Availability of essential amino acids and nitrogen in vegan diets.

Vegan children often fail to grow as well as their omnivorous cohorts despite protein intakes that exceed RDA. Explanations for inadequate growth include deficiencies of energy, calcium, zinc and vitamins B-12 and D. Due to decreased bioavailability, amino acids and nitrogen in vegan diets may be inadequate to support normal growth. Bioavailability of amino acids and nitrogen may be decreased by dietary fiber, food processing and storage, inadequate energy, and other unknown factors. Bioavailability should be considered when evaluating adequacy of intakes of protein, amino acids and nitrogen from vegan diets by infants and children.

Nutrient intake of treated infants with phenylketonuria.

Growth, energy, and nutrient intake of 88 treated infants in the Collaborative Study of Children Treated for Phenylketonuria were evaluated longitudinally and compared to normative data and by treatment group. Growth parameters (height and weight) did not differ according to treatment group assignment, nor did they differ from normative data. Subjects in treatment group 2 had a significantly higher intake of phenylalanine than did subjects in treatment group 1. Differences in intake of other nutrients disappeared when intake was compared on an energy or body weight basis. Differences in intake by males and females also disappeared when compared on an energy and a body weight basis. From none to 10% of the subjects had energy intakes below two-thirds of the 1968 Recommended Dietary Allowances (RDA). Low individual energy intakes were more commonly found in the first and fourth quarters, and only during the first quarter of infancy did mean energy intake meet the RDA. From 48 to 80% of subjects had intakes of preformed niacin below two-thirds of the 1968 RDA. Few subjects had low intakes of protein, iron, or vitamin A, and intakes of all subjects were greater than 67% of the RDA for calcium, phosphorus, thiamin, riboflavin, and ascorbic acid. It is suggested from the data presented that a supplemental casein hydrolysate supplies adequate essential amino acids and nitrogen to support normal growth in infants when protein and energy intakes are fed at the levels described.

Phenylalanine intakes of 1- to 6-year-old children with phenylketonuria undergoing therapy.

Mean of median phenylalanine intakes of 1- to 6-yr-old treated phenylketonuria patients who were growing normally were evaluated by age, sex, and treatment group assignment. Total daily means of median phenylalanine intakes of subjects in treatment group 1 were significantly different from those of subjects in treatment group 2 except at the median age of 69 months. Total daily phenylalanine intakes varied from 285 +/- 10 to 453 +/- 30 mg (mean +/- SEM) by subjects in treatment group 1. Total daily phenylalanine intakes of subjects in treatment group 2 varied from 349 +/- 12 to 530 +/- 42 mg (mean +/- SEM). Mean, median phenylalanine intakes by males ranged from 30 mg/kg of body weight by the younger to 23 mg/kg of body weight by the older subjects. Means of median phenylalanine intakes of females varied from 32 mg/kg of body weight by the younger to 21 mg/kg of body weight by the older subjects. No child had a median phenylalanine intake below 10 mg/kg of body weight.

Intake of major nutrients by women in the Maternal Phenylketonuria (MPKU) Study and effects on plasma phenylalanine concentrations.

BACKGROUND: Women with untreated phenylketonuria (PKU) often have poor reproductive outcomes. OBJECTIVE: We assessed the effects of intakes of major nutrients on plasma phenylalanine concentrations and we measured phenylalanine hydroxylase activity and phenylalanine intakes in pregnant women with PKU. DESIGN: Dietary intakes and plasma phenylalanine concentrations were compared in 4 subject groups defined on the basis of plasma phenylalanine concentrations: group 1 (n = 23), <360 micromol/L by 10 wk gestation and 120-360 micromol/L throughout the remainder of pregnancy; group 2 (n = 46), <600 micromol/L but not <360 micromol/L by 10 wk gestation and 120-600 micromol/L throughout the remainder of pregnancy; group 3 (n = 24), <600 micromol/L by 10 wk gestation but >600 micromol/L at least once thereafter; group 4 (n = 147), never <600 micromol/L. RESULTS: Except in the first trimester, mean intakes of phenylalanine, energy, and fat tended to be greater in group 1 than in the other groups. The mean protein intake of group 1 tended to be greater than that of the other groups. Intakes of protein (P < 0.0001), fat (P < 0.0001), and energy (P < 0.007) were negatively correlated with maternal plasma phenylalanine concentrations. It appeared that genotype did not affect phenylalanine tolerance. CONCLUSIONS: Maternal genotype appeared to have little influence on phenylalanine requirements during the first trimester. Early decline and maintenance of maternal plasma phenylalanine concentrations at <360 micromol/L and mean protein intake greater than the recommended dietary allowance (RDA) with mean energy intake near the RDA resulted in the best reproductive outcomes. Inadequate intakes of protein, fat, and energy may result in elevated plasma phenylalanine concentrations and may contribute to poor reproductive outcomes.

