PubMed Health⌕ Search

Biomedical subjects

A C Grandjean

Publications and source records attributed to A C Grandjean.

15 recordsLinked to original sources
PubMed2000

The effect of caffeinated, non-caffeinated, caloric and non-caloric beverages on hydration.

OBJECTIVE: To examine the effect of various combinations of beverages on hydration status in healthy free-living adult males. METHODS: In a counterbalanced, crossover manner, 18 healthy adult males ages 24 to 39, on four separate occasions, consumed water or water plus varying combinations of beverages. Clinical guidelines were used to determine the fluid allowance for each subject. The beverages were carbonated, caffeinated caloric and non-caloric colas and coffee. Ten of the 18 subjects consumed water and carbonated, non-caffeinated, citrus soft drink during a fifth trial. Body weight, urine and blood assays were measured before and after each treatment. RESULTS: Slight body weight loss was observed on all treatments, with an average of 0.30% for all treatments. No differences (p>0.05) among treatments were found for body weight changes or any of the biochemical assays. Biochemical assays conducted on first voids and 24-hour urines included electrolytes, creatine, osmolality and specific gravity. Blood samples were analyzed for hemoglobin, hematocrit. electrolytes, osmolality, urea nitrogen, creatinine and protein. CONCLUSIONS: This preliminary study found no significant differences in the effect of various combinations of beverages on hydration status of healthy adult males. Advising people to disregard caffeinated beverages as part of the daily fluid intake is not substantiated by the results of this study. The across-treatment weight loss observed, when combined with data on fluid-disease relationships, suggests that optimal fluid intake may be higher than common recommendations. Further research is needed to confirm these results and to explore optimal fluid intake for healthy individuals.

Adult↗
PubMed2000

Nitrate and nitrite concentrations in human saliva for men and women at different ages and times of the day and their consistency over time.

Salivary nitrite arises from nitrate and is the main source of gastric nitrite, a precursor of carcinogenic N-nitroso compounds. We examined nitrate and nitrite levels in unstimulated saliva from subjects consuming low-nitrate low-vitamin C diets. When saliva was collected from six men at nine times of the day (Experiment 1), night time nitrite levels were significantly higher than day time values and nitrite varied more than nitrate. When saliva was collected from 29 subjects aged 19-37 or 60-84 years at four times of the day during 1991-1993 (Experiment 2), all older subjects and older men had significantly higher nitrite levels than the corresponding younger subjects, night time nitrite levels in men were significantly raised, and nitrate and nitrite levels in the same samples were closely correlated. Saliva was collected at 6.00 a.m. on two successive days in 1997 from 16 subjects who had collected saliva in 1991-1993 (Experiment 3). Nitrate and nitrite levels on day 1 of experiment 3 were closely correlated with those on day 2. Nitrate and nitrite levels on days 1 and 2 of Experiment 3 were correlated with the corresponding parameters in Experiment 2 with P = 0.04 and 0.08 for day 1, and 0.10 and 0.28 for day 2, respectively. Hence, saliva nitrite levels rose at night and were higher in older people, especially older men, and saliva nitrate and nitrite levels varied little from day to day, but varied more after 4-6 years.

Adult↗
PubMed1998

Effect of ascorbic acid dose taken with a meal on nitrosoproline excretion in subjects ingesting nitrate and proline.

We determined the dose of ascorbic acid (ASC) given to subjects with a standard 400-calorie meal that inhibited N-nitrosoproline (NPRO) formation when we gave 400 mg of nitrate one hour before and 500 mg of L-proline with the standard meal. Volunteers consumed their normal US diets but restricted their intakes of nitrate, proline, NPRO, and ASC. NPRO and N-nitrososarcosine (NSAR) were determined in the 18-hour urines by methylation followed by gas chromatography-thermal energy analysis. Mean NPRO yields were 10.7, 41.9, 33.2, 22.3, and 23.1 nmol for groups of 9-25 subjects taking proline alone, proline + nitrate, and proline + nitrate + 120, 240, and 480 mg of ASC, respectively. There was a significant trend to lower NPRO yields as the ASC dose was raised. These results correspond to inhibitions by ASC of 28%, 62%, and 60%, respectively. Pairwise comparison showed that each group taking ASC formed significantly less NPRO than the group given only proline + nitrate. Mean NSAR yields were 9.0 nmol when proline alone was taken and 16.9-24.0 nmol when proline + nitrate + ASC was taken, with no trend to increase as the ASC dose was raised. However, NPRO and NSAR yields in individual urines were correlated with each other. We concluded that 120 mg of ASC taken with each meal (360 mg/day) would significantly reduce in vivo nitrosamine formation, similar to tests by Leaf and co-workers (Carcinogenesis 8, 791-795, 1987) in which the reactants were taken between meals. The inhibitory dose of ASC may be < 120 mg/meal when doses of nitrate and proline are not taken.

