Evaluation of the potential for olestra to affect the availability of dietary phytochemicals

Olestra consumption does not predict serum concentrations of carotenoids and fat-soluble vitamins in free-living humans: early results from the sentinel site of the olestra post-marketing surveillance study

In 1996, the U.S. Food and Drug Administration approved olestra, a fat substitute, for use in snack foods. Previous studies had shown that olestra consumption could reduce absorption of carotenoids and fat-soluble vitamins. To determine the association between consumption of olestra-containing snack foods and serum concentrations of carotenoids and fat-soluble vitamins in a free-living population, we interviewed independent population-based cross-sectional samples of 1043 adults before olestra was available and 933 adults 9 mo after olestra snacks were introduced into the marketplace in Marion County, IN, the first major test market for olestra. A cohort composed of 403 adults from the first survey, oversampling those most frequently reporting olestra consumption during follow-up telephone interviews, completed a second survey. We assessed diet, lifestyle factors and olestra consumption, and collected blood for assays for the serum concentrations of six carotenoids, four fat-soluble vitamins and lipids. Nine months after the introduction of olestra into the marketplace, 15.5% of Marion County residents reported consuming an olestra-containing snack in the previous month, with a median frequency among consumers of 3.0 times per month. There were no significant associations or consistent trends for decreased serum carotenoids or fat-soluble vitamins associated with olestra consumption, although cohort members consuming >/=2 g/d of olestra had adjusted total serum carotenoids 15% lower compared with baseline. There were increases in serum vitamin K concentrations associated with olestra consumption (P = 0.03 in the cross section and P = 0.06 in the cohort). In summary, there was no statistically significant evidence in this free-living population of associations between olestra consumption and decreased serum concentrations of carotenoids and fat-soluble vitamins.

Olestra consumption is not associated with macular pigment optical density in a cross-sectional volunteer sample in Indianapolis

The associations between the intake of the fat-substitute olestra and the concentrations of macular carotenoid pigments and serum lutein and zeaxanthin were investigated in a volunteer cross-sectional sample in Indianapolis. The study was conducted in January through March, 1998 after olestra-containing savory snacks had been sold in central Indiana for a year. Volunteers (n = 280) aged 18-50 y were recruited to make a single clinic visit during which macular pigment optical density (MPOD) was determined by psychophysical flicker photometry, serum was obtained for determination of lutein and zeaxanthin concentration, usual intake of olestra, carotenoids and nutrients were assessed by 1-y food frequency questionnaire, and health habits including smoking, physical characteristics such as eye color, demographics and medical history were determined by questionnaire. Intake of olestra at least one time per month for the past year was reported by 81:280 subjects and their mean, median and 90(th) percentile intakes were 1.09, 0.34 and 2.43 g olestra/d, respectively. Mean macular pigment optical density was not significantly different between olestra consumers and nonconsumers (0.213 +/- 0.014 vs. 0.211 +/- 0.010) nor was serum lutein and zeaxanthin concentration (0.361 +/- 0.017 vs. 0.375 +/- 0. 013 micromol/L) or intake (1242 +/- 103 mg/d vs. 1042 +/- 58 mg/d) in one-way or two-way ANOVA. Olestra intake was not associated with MPOD or serum lutein and zeaxanthin before or after correction for significant covariates of MPOD. Thus, olestra intake over the past year in a cross-sectional volunteer sample in Indianapolis was not associated with MPOD.

Early adopters of olestra-containing foods: who are they?

OBJECTIVE

To identify the characteristics of people consuming olestra-containing foods when first introduced at a test-marketing site.

DESIGN

Data are from the Olestra Postmarketing Surveillance Study (OPMSS). After the introduction of olestra into a large test-marketing site, study participants received 3 follow-up telephone calls, at 3-month intervals, in which they were questioned about their diets during the previous month.

SUBJECTS/SETTING

1,007 adults in Indianapolis, Ind, who participated in a baseline clinic visit (before introduction of olestra into the food market) and completed at least 2 of 3 follow-up telephone calls (after the introduction of olestra into the market).

STATISTICAL ANALYSES PERFORMED

Logistic regression was used to examine associations between olestra consumption and sociodemographic characteristics, health conditions, attitudes toward health and diet, and health-related behaviors.

