Dietary carnitine effects on carnitine concentrations in urine and milk in lactating women

The effect of dietary carnitine on urinary excretion of free and total carnitine and on breast-milk secretion of the carnitine fractions in 15 control and 16 lactating women aged 21-40 y was measured. Free and total carnitine excretions, obtained from 24-h urine collections, correlated with carnitine consumed on the collection day (P less than 0.03, P less than 0.01, respectively) but not with the mean intake calculated from 3-d diet records. The immediate responses of the control and lactating groups were not significantly different. Urinary excretion of carnitine (n = 31) was 82 +/- 13 mumol/d for free excretion and 226 +/- 22 mumol/d for total excretion. Milk free, acid-soluble acyl-, acid-insoluble acyl-, or total carnitine did not correlate with dietary carnitine or with the duration of lactation (1-10 mo). Milk total carnitine was 45 +/- 3 mumol/L. With the carnitine content of breast milk remaining stable for greater than or equal to 10 mo, the importance of exogenous carnitine throughout infancy is suggested.     

Dietary carnitine intake and carnitine status in endurance-trained males

Background: Carnitine is an integral component of fatty acid transfer into the mitochondria, and also buffers excess intramitochondrial acyl‐CoA. It has previously been suggested that athletes may be at risk of low carnitine status and could therefore benefit from carnitine supplementation. Objective: To report the habitual dietary carnitine intakes of endurance‐trained adult males, and to determine whether they are at risk of carnitine insufficiency by measuring plasma and urinary carnitine concentrations. Methods: Fourteen non‐vegetarian endurance‐trained males completed a seven‐day weighed food record and exercise logs to determine habitual dietary carnitine intake. Resting venous blood samples and 24‐hour urine collections were used to determine plasma carnitine concentration and urinary carnitine excretion. Results: The mean dietary carnitine intake was 64 (range 21–110) mg/day. Mean ± SD resting plasma total carnitine was 44 ± 7 µmol/L and acyl : free carnitine ratio was 0.28 ± 0.11, which were within normal ranges. Urinary carnitine excretion was 437 ± 236 µmol/day. There was no correlation between dietary carnitine intake or dietary macro‐ and micronutrients and plasma carnitine or urinary carnitine excretion. Conclusion: The results of the present study indicate there is no evidence that endurance‐trained males consuming a mixed diet are at risk of carnitine insufficiency.     

Dietary intake related to prevalent functional limitations in midlife women

Physical functioning measures are considered integrated markers of the aging process. This prospective investigation examined relations between dietary intake of women at midlife in 1996-1997 and prevalence of physical functioning limitations 4 years later, defined by the Medical Outcomes Study Short-Form 36. The sample included 2,160 multiethnic women, aged 42-52 years, from six geographic areas participating in the Study of Women's Health Across the Nation (SWAN). Associations between measures of diet quality and number of fruit and vegetable servings and prevalent physical functional limitations (no, moderate, or substantial limitations) were tested by logistic regression. The prevalence of moderate and substantial functional limitations was 31% and 10%, respectively. Women in the highest quartile of cholesterol intake had 40% greater odds (odds ratio = 1.4, 95% confidence interval: 1.1, 1.8) of being more limited versus those in the lowest quartile. Women in the highest quartile of fat and saturated fat intakes were 50% and 60% more likely to be more limited, with respective odds ratios of 1.5 and 1.6 (95% confidence intervals: 1.2, 2.0 and 1.2, 2.1) versus those in the lowest quartiles. Lower fruit, vegetable, and fiber intakes were related to reporting greater functional limitations. Modifying dietary practices could be important in minimizing physical limitations.     

Relation of plasma leptin concentrations to sex, body fat, dietary intake, and peak oxygen uptake in young adult women and men

The purpose of this study was to examine the relation of leptin to metabolic and dietary factors in college-age adults. Young adult women and men (n = 32) were recruited and underwent testing for measurement of body mass index, body composition, peak oxygen consumption (VO2peak), dietary intake, and plasma levels of leptin and insulin. Ln leptin was significantly greater for women than for men (2.1 versus 1.2 ng/mL, respectively). This difference remained significant even after adjusting ln leptin for fat mass and fat-free mass as covariates in separate analyses. VO2peak was higher for men than for women and this remained significant after adjustment for differences in fat-free mass and total body mass. Significant correlations were found between ln leptin and indicators of fat mass in women and men, with higher correlations for similar variables observed in men (r = 0.548, 0.674, and 0.732 for body mass index, percentage of body fat, and fat mass [kg] for women, respectively, and r = 0.740, 0.888, 0.858 for body mass index, percentage of body fat, and fat mass [kg] for men, respectively). Ln leptin showed a significant inverse relationship with VO2peak (r = -0.751) in men only. After adjusting ln leptin for body fat mass using partial correlations, ln leptin was not significantly associated with any of the measured variables. Alternatively, after normalization of ln leptin using fat mass as the divisor, a less adequate statistical analysis method, men showed statistical significant correlations between ln leptin and dietary intake and VO2peak. Although plasma leptin values were higher in women, stronger associations were evident for men than for women between leptin and metabolic and dietary factors.     

