from protein correlated strongly (r(2) = 0.86) with urinary nitrogen. Urinary recovery of protein sulfur and nitrogen decreased from 84% at average protein intakes (72 g/d) to 70% at high protein intakes (212 g/d). The nitrogen:sulfur ratio (in g) of the protein in the study diets was 18.9, which was maintained in urine (18.4 +/- 0.1) after dietary inorganic sulfur intake was subtracted from urinary sulfate. Therefore, inorganic sulfur intake (g/d) = urinary sulfur (g/d) - 0.054 x urinary nitrogen (g/d). For typical UK intakes of inorganic sulfur (0.25 g/d), this biomarker should produce mean (+/- SD) values of 0.24 +/- 0.10 g S/d. CONCLUSION: Twenty-four-hour urinary nitrogen and sulfate values can be used to predict inorganic sulfur intake.     

Effects of dietary protein intake on carnitine status in Thai men

Healthy men receiving adequate intakes of energy and fat without protein and carnitine for 14 days had significantly higher mean 24-h urinary free, acyl, and total carnitine excretions than the control subjects. Hen egg was the sole source of protein in this study and constained 7.77 μmol of carnitine/100 g. The stress stimuli due to the lack of protein and carnitine intakes were alleviated with the protein intakes of 0.35, 0.50, 0.55, 0.65, 0.70, and 0.85 g/kg/d, evidenced by the significant decreases in the 3 forms of 24-h urinary carnitine excretions. Their significantly lower in the 3 forms of 24-h urinary carnitine excretions than the control subjects with carnitine intake of 176 μmol/d were due to their limited intakes of carnitine: 12–30 μmol/d. Their significant increases in urinary acylcarnitine/total carnitine ratios indicated the utilization of carnitine in fatty acid oxidation.     

Reliability of studies of iodine intake and recommendations for number of samples in groups and in individuals

The iodine intake level in a population is determined in cross-sectional studies. Urinary iodine varies considerably and the reliability of studies of iodine nutrition and the number of samples needed is unsettled. We performed a longitudinal study of sixteen healthy men living in an area of mild to moderate iodine deficiency. Iodine and creatinine concentrations were measured in spot urine samples collected monthly for 13 months. From these data we calculated the number of urine samples needed to determine the iodine excretion level for crude urinary iodine and for 24 h iodine excretion estimated from age- and gender-specific creatinine excretions. We found that mean urinary iodine excretion varied from 30 to 87 microg/l (31 to 91 microg/24 h). Sample iodine varied from 10 to 260 microg/l (20 to 161 microg/24 h). Crude urinary iodine varied more than estimated 24 h iodine excretion (population standard deviation 32 v. 26; individual standard deviation 29 v. 21; Bartlett's test, P < 0.01 for both). The number of spot urine samples needed to estimate the iodine level in a population with 95 % confidence within a precision range of +/- 10 % was about 125 (100 when using estimated 24 h iodine excretions), and within a precision range of +/- 5 % was about 500 (400). A precision range of +/- 20 % in an individual required twelve urine samples or more (seven when using estimated 24 h iodine excretions). In conclusion, estimating population iodine excretion requires 100-500 spot urine samples for each group or subgroup. Less than ten urine samples in an individual may be misleading.     

Salt Intake of Lactating Women as Assessed by Modified Food Weighted Records

Objective: High salt intake among lactating women can increase the risk of hypertension and cardiovascular disease in infants/offspring. However, considering the limited salt intake data in lactating women, the aims of this study were to compare the salt intake assessed by modified food weighted records (FWR) with that estimated by 24-h urinary sodium excretion and to investigate the salt intake of lactating women.

Methods: In total, 30 lactating women aged 20–39 years who were 2 to 4 months postpartum were recruited from the cities of Tianjin and Luoyang in China. The household salt intakes of the lactating women were collected by modified FWR for 3 days. Information on the gender, age, eating behaviours and labour intensity of the family members and guests dining at home during the 3 days was recorded. Meanwhile, 24-h urine samples of lactating women were collected.

