High-performance liquid chromatographic determination of tocopherols and tocotrienols and its application to diets and plasma of Finnish men. II. Applications

The composed one-day diets and plasma of 40 Finnish men screened for a selenium supplementation study were analyzed for tocopherols and tocotrienols. The men were divided into a low-Se group (in the screening phase plasma Se levels less than 70 micrograms/l and plasma alpha-tocopherol levels less than 1.2 mg/100 ml) and a high-Se group (plasma Se greater than 70 micrograms/l, plasma alpha-tocopherol not determined before the study). In the low-Se group plasma levels of alpha-tocopherol averaged 0.97 +/- 0.18 mg/100 ml. The daily dietary intake of alpha-tocopherol was 6.1 +/- 2.7 mg and that of total vitamin E 7.3 +/- 3.1 mg of alpha-tocopherol equivalents. In the high-Se group the corresponding average values were 1.16 +/- 0.21 mg of alpha-tocopherol/100 ml of plasma, 8.8 +/- 4.3 mg of alpha-tocopherol/day and 10.3 +/- 5.1 mg of alpha-tocopherol equivalents/day. The overall average for the contribution of alpha-tocopherol to the total dietary tocopherols was 44.6 +/- 11.0%. In the plasma samples alpha-tocopherol accounted for 92.0 +/- 2.1%, beta-tocopherol for 2.7 +/- 0.7% and gamma-tocopherol for 5.3 +/- 2.1% of the total amount of tocopherols.     

The tocopherol, tocotrienol, and vitamin E content of the average Finnish diet.

The Finns average intake of tocopherols, tocotrienols, and vitamin E (alpha-tocopherol equivalents) was determined. The food consumption data were derived mainly from the national food balance sheets (for 1987). The average Finnish daily diet was composed and analyzed both in spring and in autumn in order to minimize the effect of seasonal variation. The four tocopherols and four tocotrienols were then determined using high-performance liquid chromatography (HPLC). For comparison, the intake of vitamin E compounds was also calculated using the most recent Finnish analytical data on tocopherols and tocotrienols in food. According to the analytical results, the average daily vitamin E intake in Finland was 10.7 mg alpha-tocopherol equivalents (alpha-TE) of which amount 85% is due to alpha-tocopherol. The analyzed values (10.8 mg alpha-TE in spring and 10.7 mg alpha-TE in autumn) of vitamin E intake did not markedly differ from the calculated value (10.3 mg alpha-TE), thus indicating that the Finnish food composition data upon tocopherols and tocotrienols is up-to-date and accurate. The best food sources of vitamin E were dietary fat (41% of the total amount), cereals (18%), and dairy products and eggs (13%). The average Finnish diet contained 9.5 g of polyunsaturated fatty acids (PUFA), which leads to the ratio of 0.9 between alpha-tocopherol (mg) and PUFA (g). According to these results, the dietary recommendations for vitamin E are met in Finland.     

Impact of diets with corn oil or olive/sunflower oils on DNA damage in healthy young men

BACKGROUND: Plant fats and oils are major sources of mono- and polyunsaturated fatty acids as well as vitamin E, the major fat-soluble antioxidants in human nutrition. Dietary antioxidants are expected to reduce cancer risk by minimizing DNA damage. AIM OF THE STUDY: To compare the effects of gamma-tocopherol rich corn oil and the mixture of the alpha-tocopherol rich olive/sunflower oil on plasma concentration of tocopherols and on the frequency of sister chromatid exchange (SCE), an indicator of DNA damage. METHODS: This study had a double-blind, cross-over design and was conducted in 20 normal healthy non-smoking males aged 19-31 years. Design included a 2-week adjustment period and two 2-week test periods in which diets containing 30% energy as fat including either 80 g of corn oil (CO) (20 mg alpha-tocopherol, 100 mg gamma-tocopherol) or 80 g of olive/ sunflower oil (OSO) (24 mg alpha-tocopherol, 2.4 mg gamma-tocopherol), as the main fat-source, were given. Blood samples for analysis of SCE rate and content of tocopherols were collected at the beginning (T0), after adjustment (T1) and after the test period (T2) in intervals of 2 weeks. RESULTS: After two weeks of the corn oil diet, the plasma concentration of gamma-tocopherol increased but alpha-tocopherol decreased significantly compared to the olive/sunflower oil diet. The concentration of alpha-tocopherol increased (CO: 22.99 +/- 1.11 vs. OSO: 24.40 +/- 1.49 micromol/l) and that of gamma-tocopherol decreased (CO: 4.19 +/- 0.29 vs. OSO: 2.99 +/- 0.25 micromol/l) after the olive/sunflower oil diet. Intake of the corn oil diet was associated with reduced SCE rate and intensity, whereas there was no change in SCE after the olive/sunflower oil diet (CO: 7.66 +/- 0.25 vs. OSO: 8.06 +/- 0.47 mean SCE/cell) CONCLUSIONS: The combination of gamma-tocopherol with alpha-tocopherol in corn oil diet despite the lower alpha-tocopherol equivalents/diene acid equivalents ratio achieved better protection against DNA damage than alpha-tocopherol alone in the olive/sunflower oil diet.     

