Biomedical subjects

J T Snook

Publications and source records attributed to J T Snook.

At least 37 records · Page 2Linked to original sources

PubMed1987

Effect of a high-protein, very-low-calorie diet on resting metabolism, thyroid hormones, and energy expenditure of obese middle-aged women.

A 4-6 mo study was conducted to examine effects of a very-low-calorie, high-protein diet and realimentation on energy expenditure, resting metabolic rate (RMR), and serum thyroid hormones of obese women aged 30-54 yr. Fifteen healthy women, greater than or equal to 126% ideal body weight, were placed on the diet (420 kcal/day) and lost an average of 1.1 kg/wk until a predetermined goal weight was attained. RMR, triiodothyronine (T3), and reverse T3 decreased significantly (p less than 0.05). Thyroxine remained unchanged. Upon gradual realimentation onto solid foods, all metabolic parameters increased significantly within 5 wk toward pre-diet baseline values, but RMR (kcal/h) and T3 values remained significantly below pre-study values. Estimates of mean energy expenditure, utilizing a technique based on energy intake and body composition changes, averaged 1719 kcal/day during the diet period.

Adult↗

PubMed1987

Selenium content of foods purchased or produced in Ohio.

Approximately 450 samples of about 100 types of foods consumed by rural and urban Ohioans were analyzed for selenium. Meat, dairy products, eggs, and grain products produced in Ohio have considerably lower selenium content than corresponding products produced in high selenium areas, such as South Dakota. Retail Ohio foods with interregional distribution tended to be higher in selenium content than corresponding foods produced in Ohio. Best sources of selenium in Ohio foods commonly consumed were meat and pasta products. Poor sources of selenium were fruits, most vegetables, candies, sweeteners, and alcoholic and nonalcoholic beverages. Establishment of an accurate data base for selenium depends on knowledge of the interregional distribution of foods, the selenium content of foods at their production site, and the selenium content of foods with wide local distribution.

Food Analysis↗

PubMed1985

Effect of moderate to very low fat defined formula diets on serum lipids in healthy subjects.

Serum total cholesterol, high density lipoprotein (HDL) cholesterol, and triglyceride levels were studied in healthy male and female subjects consuming for one-week periods a diet of conventional food (CF) providing 42% of energy as fat, principally butter fat, and then in random order nutritionally complete, defined formula diets of moderate (32%) to very low (1%) fat content. Compared to CF, the formula with 32% of energy as corn oil lowered serum cholesterol by 25% and the ratio of total to HDL-cholesterol by 13%. Low (9%) and very low (1-3%) fat formulas reduced HDL-cholesterol by as much as 40%, raised the total:HDL-cholesterol ratio by about 20% and raised serum triglyceride levels by as much as 100%. When low and very low fat formulas were ingested for three weeks, these effects persisted although maximal responses occurred during the first week. These results demonstrated that a moderate fat formula diet with a high P/S ratio had a more favorable effect on serum lipid levels than various low fat formulas. Low fat conventional food diets should be studied in long-term controlled metabolic experiments before such diets are recommended to the general population for coronary heart disease or cancer prevention.

Cholesterol, HDL↗

PubMed1984

Estimation of energy expenditure and maintenance energy requirements of college-age men and women.

Data from two nationwide dietary surveys have led to the suggestion that human energy requirements have been overestimated. A 5-wk energy balance study was conducted to estimate the energy expenditure and maintenance energy requirements of 12 college-age men and women, 20 to 29 yr of age, by the factorial method and by measurement of energy intake and changes in body energy content (intake/balance technique). Mean daily energy expenditure estimated by the intake/balance technique and the factorial method, respectively, was 3081 and 3040 kcal (r = 0.90) for the male subjects and 2183 and 2283 kcal (r = 0.53) for the female subjects. Although differences between the intake/balance and factorial estimations of energy expenditure tended to be greater for individuals than groups and for females than males, the factorial method as performed in this study provided accurate estimations of energy expenditure. In addition, the estimated energy requirements of the college-age subjects in this study provide evidence to support the Recommended Dietary Allowances for energy for this age group.