Results: The salt intakes of the lactating women estimated by modified FWR and 24-h urinary sodium excretion were 8.50 ± 5.32 g/d and 9.34±3.74 g/d (t=?1.29, P=0.207), respectively, which exceeded the WHO recommendation of 5 g/d. There was a significant correlation (r=0.628, P < 0.001) between the salt intakes assessed by the two methods. A Bland-Altman plot showed no significant mean difference between the two methods (salt intake measured by 24-h urinary sodium excretion-salt intake assessed by modified FWR=0.46 g/d, P=0.207).

Conclusions: The modified FWR is a reliable tool to assess the salt intake of lactating women. The salt intake of lactating women in China remains higher than the WHO recommendation and should be restricted through further efforts.     

Sodium and potassium intake and balance in adults consuming self-selected diets

Twenty eight adults, 12 men and 16 women, participated in a 1-yr study designed to assess daily nutrient intake accurately. All subjects lived at home, consumed self-chosen diets, and maintained a detailed daily dietary record throughout the year. During four 7-day balance studies, one in each season of the year, meals, beverages, urine, and feces were analyzed for sodium and potassium content by atomic absorption spectrometry. Total intakes averaged 3.4 g/day for sodium and 2.8 g/day for potassium. The Na:K ratio for all diets analyzed averaged 1.3. Nutrient densities of sodium and potassium were 1.8 and 1.5 g/1000 kcal, respectively. Apparent absorptions of sodium and potassium were 98 and 85%, respectively, and did not change significantly over the wide range of intakes. Average urinary excretions of sodium and potassium were 86 and 77% of total intake, respectively. Mean metabolic balances were positive for sodium, +0.47 g/day, and potassium, +0.28 g/day. The data of this study provide useful information concerning the dietary intakes, excretions, and balances of sodium and potassium for adults based on analytic determination.     

The effect of prenatal dietary protein intake on birth weight

From 1940 to 1980, protein deficiency was implicated in depressed fetal growth and impaired infant development. Consequently, increasing protein intake in pregnancy was recommended. In 1980, a randomized controlled trial found high protein supplements to be associated with depressed birth weight in low-income pregnant women. The objective of this study was to assess the role of dietary protein during pregnancy in women consuming a self-selected diet. The relation between dietary protein intake and pregnancy outcome was explored in an observational, longitudinal study of low income, mostly urban women. Protein intake was estimated using the average of two 24-hour dietary recalls, the first generally completed between months 4 to 6 and the second in month 8 of pregnancy. Hierarchical multiple regression analyses were conducted, adjusted for maternal, infant and socio-demographic characteristics and for duration of gestation and maternal energy intake. This study found that mean protein intake ≥85 g/day was associated with a 71 g decrement in birth weight (n = 2163, p = 0.009) compared to intermediate (50–84.9 g/day) average protein intake. About 36% of the women studied reported mean intakes of ≥85 g protein daily during pregnancy, whereas only 12% had low protein intakes (<50 g/day). Thus, the negative effect of high protein intake on birth weight may have considerable public health significance and should not be encouraged.     

Accuracy of dietary recall using the USDA five-step multiple-pass method in men: an observational validation study