Vitamin D, 25-hydroxy-vitamin D and 1,25-dihydroxy-vitamin D in cow's milk, infant formulas and breast milk during different stages of lactation

Vitamin D and its metabolites were determined in cow's milk, infant formulas, and colostrum, transitional and mature breast milk by specific protein-binding assays following HPLC (high-pressure liquid chromatography). Cow's milk contains (mean +/- SEM) 50.4 +/- 4.1 pg/ml vitamin D (n = 10), 499 +/- 47 pg/ml 25-OH D (n = 10) and 9.7 +/- 1.0 pg/ml 1,25 (OH)2D (n = 3). 86.6% of the added vitamin D3 was recovered from infant formulas. The mean content (mean +/- SEM) of 25-OH D and 1,25(OH)2D of infant formulas are 299 +/- 35 pg/ml and 5.4 +/- 0.9 pg/ml (n = 9), respectively. Vitamin D concentration of colostrum and mature breast milk is 122 +/- 3.4 pg/ml (n = 7, mean +/- SEM) and 38 +/- 3.3 pg/ml (n = 9) respectively; the 25-OH D content increases from 294 +/- 50.6 pg/ml (n = 10) to 845 +/- 190 pg/ml (n = 14) during lactation. The increase of 1,25-(OH)2D from early to mature breast milk (3.2 +/- 0.6 pg/ml, n = 8 versus 5.3 +/- 0.7 pg/ml, n = 20) is still statistically significant.     

Vitamin E status of Congolese children in a rural area

The role of vitamin E in severe malnutrition is controversially discussed. In order to evaluate the vitamin E status of unselected African children the plasma tocopherol levels of 52 children from a village in the People's Republic of Congo were assessed by HPLC and related to the plasma lipid values. Although plasma concentrations of total tocopherols (mean 351.1 +/- 59.4 micrograms/dl) and alpha-tocopherol (mean 313.3 +/- 57.0 micrograms/dl) were found to be low, normal ratios of total tocopherols to total lipids (mean 0.99 +/- 0.17 mg/g) and alpha-tocopherol to total lipids (mean 0.89 +/- 0.09 mg/g) were estimated. It is concluded that plasma vitamin E levels should be related to plasma lipids if populations are monitored in which low lipid concentrations have to be expected. These data on Congolese children may be used for comparison if the vitamin E status in other agrogeographical areas of Africa or in clinically abnormal groups is investigated.     

Retinol, carotenoids, and tocopherols in the milk of lactating adolescents and relationships with plasma concentrations