RESULTS

Olestra consumption on at least 1 of the follow-up telephone calls was reported by 41.5% of the study sample, and consumption on 2 or more telephone calls was reported by 20.0% of the sample. Factors associated with early adoption of olestra-containing foods included white ethnicity, higher education, overweight, absence of diabetes, attitudes indicative of diet and health concerns (e.g.; perceptions that there is a strong relationship between diet and disease), and a lower fat intake.

APPLICATIONS/CONCLUSIONS

In spite of the controversy surrounding the introduction of olestra into the food market persons with attitudes indicative of diet and health concerns were likely to be early adopters of olestra-containing foods. Dietitians and other health care providers should inquire about intake levels of foods with fat substitutes and ensure that these foods are not being consumed in excessive amounts or being consumed instead of nutrient-dense foods that are naturally low in fat.

Interaction of dietary antioxidants in vivo: how fruit and vegetables prevent disease?

Epidemiological studies indicate that fruit and vegetables are health-promoting and protective against disease, particularly cardiovascular disease and cancer. Possible plant nutrients providing this protection include antioxidants and dietary fibre. Clinical trials with antioxidant supplements give inconsistent results for protection against lung cancer in smokers, invasive cervical cancer, oesophageal and gastric cancers, colorectal polyps and coronary heart disease. The antioxidants used in trials may be contributing to a more complex system. Antioxidants have differing solubilities which partition across the phases of tissues, cells and macromolecular structures: water-soluble ascorbate, glutathione and urate; lipid-soluble tocopherols and carotenoids, and intermediatory-soluble flavonoids and hydroxycinnamic acids. The health protection provided by fruit and vegetables could arise through an integrated reductive environment delivered by plant antioxidants of differing solubility in each of the tissue, cellular and macromolecular phases.

Olestra formulation and the gastrointestinal tract

Olestra is a mixture of compounds comprising sucrose esterified with 6-8 long-chain fatty acids. It is not hydrolyzed by pancreatic lipase and as a result is not absorbed from the small intestine. Olestra in general has physical properties similar to those of a triacylglycerol with the same fatty acid composition. Foods made with olestra are virtually identical in taste and texture to those made with typical triacylglycerols. Olestra consumption does not generate hydrolytic products in the small intestine and, therefore, does not generate some of the signals that alter motility in the gastrointestinal tract. A reduction in gastroesophageal reflux with olestra, in contrast to triacylglycerols, is consistent with a lack of effect on stomach emptying. Unlike triacylglycerols that are absorbed in the proximal small intestine, olestra is distributed throughout the small intestine during transit and passes into the colon. In the colon, olestra's effects depend on its physical properties. Liquid nondigestible lipids result in separation of oil from the fecal matrix. Olestra formulations made with specific fatty acid compositions, particularly those containing a solid sucrose polyester component including behenic acid, possess appropriate rheology to hinder separation of oil from the rest of the fecal matrix, thereby reducing gastrointestinal symptoms.

Review article: olestra and its gastrointestinal safety

Olestra is a fat substitute made from sucrose and vegetable oil. Olestra is neither digested nor absorbed, and therefore adds no calories or fat to the diet. Because the gut is the only organ that is exposed to olestra, the potential for olestra to affect gastrointestinal structure and function, and the absorption of nutrients from the gut, has been investigated. Histological evaluations performed after long-term feeding studies have shown no indications that olestra causes injury to the gastrointestinal mucosa. Olestra is not metabolized by the colonic microflora, and has no meaningful effects on the metabolic function of these organisms. Studies of gastrointestinal transit have shown that the consumption of olestra with food does not affect gastric emptying, or small or large bowel transit times. Olestra does not affect the absorption of macronutrients, water-soluble vitamins or minerals. It causes a dose-responsive decrease in the availability of the fat-soluble vitamins A, D, E and K; however, this potentially adverse effect is offset by the addition of vitamins to olestra-containing foods. Olestra has no consistent effect on the amount of total bile acids excreted in the faeces, and therefore probably has no significant effect on bile acid absorption. The occurrence of gastrointestinal symptoms, including diarrhoea, loose stools, gas and abdominal cramping, after consumption of olestra under ordinary snacking conditions is comparable to that following consumption of triglyceride-containing snacks.

