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Biomedical subjects

K D Lawson

Publications and source records attributed to K D Lawson.

11 recordsLinked to original sources
PubMed1997

Comparison of olestra absorption in guinea pigs with normal and compromised gastrointestinal tracts.

Female guinea pigs (12/group) were given a single dose of [14C]olestra by gavage after consuming either 3% poligeenan in tap water (Compromised group) or just tap water (Normal group) for 5 weeks. A Sentinel group (N = 2) was given 3% poligeenan for 5 weeks. Ten sentinel animals were killed 1 day before and 10 1 day after the other animals were dosed with [14C]olestra and their gastrointestinal tracts were examined by histology. The Compromised and Normal animals were endoscoped just before dosing with [14C]olestra. Urine and feces were collected continuously and CO2 was collected for 7 days after dosing. The samples were analyzed for 14C and urine was also analyzed for [14C]sucrose. Animals (3/group) were killed 1, 3, 7, and 21 days after dosing, and tissues were collected and assayed for 14C. Tissue lipids were extracted, fractionated by high-pressure liquid chromatography, and analyzed for [14C]olestra by liquid scintillation. Animals fed poligeenan showed mucosal edema, congestion, ulceration, and fibrin deposition within the distal colon and rectum. Histology revealed inflammation, epithelial degeneration, and multifocal ulceration of the cecum, distal colon, and rectum. The gastrointestinal mucosae of nonpoligeenan fed animals were normal. No [14C]olestra was detected in liver lipids and no [14C]sucrose was found in the urine for any animal in the Normal or Compromised groups, indicating that intact olestra was not absorbed. The amount, distribution, and elimination of absorbed 14C did not differ between guinea pigs with normal and compromised gastrointestinal tracts. The poligeenan-treated animals displayed mucosal damage similar to that seen in human inflammatory bowel diseases; therefore, these results suggest that patients with inflammatory bowel conditions will not absorb olestra to any greater extent than normal healthy people.

Administration, Oral↗
PubMed1997

Assessment of the nutritional effects of olestra, a nonabsorbed fat replacement: introduction and overview.

Olestra is a mixture of polyesters formed from sucrose and fatty acids derived from edible fats and oils. It is not absorbed or digested and can serve as a zero-calorie replacement for dietary fat. Because olestra is lipophilic and not absorbed, it has the potential to interfere with the absorption of other dietary components, especially lipophilic ones, when it is in the digestive tract with those components. A series of studies were conducted in the domestic pig and in healthy adult humans to define the nature and extent of olestra's effect on fat-soluble vitamins, selected water-soluble micronutrients, and macronutrients, and to demonstrate that the effects of olestra on the absorption of fat-soluble vitamins can be offset by adding extra amounts of the affected vitamins to olestra foods. Before conducting the human and pig studies, the intake of olestra from the consumption of snack foods made with olestra was estimated for various subgroups. The potential for olestra to affect the absorption of nonessential but potentially beneficial dietary phytochemicals was also assessed. In addition, an assessment of how consumption patterns influence the effect of olestra on the absorption of the highly lipophilic carotenoids was made. Finally, the results from the pig and human studies were used to assess the potential for olestra to affect the nutritional status of subgroups of the population who have particularly high nutrient needs or unique dietary patterns that may lead to large olestra-to-nutrient intake ratios.

Adult↗
PubMed1997

Assessment of the nutritional effects of olestra, a nonabsorbed fat replacement: summary.