Trans-fatty acid intake in relation to serum lipid concentrations in adult men.

The relation of trans-fatty acid intake to fasting serum lipid concentrations was evaluated in a cross-sectional study of 748 men aged 43-85 y. Multiple-linear-regression analysis was used to adjust for age, body mass index, waist-to-hip circumference ratio, smoking status, physical activity, alcohol intake, total energy, dietary cholesterol and linoleic acid, and previous serum cholesterol concentration. Trans-fatty acid intake was directly related to total serum (r = 0.07, P = 0.04) and low-density-lipoprotein cholesterol (LDL) (r = 0.09, P = 0.01), and inversely related to high-density-lipoprotein (HDL) cholesterol (r = 0.08, P = 0.03). Trans-fatty acid intake was positively associated with the ratios of total to HDL cholesterol (r = 0.11, P = 0.002) and LDL to HDL cholesterol (r = 0.12, P = 0.001). The estimated ratios of total to HDL cholesterol were 4.4 and 4.9 for persons at the 10th (2.1 g/d) and 90th (4.9 g/d) percentiles of trans-fatty acid intake, respectively. On the basis of results from other studies, these ratios would correspond to a 27% increase in risk of myocardial infarction.     

Dietary mono- and polyunsaturated fatty acids similarly increase plasma apolipoprotein A-IV concentrations in healthy men and women

We investigated the effect of dietary fatty acid composition on plasma apolipoprotein (apo) A-IV concentrations. Plasma apo A-IV concentrations were measured by ELISA in plasma of 48 healthy men and women in a controlled dietary study. First, all participants consumed a 2-wk baseline diet rich in saturated fatty acids (SFA). Then, they were randomly assigned to one of three dietary treatments, which contained refined olive oil [rich in monounsaturated fatty acids (MUFA), n = 17], rapeseed oil [rich in MUFA and alpha-linolenic acid [18:3(n-3)], n = 13], or sunflower oil [rich in (n-6) PUFA, n = 18] as the principal source of fat for 4 wk. The plasma concentrations of apo A-IV increased when subjects consumed the diets rich in unsaturated fatty acids, by 16% or 13.0 mg/L [F((2,76)) = 12.874, P < 0.001 by repeated-measures ANOVA]. The increase was not affected by diet group affiliation, gender or apo A-IV genotype. In conclusion, diets rich in unsaturated fatty acids, independent of the degree of unsaturation, gender and apo A-IV genotype, increase plasma apo A-IV concentrations compared with a baseline diet rich in SFA in healthy men and women.     

Marginal protein intake results in reduced plasma IGF-I levels and skeletal muscle fiber atrophy in elderly women

We investigated the effects of dietary protein on plasma IGF-I levels and muscle fiber cross-sectional area (CSA). Twelve healthy elderly women were randomly assigned to a weight-maintaining diet containing either 1.47 (marginal) or 2.94 (adequate) g protein/kg body cell mass (BCM)/d, (0.45 and 0.92 g/kg body weight/d, respectively) for 10wks. Plasma IGF-I levels and muscle fiber areas and distributions were evaluated at baseline and 10wks. After 10wks, both IGF-I and type I fiber CSA had declined significantly in subjects fed the marginal diet (30.1+/-2.1% and 32.7+/-7.9%, respectively) while they increased in those fed the adequate diet (19.5+/-7.0% and 22.3+/-7.5%, for IGF-I and type I CSA, respectively). The change in IGF-I was the only significantly associated with the change in type I fiber CSA (r2=0.70; p<0.03). These findings show that marginal dietary protein intakes will result in losses of muscle mass in the elderly and suggest a role for plasma IGF-I as a biochemical marker for the histological changes in skeletal muscle.     

