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

The colloid and interface strategies to inhibit lipid digestion for designing low-calorie food

Although fat is one of the indispensable components of food flavor, excessive fat consumption could cause obesity, metabolism syndromes and an imbalance in the intestinal flora. In the pursuit of a healthy diet, designing fat reducing foods by inhibiting lipid digestion and calorie intake is a promising strategy. Altering the gastric emptying rates of lipids as well as acting on the lipase by suppressing the enzymatic activity or limiting lipase diffusion via interfacial modulation can effectively decrease lipolysis rates. In this review, we provide a comprehensive overview of colloid-based strategies that can be employed to retard lipid hydrolysis, including pancreatic lipase inhibitors, emulsion-based interfacial modulation and fat substitutes. Plants-/microorganisms-derived lipase inhibitors bind to catalytic active sites and change the enzymatic conformation to inhibit lipase activity. Introducing oil-in-water Pickering emulsions into the food can effectively delay lipolysis via steric hindrance of interfacial particulates. Regulating stability and physical states of emulsions can also affect the rate of hydrolysis by altering the active hydrolysis surface. 3D network structure assembled by fat substitutes with high viscosity can not only slow down the peristole and obstruct the diffusion of lipase to the oil droplets but also impede the transportation of lipolysis products to epithelial cells for adsorption. Their applications in low-calorie bakery, dairy and meat products were also discussed, emphasizing fat intake reduction, structure and flavor retention and potential health benefits. However, further application of these strategies in large-scale food production still requires more optimization on cost and lipid reducing effects. This review provides a comprehensive review on colloidal approaches, design, principles and applications of fat reducing strategies to meet the growing demand for healthier diet and offer practical insights for the low-calorie food industry.

Authors' financial relationships with the food and beverage industry and their published positions on the fat substitute olestra

OBJECTIVES

This study examined the association between authors' published positions on the safety and efficacy in assisting with weight loss of the Procter & Gamble (P&G) fat substitute olestra and their financial relationships with the food and beverage industry.

METHODS

Journal articles about olestra, and their authors, were classified as supportive, critical, or neutral with respect to its use. Authors not known to have industry affiliations were surveyed about their financial relationships.

RESULTS

Supportive authors were significantly more likely than critical or neutral authors to have financial relationships with P&G (80% vs 11% and 21%, respectively; P <.0001). All authors disclosing an affiliation with P&G were supportive.

CONCLUSIONS

Because authors' published opinions were associated with their financial relationships, obtaining noncommercial funding may be more essential to maintaining objectivity than disclosing personal financial interests.

The biochemistry and medical significance of the flavonoids

Flavonoids are plant pigments that are synthesised from phenylalanine, generally display marvelous colors known from flower petals, mostly emit brilliant fluorescence when they are excited by UV light, and are ubiquitous to green plant cells. The flavonoids are used by botanists for taxonomical classification. They regulate plant growth by inhibition of the exocytosis of the auxin indolyl acetic acid, as well as by induction of gene expression, and they influence other biological cells in numerous ways. Flavonoids inhibit or kill many bacterial strains, inhibit important viral enzymes, such as reverse transcriptase and protease, and destroy some pathogenic protozoans. Yet, their toxicity to animal cells is low. Flavonoids are major functional components of many herbal and insect preparations for medical use, e.g., propolis (bee's glue) and honey, which have been used since ancient times. The daily intake of flavonoids with normal food, especially fruit and vegetables, is 1-2 g. Modern authorised physicians are increasing their use of pure flavonoids to treat many important common diseases, due to their proven ability to inhibit specific enzymes, to simulate some hormones and neurotransmitters, and to scavenge free radicals.

Pharmacological approaches for the treatment of obesity

The high incidence of obesity, its multifactorial nature, the complexity and lack of knowledge of the bodyweight control system, and the scarcity of adequate therapeutics have fuelled anti-obesity drug development during a considerable number of years. Irrespective of the efforts invested by researchers and companies, few products have reached a minimum level of effectiveness, and even fewer are available in medical practice. As a consequence of anti-obesity research, our knowledge of the bodyweight control system increased but, despite this, the pharmacological approaches to the treatment of obesity have not resulted yet in effective drugs. This review provides a panoramic of the multiple different approaches developed to obtain workable drugs. These approaches, however, rely in only four main lines of action: control of energy intake, mainly through modification of appetite;control of energy expenditure, essentially through the increase of thermogenesis;control of the availability of substrates to cells and tissues through hormonal and other metabolic factors controlling the fate of the available energy substrates; andcontrol of fat reserves through modulation of lipogenesis and lipolysis in white adipose tissue. A large proportion of current research is centred on neuropeptidic control of appetite, followed by the development of drugs controlling thermogenic mechanisms and analysis of the factors controlling adipocyte growth and fat storage. The adipocyte is also a fundamental source of metabolic signals, signals that can be intercepted, modulated and used to force the brain to adjust the mass of fat with the physiological means available. The large variety of different approaches used in the search for effective anti-obesity drugs show both the deep involvement of researchers on this field and the large amount of resources devoted to this problem by pharmaceutical companies. Future trends in anti-obesity drug research follow closely the approaches outlined; however, the increasing mass of information on the molecular basis of bodyweight control and obesity will in the end prevail in our search for effective and harmless anti-obesity drugs.