Nutrition studies with White Mountain Apache preschool children in 1976 and 1969.

Nutrition studies were undertaken with two cohorts of White Mountain Apache preschool children, first in 1969 and again in 1976. Under the direction of the same investigator, similar procedures were used in the two studies to evaluate dietary, clinical, and biochemical status. The proportion of children in 1976 with low intakes of calories and of several micronutrients (calcium, vitamin A, vitamin C, thiamin, and iron) and with abnormal biochemical values (hemoglobin, serum iron, vitamin A, and vitamin C), was about half that in 1969. Height for age and weight for age were the same in the two studies. Skinfold thickness were slightly greater in 1976. Overall, these changes in nutritional status were in keeping with changes in the environment and in the economic and health care situations on the Fort Apache Reservation.

The effect of a phenylalanine and tyrosine restricted diet on elemental balance studies and plasma aminograms of patients with disseminated malignant melanoma.

Previous studies indicate dietary phenylalanine and tyrosine restriction may be of value in managing advanced cancer patients. To further evaluate this approach, we performed a 60-day study in which four patients with advanced malignant melanoma received formula diets via nasogastric tube containing only 8 mg total phenylalanine and tyrosine per kg lean body mass per day. Two of three patients completing elemental balance studies were in negative nitrogen, potassium, and phosphorus balance, suggesting an essential nutrient deficiency. Three patients tolerated the diet well, but one was non-compliant. Although no serious toxicity developed, serum albumin, total iron binding capacity and cholesterol significantly decreased (p less than 0.01) in the three complaint patients. Fasting plasma phenylalanine and tyrosine values did not significantly change during the study, but two-hour postprandial plasma phenylalanine and tyrosine concentrations fell below normal and were significantly lower than preprandial levels (p less than 0.01). There were no tumor responses.

RSH/SLO (Smith-Lemli-Opitz) syndrome: designing a high cholesterol diet for the SLO syndrome.

A high cholesterol diet has been suggested to help prevent the poor reproductive outcomes found in heterozygote carriers of fetuses affected with the Smith-Lemli-Opitz (SLO) syndrome. The theory has also been presented that a high cholesterol medical food may enhance myelination of the central nervous system of the infant and prevent demyelination in the child and adult with SLO. Clinical studies are required to test this hypothesis and to determine the optimal composition of such medical foods. FDA requires proof of efficacy and controls nutrient composition, ingredients, and label claims of medical foods.

Feeding the vegan infant and child.

Nutrients that may be deficient in diets of vegetarian infants and preschoolers and that affect growth and development are energy, protein, calcium, iron, zinc, riboflavin, and vitamins B-12 and D. Reasons for these nutrient deficiencies include: limited volumetric capacity of the stomach of infants, toddlers, and preschoolers; low-caloric-density foods eaten by vegans; limited food choices; and restriction of number of meals and snacks eaten by vegan children. Suggestions are made for meeting the energy and nutrient needs of infants and children within the food ways of their families.

Osmolalities of selected enteral products and carbohydrate modules used to treat inherited metabolic disorders.

Osmolalities of selected defined-formula products for use in treatment of inherited disorders of amino acid metabolism were measured at 12 energy concentrations. Osmotic behaviors of six carbohydrate modules as components of L-amino acid formulas were also studied. Osmolality measurements were made using a Wescor vapor pressure depression osmometer (model 5100 C). Phenyl-Free at concentrations greater than 10 kcal/oz yielded high osmolalities that exceeded the recommended level for infants. Lofenalac, Low Phe/Tyr Diet Powder, and MSUD Diet Powder at concentrations up to but no greater than 20 kcal/oz exerted osmolalities acceptable for use with infants. Low Methionine Diet Powder produced the lowest osmolality of the products tested. Differences among products can be explained by the formulations of the products, with sources of nitrogen and carbohydrate and percents of protein, carbohydrate, and fat considered. Carbohydrate type significantly affected formula osmolality; differences among carbohydrate sources can be attributed to their molecular sizes. Formulas that contained glucose exerted the highest osmolalities, while those with corn syrup or sucrose yielded the next highest. Protein Free Diet Powder, Polycose, and Moducal exerted reasonably low osmolalities.

