Static in vitro digestion model adapted to the general older adult population: an INFOGEST international consensus

Understanding the mechanisms of food digestion is of paramount importance to determine the effect foods have on human health. Significant knowledge on the fate of food during digestion has been generated in healthy adults due to the development of physiologically-relevant in vitro digestion models. However, it appears that the performance of the oro-gastrointestinal tract is affected by ageing and that a model simulating the digestive conditions found in a younger adult (<65 years) is not relevant for an older adult (>65 years). The objectives of the present paper were: (1) to conduct an exhaustive literature search to find data on the physiological parameters of the older adult oro-gastrointestinal tract, (2) to define the parameters of an in vitro digestion model adapted to the older adult. International experts have discussed all the parameters during a dedicated workshop organized within the INFOGEST network. Data on food bolus properties collected in the older adult were gathered, including food particle size found in older adult boluses. In the stomach and small intestine, data suggest that significant physiological changes are observed between younger and older adults. In the latter, the rate of gastric emptying is slowed down, the pH of the stomach content is higher, the amount of secretions and thus the hydrolytic activities of gastric and intestinal digestive enzymes are reduced and the concentration of bile salts lower. The consensus in vitro digestion model of the older adult proposed here will allow significant progress to be made in understanding the fate of food in this specific population, facilitating the development of foods adapted to their nutritional needs. Nevertheless, better foundational data when available and further refinement of the parameters will be needed to implement the proposed model in the future.

Direct contact ultrasound assisted freezing of chicken breast samples

Nowadays, rapid freezing is sought to favor the formation of small ice crystals. Several studies have shown that the application of ultrasounds (US) accelerates the processes of energy and mass transfer when they are applied through immersion systems. However, there are hardly any studies on its application in direct systems without the use of a liquid medium for its transmission. Therefore, the objective of this work was to evaluate the potential of the application of US for improving the freezing process of chicken breast samples. First, the application of intermittent US treatments at different net sonication times of 7, 17, 37, 50 and 67% during the freezing of distilled water samples in a conventional freezer was evaluated. It was observed that net sonication times of 37, 50 and 67% reduced the phase change period by 30.0, 21.4, 27.0%, respectively. The effective freezing time was also reduced by 12.4 and 12.8% by applying net sonication times of 37 and 50%. Considering these results, an intermittent US treatment with a net sonication time of 37% was chosen for chicken breast freezing in an air-forced cooling tunnel at ambient temperatures from -13 to -22 °C. The length of all the freezing phases was reduced upon application of US, leading to an overall process time reduction of approx. 11%. On the other hand, no significant differences were found either in the Water Holding Capacity (WHC) or Cooking Loss (CL) values between control and US assisted frozen chicken breast samples. Furthermore, in vitro experiments showed that US-assisted freezing did not influence protein digestibility of chicken meat samples. This study demonstrates the potential of the application of US by direct contact to favor energy transfer processes during freezing of water and chicken breasts samples. However, its effect on the quality of the frozen products should be further studied.

Depression and lack of physical activity as factors leading to higher health care utilisation

Background

Depressive symptoms and lack of physical activity (PA) often occur simultaneously, since depression, associated with listlessness can lead to lack of PA, and lack of PA, associated with poor quality of life and health satisfaction can lead to depressive symptoms. Both factors are independent risk factors for a higher health care utilisation. We aimed to assess the effects of the combination of depressive symptoms and lack of aerobic PA on the probability of using in- and outpatient health care services.

Methods

Data from 15.770 people from the nationally representative Austrian Health Interview Survey from 2014 were used for the analysis.

Results

In analysis, adjusted for socio-demographic, health related, and lifestyle-related factors, the combination of depressive symptoms and lack of PA were associated with higher odds of outpatient health care utilisation (OR: 1.43; 95%CI: 0.99-2.07) in men and (OR: 2.02; 95%CI: 1.50-2.73) in women, and with higher odds of inpatient health care utilisation (OR: 1.52; 95%CI: 1.02-2.26) in men and (OR: 1.75; 95%CI: 1.28-2.40) in women. Being affected by depressive symptoms alone showed slightly lower, and being affected by lack of PA alone showed clearly lower OR for health care utilisation compared to the combination of the two factors

Conclusions

Our results show that the combination of depressive symptoms and lack of PA are associated with a higher health care utilisation. Both factors are often neglected health hazards in the health care system and the attendance of affected people could be regarded as opportunity to address those factors properly.