OBJECTIVE: This observational validation study was conducted under controlled conditions to test the accuracy of dietary recall in normal weight, overweight, and obese men using the USDA five-step multiple-pass method for dietary recall. DESIGN: Cross-sectional analysis of actual and recalled intake of food during 1 day. SUBJECTS/SETTING: Forty-two men ranging in age from 21 to 65 years and in body mass index from 21 to 39 kg/m(2) who lived in the metropolitan Washington DC area were studied. INTERVENTION: The subjects selected and consumed all meals and snacks, for 1 day, from a wide variety of foods provided at a human study facility. MAIN OUTCOME MEASURES: Actual and recalled energy, protein, carbohydrate, and fat intakes were determined by direct observation and by a 24-hour dietary recall, respectively. Dietary recall was determined via telephone administration of the USDA five-step multiple-pass method the following day. STATISTICAL ANALYSES PERFORMED: Analysis of variance and covariance tested the overall accuracy of recall and the effect of body mass index on dietary recall. Bland-Altman plots were used to assess bias in recall of food intake. RESULTS: In this population of men, there were no significant differences between actual and recalled intakes of energy (3,294+/-111 and 3,541+/-124 kcal/day), protein (117+/-5 and 126+/-5 g/day), carbohydrate (414+/-16 and 449+/-16 g/day), or fat (136+/-7 and 146+/-8 g/day), respectively. Accuracy of recall was not related to body mass index in that the obese men recalled food intake as accurately as the nonobese men. The energy intake of these men was significantly correlated (r=0.57, P<.05) with their estimated energy requirements. Significant interindividual variation in accuracy of recall was found. CONCLUSIONS: Under controlled conditions, the USDA five-step multiple-pass method can accurately assess intakes of energy, protein, carbohydrate, and fat in a population of men regardless of their body mass index. Researchers and clinical dietitians need to continue to examine factors that influence underreporting and overreporting of food intake by the multiple-pass 24-hour recall method.     

Food and nutrient intakes and their associations with lower BMI in middle-aged US adults: the International Study of Macro-/Micronutrients and Blood Pressure (INTERMAP)

BACKGROUND: Clinical trial data show that reduction in total energy intake enhances weight loss regardless of the macronutrient composition of the diet. Few studies have documented dietary patterns or nutrient intakes that favor leanness [BMI (in kg/m(2)) ≤25] in free-living populations. OBJECTIVE: This investigation examined associations of usual energy, food, and nutrient intakes with BMI among US participants of the International Study of Macro-/Micronutrients and Blood Pressure (INTERMAP). DESIGN: The INTERMAP is an international cross-sectional study of dietary factors and blood pressure in men and women (ages 40-59 y) that includes 8 US population samples. The present study included data from 1794 Americans who were not consuming a special diet and who provided four 24-h dietary recalls and 2 timed 24-h urine collections. Multivariable linear regression with the residual method was used to adjust for energy intake; sex-specific associations were assessed for dietary intakes and urinary excretions with BMI adjusted for potential confounders including physical activity. RESULTS: Lower energy intake was associated with lower BMI in both sexes. Univariately, higher intakes of fresh fruit, pasta, and rice and lower intakes of meat were associated with lower BMI; these associations were attenuated in multivariable analyses. Lower urinary sodium and intakes of total and animal protein, dietary cholesterol, saturated fats, and heme iron and higher urinary potassium and intakes of carbohydrates, dietary fiber, and magnesium were associated with lower BMI in both sexes. CONCLUSION: The consumption of foods higher in nutrient-dense carbohydrate and lower in animal protein and saturated fat is associated with lower total energy intakes, more favorable micronutrient intakes, and lower BMI.     

Urinary total flavonoid excretion but not 4-pyridoxic acid or potassium can be used as a biomarker for the intake of fruits and vegetables

To gain better insight into the potential health effects of fruits and vegetables, reliable biomarkers of intake are needed. The main purpose of this study was to investigate the ability of flavonoid excretion in both 24-h and morning urine samples to reflect a low intake and moderate changes in fruit and vegetable consumption. Furthermore, the urinary excretions of 4-pyridoxic acid (4-PA) and potassium were investigated as other potential biomarkers of fruit and vegetable intake. The study was designed as a 5-d randomized, controlled crossover study. On d 1-3, the men (n = 12) consumed a self-restricted flavonoid-free diet. On d 4, they were provided a strictly controlled diet containing no fruits or vegetables (basic diet). On d 5, they consumed the basic diet supplemented with 300 or 600 g of fruits and vegetables. The total excretion of flavonoids in 24-h urine samples increased linearly with increasing fruit and vegetable intakes (r(s) = 0.86, P < 1 x 10(-6)). The total excretion of flavonoids in morning urine also increased, but the association was weaker (r(s) = 0.59, P < 0.0001). Urinary 4-PA in 24-h and morning urine samples increased significantly only with the 600-g increase in fruit and vegetable intake, whereas the excretion of potassium in urine did not reflect the changes in fruit and vegetable intake. We conclude that the total excretion of flavonoids in 24-h urine may be used as a new biomarker for fruit and vegetable intake.     