Functions of dietitians providing nutrition support to patients with inherited metabolic disorders.

This article examines functions of dietitians who provide nutrition services to patients with inherited metabolic disorders. A survey questionnaire was developed and pilot-tested in a sample of dietitians, revised, and mailed to all dietitians in the United States who treat patients with inherited metabolic disorders. One hundred forty-two usable questionnaires were returned. Descriptive statistics were used to calculate response frequency. The highest academic degree attained by 37% of the dietitians was a bachelor's degree; 58% had earned a master's degree and 5% a doctorate. Dietitians provided nutrition services during diagnosis, critical illness, and long-term care. More than 90% of the dietitians performed these functions: evaluated nutrition status; prepared, implemented, and evaluated the nutritional support plan; revised the nutrition support plan as needed; monitored dietary compliance; coordinated care with other agencies; developed materials and educated parents, caregivers, and patients about the nutrition support plan; and recorded information in the medical record. Without nutrition support, patients with inherited metabolic disorders may become mentally retarded, experience neurologic or metabolic crises, or die.

Computer-implemented nutrition support of phenylketonuria.

This project demonstrates that computers can fill diet prescriptions for nutrition support but only if nutritionists who know how to fill diet prescriptions do the programming. The computer can provide information that is required to improve nutrition support, as well as save time that the dietitian can use in patient education. The computer, however, cannot replace the dietitian. It merely performs mathematical calculations. Establishment of the diet prescription, choice of products, and the use of the final formula and foods require trained judgment used in conjunction with appropriate clinical and laboratory data.

Methods of dietary inception in infants with PKU.

Information on methods of initiating the phenylalanine-restricted diet was obtained from the medical personnel of sixteen clinics in the Collaborative Study of Children Treated for Phenylketonuria. The four dietary methods used initially to lower serum phenylalanine were: Normal dilution Lofenalac, Lofenalac, with phenylalanine added as milk, Lofenalac with milk added to provide 200 mg. phenylalanine per day, and alternating bottles of normal dilution Lofenalac and cow's milk during the first four days of therapy. During the first week of treatment, eight clinics obtained serum phenylalanine determinations daily or every other day. The nutritionist prescribed the phenylalanine-restricted diet following diagnosis in nine of the clinics. In most clinics, the nutritionist was responsible for obtaining information relating to dietary management and follow-up contacts during the first month of treatment. The initial dietary instruction was accomplished in most clinics by a combination of lecture/discussion/demonstration methods. Both parents attended the initial dietary instruction in thirteen clinics. Neither the professional person(s) nor the method of initial dietary instruction, if detailed and comprehensive, made any difference in control of serum phenylalanine during the first year of life.

Nutrients in vegetarian foods.

Persons who use tables of food composition have often found that foods that vegetarians commonly eat are not included. To help remedy this situation, a table is presented which includes the 49 foods on the vegetarian Exchange Lists and 18 additional nonmeat foods. Nutrient contents of household measures of these foods are given for water, protein, fat, carbohydrate, calcium, phosphorus, iron, potassium, zinc, vitamin A, thiamin, riboflavin, niacin, vitamin C, and folacin. Nutrient amounts were derived from USDA sources and from other published research when available. Nutrient amounts from foods assumed to be identical to those in the table were placed in parentheses. When nutrient amounts were not available, they were estimated from similar foods and placed in brackets. When values found for a single nutrient in a food varied by 20% or more, the total range was shown. When a dash was found in a literature reference and the amount of the nutrient was known to be insignificant, a zero was presented in the table. Thus, there are no gaps in the table. Until accurate laboratory-derived data are available for the nutrients in vegetarian foods, this table, used with appropriate judgment, should be useful for estimating the nutrient intakes of persons who eat vegetarian foods.

Dietary selenium intakes and plasma selenium concentrations of formula-fed and cow's milk-fed infants.