Key messages

The combination of depressive symtoms and lack of physical activity lead to higher health care utilisation. Addressing those factors in the health care system properly would be a good opportunity to address those important health hazards.

Association of depression symptoms with receipt of healthcare provider advice on physical activity among US adults

BACKGROUND

Given the high burden and prevalence of depression, various guidelines underscore the role of healthcare providers in supplying advice on physical activity (PA) as a potential modifying factor influencing the incidence and severity of depressive symptoms in adults. We aimed to investigate the extent to which healthcare providers provide PA advice to adults with depressive symptoms in the US.

METHODS

Data on adults aged 20-64 years (n = 4971) in the National Health and Nutrition Examination Study between 2011 and 2016 were analysed. Depressive symptoms were assessed using the Patient Health Questionnaire and response options were categorised as "none or minimal", "mild", "moderate-severe". Receipt of PA advice from a healthcare provider was self-reported. We restricted our study sample to adults free from chronic diseases.

RESULTS

Higher odds of receiving advice to exercise were reported among adults with mild (OR = 1.7, 95% CI: 1.3-2.3) and moderate-severe depressive symptoms (OR = 1.7, 95% CI: 1.0-2.8). Furthermore, exercise advice was more commonly reported among adults who were overweight, obese, Hispanic, Asian, being insured with private insurance, with education higher than high school, and had access to a routine place for health care.

LIMITATIONS

Social and culutral aspects of overweight/obesity may prohibit generalizations. Cross sectional design does not allow for causal realtionships.

CONCLUSIONS

In the US, fewer than one in three adults experiencing symptoms of depression report having received exercise advice from a healthcare provider. Providing such advice may be a sustainable clinical strategy in reducing the incidence and severity of depression symptoms.

[Gender, socioeconomic status, and ethnicity in the context of health and migration]

This article deals with the significance of gender as a social determinant of health and questions the influence of gender roles in health-care services. In the context of worldwide migration, women and men of different ethnicity or social class meet with health-care providers in cross-cultural medical settings. This setting is a challenge for the European Region and in order to allow for diversity and gender sensitivity in health-care practice, interventions should address a range of factors. The concept of intersectionality goes beyond gender sensitivity and includes the consideration of other dimensions of difference, such as age, social class, education, and ethnicity. The interaction between these social dimensions of health shapes the health needs of patients and also influences doctor-patient communiation and social interaction.

[Health awareness as dominating impact factor on the development of overweight--a health questionnaire among the rural population of Austria]

Using a health survey among the rural population of Austria (n=12,484), risk factors for overweight and obesity are analysed. Health awareness turned out as essential mediator, which helps to promote a weight-stabilising life-style. An adverse health behaviour is often due to an unrealistic assessment of a risky overweight condition in connection with a negative attitude to reduce weight. Target groups should be informed about the clearly better health status in normal weight compared with that in overweight and obese people, in order to raise health awareness and motivate people at risk to undergo a modification of their life-style.

The channel-activating protease CAP1/Prss8 is required for placental labyrinth maturation

The serine protease CAP1/Prss8 is crucial for skin barrier function, lung alveolar fluid clearance and has been unveiled as diagnostic marker for specific cancer types. Here, we show that a constitutive knockout of CAP1/Prss8 leads to embryonic lethality. These embryos presented no specific defects, but it is during this period, and in particular at E13.5, that wildtype placentas show an increased expression of CAP1/Prss8, thus suggesting a placental defect in the knockout situation. The placentas of knockout embryos exhibited significantly reduced vascular development and incomplete cellular maturation. In contrary, epiblast-specific deletion of CAP1/Prss8 allowed development until birth. These CAP1/Prss8-deficient newborns presented abnormal epidermis, and died soon after birth due to impaired skin function. We thus conclude that a late placental insufficiency might be the primary cause of embryonic lethality in CAP1/Prss8 knockouts. This study highlights a novel and crucial role for CAP1/Prss8 in placental development and function.