OBJECTIVE: We determined the concentrations of retinol, carotenoids, and tocopherols in breast milk of adolescents and evaluated their associations with plasma levels and with maternal characteristics (period of lactation, body mass index, age of menarche, and years postmenarche). METHODS: This was a single cross-sectional survey of retinol, carotenoid, and tocopherol composition of milk and plasma of lactating adolescent mothers (n = 72; 30-120 d postpartum) attending public daycare clinics in Rio de Janeiro, Brazil. Milk and plasma components were analyzed by high-performance liquid chromatography. RESULTS: Nutrient concentrations (micromoles per liter, mean +/- SE) in plasma and milk were, respectively, retinol 2.1 +/- 0.5 and 0.62 +/- 0.44, beta-carotene 0.18 +/- 0.19 and 0.016 +/- 0.017, alpha-carotene 0.05 +/- 0.04 and 0.0035 +/- 0.002, lutein plus zeaxanthin 0.15 +/- 0.11 and 0.025 +/- 0.024, lycopene 0.1 +/- 0.11 and 0.016 +/- 0.025, alpha-tocopherol 10.8 +/- 5.3 and 2.7 +/- 1.8, gamma-tocopherol 2.6 +/- 2.3 and 0.37 +/- 0.15. The milk/plasma molar ratios of retinol and tocopherols were two times higher than those of carotenoids. Significant correlations (P < 0.001) between milk and plasma nutrient levels were observed for beta-carotene (r = 0.41), alpha-carotene (r = 0.60), and lutein plus zeaxanthin (r = 0.57), but not for lycopene, retinol, and tocopherols. Nutrient concentrations in plasma and in milk were not associated with the maternal characteristics investigated. CONCLUSION: Concentrations of the nutrients studied, especially retinol and alpha-tocopherol, in mature milk of lactating adolescents were, in general, lower than in milk of adult lactating women. Milk concentrations were associated with plasma concentrations only for beta-carotene, alpha-carotene, and lutein plus zeaxanthin.     

Fat-soluble and water-soluble vitamin contents of breast milk from Japanese women

To determine the concentrations of fat-soluble and water-soluble vitamins in the maternal milk of Japanese women, we collected human milk samples from more than 4,000 mothers living throughout Japan between December 1998 and September 1999, and defined as group A the 691 samples among these that met the following conditions: breast milk of mothers who were under 40 y of age, who did not smoke habitually and/or use vitamin supplements, and whose babies showed no symptoms of atopy and had birth weights of 2.5 kg or more. We then analyzed the contents of vitamins individually. Large differences were observed among the contents of individual human milk samples. The mean contents of each component were as follows: vitamin A, 159.0 +/- 95.2 IU/100 mL; vitamin E, 0.325 +/- 0.165 alpha-TE mg/100mL; vitamin D3 (cholecalciferol), 8.0 +/- 10.7 ng/100mL; vitamin B1 (thiamin), 12.3 +/- 3.2 microg/100 mL; vitamin B2, 38.4 +/- 12.7 microg/100 mL; vitamin B6, 5.7 +/- 2.5 microg/100 mL; vitamin B12, 0.04 +/- 0.02 microg/100 mL; vitamin C, 5.1 +/- 1.9 mg/100 mL; biotin, 0.50 +/- 0.23 microg/100 mL; choline, 9.2 +/- 1.8 mg/100 mL; folic acid, 6.2 +/- 2.9 microg/100 mL; inositol, 12.6 +/- 3.6 mg/100 mL; niacin (nicotinamide), 32.9 +/- 20.4 microg/100 mL and pantothenic acid, 0.27 +/- 0.09 mg/100 mL. The concentrations of derivatives and/or related compounds of vitamin A (retinol, beta-carotene), vitamin E (alpha-, beta-, gamma-, and delta-tocopherol), and B2 (riboflavin, FMN, and FAD) were determined separately. The contents of each were found to vary greatly as the duration of lactation increased. The present results indicate that it is necessary to evaluate individual differences in human milk in order to perform valid research regarding infant formula.     

Anti-schistosomal activity of colostral and mature camel milk on Schistosoma mansoni infected mice

The aim of the present study was to investigate the anti-schistosomal activity of colostral and mature camel milk on Schistosoma mansoni infected mice. Six weeks post infection, mean percentage of protection was detected through the hepatic portal vein. Glutathione-s-transferase (GST), alanine, aspartate transaminase (ALT and AST) and immunoglobulin G (IgG) levels were detected in sera of treated mice before and after infection. Antischistosomal activity of colostral and mature camel milk on Schistosoma mansoni infected mice were 12.81% and 31.60% respectively. The results showed that GST levels in sera of mice fed on colostral and mature camel milk were increased with mean values of 0.070, 0.108, 0.128 and 0.120 in colostral milk groups and 0. 072, 0.085, 0.166 and 0.20 in mature camel milk groups compared with the mice fed on basal diet with means values of 0.070, 0.085, 0.078 and 0.069 before infection and after two, four and six weeks of infection, respectively. On the other hand, there were slight differences on ALT and AST activities. Mice treated with colostral and mature milk (200 microl/day) showed an immunostimulatory effect by inducing IgG titers against soluble worm antigen preparation (SWAP) compared with control. Nevertheless, the difference was not considered significant (0.31 +/- 0.1) for colostrum (0.34 +/- 0.1) and for mature milk, as compared to normal control (0.2 +/- 0.04). Two, four and six weeks post infection, IgG level showed no significant change in sera from mice treated with colostral and mature milk as compared to control. In conclusion, colostral and mature camel milk showed an immuno-modualatory effect in normal healthy mice by inducing IgG and GST levels before and after infection with Schistosoma mansoni. Colostral and mature camel milk have a protective response against schistosomiasis.     