The plasma selenium concentrations of 57 infants 8 to 12 months of age were assessed using flameless atomic absorption spectrophotometry. The infants ingested either cow's milk or whey-predominant milk-based infant formula as their primary beverage as part of a mixed diet for at least 3 months. The calculated mean +/- standard deviation (SD) daily dietary selenium intake of 26 infants fed cow's milk (34 +/- 13 micrograms), assessed by a 3-day diet record and/or a 24-hour diet recall, was significantly (p less than or equal to .001) greater than that of 31 formula-fed infants (22 +/- 11 micrograms). The mean +/- SD plasma selenium concentration of infants fed cow's milk (39 +/- 11 micrograms/L) was also significantly (p less than or equal to .05) greater than that of infants fed formula (31 +/- 12 micrograms/L). Both groups of infants ingested similar amounts of total energy; however, the infants fed cow's milk received more total protein and selenium and a greater percentage of protein and selenium from their primary beverage than did the infants receiving formula. Both groups of infants were consuming a mixed diet with similar sources of selenium. To examine the selenium status of infants as well as other individuals better, further analysis of foods is clearly needed to provide more information on dietary selenium sources. The influence of variables such as body size and ethnicity, intake, sources and forms of dietary protein, and dietary forms of selenium on plasma selenium concentrations must also be investigated.

Trace element status of children with PKU and normal children.

The trace mineral (chromium, copper, iron, selenium, and zinc) status of 10 children (4 to 13.8 years) with phenylketonuria (PKU) and 9 normal children (6.5 to 15.9 years) was assessed. The children with PKU were treated with a phenylalanine-free L-amino acid mix that supplied the following percentages (mean +/- standard deviation) of total daily intake: energy, 45 +/- 13; protein, 75 +/- 11; copper (Cu), 62 +/- 10; iron (Fe), 82 +/- 7; selenium (Se), 40 +/- 20; and zinc (Zn) 87 +/- 8. Diet records and blood samples were collected from each subject. Children with PKU had significantly greater mean intakes of Cu, Fe, and Zn than normal children. Mean serum Cu, Fe, and Zn concentrations of the children with PKU and normal children were not different despite significantly greater intakes by the children with PKU. Normal children had a significantly greater mean serum Se concentration and a mean blood chromium concentration 1.6 times that of children with PKU. Individuals whose primary source of protein is an elemental diet are especially at risk for multiple trace mineral deficiencies. Manufacturers of chemically defined medical foods should evaluate composition, specifically molar ratios between minerals, as a basis for product formulation.

Effect of simultaneous ingestion of L-amino acids and whole protein on plasma amino acid and urea nitrogen concentrations in humans.

The effect of whole protein and L-amino acid ingestion on plasma amino acid (PAA) and urea nitrogen (UN) concentrations was investigated. Ten males ingested equivalent amounts of nitrogen as (trial 1) cottage cheese, (trial 2) an L-amino acid mixture, (trial 3) cottage cheese and L-amino acids. Mean changes in total PAA between trials 1 (342 mumol/liter) and 2 (719 mumol/liter) and trials 1 (342 mumol/liter) and 3 (981 mumol/liter) at 30 min and trials 1 (547 mumol/liter) and 3 (143 mumol/liter) at 150 min differed significantly. Mean changes in essential PAA between trials 1 (180 mumol/liter) and 2 (420 mumol/liter) and trials 1 (180 mumol/liter) and 3 (500 mumol/liter) at 30 min differed significantly. Mean changes in essential PAA between trials 1 (247 mumol/liter) and 3 (334 mumol/liter) at 60 min and between trials 1 (252 mumol/liter) and 3 (80 mumol/liter) at 150 min differed significantly. Mean increments in total and essential PAA were higher and peaked faster but decreased more quickly after trials 2 and 3 than after trial 1. Mean changes in plasma UN did not differ between trials. Ingestion of either L-amino acids, whole protein or the mixture of L-amino acids and whole protein was equally effective in increasing total PAA over 4 hr.

Trace element status of PKU children ingesting an elemental diet.