[Learning about family medicine and the doctor-patient relationship: student views]

The five university institutes/units for family medicine in Switzerland are now responsible for teaching family medicine to medical students, particularly through the introductory cleckship in primary care in the 2nd year. During four half-days, the students attend the office of a family doctor and discover the characteristics of family medicine according to the definition of the World Association of Family Doctors (WONCA). This article shows how these training sessions are a profound and enriching learning experience for students. Different skills are presented and are illustrated by extracts from the reports students write at the end of the four half-days.

[Scientific research in family medicine: practitioners' experience, barriers and needs]

Scientific data from family medicine are relevant for the majority of the population. They are therefore essential from an ethical and public health perspective. We need to promote quality research in family medicine despite methodological, financial and logistic barriers. To highlight the strengths and weaknesses of research in family medicine in the French-speaking part of Switzerland we asked practitioners from this region to share their experience, critics and needs in relation to research. This article summarizes their contribution in light of the international literature.

[Chronic pain patients and their expectations towards physician care. Results from the Austrian Patient Report]

BACKGROUND

The Austrian Patient Report illustrates the preferences of Austrian chronic disease patients for the first time.

MATERIAL AND METHODS

A standardised, self-administered questionnaire was used with items in the fields of general information, information flow, medicine and health, social and societal aspects and statistics.

RESULTS

The most important item for Austrian chronic pain patients is a comprehensive discussion with their physician, which is even more important than a reduction in pain intensity.

CONCLUSIONS

More efforts have to be made to educate and inform chronic pain patients adequately from the doctor's side.

[Diabetes and research in primary care: how to improve the care of our patients?]

Family practitioners are well aware of the guidelines for diabetic care yet they often find it difficult to apply them in practice. Experience from the literature as well as our own research provide guidance on ways to address this problem in Primary care: 1) collaboration with a nurse practitioner for the prevention of micro and macro-angiopathic complications, 2) the use of motivational interviewing techniques to motivate patients to lifestyle changes, 3) multidisciplinary collaboration (with specialists, nurses, colleagues, pharmacists, etc) and the support of information technology. Research within the Swiss academic institutes of Primary care should provide further, more concrete, guidance on ways to apply these different options in Switzerland to improve the quality of care for diabetic patients.

Prevalence of self-reported neuropathic pain and impact on quality of life: a prospective representative survey

BACKGROUND

Data on the incidence of neuropathic pain (NeP) in Austria, its general characteristics and consequences for the quality of life (QOL) are still lacking. The prevalence in the United Kingdom is 8%.

METHODS

A representative survey (n=7707) was carried out. Patients with NeP were identified using previously validated criteria and subsequently asked to complete a questionnaire on QOL and detailed pain characteristics.

RESULTS

The prevalence of NeP was 3.3% (n=260). A higher prevalence was found in 41-50-year-olds (26%) and 51-60 year olds (24%). Pain was long lasting (>1 year: 66%; >5 years: 41%) and severe at onset (mean 6.8; numerical rating scale) as well as later (mean 4.7; 20% 8 or higher). Strong or predominant restriction of daily activities was reported in 65%, strong or predominant sleep disturbances in 60%, feelings of depression in 34% and anxiety in 25%.

CONCLUSION

For the first time, data on the prevalence of NeP in Austria are available. Pain patterns in those affected are characteristic and impact on QOL as well as pain intensity are severe.

Effects of socio-demographic variables on health-related quality of life determined by the quality of life index--German version

STUDY OBJECTIVE

The purpose of this study was to determine subjective health-related quality of life (HRQoL) in a sample of the Austrian population over 14 years of age in order to evaluate the effect of socio-demographic variables on HRQoL.

DESIGN/SETTING

HRQoL was determined by means of the quality of life index-German version (QLI-Ge). The influence of socio-demographic variables on HRQoL was assessed by statistical analysis using the Kruskal-Wallis test and an analysis of variance.

PARTICIPANTS

A random-quota procedure was used to get balanced representation from regions and demographic groups of the Austrian population. The sample consisted of 1049 participants, 493 men and 556 women.

MAIN RESULTS

Age was found to influence the QLI-Ge total score (index score) and most individual items, with increasing age resulting in a decrease in HRQoL. Differences between the sexes were observed in three dimensions: males scored higher in 'physical well-being', 'psychological well-being' and 'occupational functioning'. Marital status impacted most items with married persons showing better values than divorced persons or singles. Profession had only a minor effect on HRQoL, the level of education showed no influence at all.