Relation of the tocopherol forms to incident Alzheimer disease and to cognitive change

BACKGROUND: High intake of vitamin E from food (tocopherol), but not from supplements (which usually contain alpha-tocopherol), is inversely associated with Alzheimer disease. OBJECTIVE: We examined whether food intakes of vitamin E, alpha-tocopherol equivalents (a measure of the relative biologic activity of tocopherols and tocotrienols), or individual tocopherols would protect against incident Alzheimer disease and cognitive decline over 6 y in participants of the Chicago Health and Aging Project. DESIGN: The 1993-2002 study of community residents aged >or=65 y included the administration of 4 cognitive tests and clinical evaluations for Alzheimer disease. Dietary assessment was by food-frequency questionnaire. RESULTS: Tocopherol intake from food was related to the 4-y incidence of Alzheimer disease determined by logistic regression in 1041 participants who were clinically evaluated (n=162 incident cases) and to change in a global cognitive score determined by mixed models in 3718 participants. Higher intakes of vitamin E (relative risk: 0.74 per 5 mg/d increase; 95% CI: 0.62, 0.88) and alpha-tocopherol equivalents (relative risk: 0.56 per 5 mg/d increase; 95% CI: 0.32, 0.98) were associated with a reduced incidence of Alzheimer disease in separate multiple-adjusted models that included intakes of saturated and trans fats and docosahexaenoic acid. alpha- and gamma-Tocopherol had independent associations. In separate mixed models, a slower rate of cognitive decline was associated with intakes of vitamin E, alpha-tocopherol equivalents, and alpha- and gamma-tocopherols. CONCLUSION: The results suggest that various tocopherol forms rather than alpha- tocopherol alone may be important in the vitamin E protective association with Alzheimer disease.     

Weekly vitamin A and iron supplementation during pregnancy increases vitamin A concentration of breast milk but not iron status in Indonesian lactating women

Studies on the effect of vitamin A and iron supplementation during pregnancy on maternal iron and vitamin A status postpartum are scarce. We investigated whether retinol and iron variables in breast milk and in serum postpartum were enhanced more with weekly vitamin A and iron supplementation during pregnancy than with weekly iron supplementation. During pregnancy, subjects were randomly allocated to two groups and received either (n = 88) a weekly supplement of iron (120 mg Fe as FeSO(4)) and folic acid (500 microg) or (n = 82) the same amount of iron and folic acid plus vitamin A [4800 retinol equivalents (RE)]. Transitional milk (4-7 d postpartum) had higher (P < 0.001) concentrations of retinol and iron than mature milk (3 mo postpartum). Compared with the weekly iron group, the weekly vitamin A and iron group had a greater (P < 0.05) concentration of retinol in transitional milk (as micromol/L) and in mature milk (as micromol/g fat). Although serum retinol concentrations approximately 4 mo postpartum did not differ significantly, the weekly vitamin A and iron group had significantly fewer (P < 0.01) subjects with serum retinol concentrations < or = 0.70 micromol/L than the weekly iron group. Iron status and concentrations of iron in transitional and mature milk did not differ between groups. We have shown that weekly vitamin A and iron supplementation during pregnancy enhanced concentrations of retinol in breast milk although not in serum by approximately 4 mo postpartum. However, no positive effects were observed on iron status and iron concentration in breast milk.     