Adult↗

PubMed1983

Supplementation frequency and ascorbic acid status in adult males.

This study was performed to determine if experimental subjects given ascorbic acid (AA) in a 240-mg dose every 4 days maintain blood levels of AA similar to levels of control subjects given 20 mg three times per day. All subjects ingested foods providing 6 to 7 mg AA/day but adequate in other nutrients. Mean serum AA for all subjects was 1.26 mg/dl initially indicating a habitual AA intake of over 100 mg/day. After 32 days on 66 mg AA/day, mean serum AA of control subjects remained below 0.7 mg/dl. After the first depletion period experimental subjects had significantly lower (p less than 0.05) serum AA than control subjects (0.74 versus 1.02 mg/dl). By the third depletion period experimental subjects adjusted to the less frequent dosage such that serum levels of AA were not lower. They were sometimes significantly higher (p less than 0.05) 1 day after the 240-mg dose. Experimental subjects had similar or higher mean white blood cell AA throughout the experiment. White blood cell AA was significantly (p less than 0.05) and negatively correlated with white blood cell count (r = -0.65) Results suggest that subjects adjust to receiving supplements of AA on a periodic basis at least under the conditions imposed in this study.

Adult↗

PubMed1983

Selenium status of a rural (predominantly Amish) community living in a low-selenium area.

Selenium intake and blood selenium and selenium-dependent glutathione peroxidase concentrations were assessed in a rural, 71% Amish, sample of residents in a region with low availability of soil selenium and in urban (Columbus, OH) residents. Subjects were interviewed (24-h dietary recalls) on three separate occasions over an 18-month period, and blood and food samples were taken for analysis (maximum subject observations = 452). Mean selenium intake of the entire population was 82.8 +/- 4.4 micrograms/day. Rural and urban residents at 82.0 +/- 4.9 and 83.6 +/- 4.4 micrograms/day, respectively, did not differ significantly in intake. A breakdown by gender within location demonstrated that rural males consumed the most selenium (104.7 +/- 6.1 micrograms/day) and rural females the least (59.3 +/- 6.3 micrograms/day). Rural subject groups had significantly lower mean whole blood, plasma, and erythrocyte selenium levels (12.5 to 14.5%) as well as blood selenium-dependent glutathione peroxidase concentrations (5.6 to 10.8%) than urban groups. Subjects in both cohorts were in adequate selenium status as judged by blood parameters, even though about one-fourth of the dietary observations were below the safe and adequate range of selenium intake established by the Food and Nutrition Board. The rural diet was 18.3% lower in selenium density than the urban diet. High selenium grain products (greater than 0.2 micrograms/g) were the most important dietary selenium source in both groups, providing 29.3 to 41.6% of total intake.

Adolescent↗

PubMed1975

Effect of age and long-term diet on exocrine pancreas of the rat.

Effects of age and long-term nutritional treatment on pancreas composition and digestive function were determined in rats fed a cereal-type chow after weaning (experiment 1) or diets with 30% casein and 34% butterfat, 54% starch, or 54% sucrose after 9 mo (experiment 2). The rats were adapted for 1-2 wk to a 15% whole-egg protein diet before killing. In experiment 1, pancreas size, nucleic acid, and digestive enzyme content increased significantly with age up to 3 mo. Values for pancreatic weight and DNA were significantly greater in 28-mo-old rats than in 12-mo-old rats. Pancreatic digestive enzyme content was 65-100% lower in rats with and without gross pathologic lesions. In experiment 2, mortality was higher and pathologic changes were more pronounced by 24 mo in rats fed the butterfat or sucrose diet. Usually, pancreatic enzymes were not reduced as much as in experiment 1, although chymotrypsinogen and trypsinogen concentrations were significantly and negatively correlated with the degree of pathologic change. Apparent digestibility of dietary nitrogen and food energy content was not reduced in rats with reduced enzyme reserves. The rate of incorporation in vitro of label into pancreatic protein and RNA did not differ significantly among aged and control rats.

Age Factors↗

PubMed1974