Adult↗
PubMed1997

Diets of elite athletes: has the discipline of sports nutrition made an impact?

Although numerous descriptions exist of special diets and particular foods used by Greek athletes as early as 580 B.C., survey data on diets of Olympians of the modern era are virtually nonexistent. A survey in Helsinki in 1952 reported the diets of Olympic athletes to be high energy, high fat, and high protein. The 1952 Olympians reportedly consumed an average daily energy intake of 18,841 kJ, with 40% of energy coming from carbohydrate, 20% from protein, and 40% from fat. More recent data on elite level athletes reveal wide variation in dietary intake. For example, energy intakes of athletes from four countries ranged from 7699 to 24,845 kJ. Group percentages of energy from carbohydrate, protein, and fat ranged from 33 to 57%, 12 to 26%, and 29 to 49%, respectively. Comparing dietary intake data of athletes on an absolute basis, however, is primarily a comparison of body size. When the protein and carbohydrate intakes of elite athletes are calculated as grams per kilogram body weight, the range for protein is 1.0-4.3 g/kg body wt for protein and 3.5-6.9 g/kg body wt for carbohydrate. Interestingly, variations in carbohydrate intake diminished while protein intake varied by country. Although some data on diets of Olympians exist, the most remarkable finding when reviewing the literature is the paucity of data. The discipline of sports nutrition has arguably had a positive effect on sports performance. However, many unanswered questions remain and great strides remain to be made.

Diet↗
PubMed1994

The effect of garlic extract on human metabolism of acetaminophen.

Several studies suggest that the constituents of garlic may inhibit experimentally induced carcinogenesis. To evaluate the chemopreventive properties of garlic in humans, the effects of chronic administration of an aged garlic extract on the disposition of acetaminophen and metabolites were studied. This commonly used drug was chosen because it forms a reactive electrophilic metabolite after oxidative metabolism. Sixteen subjects ingested daily doses of garlic extract (approximately equivalent to six to seven cloves of garlic) for 3 months. Before the course of garlic, at the end of each month and 1 month after termination of garlic administration, a 1-g oral dose of acetaminophen was given to each subject. Plasma and urine were measured for acetaminophen and the glucuronide, sulfate, cysteinyl, mercapturate, and methylthio metabolites. It was found that garlic treatment had no discernible effect on oxidative metabolism but was associated with a slight increase in sulfate conjugation of drug. These findings suggest that garlic extract has limited potential as a chemopreventive agent.

Acetaminophen↗
PubMed1994

Nutrition for cyclists.

Good nutrition is important at every stage of training and competition. Both the serious competitive cyclist as well as the recreational cyclist should eat a balanced diet that provides calories adequate to meet energy demands. Athletes consuming less than 2000 calories a day may have difficulty meeting nutrient needs, particularly for iron and calcium. Weight loss, glycogen depletion, and dehydration also are possible results of an inadequate diet. Dietary strategies to enhance or maintain the body's carbohydrate stores are necessary for performance, especially for cyclists with high training miles or participating in road racing and other endurance events. Additionally, cyclists should be encouraged to drink plenty of fluids, especially when in a hot environment. It appears that protein requirements of endurance athletes increase as the duration and intensity of exercise increases. However, factors such as total calorie intake and protein quality should be considered when determining protein needs. Many athletes are concerned about vitamin and mineral intake and often use nutritional supplements both for "insurance" as well as performance reasons. The supplements taken most often include vitamin C, the B-complex, and iron. Vitamins and minerals in excess of the RDA do not improve performance and can be toxic when consumed in large amounts. On the other hand, vegetarians and cyclists with low-calorie intakes may benefit from a multivitamin or mineral supplement.

Bicycling↗
PubMed1993

Practices and recommendations of sports nutritionists.

A three-part questionnaire was used to identify professionals in sports nutrition and survey their recommendations on various aspects of sports nutrition. The majority of respondents were women. Over half of the sample reported working in sports nutrition for 6 years or less, and 72% indicated that 40% or less of their job is dedicated to sports nutrition. A portion of the questionnaire assessed the subjects' opinions on various sports nutrition topics. Statements on water and electrolytes generated the most agreement while statements on protein generated the least agreement. There was a positive correlation (p < 0.004) between level of education and whether or not the respondents recommended glycogen loading, and a positive correlation (p < 0.008) between the subjects' use of dietary supplements and the fact that they recommended supplements to the athletes they counseled. The majority of professionals in this study worked with recreational athletes and were more concerned about encouraging a healthy diet than improving athletic performance.

Adult↗
PubMed1986

Nutrition for swimmers.