Dietary fish intake and plasma phospholipid n-3 polyunsaturated fatty acid concentrations in men and women in the European Prospective Investigation into Cancer-Norfolk United Kingdom cohort

BACKGROUND: The n-3 polyunsaturated fatty acids (n-3 PUFAs) docosahexaenoic acid and eicosapentaenoic acid, found in fish and fish-oil supplements and also formed by conversion of alpha-linolenic acid in soy and rapeseed (canola) oils, are thought to have cardioprotective effects. OBJECTIVE: Because the relative feasibility and measurement error of dietary methods varies, this study compared fish and fish-oil intakes obtained from 4 dietary methods with plasma n-3 PUFAs in men and women in a general population. DESIGN: The study participants were 4949 men and women aged 40-79 y from the European Prospective Investigation into Cancer-Norfolk United Kingdom cohort. Measurements of plasma phospholipid n-3 PUFA concentrations and fish intakes were made with the use of 4 dietary methods (food-frequency questionnaire, health and lifestyle questionnaire, 7-d diary, and first-day recall from the 7-d diary). RESULTS: Amounts of fish consumed and relations with plasma phospholipid n-3 PUFAs were not substantially different between the 4 dietary methods. Plasma n-3 PUFA concentrations were significantly higher in women than in men, were 20% higher in fish-oil consumers than in non-fish-oil consumers, and were twice as high in fatty fish consumers as in total fish consumers. Only approximately 25% of the variation in plasma n-3 PUFA was explained by fish and fish-oil consumption. CONCLUSIONS: This large study found no substantial differences between dietary methods and observed clear sex differences in plasma n-3 PUFAs. Because variation in n-3 PUFA was only partially determined by fish and fish-oil consumption, this could explain the inconsistent results of observational and intervention studies on coronary artery disease protection.     

Dietary sucrose intake is related to serum leptin concentration in overweight pregnant women

Background  

Overweight, characterized by low-degree systemic inflammation, predisposes women to impaired glucose metabolism during pregnancy. Adipokine leptin participates in the regulation of energy balance and immune action.     

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%).     

Soy intake is related to a lower body mass index in adult women

BACKGROUND: Experimental and epidemiologic studies suggest that soy may promote weight loss. AIM OF THE STUDY: The goal of this study was to examine the relation of soy intake with body weight over the lifespan of women with Caucasian, Japanese, and Native Hawaiian ancestry. METHODS: We assessed the relation between lifetime soy consumption and body mass index (BMI) among 1,418 women in Hawaii. All subjects reported anthropometric measures, regular diet, and soy intake throughout life. The lifetime soy questionnaire was completed again by a subset of 356 women 5 years after study entry and the kappa values indicated moderate agreement. We regressed soy intake on BMI at study entry and at age 21 while controlling for confounding variables, computed least square means, and performed trend tests. RESULTS: Higher soy consumption in adulthood was related to a lower BMI (P=0.02). This association was only significant for Caucasian women and for postmenopausal subjects. The women in the highest category also experienced a smaller annual weight change since age 21 (by 0.05 kg/year) than the low soy intake group (P=0.02). We observed no association between early life soy intake and BMI. High vegetable consumption was significantly associated with a higher soy intake among Caucasian women. CONCLUSIONS: In this study, women consuming more soy during adulthood had a lower BMI, but the relation was primarily observed for Caucasian and postmenopausal subjects. This indicates that the association may be due to other nutritional factors and behaviors common in women with high soy intake.     

Dietary protein intake and subsequent falls in older men and women: The Framingham study

Background  

Poor nutritional status is often present among older adults who experience a fall. However, dietary intake and weight loss are often overlooked as potential factors. The objective of this study was to test the association between dietary protein intake and risk of subsequent falls in a population-based cohort of elderly men and women.     

Vitamin A intake and plasma retinol levels in healthy elderly men and women

We examined intakes of vitamin A (diet plus supplement) and plasma retinol levels in a select group of elderly men (n = 90) and women (n = 110) on three separate occasions over a 4-y period. Median dietary levels remained at approximately 1400 retinol equivalents (RE) in men and 1250 RE in women. There were no time trends or gender differences noted in plasma retinol concentrations. Approximately 44% of the elderly men and women consumed an average of 2000 RE of a vitamin A supplement daily. Those taking supplement had a greater mean plasma retinol concentration than those not taking a supplement. This effect was greater in men than in women. A review of previous studies revealed that plasma retinol increases from a mean of approximately 35 micrograms/dL (1.22 mumol/L) at preschool age to a plateau of approximately 60 micrograms/dL (2.09 mumol/L) by age 40 y in men and 60 y in women.     

Dietary silicon intake in post-menopausal women

Si has been suggested as an essential element, and may be important in optimal bone, skin and cardiovascular health. However, there are few estimates of dietary Si intakes in man, especially in a UK population. Following the development of a UK food composition database for Si, the aim of the present study was to investigate dietary intakes of Si amongst healthy women aged over 60 years and to identify important food sources of Si in their diet. Healthy, post-menopausal female subjects (>60 years of age; n 209) were recruited from the general population around Dundee, Scotland as part of an unrelated randomised controlled intervention study where dietary intake was assessed using a self-administered, semi-quantitative food-frequency questionnaire at five time-points over a 2-year period. Food composition data on the Si content of UK foods was used to determine the Si content of food items on the food-frequency questionnaire. Mean Si intake was 18.6 (sd 4.6) mg and did not vary significantly across the 2 years of investigation. Cereals provided the greatest amount of Si in the diet (about 30 %), followed by fruit, beverages (hot, cold and alcoholic beverages combined) and vegetables; together these foods provided over 75 % about Si intake. Si intakes in the UK appear consistent with those reported previously for elderly women in Western populations, but lower than those reported for younger women or for men.     