Olestra is a zero-calorie fat replacement intended to replace 100% of the fat used in the preparation of savory snacks. Olestra can affect the absorption of other dietary components, especially highly lipophilic ones, when ingested at the same time. The potential effects of olestra on the absorption of essential fat-soluble and water-soluble dietary components have been investigated in pigs and in humans. In these studies, subjects were fed daily amounts of olestra up to 10 times the estimated mean intake from savory snacks and the olestra was eaten each day of the studies. In real life, snacks are eaten on average five times in a 14-d period. Olestra did not affect the availability of water-soluble micronutrients or the absorption and utilization of macronutrients. Olestra reduced the absorption of fat-soluble vitamins A, D, E and K; however, the effects can be offset by adding specified amounts of the vitamins to olestra foods. Olestra also reduced the absorption of carotenoids; analysis of dietary patterns showed that in real life the reduction will likely be <10%. Any effect on vitamin A stores caused by a reduction in carotenoid uptake is offset by the addition of vitamin A to olestra foods. Because of the olestra-to-nutrient ratios fed and the nutritional requirements of the test subjects, the effects of olestra on nutritional status of subgroups of the population are unlikely to be different than those measured in the studies. An analysis of lipophilicity showed that olestra is unlikely to significantly affect the uptake of potentially beneficial phytochemicals from fruits and vegetables. Some people eating large amounts of olestra snacks may experience common GI symptoms such as stomach discomfort or changes in stool consistency, similar to symptoms accompanying other dietary changes. These symptoms present no health risks.

Animals↗
PubMed1997

Olestra, a nonabsorbed, noncaloric replacement for dietary fat: a review.

Olestra has been shown to be safe for its intended use by extensive testing in animals and in humans. It is not digested or absorbed and has no effect on the structure or physiology of the GI tract, the only organ of the body that it contacts. Olestra can interfere with the absorption of other lipophilic substances from the GI tract. The interference occurs because a portion of those molecules that are sufficiently lipophilic partition into the nonabsorbed olestra and is carried out of the body. Whether olestra will interfere with the absorption of a specific molecule can be predicted from the octanol-water partition coefficient of the molecule, a parameter that can be measured or calculated from a knowledge of the structure of the molecule. Olestra does not affect the absorption or efficacy of oral drugs because, in general, they are not sufficiently lipophilic to partition into the olestra. Olestra does not affect the absorption of water-soluble micronutrients or the absorption and utilization of macronutrients. Olestra can reduce the absorption of the fat-soluble vitamins when olestra foods and the vitamins are coingested. These effects can be offset by adding specific amounts of the vitamins to foods made with olestra. Other than the carotenoids and vitamins A and E, olestra does not affect the absorption of potentially beneficial components of fruits and vegetables. The effects on the vitamins can be offset by adding the vitamins to olestra foods. The reduction in the absorption of carotenoids will be less than 6-10% when olestra snacks are eaten under free-living dietary patterns. Any effect this reduction has on vitamin A status can be offset by addition of vitamin A to the foods. The absorption of flavonoids, polyphenols, and most other phytochemicals in fruits and vegetables, which have been shown to provide beneficial health effects, will not be affected by olestra because they are not sufficiently lipophilic. Individuals consuming large quantities of olestra may experience mild or moderate common GI symptoms such as loose or soft stools, gas, or nausea, symptoms similar to those experienced with certain other foods or changed dietary habits. When olestra snack foods are eaten under free-living dietary patterns, the symptoms are not different from those experienced when eating full-fat snack products, in either incidence or severity. When they are experienced, the symptoms resolve in 1-2 days, but may recur. They do not worsen with continued or increased olestra consumption and pose no health risk to the consumer. Olestra products will carry an information label alerting consumers to the possibility of GI symptoms. Olestra foods provide an additional option to those individuals who want or need to lower their total energy intake and body weight. These individuals will find it easier to change dietary habits and to maintain healthful nutritional practices when they use olestra foods. For those who want or need to reduce fat intake but not lose weight, olestra foods can reduce fat intake without affecting energy. Because olestra foods have taste and other organoleptic properties that are similar to those of full-fat foods, individuals will find it easier to switch to low-fat diets.

Animals↗
PubMed1996

Disposition of ingested olestra in weanling mini-pigs.