Good nutrition is one of the elements of training and conditioning necessary for optimal performance. The athlete should consume a diet composed of a wide variety of foods to help ensure that nutrient needs are met, whereas maintenance of ideal competitive weight is the indicator of adequate calorie intake. The best diet is one that considers physiological, sociological, and psychological factors--an individualized diet. The precompetition meal should consist of foods the athlete likes, tolerates well, and usually eats. The main nutrition consideration during the all-day meet is fluid replacement, and swimmers should be encouraged to drink ample water, especially when in a hot environment. Foods and beverages the athlete likes, taken in small amounts throughout the day, can ward off hunger, provide needed calories, help maintain blood glucose levels, and meet fluid needs. Although vitamins and minerals taken at levels in excess of the RDA have been shown not to benefit performance, use of high levels of supplements is not uncommon among athletes. Athletes are often unaware that some nutrients can be toxic when taken in excess.

Adolescent↗
PubMed1984

Nutritional status of an institutionalized aged population.

The nutritional status of 146 elderly residents in a long-term care facility was evaluated using biochemical and anthropometric measures. The level of nursing care required and meal locale had no significant effect on the overall nutritional status of the residents. The biochemical data indicated three nutritional problems requiring treatment and follow-up: anemia, low vitamin B6 status, and reduced albumin levels. The incidence of these problems in other groups of elderly deserves further study. Six percent of the study population were anemic, with 13% having low serum folate, 6% with low transferrin saturation, and 31% with low TIBC values suggesting more than one factor involved in the anemia. Low vitamin B6 status was observed in 28% of the population. Whether this is due to poor intake, poor absorption, or both is not known. The percentage of residents with decreased albumin levels was slightly higher than that observed in other studies of the elderly, and may be related to the more advanced age of this population.

Aged↗
PubMed1983

Vitamins, diet, and the athlete.

Good nutrition is necessary for good performance and optimal nutrition can make the difference in a championship performance. Optimal nutrition, however, is the result of good dietary habits and is not achieved by following a special diet for several days or by consuming a special food or supplement. Ergogenic aids can be categorized as mechanical, psychological and psychophysiologic, pharmacologic, and nutritional. The category of nutritional ergogenic aids includes special dietary regimens, special foods, and supplements. Of these, supplements, especially vitamins, pseudovitamins, and nonvitamins, are the most widely used. Supplements promoted as vitamins are more realistically described as vitamins, pseudovitamins, and nonvitamins. Pseudovitamins do have some activity related to vitamins, but at present no evidence exists for their requirement by humans. Nonvitamins are substances that may be found in naturally occurring foods but have no demonstrated nutritional value and are therefore not considered essential nutrients for humans or animals. Nutritional deficiencies can result in decreased performance. However, there is no evidence that consumption of nutrients beyond the requirements of the organism is beneficial and, in fact, some nutrients ingested at high levels for long periods of time result in toxicity. A review of the literature reveals that deterioration of physical performance resulting from prolonged vitamin deficiency is well documented. Numerous studies substantiate that once vitamin requirements are met, there appears to be no value in consuming additional amounts. Unfortunately, the literature is not as complete regarding vitamin or mineral toxicity. However, there is ample evidence to show that the possibility of toxicity is a genuine concern. Supplementation is common among athletes, with reported occurrence ranging from 54 to 84 per cent. Studies on the general public place the incidence of supplementation between 40 and 67 per cent. Although some dietary studies of athletes report the frequency of use of supplementation, few report the levels being consumed. A study currently in progress has found world-class amateur and professional athletes to use supplements at an incidence comparative to that reported in other studies of athletes. However, the levels at which supplements were taken are considered extremely high. Maintaining ideal weight and variety are the quantity and quality indexes for diet. Following sound nutritional principles will help to insure the athlete's ability to perform at his or her best. In general, a diet that provides 45 to 55 per cent of the calories from carbohydrate, 12 to 15 pr cent from protein, and 30 to 40 per cent from fat will meet the athlete's needs.(ABSTRACT TRUNCATED AT 400 WORDS)

Attitude to Health↗
PubMed1981

Nutritional status of elderly participants in a congregate meals program.