Nutritional Adequacy of Commercial Infant Milk Formulas

The nutritional adequacy of six commonly consumed commercial infant milk formulas were evaluated chemically and biologically in growing rats. Infant formulas (per 100 kcal) provided protein (2.2-2.6 g), fat (4.9-5.4 g), available carbohydrates (10.3-11.4 g), Ca (62.5-80.8 mg), P (31.3-66.1 mg), Fe (0.7-1.8 mg), Zn (0.5-0.8 mg), and Cu (0.05-0.08 mg). The energy density varied between 503 and 526 kcal/100 g. Higher levels of linoleic and saturated fatty acids than in human milk were found. Methionine, tryptophan and lysine were the first, second, and third limiting amino acids in all infant formulas. The true protein digestibility (TD), net protein utilization (NPU), biological value (BV) and utilizable protein (UP) varied from 93-96%, 0.75-0.79, 80-82% and 8.7-10.5% respectively. The protein quality of infant formulas was lower than in cow's milk and human milk.     

Fatty acid and sn-2 fatty acid composition in human milk from Granada (Spain) and in infant formulas

OBJECTIVE: To investigate differences in fatty acid and sn-2 fatty acid composition in colostrum, transitional and mature human milk, and in term infant formulas. SETTING: Departament de Nutrició i Bromatologia, University of Barcelona, Spain and University Hospital of Granada, Spain. SUBJECTS: One-hundred and twenty mothers and 11 available types of infant formulas for term infants. DESIGN: We analysed the fatty acid composition of colostrum (n=40), transitional milk (n=40), mature milk (n=40) and 11 infant formulas. We also analysed the fatty acid composition at sn-2 position in colostrum (n=12), transitional milk (n=12), mature milk (n=12), and the 11 infant formulas. RESULTS: Human milk in Spain had low saturated fatty acids, high monounsaturated fatty acids and high linolenic acid. Infant formulas and mature human milk had similar fatty acid composition. In mature milk, palmitic acid was preferentially esterified at the sn-2 position (86.25%), and oleic and linoleic acids were predominantly esterified at the sn-1,3 positions (12.22 and 22.27%, respectively, in the sn-2 position). In infant formulas, palmitic acid was preferentially esterified at the sn-1,3 positions and oleic and linoleic acids had higher percentages at the sn-2 position than they do in human milk. CONCLUSION: Fatty acid composition of human milk in Spain seems to reflect the Mediterranean dietary habits of mothers. Infant formulas resemble the fatty acid profile of human milk, but the distribution of fatty acids at the sn-2 position is markedly different.     

Binding form of vitamin B2 in bovine milk: its concentration, distribution and binding linkage

The contents of total, free, and bound vitamin B2 (B2) in bovine milk and their distribution in four separate milk fractions, including milk during the early lactation stage, were estimated. The total B2 content in whole mature milk was 179 +/- 25 micrograms/100 g (n = 16), and its distribution in the cream, whey, skim milk membrane, and casein fractions was 6, 67, 9, and 18%, respectively. The amount of flavins bound to protein in the total B2 was 13.6% in whole milk and rich in membrane fraction. The total B2 content (micrograms/100 g of milk) was higher in colostrum at 1-3 days (287 +/- 120) than in colostrum at 4-7 days (173 +/- 27), in transitional milk (182 +/- 33), and in mature milk (179 +/- 44). The bound flavin content decreased slightly as lactation progressed (20-30 micrograms/100 g), but the ratio of bound/total B2 did not vary (12-15%). Milk fat globule membrane (MFGM) contained 414 +/- 65 micrograms of B2/g of protein, most of it being bound to protein (92%). Market milks contained as much total B2 as raw whole milk, but the amount of bound form was only 2%. Guanidine HC1, urea, sodium dodecyl sulfate, pH at 3.0-3.5, delipidation, and boiling released most of the B2 bound to protein, suggesting that bound flavins bind to milk proteins by a hydrophobic linkage.     