Chemoprevention of lung cancer: the rise and demise of beta-carotene

Beta-carotene and retinoids were the most promising agents against common cancers when the National Cancer Institute mounted a substantial program of population-based trials in the early 1980s. Both major lung cancer chemoprevention trials not only showed no benefit, but had significant increases in lung cancer incidence and in cardiovascular and total mortality. A new generation of laboratory research has been stimulated. Rational public health recommendations at this time include: 1. Five-A-Day servings of fruits and vegetables, a doubling of current mean intake; 2. systematic investigation of the covariates of extremes of fruit and vegetable intake; 3. discouragement of beta-carotene supplement use, due to adverse effects in smokers and no evidence of benefit in non-smokers; 4. multilevel research to develop and evaluate candidate chemoprevention agents to prevent lung and other common cancers; and 5. continued priority for smoking prevention, smoking cessation, and avoidance of known carcinogens in the environment.

Lycopene: chemistry, biology, and implications for human health and disease

A diet rich in carotenoid-containing foods is associated with a number of health benefits. Lycopene provides the familiar red color to tomato products and is one of the major carotenoids in the diet of North Americans and Europeans. Interest in lycopene is growing rapidly following the recent publication of epidemiologic studies implicating lycopene in the prevention of cardiovascular disease and cancers of the prostate or gastrointestinal tract. Lycopene has unique structural and chemical features that may contribute to specific biological properties. Data concerning lycopene bioavailability, tissue distribution, metabolism, excretion, and biological actions in experimental animals and humans are beginning to accumulate although much additional research is necessary. This review will summarize our knowledge in these areas as well as the associations between lycopene consumption and human health.

An indirect means of assessing potential nutritional effects of dietary olestra in healthy subgroups of the general population

The potential for olestra to affect the absorption of dietary components was measured in 18- to 44-y-old humans and the weanling pig. Results from the studies were assessed to determine if they were relevant to subgroups of the population not included in the studies. Hypothetrically, two factors that might cause the study results not to be relevant to certain subgroups are dietary pattern and metabolic need. A dietary pattern resulting in olestra-to-nutrient intake ratios greater than those tested in the studies might produce effects greater than those measured. Metabolic needs (i.e., nutrient requirements) among subgroups greater than those of the study population might mean that any effects on nutrient absorption seen in the studies would be larger among subgroups. If olestra-to-nutrient ratios and nutrient requirements of a subgroup were less than those covered in the studies, then the effects of olestra on the nutritional status of the subgroup should be no different than the effects measured in the studies. Subgroups with high olestra-to-nutrient intake ratios were identified by calculating the ratios for those nutrients assessed in the studies [i.e., macronutrients, vitamins A (including beta-carotene), D, E and K, folate, vitamin B12, calcium, iron and zinc]. Subgroups with the greatest olestra-to-nutrient intake ratios for one or more nutrients included children, teenagers and young adults, women from low income families and vegetarians. Subgroups with the greatest metabolic need for one or more nutrients included children, teenagers, and pregnant and lactating women. The olestra-to-nutrient ratios and nutrient requirements of the subgroups having the greatest ratios and requirements were compared with those of the test population. The olestra-to-nutrient intake ratios fed in the studies were greater than those for any subgroup for all nutrients except calcium, which is not affected by olestra. Metabolic needs of the test population were greater than those of all population subgroups for all nutrients. The effects of olestra on nutritional status should not be different or greater than those measured in the controlled clinical tests for subgroups not directly tested.

Olestra's effect on vitamins D and E in humans can be offset by increasing dietary levels of these vitamins

One hundred two normal healthy males and females were given 0, 8, 20 or 32 g/d olestra to which had been added graded amounts of vitamins A, D and E for 8 wk in a parallel, double-blind study. The primary purpose of the study was to determine the amounts of vitamins D and E needed to offset the effect of olestra on the availability of these vitamins. Serum concentrations of retinol, carotenoids, 25-hydroxyvitamin D metabolites, alpha-tocopherol, phylloquinone, lipids, ferritin and total iron, iron-binding capacity and hematology parameters, plasma concentrations of des-gamma-carboxyprothrombin and prothrombin, and urinary gamma-carboxyglutamic acid (Gla) excretion were measured biweekly. Clinical chemistry and urinalysis parameters, vitamin B12 absorption, and serum 1,25-dihydroxyvitamin D concentration were measured at wk 0 and 8. Serum concentrations of alpha-tocopherol and 25-hydroxyergocalciferol were restored to control concentration by adding 2.1 mg d-alpha-tocopheryl acetate and 0.06 microg ergocalciferol per gram of olestra, respectively, to the diet. Olestra reduced serum concentrations of 25-hydroxyergocalciferol, carotenoids and phylloquinone in a dose-responsive manner but did not affect Gla excretion, plasma des-gamma-carboxyprothrombin and prothrombin concentrations, overall vitamin D status, vitamin B12 absorption or iron status. Laboratory evaluations showed no olestra-related effects. Subjects in all groups reported mild to moderately severe transient gastrointestinal symptoms. These symptoms did not affect study compliance or the integrity of the data.