Postmarketing Surveillance of New Food Ingredients: Results from the Program with the Fat Replacer Olestra

Market introduction of savory snacks containing olestra offered an opportunity to evaluate the safety of olestra in a free-living population and thereby compare the outcome to the previously established safety profile determined in clinical trials in which subjects were required to eat predetermined amounts at prescribed intervals. Therefore, a multifaceted postmarketing surveillance program was designed to evaluate consumer experience and safety of olestra in the marketplace. Customer comments were solicited through toll-free telephone numbers. Collected data were evaluated by both internal and external medical experts. About 10% of toll-free telephone calls reported health effects, most of which were gastrointestinal (GI) in nature. Clinical studies were designed and conducted to determine potential GI effects under the range of consumption patterns reported by toll-free calls. Health effects reported were those found commonly in the general population and analyses of the data found no biological reason to conclude that serious or meaningful health effects were the result of olestra consumption.

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.

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.

Identification of the major intestinal fatty acid transport protein

While intestinal transport systems for metabolites such as carbohydrates have been well characterized, the molecular mechanisms of fatty acid (FA) transport across the apical plasmalemma of enterocytes have remained largely unclear. Here, we show that FATP4, a member of a large family of FA transport proteins (FATPs), is expressed at high levels on the apical side of mature enterocytes in the small intestine. Further, overexpression of FATP4 in 293 cells facilitates uptake of long chain FAs with the same specificity as enterocytes, while reduction of FATP4 expression in primary enterocytes by antisense oligonucleotides inhibits FA uptake by 50%. This suggests that FATP4 is the principal fatty acid transporter in enterocytes and may constitute a novel target for antiobesity therapy.

Drug, meal and formulation interactions influencing drug absorption after oral administration. Clinical implications

Drug-drug, drug-formulation and drug-meal interactions are of clinical concern for orally administered drugs that possess a narrow therapeutic index. This review presents the current status of information regarding interactions which may influence the gastrointestinal (GI) absorption of orally administered drugs. Absorption interactions have been classified on the basis of rate-limiting processes. These processes are put in the context of drug and formulation physicochemical properties and oral input influences on variable GI physiology. Interaction categorisation makes use of a biopharmaceutical classification system based on drug aqueous solubility and membrane permeability and their contributions towards absorption variability. Overlaying this classification it is important to be aware of the effect that the magnitudes of drug dosage and volume of fluid administration can have on interactions involving a solubility rate limits. GI regional differences in membrane permeability are fundamental to the rational development of extended release dosage forms as well as to predicting interaction effects on absorption from immediate release dosage forms. The effect of meals on the regional-dependent intestinal elimination of drugs and their involvement in drug absorption interactions is also discussed. Although the clinical significance of such interactions is certainly dependent on the narrowness of the drug therapeutic index, clinical aspects of absorption delays and therapeutic failures resulting from various interactions are also important.

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.

A randomized, double-blind study of the effect of olestra on disease activity in patients with quiescent inflammatory bowel disease. Olestra in IBD Study Group

PURPOSE

To determine the effects of olestra, a zero-calorie fat substitute that is neither digested nor absorbed, on the well-being and disease state of persons with chronic inflammatory bowel disease (IBD) in remission.

PATIENTS AND METHODS

Eighty-nine patients with mild to moderate ulcerative colitis (n = 43) or Crohn's disease (n = 46) in remission, with a history of disease of 2 years or longer, were enrolled in this prospective study from nine private practices, three university-based medical centers, and one Veterans Administration medical center in the United States. Forty-four patients were randomly assigned to receive olestra and 45 to receive triglycerides in chips or cookies daily for 4 weeks. At Week 4, patients were classified as in remission, worsened, or relapsed according to an investigator's global assessment based on sigmoidoscopy (for ulcerative colitis) or the Crohn's disease activity index, laboratory findings, and clinical course.

RESULTS

At Week 4, the olestra and triglyceride groups did not differ significantly with respect to the percentages of patients who relapsed (P = 0.494; difference = 2.4%; upper 95% CL = 8.8%) or with respect to the percentages of patients who experienced any worsening of their symptoms (P = 0.630; difference = 0.2%; upper 95% CL = 13.3%). Of evaluable patients, 90% (37 of 41) given olestra remained in remission with no worsening, compared with 90% (38 of 42) given triglycerides. Gastrointestinal symptoms were comparable between the treatment groups, and there were no treatment-related laboratory abnormalities. Six patients were excluded from analysis for reasons unrelated to treatment.

CONCLUSION

Olestra did not affect the activity of quiescent mild to moderate IBD.

Randomized, double-blind, placebo-controlled, consumer rechallenge test of Olean salted snacks

Olestra is a zero-calorie fat substitute that is neither digested nor absorbed. A randomized, double-blind, placebo-controlled, within-subject, crossover rechallenge study was conducted to compare the occurrence of gastrointestinal symptoms after ingestion of chips made with Olean brand of olestra or conventional triglycerides in subjects who had previously experienced gastrointestinal symptoms they attributed to consuming Olean. A total of 57 male or female subjects received 2 oz of Olean potato chips or triglyceride potato chips at each of four weekly site visits. The occurrence of gastrointestinal effects after product consumption was noted in follow-up telephone interviews 3 to 5 days after each visit. There was no significant difference in the frequency of any gastrointestinal symptoms (abdominal cramping, diarrhea, loose stools) following consumption of Olean chips or triglyceride chips, and the severity of diarrhea, loose stools, and abdominal cramping was similar. We conclude that consumption of a 2-oz serving of Olean chips is no more likely to result in reports of gastrointestinal symptoms than consumption of triglyceride snacks as a part of the usual diet, even in individuals who have claimed intolerance to Olean. The data suggest that subjects who previously experienced symptoms that they attributed to consuming products made with Olean may have mistakenly attributed their symptoms to these products.

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.

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.