Consistent Iodine Status Assessment in Chinese Adults by Different Spot Urinary Iodine Concentrations in a Day Together With Corresponding Correction Coefficients

Abstract

Objective: The aim of this research was to determine the correction coefficients of different spot urinary iodine concentrations (UICs) in a day to predict the early morning UIC, to make the different spot UICs of a day comparable in assessing iodine status in the same population.

Methods: In total, 424 participants aged 18 to 28?years were recruited from Tianjin, China. Three spot urine samples were collected from each participant during three periods of the day (6:30–7:00, 10:00–10:30, and 16:00–16:30). A total of 1272 urine samples were collected. A 24-hour dietary record was reported by each participant for 3 consecutive days.

Results: Both the UICs at 10:00–10:30 and 16:00–16:30 were higher than that at 6:30–7:00 (181.75 or 198.15μg/L vs 157.69?μg/L; all p?<?0.05). Bland-Altman plot showed no good agreements between the other two spot UICs and that at 6:30–7:00 with both Bland-Altman indexes of 7.1%. Correction coefficients used to predict UIC at 6:30–7:00 from the UIC at 10:00–10:30 and 16:00–16:30 were 0.9231 and 0.8592, respectively. The predicted UICs at 6:30–7:00 by using the UIC at 10:00–10:30 and 16:00–16:30 both had no statistically significant difference with the actual UIC at 6:30–7:00 (all p?>?0.05). Bland-Altman plot showed good agreements between the predicted UICs and actual UICs at 6:30–7:00 with both Bland-Altman indexes of 4.5%.

Conclusions: It was reliable to predict the early morning UIC using correction coefficients of other spot UIC of the day, which gave a new idea for standardizing the methodology of surveys assessing iodine status of a population.     

Biochemical markers for assessment of niacin status in young men: urinary and blood levels of niacin metabolites

Biochemical markers of niacin status were studied in healthy young men fed 6.1 to 32 niacin equivalents (NE) per day over an 11-wk period while residing in a metabolic unit. Methylated metabolites of niacin, N1-methylnicotinamide (NMN) and N1-methyl-2-pyridone-5-carboxamide (2-pyr), in urine and plasma were determined during periods of low (6.1 or 10.1 NE per day), adequate (19 NE per day = 1 RDA) and high (25 or 32 NE per day) niacin intakes and after small test doses of nicotinamide. Urine excretion of less than 1.2 mg/d of either NMN or 2-pyr was a reliable indicator of subjects receiving the lowest intake of 6.1 NE/d, but the NMN metabolite was a better marker of subjects ingesting 10.1 NE/d. The ratio of 2-pyr/NMN in urine was not as good a measure of the 6.1 NE/d intake as the individual metabolite excretions and was not responsive to the 10.1 NE/d intake. Plasma niacin metabolites were generally not as reliable as urinary metabolites for identifying subjects receiving low niacin intakes, however, values for plasma 2-pyr dropped quickly and were eventually nondetectable. After a 1 RDA oral dose of nicotinamide, increases in urine and plasma 2-pyr levels above pre-dose baseline values were significantly decreased in subjects receiving low, as compared to adequate, niacin intake. A leucine supplement had no effect on the rate of repletion of niacin-deficient subjects nor on the level of methylated niacin metabolites in urine or plasma.     