Dietary monoglutamate and polyglutamate folate are associated with plasma folate concentrations in Dutch men and women aged 20-65 years

Dietary folate consists of monoglutamate and polyglutamate folate species. In the small intestine, folate polyglutamate is deconjugated to the monoglutamate form before absorption takes place. This enzymatic deconjugation might limit the bioavailability of polyglutamate folate. Until now, no data have been available on dietary intake of both folate forms and their associations with folate status. Therefore, we estimated the intake of monoglutamate and polyglutamate folate in the Dutch population and studied whether the association with plasma folate is different for these two folate forms. Dietary intake of monoglutamate and polyglutamate folate from nonfortified foods was estimated for 2435 subjects (1275 men; 1160 women) aged 20-65 y. The intake of monoglutamate folate was about one third of total folate intake, derived mainly from bread (approximately 20%) and meat (approximately 18%), whereas two thirds consisted of polyglutamates, derived mainly from vegetables (approximately 25%). The predictive power of the regression model with total folate intake as the independent variable adjusted for age, smoking and alcohol intake, did not increase when including the ratio of monoglutamate to polyglutamate folate intake. In addition, linear regression models showed that both monoglutamate and polyglutamate folate intake were associated positively with plasma folate levels. However, in men, the monoglutamate folate form appeared to be a threefold stronger determinant of plasma folate levels than polyglutamate folate, whereas in women, both folate forms were equally strong determinants. This might be explained by different food intake patterns of men and women, including alcohol intake. At present, it does not seem necessary to distinguish between food folate forms in advising an increase in folate intake from nonfortified foods.     

Dietary selenium intake and selenium concentrations of plasma, erythrocytes, and breast milk in pregnant and postpartum lactating and nonlactating women

The selenium status of a group of 23 lactating and 13 nonlactating women was assessed from 37-wk gestation through 6-mo postpartum. The mean overall dietary Se intake of both groups of women was 80 +/- 37 micrograms/d. Plasma and erythrocyte Se levels were lower in the lactating than in the nonlactating mothers both before and after parturition. Breast-milk Se concentrations fell from 20 micrograms/L (0.25 mumol/L) at 1-mo postpartum to 15 micrograms/L (0.19 mumol/L) at 3- and 6-mo postpartum. A weak (r = 0.38) but statistically significant (p less than 0.025) relationship was observed between maternal plasma Se level and breast-milk Se concentration. The dietary Se intake of these lactating North American women appears sufficient to maintain satisfactory Se nutriture in their breast-fed infants during the first 6 mo of lactation.     

Hypo- and hyperresponse to egg cholesterol predicts plasma lutein and beta-carotene concentrations in men and women

The purpose of this study was to determine whether the plasma response to dietary cholesterol from eggs is associated with the plasma carotenoid response and whether gender influences the carotenoid response. Using a crossover design, 40 subjects classified as either hyper- (10 men and 10 women) or hyporesponders (10 men and 10 women) to dietary cholesterol consumed an egg (EGG, 640 mg/d additional dietary cholesterol and 600 microg lutein + zeaxanthin) or placebo (SUB, 0 mg/d cholesterol, 0 microg lutein + zeaxanthin and 568 microg beta-carotene) diet for 30 d, followed by a 3-wk washout period and the alternate diet. Plasma concentrations of lutein and beta-carotene after each dietary period were then examined to determine whether the response to carotenoid intake was similar to that seen for dietary cholesterol. After the EGG period, the increase in plasma lutein in female hyperresponders (mean increase +/- SD; 0.32 +/- 0.19 micromol/L) and male hyperresponders (0.26 +/- 0.11 micromol/L) was significantly greater than that of their hyporesponsive counterparts (0.16 +/- 0.18 micromol/L for women and 0.14 +/- 0.11 micromol/L men). Gender was not a significant factor influencing lutein response. Both men and women classified as hyperresponders significantly increased plasma beta-carotene after the SUB period, whereas their hyporesponsive counterparts were not affected. The increase in plasma beta-carotene in female hyperresponders (0.29 +/- 0.48 micromol/L) was significantly greater than that in male hyperresponders (0.07 +/- 0.07 micromol/L). We conclude that plasma responses to cholesterol and carotenoids are related and that gender influences the beta-carotene response to a greater degree than the lutein response.