We assessed the trace metal status of 10 children (3.5 to 13.3 yr) with phenylketonuria (PKU) who were successively treated for at least 6 months with a semi-synthetic formula restricted in phenylalanine, then for 6 months with a reformulated formula. The reformulated product contained higher concentrations of magnesium (Mg), potassium (K), phosphorus (P), selenium (Se), and zinc (Zn) and lower concentrations of calcium (Ca), sodium (Na), and unsaturated fats. Diet records, blood samples, and urine specimens were collected from each subject. Mean intakes of Mg, K, and Zn increased significantly when subjects were switched to the reformulated product. The subject's mean intakes of Se (for all age groups) and Zn (children 11 to 14 yr old) were below 67% of recommended intakes while they were ingesting the original formula. The mean trace metal concentrations of urine, blood, and serum did not differ significantly during the two periods. Mean serum Zn, Se, and Cu concentrations of the subjects were less than those reported for normal children. Significant negative correlations were obtained between serum Zn concentrations and the molar ratio of dietary (Ca + P):Zn, and the molar ratio of dietary Fe:Zn. No significant differences in mean urinary Cu and Zn excretion (mg/g creatinine) were observed in subjects after they were changed to the reformulated product. Individuals whose primary source of energy and protein is derived from semi-synthetic elemental diets are especially at risk for multiple trace element deficiencies.

Zinc and copper status of treated children with phenylketonuria.

Children with phenylketonuria (PKU) are treated with semi-synthetic diets restricted in phenylalanine. Low or phenylalanine-free formulae provide the majority of protein and energy in the diet while phenylalanine requirements are met by low-protein natural foods. Because of the restriction of natural protein sources in this diet, the study assessed the zinc and copper nutriture of treated children with PKU and correlated linear growth with zinc status. The plasma zinc of the PKU population was 66.6 +/- 3.3 micrograms/dl (mean +/- SEM). The hair zinc was 70.2 +/- 11.5 micrograms/g (mean +/- SEM). The mean plasma and hair zinc of the PKU population were significantly different (p less than 0.05) when compared to normal values of 84.2 +/- 2.9 micrograms/dl and 130.7 +/- 8.3 micrograms/g (mean +/- SEM), respectively. The dietary zinc intake of 10 PKU patients was 8.56 +/- 2.68 mg/day (mean +/- SD). No significant differences (p less than 0.123) were found when the mean zinc intake was compared with recommended dietary allowances for age of 10 mg/day. No significant correlations were found when plasma and hair zinc were plotted with height percentiles. Plasma copper of the PKU subjects (87.6 +/- 6.6 micrograms/dl, mean +/- SEM) was significantly less than that of normal young children (121.5 +/- 3.1 micrograms/dl, mean +/- SEM) despite a copper intake a 1.45 +/- 0.35 mg/day (mean +/- SD).

Nutritional therapy for pregnant women with a metabolic disorder.

Nutritional therapy is essential for a normal reproductive outcome in phenylketonuric women. In homocystinuria, fetal outcome is good in women whose disorder is responsive to vitamin B6 therapy and is poor in women whose disorder is unresponsive to therapy. Pregnancy in galactosemia is rare because of the almost universal ovarian dysfunction present in female patients with this disorder. Transplantation of the fertilized ovum is a promising possibility for these women. In women with MSUD, there has been only one case of pregnancy reported to date.

Plasma micronutrient concentrations in infants undergoing therapy for phenylketonuria.

Twenty-seven infants with classical phenylketonuria were evaluated longitudinally for 6 mo while ingesting Phenex-1 Amino Acid Modified Medical Food With Iron as their primary protein source. Intake of selected nutrients and biochemical indices of trace and ultratrace mineral status and plasma retinol and alpha-tocopherol concentrations were evaluated. The means of iron status indices (complete blood count, plasma ferritin, iron, transferrin saturation, total iron binding capacity) and the plasma concentrations of trace and ultratrace minerals (copper, manganese, molybdenum, selenium, zinc) and plasma retinol and alpha-tocopherol were in the reference ranges. Vitamin A intakes (r = 0.49, p < 0.05) and plasma retinol-binding protein concentrations (r = 0.42, p < 0.05) were positively correlated with plasma retinol concentrations at 3 mo of study. At 6 mo, concentrations of plasma transthyretin (r = 0.72, p < 0.01) and retinol-binding protein (r = 0.48, p < 0.05) were positively correlated with plasma retinol concentrations. At 6 mo, concentrations of plasma transthyretin (r = 0.52, p < 0.05) were positively correlated with retinol-binding protein concentrations. Phenex-1 supports normal mean iron status indices and mean concentrations of trace and ultratrace minerals, retinol, and alpha-tocopherol when fed in adequate amounts.