Vitamin E, lipid fractions, and fatty acid composition of colostrum, transitional milk, and mature milk: an international comparative study

Triglycerides, cholesterol, fatty acid composition, and tocopherols were determined in colostrum, transitional milk, and mature milk in St Lucia. With progress of lactation, triglycerides and percentage medium-chain fatty acids increased whereas tocopherols, cholesterol, and percentage long-chain polyunsaturated fatty acids decreased. These changes reflect augmented de novo synthesis of fatty acids (8:0, 10:0, 12:0, and 14:0) in the mammary gland and a tendency of increasing fat-globule size as milk matures. Transitional and mature milks, but particularly colostrum, contained higher concentrations of components considered to be derived from the fat-globule membrane (cholesterol, tocopherols, percentage long-chain polyunsaturated fatty acids) compared with those reported for Western countries. Percentage medium-chain fatty acids in mature milk was two to three times higher than in developed countries. Differences from data from studies in Western countries are discussed in relation to analytical methods and possible consequences for lipid digestion, lipid absorption, growth, and brain development.     

Fluoride content of powdered infant formula meets Australian Food Safety Standards

Objectives: To identify the fluoride content of powdered formula for infants 0‐12 months in products available from Brisbane stores in 2006/07 and compare this with the fluoride content of infant formula products available in Australia 10 years earlier. Methods: A range of available infant formula powders were collected from major supermarkets and chemists in Brisbane, Queensland. The fluoride levels in infant formula powder samples were determined using a modification of the micro‐diffusion method of Silva and Reynolds 1 utilising perchloric acid and silver sulphate and measured with an ion selective (fluoride) electrode/meter. Fluoride content both prior to and after reconstitution, as well as estimated daily intake according to age was calculated. Results: Formula samples contained an average of 0.49 μg F/g of powder (range 0.24–0.92 μg F/g). After reconstitution with water containing 0mg/L fluoride, the fluoride content averaged 7.09μg F/100mL (range 3.367–22.72 μg F/100mL). Estimated infant fluoride intakes ranged from 0.0039 mg/kg/day for a 6‐12 month old infant when reconstituting milk‐based formula with non‐fluoridated water (0 mg/L), to 0.1735 mg/kg/day for a 0‐3 month old infant when reconstituting soy‐based formula with fluoridated water (1.0 mg/L). Conclusions: Infant formula powders contain lower levels of fluoride than previously found in Australia in 1996. Implications: This confirms that infants consume only a small amount of fluoride from milk‐based powdered infant formula. Although soy‐based infant formulas contain more fluoride than milk‐based products, the levels still comply with national food standards.     

Granulométrie des globules gras du lait humain

Despite its importance regarding fat digestion in the infant, data available regarding the size of human milk fat globules in the 2 first days postpartum (p.p.) was scarce. Therefore, we measured the fat globule size distribution and its typical size parameters in colostrum and transitional milk from 17 mothers during 4 days p.p. The results were compared with mature milk from other mothers and infant formulas. The change in size after freezing and the electrokinetic potential (ζ) of mature milk fat globules was also measured for one mother. Before 12 h p.p., the mode diameter was 8.9 ± 1.0 µm vs 2.8 ± 0.3 µm at 96 h p.p. (P < 0.02). The specific surface area thus increased from 1.1 ± 0.3 to 5.4 ± 0.7 m²/g between colostrum and transitional milk (P < 0.02). In mature milk, the average modal diameter was 4 µm and increased throughout lactation. Freezing increased the diameter by 10%. Lipid droplets in infant formulas were much smaller, namely sizing 0.4 µm. ζ-potential of the mature human fat globules studied was -7.8±0.1 mV, which is a lower charge than for bovine milk fat globules. These structural differences could be of nutritional significance for infants and toddlers.     

Quantitation of the major whey proteins in human milk,and development of a technique to isolate minor whey proteins

Several whey proteins of human milk have important nutritional and physiological roles for the breast fed infant. Only 75 to 85% of the proteins in whey have been identified and quantitated, leaving a remaining protein fraction containing many proteins of probable nutritional and physiological significance. In this study, colostrum and mature milk samples were collected, and the concentrations of five major whey proteins were measured using immunoelectrophoresis or immunodiffusion. Based on Kjeldahl nitrogen analysis, the total concentration of whey proteins in colostrum was 17.05 mg/ml and in mature milk 5.95 mg/ml. The concentration of α-lactalbumin was 3.7 mg/ml and 1.7 mg/ml in colostrum and mature milk, respectively; lactoferrin concentration was 7.3 and 1.5 mg/ml; and secretory IgA concentration was 4.7 and 1.2 mg/ml. In both colostrum and mature milk, concentrations of serum albumin and lysozyme were 0.37 and 0.07 mg/ml, respectively. The sum of these major whey proteins expressed as a percentage of the total whey protein accounted for 81% of mature whey protein, and 94% of colostral whey protein, leaving 19% and 6% in the remaining protein fraction. A method was developed to isolate this remaining protein fraction from the major whey proteins using gel filtration and immunoaffinity chromatography. The quantitatively minor whey protein fraction obtained was further characterized using polyacrylamide gel electrophoresis and ion exchange chromatography.     