Dairy foods are an important source of calcium and vitamin D among Canadian-born and Asian-born Chinese in Edmonton,Alberta

Low intakes of calcium and vitamin D increase the risk for osteoporosis, bone fracture, and other health problems. This study aimed to examine the calcium and vitamin D intakes of Canadian-born Chinese (CBC) and Asian-born Chinese (ABC) in Edmonton, Canada, and to identify usual food sources of these nutrients. We hypothesized that CBC would have higher intakes of calcium and vitamin D than ABC and that the food sources of these nutrients would differ by region of birth (Canada vs Asia). Two in-person multipass 24-hour dietary recalls were administered for 1 weekday and weekend day for 81 healthy ethnically Chinese aged 18 to 58 years. The risks for calcium and vitamin D inadequacy were calculated as were the contributions of specific foods to calcium and vitamin D intakes. Calcium intake was 781 ± 337 mg/d for CBC and 809 ± 369 mg/d for ABC (P = .737). Vitamin D intake was 3.8 ± 3.4 μg/d for CBC and 5.0 ± 3.9 μg/d for ABC (P = .158). Respective risks for calcium and vitamin D inadequacy were 36% and 98% for men and 78% and 100% for women. Dairy contributed most to the calcium (43%) and vitamin D (52%) intake of participants. For ABC, soybean products contributed to 8.1% of calcium, whereas fatty fish contributed to 16.7% of vitamin D. For CBC, red meats contributed to 11.1% of vitamin D. Dietary intakes of calcium and vitamin D need to be increased in Chinese Canadians through the promotion of dairy and culturally relevant sources of these nutrients.     

中国居民膳食生物素平均每日摄入量评估

目的采用食物分类计算法评估中国居民膳食生物素平均摄入量。方法 448种食物,采用微生物法测定生物素含量后,根据2002年中国居民营养与健康状况调查报告分为31类,计算各类食物算术均值和几何均值,乘以相应的食物消费量加和计算城乡居民和2岁以上各年龄段人群生物素平均摄入量。结果全国居民总体生物素摄入量(算术均值)为40.0 g/d,城乡范围36.8~48.9 g/d,几何均值计算结果比算术均值约低9 g/d。30岁前生物素摄入量随年龄增加,到30～45岁时达到最高;其中女性(38.7 g/d)低于男性(43.8 g/d);45岁后随老龄化生物量摄入逐渐下降,70岁时女性仅为31.2 g/d(算术均值)。结论我国城乡居民膳食生物素平均摄入量基本可以达到中国营养学会推荐营养素适宜摄入量(AI),育龄妇女和老年妇女生物素摄入量相对偏低。     

Dietary Plant Sterols and Phytosterol-Enriched Margarines and Their Relationship with Cardiovascular Disease among Polish Men and Women: The WOBASZ II Cross-Sectional Study

Dietary cholesterol has been suggested to increase the risk of cardiovascular disease (CVD). Phytosterols, present in food or phytosterol-enriched products, can reduce cholesterol available for absorption. The present study aimed to investigate the association between habitual intake of total and individual plant sterols (β-sitosterol, campesterol, and stigmasterol) or a diet combined with phytosterol-enriched products and CVD in a cross-section of Polish adults, participants of the Multicenter National Health Survey II (WOBASZ II). Among men (n = 2554), median intakes of plant sterols in terciles ranged between 183–456 mg/d and among women (n = 3136), 146–350 mg/d in terciles. The intake of phytosterols, when consumed with food containing phytosterols, including margarine, ranged between 184–459 mg/d for men and 147–352 mg/d for women. Among both men and women, beta-sitosterol intake predominated. Plant sterol intake was lower among both men and women with CVD (p = 0.016) compared to those without CVD. Diet quality, as measured by the Healthy Diet Index (HDI), was significantly higher in the third tercile of plant sterol intake for both men and women and the entire study group (p < 0.0001). This study suggests that habitual dietary intake of plant sterols may be associated with a lower chance of developing CVD, particularly in men.     