The disposition of ingested olestra in Hanford mini-pigs was examined by following a single oral gavage dose of radiolabelled (U-14C-sucrose) olestra Eight dosed animal (four/sex) and one undosed animal were killed 1, 3 and 7 days after dosing, and tissues were collected and counted. Urine and faeces were collected continuously and counted. Tissue lipids were extracted and analysed for intact radiolabelled olestra by size exclusion chromatography. Sucrose will be excreted in urine if olestra is absorbed and metabolized. Mean recovery of radiolabel was 96.6% of the administered dose. Of the recovered radiolabel, more than 99.4%, on average, was not absorbed and found in faeces, or cage and animal wash solutions. The absorbed radiolabel (0.6%), was distributed across the carcass, all tissues and blood, or excreted in urine. This radiolabel primarily came from the metabolism of glucose and fructose resulting from the hydrolysis of the trace levels of penta- and lower sucrose esters present in the test material. No radiolabel was found in the olestra-containing fraction of liver lipids, the primary measure of absorbed and non-metabolized olestra, at a detection limit of 0.0002% of dose. A conservative estimate of the amount of 14C-sucrose excreted in the urine was 0.0012%. The total absorption of intact olestra was thus less than 0.0014% of the dose, the sum of the two measures. These results indicate that intact olestra is essentially not absorbed by the weanling mini-pig, an animal with a young developing gastrointestinal tract similar to that of young children (2-5 yr).

Administration, Oral↗
PubMed1995

Disposition of ingested olestra in the Fischer 344 rat.

Four studies were conducted in the Fischer 344 rat to determine the disposition of orally gavaged olestra. Twenty-four rats were used for each study. Three olestra samples, differing in the degree of saturation of the fatty acid chains, were tested; one sample was heated to simulate olestra's intended use in preparing fried foods. In addition, a sucrose polyester (SPE) sample containing 28% short-chain penta- and lower polyesters was tested. All test samples were uniformly labeled with 14C in the sucrose moiety. Urine, feces, and CO2 were continuously collected and counted. Urine also was analyzed for [14C]sucrose by HPLC. If olestra were absorbed and systemically metabolized, [14C]sucrose would be excreted in the urine. Rats were killed 1, 3, 7, and 21 days after dosing, and tissues were collected and counted. Tissue lipids were extracted and analyzed for intact olestra or SPE by HPLC. Less than 0.15% of the dose of 14C was absorbed from the olestra samples, and about 1.3% from the SPE sample. The disposition of the absorbed radiolabel suggested that its source was glucose and fructose resulting from the intestinal hydrolysis of short-chain penta- and lower sucrose polyesters. For rats dosed with olestra, < 8 x 10(-4)% of the dose of radiolabel was recovered in the olestra-containing fraction of lipids extracted from liver, the target organ for absorbed olestra, and no [14C]sucrose was found in urine, indications that olestra essentially was not absorbed. Heating olestra did not change this result.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

The effects of wearing diapers on skin.

Wearing dry and wet cloth and disposable diaper materials has certain effects on the degree of skin wetness. These, in turn, affect the coefficient of skin friction, the skin's susceptibility to abrasion damage, its permeability, and its support of microbial growth. These effects were explored using an adult model wearing forearm patches. The adult model was validated by comparisons of skin wetness and friction values for infants and adults determined under similar conditions. Skin wetness was proportional to diaper wetness. With increased skin wetness, there were increased coefficients of friction and increased abrasion damage, skin permeability, and microbial growth. Cloth diaper material produced wetter skin than did disposable diaper material at equivalent loadings.

Adult↗
PubMed1986

Diaper dermatitis: frequency and severity among a general infant population.

The frequency and severity of diaper dermatitis was measured among a midwestern suburban population of 1089 infants ranging in age from 1 to 20 months. No diagnosis of specific etiology was made. Fecal samples were collected and analyzed for Candida albicans, and information on family characteristics, infant diet, general health, history of rash, and diapering habits and practices was collected by questionnaire. The distribution of the severity of observed diaper rash can be described as a logarithmic-normal function, implying several multiplicative causative factors. Within the total severity range, there appear to be three subcategories of diaper rash, differing in some manner, perhaps reflecting different etiologies. The frequency of observed diaper rash was a function of the maturity of the infant, reaching a maximum around 9 to 12 months of age. The prevalence of severe rash correlated with the presence and level of fecal C. albicans. Infants diapered exclusively in disposable diapers showed less rash (P less than 0.001) than those diapered exclusively or sometimes in cloth diapers.

Age Factors↗