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.

Assessment of the nutritional effects of olestra

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.

The domestic pig as a model for evaluating olestra's nutritional effects

Experimental conditions for measuring the effect of the noncaloric fat substitute olestra on the availability of dietary nutrients were established in the weanling domestic pig. To evaluate the tolerance of the pig for dietary fat levels similar to those in the human diet, groups were fed a standard corn-soy-based swine feed with and without 14% (30% of energy) added fat for 4 wk. To evaluate the adequacy of a purified diet to produce good growth, groups of pigs were fed purified diets providing 30% of energy from fat and micronutrients at 1, 1.3 or 1.6 times the NRC's requirements for 5- to 10-kg swine. Cumulative body weight gain, digestible feed efficiency and a lack of adverse effects showed that the pig can tolerate diets providing 30% of energy from fat and that a purified diet providing the NRC's requirements for micronutrients produces growth comparable to a nutritionally complete swine feed. To determine whether tissue concentrations of vitamins A, D, E and K in the pig respond to olestra and dietary concentrations of the vitamins, two groups were fed purified diet providing 1 or 1.6 times the NRC's requirements for micronutrients and 4.8% olestra. Significant increases occurred in the serum concentration of 25-hydroxyergocalciferol and liver concentrations of retinol and alpha-tocopherol with increasing dietary concentrations of the vitamins. Olestra reduced the tissue concentrations of vitamins A, D and E. Prothrombin time was not affected by dietary concentration of either phylloquinone or olestra. To determine the amount of UV light exposure required to produce 50-80% of vitamin D status from vitamin D3, a range typical of humans, two groups of pigs were fed the NRC requirement for vitamin D and exposed to 15 or 45 min/d of UV light. Serum concentration of 25-hydroxycholecalciferol increased with increased exposure time. UV exposure of 1-2 min/d was calculated to be sufficient to produce 50-80% of total vitamin D status from vitamin D3. No antemortem observations indicated an adverse olestra effect.

Olestra dose response on fat-soluble and water-soluble nutrients in humans

Ninety normal healthy adults were given 0, 8, 20 or 32 g/d olestra for 8 wk as part of a diet that provided 1 +/- 0.2 of the recommended dietary allowance (RDA) of vitamins A, D, E and K, folate zinc, calcium and iron. In addition, a 20 microg/d supplement of vitamin D was supplied. The diet provided 15% of energy from protein, 35% from fat and 55% from carbohydrate. The purpose of the study was to determine the dose response of olestra on vitamins D, E and K, carotenoids, vitamin B12, folate and zinc. Circulating concentrations of retinol, carotenoids, tocopherols, 25-hydroxy- and 1,25-dihydroxyvitamin D metabolites, phylloquinone, des-gamma-carboxyprothrombin, prothrombin, folate and hematological parameters were measured biweekly, as were urine concentrations of zinc and gamma-carboxyglutamic acid (Gla). Clinical chemistry, urinalysis and vitamin B12 absorption were measured at wk 0 and 8. Olestra reduced serum concentrations of carotenoids, alpha-tocopherol, 25-hydroxyergocalciferol and phylloquinone in a dose-responsive manner. Olestra did not affect Gla excretion, plasma des-gamma-carboxyprothrombin or prothrombin concentrations, prothrombin time, vitamin B12 absorption, overall vitamin D status or the status of folate or zinc. Laboratory evaluations showed no health-related effects of olestra. Subjects in all groups reported common gastrointestinal symptoms such as loose stools, fecal urgency and flatulence, which were transient and generally mild to moderate in severity. These symptoms did not affect protocol compliance or the ability to measure the potential for olestra to affect nutrient availability.