Healthy pregnant women in Canada are consuming more dietary protein at 16- and 36-week gestation than currently recommended by the Dietary Reference Intakes,primarily from dairy food sources

Adequate dietary protein intake throughout pregnancy is essential to ensure healthy fetal development. Insufficient and excessive maternal dietary protein intakes are both associated with intrauterine growth restriction, resulting in low birth weight infants. The aim of this study was to analyze the dietary protein intake patterns of healthy pregnant women in Vancouver, British Columbia, during early and late gestation. We hypothesized that women would be consuming higher protein during late stages of pregnancy compared with early stages of pregnancy. Interviewer-administered food frequency questionnaires were collected prospectively from 270 women at 16- and 36-week gestation; food frequency questionnaires from 212 women met study criteria. Maternal anthropometrics at both stages and infant weight at birth were collected. Wilcoxon signed rank tests were used to determine significant gestational differences in protein intakes. Spearman correlation was used to determine the influence of protein intakes and maternal anthropometrics on pregnancy outcomes. Median (25th and 75th percentiles) protein intakes adjusted for body weight were 1.5 (1.18 and 1.79) and 1.3 (1.04 and 1.60) g/kg per day at 16- than 36-week gestation, respectively. Primary protein sources were identified as dairy products. Protein intakes were negatively correlated with birth weight (P < .05), whereas maternal height, weight, body mass index, and weight gain to 36-week gestation were positively correlated with birth weight (P < .05). This study provides current dietary protein intake patterns among healthy Canadian women during pregnancy and indicates higher intakes than current Dietary Reference Intakes recommended dietary allowance of 1.1 g/kg per day, especially during early gestation.     

Exposure assessment of phthalate esters in Japanese pregnant women by using urinary metabolite analysis

Objectives  Our objectives were (1) to evaluate whether single spot urine is suitable media for longer-term phthalate esters exposure assessment, and (2) to estimate intake level of phthalate esters of Japanese pregnant women using urinary metabolites as an indicator of prenatal exposure level in their offspring. Methods  We analyzed nine metabolites (MMP, MEP, MnBP, MBzP, MEHP, MEOHP, MEHHP, MINP, MnOP) of seven phthalate esters in spot urine samples from 50 pregnant women by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Using four urine samples collected from each of 12 subjects from 50 pregnant women within 5–12 weeks, we compared intra- and interindividual variation in urinary metabolites by calculation of intraclass correlation coefficient (ICC). We estimated daily intakes of 50 pregnant women from their urinary metabolite concentrations. Results  ICCs for seven phthalate metabolite concentrations in single spot urine samples were: MMP (0.57), MEP (0.47), MnBP (0.69), MBzP (0.28), MEHP (0.51), MEHHP (0.43), and MEOHP (0.41) in 12 pregnant women. Phthalate ester metabolites had high detection rates in 50 subjects. The mean daily intake ranged from 0.01 to 2 μg/kg per day. The daily intake levels in all subjects were lower than corresponding tolerable daily intake (TDI) set by the European Food Safety Authority (EFSA), though maximum value for DnBP of 6.91 μg/kg per day accounted for 70% of TDI value. Conclusions  Higher ICCs indicated that phthalate metabolite levels in single spot urine could reflect longer-term exposure to the corresponding diesters of subjects. Although the current exposure level was less than TDIs, further studies and exposure monitoring are needed to reveal the toxicity of phthalate esters to sensitive subpopulation.     

A lowered salt intake does not compromise iodine status in Cape Town,South Africa,where salt iodization is mandatory

ObjectiveUniversal salt iodization is an effective strategy to optimize population-level iodine. At the same time as salt-lowering initiatives are encouraged globally, there is concern about compromised iodine intakes. This study investigated whether salt intakes at recommended levels resulted in a suboptimal iodine status in a country where salt is the vehicle for iodine fortification.MethodsThree 24-h urine samples were collected for the assessment of urinary sodium and one sample was taken for urinary iodine concentrations (UICs) in a convenience sample of 262 adult men and women in Cape Town, South Africa. Median UIC was compared across categories of sodium excretion equivalent to salt intakes lower than 5, 5 to 9, and greater than or equal to 9 g/d.ResultsThe median UIC was 120 μg/L (interquartile range 75.3–196.3), indicating iodine sufficiency. Less one-fourth (23.2%) of subjects had urinary sodium excretion values within the desirable range (salt <5 g/d), 50.7% had high values (5–9 g/d), and 22.8% had very high values (≥9 g/d). No association between urinary iodine and mean 3 × 24-h urinary sodium concentration was found (r = 0.087, P = 0.198) and UIC status did not differ according to urinary sodium categories (P = 0.804).ConclusionIn a country with mandatory universal salt iodization, consumers with salt intakes within the recommended range (<5 g/d) are iodine replete, and median UIC does not differ across categories of salt intake. This indicates that much of the dietary salt is provided from non-iodinated sources, presumably added to processed foods.     