This study was conducted to determine the nutritional status of elderly subjects participating in a congregate meals program. Twenty-four-hour recalls, anthropometric measurements, and biochemical determinations were the criteria used to determine nutritional status of the 30 volunteers. Information regarding use of dietary supplements was also obtained. Ninety-three percent of the participants consumed diets providing at least 70 percent of the RDA for the 13 nutrients calculated. Seven percent consumed diets rated as "poor," but none of the participants consumed diets supplying less than 54 percent of the RDA. Twenty-seven percent of the sample reported daily use of dietary supplements. Height, weight, mid-arm circumference, triceps skinfold, and abdominal circumference were measured. The incidence of obesity was high, with 42 percent of the women and 78 percent of the men being over 119 percent of ideal body weight. Mid-arm circumference, triceps skinfold, and abdominal circumference data agreed with the weight-for-height data. The incidence of obesity was greater in this study than in other studies cited, and, as was not the case in other studies, the incidence of obesity was greater in men. Biochemical determinations included hemoglobin, hematocrit, serum albumin, serum folate, ascorbic acid, and vitamins A, B6, and B12. Comparison of biochemical data with accepted standards indicated that the nutritional status of the participants was adequate.

Age Factors↗
PubMedDate not supplied

N-nitrosoproline excretion by rural Nebraskans drinking water of varied nitrate content.

The N-nitrosoproline (NPRO) test for in vivo nitrosation was applied in a study of 44 rural Nebraska men drinking high- or low-nitrate water from private wells. The subjects followed diets low in NPRO and nitrate for 5 days. On days 4 and 5 they avoided ascorbate-rich foods. Urine was collected for 24 h on day 4 while the subjects followed normal activities and on day 5 after an overnight fast and taking 500 mg L-proline. We determined NPRO, nitrate, creatinine, and specific gravity in the urines, and nitrite and nitrate in single saliva specimens collected on days 4 and 5. Results for all variables were separated into those above and below the median values and were analyzed by univariate and multivariate consideration of the contingency tables. Nitrate concentration in drinking water (> or = or < 10 ppm nitrate-nitrogen) was significantly associated with both day 4 and day 5 NPRO (> or = or < 1.5 micrograms/day; P < 0.04); and with urine nitrate (> or = or < 1.5 mmol/day), saliva nitrite (> or = or < 5 mg/liter), and saliva nitrate (> or = or < 25 mg/liter) (P < or = 0.002). Urine nitrate was significantly (P < or = 0.03) associated with both day 4 and day 5 NPRO, with odds ratios of 4.2 and 5.4, respectively. Creatinine was positively associated with NPRO on day 4 (P = 0.04). These findings, like those of a recent study in Denmark, showed an association between nitrate intake in water and NPRO formation. Their significance for people drinking high-nitrate water remains to be determined.

Adult↗
PubMedDate not supplied

Dosing time with ascorbic acid and nitrate, gum and tobacco chewing, fasting, and other factors affecting N-nitrosoproline formation in healthy subjects taking proline with a standard meal.

The N-nitrosoproline (NPRO) test measures the potential for intragastric formation of carcinogenic nitrosamines in humans. Nitrate and L-proline are administered to volunteers. Noncarcinogenic NPRO is produced by an acid-catalyzed reaction of proline (a model for ingested amines) with nitrate-derived nitrite in the stomach. It is then absorbed and excreted in the urine, which is analyzed for NPRO. We studied the effect of certain dietary and other factors on the levels of urinary NPRO. For (generally) 5 days, healthy adult subjects (mostly men) followed a diet low in preformed NPRO, nitrate, proline, and (on days 4 and 5) ascorbic acid. The tests were conducted on days 4 and 5. In the standard test, the subjects took 400 mg nitrate at 11 a.m., and at noon they ate a standard 700-calorie meal containing 500 mg proline. (In previous tests, proline was given 1 h after or between meals.) Urines were collected for 24 h, and samples were analyzed for NPRO by published methods. This standard test yielded 26 +/- 2 (mean +/- SE) nmol NPRO compared with 5 +/- 1 nmol NPRO when proline alone was taken. In variations of the standard test, NPRO yield was not significantly affected by the subjects' gender, the time at which the standard meal was eaten, the size of the meal, or the drinking of extra water after the meal. Doses of 100 and 200 mg nitrate had lesser effects on NPRO yield than did the dose of 400 mg nitrate. Nitrate (400 mg) produced the most NPRO when it was given 1 h before the meal. Fasting increased NPRO yield by 3-4 times compared to giving proline with a meal. One g of ASC given 5 or 2 h before, with, or 1 or 2 h after the meal with proline inhibited NPRO formation by mean values of 0, 71, 71, 67, and 19%, respectively. Chewing gum or tobacco for 2-3 h after the test meal did not increase NPRO formation or salivary nitrate levels, but salivary nitrite was not taken, chewing tobacco appeared to increase salivary nitrite and nitrate levels. The weak carcinogen N-nitrososarcosine (NSAR) was also detected in some tests, and the standard group showed 21 +/- 3 nmol NSAR. A high NSAR result (44 +/- 7 nmol) for women undergoing the standard test should be reexamined. We discuss applying these results to the conduct of future NPRO tests, as well as their implications for reducing the potential production of carcinogenic nitrosamines in the stomach.

Adult↗