Effect of feeding polyunsaturated fatty acids with a low vitamin E diet on blood levels of tocopherol in men performing hard physical labor.

A diet made low in vitamin E by elimination of foods considered good sources of the vitamin was fed for 13 months to two groups of men engaged in strenuous labor. With a daily average dietary intake of about 9.4 mg of total tocopherols, a progressive decline in blood levels of tocopherol from 1.42 to 0.81 mg/100 ml was observed in the five control subjects. The test group of 30 men received a daily supplement of tocopherol-stripped safflower oil containing 88 g of polyunsaturated fatty acids and 2.3 mg of tocopherols. Average blood plasma levels of tocopherol in this group dropped rapidly from an initial value of 1.01 to about 0.5 mg/100 ml within 5 months and remained relatively stable thereafter. No muscular weakness or other physical symptoms were reported.     

Riboflavin levels in maternal milk: the influence of vitamin B2 status during the third trimester of pregnancy

OBJECTIVE: The aim of the present investigation was to study the relationship between riboflavin status during the third trimester of pregnancy and levels of this vitamin in transition milk (days 13 to 14 of lactation) and mature milk (day 40 of lactation). METHODS: The pregnancies and lactation periods of 57 healthy women between 18 and 35 years of age (27+/-3.7 years) were monitored, vitamin intake during the third trimester was determined by recording the consumption of foods over five days and by registering the quantities provided by dietary supplements. Riboflavin status during this stage of pregnancy was determined via the measurement of the activation of erythrocyte glutathione reductase (EGR) by flavine adenine dinucleotide (FAD). Milk riboflavin levels were determined by fluorometry. RESULTS: Those subjects with riboflavin intakes below recommended (1.6 mg/day) (Group L) showed lower consumption of milk products (305.2+/-88.5 g/day) than did those with greater intakes (Group H) (507.9+/-137.2 g/day). The consumption of riboflavin containing supplements was very low and was seen only in two H subjects. Transition and mature milk riboflavin levels were significantly higher in H subjects (948.1+/-700.1 nmol/L for transition milk and 993.8+/-436.6 nmol/L for mature milk) than L subjects (574.9+/-258.7 nmol/L for transition milk and 725.4+/-254.3 nmol/L for mature milk). Subjects with alpha-EGR coefficients over 1.2 in the third trimester showed significantly lower mature milk riboflavin levels (704.1+/-241.8 nmol/L) than did subjects with more satisfactory alpha-EGR coefficients (996.4+/-302.9 nmol/L). CONCLUSION: The influence of maternal vitamin B2 status during pregnancy on breast milk riboflavin levels was confirmed.     

Nutritional Adequacy of Commercial Infant Milk Formulas

The nutritional adequacy of six commonly consumed commercial infant milk formulas were evaluated chemically and biologically in growing rats. Infant formulas (per 100 kcal) provided protein (2.2–2.6 g), fat (4.9–5.4 g), available carbohydrates (10.3–11.4 g), Ca (62.5–80.8 mg), P (31.3–66.1 mg), Fe (0.7–1.8 mg), Zn (0.5–0.8 mg), and Cu (0.05–0.08 mg). The energy density varied between 503 and 526 kcal/100 g. Higher levels of linoleic and saturated fatty acids than in human milk were found. Methionine, tryptophan and lysine were the first, second, and third limiting amino acids in all infant formulas. The true protein digestibility (TD), net protein utilization (NPU), biological value (BV) and utilizable protein (UP) varied from 93–96%, 0.75–0.79, 80–82% and 8.7–10.5% respectively. The protein quality of infant formulas was lower than in cow's milk and human milk.