Dietary salt intake increases with age in Japanese adults

Excess salt intake is linked to cardiovascular disease as well as hypertension, but whether individual salt intake increases with age has not been studied. The present study was designed to test the hypothesis that individual salt intake increases with age in Japanese adults. In this retrospective observational follow-up study, men and women age ≥30 years who participated in a baseline health checkup (2008–2009) at our center and had a health checkup 10 years later (n = 2598) were enrolled and salt intake was estimated by spot urine analysis. Yearly changes in salt intake were also assessed in participants with complete annual data over the course of 10 years from baseline (n = 1543). The follow-up study demonstrated increased salt intake (8.8 ± 2.0 to 9.3 ± 2.1 g/d, P < .001) with increasing age (54.0 ± 9.7 to 64.0 ± 9.8 years). Salt intake increased year over year in participants who had a health checkup annually for the 10-year follow-up period (n = 1543; analysis of variance, P < .001). Cross-sectional analyses using propensity-matched model revealed similar regional levels of salt intake in the baseline period (8.9 ± 2.0 g/d, 55.8 ± 11.4 years, n = 5018) and at 10 years (8.8 ± 2.0 g/d, P = .21; 55.9 ± 13.0 years, P = .65, n = 5105). These results suggest that dietary salt intake increases with age in Japanese adults, which should be considered in devising population-based strategies to lower dietary salt intake.     

Effect of protein intake level on urinary energy/nitrogen ratio in Japanese

Urinary energy/nitrogen ratios were determined in 179 female and 14 male subjects given protein from various sources and at various intake levels. The ratio decreased with increasing protein intake from zero to 1 g/kg/day but was constant when protein intake was between 1 to 1.8 g/kg/day. The ratio was not affected by the variety of protein source. There was no difference between the data for semisynthetic diet and conventional diet. Mean values and standard deviations of the ratio in men and women given the diet containing 1.0 to 1.8 g protein/kg/day were 9.06 +/- 0.56 (n = 14) and 8.19 +/- 0.81 (n = 37) kcal/kg N, respectively. The difference between two figures in men and women was significant (p less than 0.05). The mean values of urinary E/N ratio actually measured did not approach those of urea (5.34 kcal/g N), the principal nitrogenous compound in urine, the proportion of which increased at higher protein intake level. Characteristically high ratios were obtained in the ma-konbu (Laminaria japonica) and enokitake (Flammulina velutipes) diet groups. The results suggest that urinary energy originates not only from nitrogen-containing compounds but also from other organic compounds containing no nitrogen. Therefore, further investigation is necessary to evaluate the urinary E/N ratio applicable to the urinary loss of incompletely oxidized nitrogenous compounds.     

A randomised controlled trial to investigate the effect of a high fibre diet on blood pressure and plasma fibrinogen.

Two hundred and one subjects (147 men and 54 women) were randomly allocated to either a high cereal fibre diet or a low cereal fibre diet for four weeks. Each group then followed the alternative diet for a further four weeks. Cereal fibre intakes were 19g/d (31 g/d 21 g/d total fibre) and 6g/d (19g/d total fibre) on the high and low fibre diets respectively (p less than 0.001). Energy, protein, fat, carbohydrate, and alcohol intakes calculated from weighed intake records did not differ between the two diets, although there was a slight difference in body weight, the mean being 0.3 kg heavier at the end of the high fibre period. The high cereal fibre diet had no detectable effect on blood pressure or plasma fibrinogen.