CONCLUSIONS

The socio-demographic variables age, sex and objective living conditions had a major influence on subjectively rated HRQoL, whereas profession and education were found to play a minor role in this context. It is recommended that in the interpretation of studies assessing HRQoL the above-mentioned objective factors be considered. This will be of particular importance when determining the effect of a pharmacotherapy on HRQoL in patients.

Work-site hypertension prevalence and control in three Central European Countries

Compared to Austria, cerebrovascular stroke (CVS) mortality is three times higher in Hungary, and twice as high in Slovakia. We hypothesized that this is due to better treatment and control of hypertension in Austria. To test this hypothesis, we carried out a cross-sectional survey of 'blue collar' employees on work sites in each of these countries. Blood pressure screening was carried out at three work sites in Austria, one in Hungary and one in Slovakia. A standardized protocol was followed in each of these countries. The Bp-TRU(TM) measuring instrument was used to provide accurate reproducible readings and eliminate interobserver error. After the exclusion of missing data and women, the study population included 323 males screened in Austria, 600 in Hungary, and 751 in Slovakia. The mean ages of the respondents ranged from 35 to 42 years. The prevalence of hypertension was 29% in Austria, 28% in Hungary and 40% in Slovakia. Of those identified as hypertensive, 73% in Austria, 45% in Hungary and 67% in Slovakia were newly diagnosed as a result of this screening. Of those treated for hypertension, 10% in Austria, 15% in Hungary and 5% in Slovakia were controlled. The differences in CVS mortality cannot be explained by better control of hypertension in Austria but indicate the involvement of other determinants.

[Social medicine aspects of the aging man]

The potential for good health is largely dependent on the prevention and reduction of early onset of fatal disease and death. The male population, in particular, is at risk from early onset of fatal disease and death. Prevention strategies must be developed in order to reduce the risk factors leading to the currently most common causes of death (heart disease, cancer, accidents). Due to the increase in life expectancy, however, other illnesses generally affecting the elderly population (osteoporosis, dementia, cancer, heart attack, incontinence etc.) are gaining in significance. The above average reduction in life expectancy in men can be counteracted particularly through preventative measures and the active promotion of good health. In particular risk factors, such as, smoking, overweight, high blood pressure and metabolic disease, are responsible for the high mortality rate in men. New research areas must be defined for the male population, which particularLy focus on the ageing male. In the field of age related illness, gender specific investigations are definitely required. The main focus has to be on therapy and prevention of those diseases and their subsequent debilitating effects, that commonly effect the elderly. Particularly with men there is still a deficit of information with regards the role of hormones and their relationship with andropause and ageing.

Classification of endocardial electrograms using adapted wavelet packets and neural networks

The discrimination of ventricular tachycardias with 1:1 retrograde conduction from sinus tachycardia still remains a challenge for rate based algorithms commonly used in dual-chamber implantable cardioverter defibrillators. Morphology based analysis techniques for a classification of antegrade and retrograde atrial activation patterns can be used to cope with this problem. Here time-domain template matching techniques are known approaches. However, a time-domain representation of endocardial electrograms is not optimal for classification tasks as the dimensionality of the underlying signal space is high and features being irrelevant for a signal characterization are involved in the analysis. Therefore, the aim of this study is to develop an enhanced morphological analysis tool for a classification of antegrade and retrograde atrial activation by using a transform domain representation of endocardial electrograms. For this, we applied an adapted wavelet-packet decomposition to extract discriminating features in endocardial electrograms representing antegrade and retrograde activation patterns. Further, a feed-forward neural network was utilized to produce a classification based on the extracted information. In using our hybrid method, no false classification of the physiological and pathological cardiac state was made. It is concluded that the proposed classification scheme represents a highly efficient approach for a classification of antegrade and retrograde atrial activation.

Body weight: the male and female perception

The aim of the present study was to examine the relationship between actual body weight, characterization of one's weight, and satisfaction with it. 246 students of medicine in the third (clinical) stage of their studies at the University of Vienna responded to a questionnaire asking about their weight and attitudes regarding their personal body weight. The results indicate that many young women and men are either unable to characterize their weight (as normal, underweight, overweight, or obese) or guess incorrectly. The results point to the fact that a lot of women and men do not estimate their body weight in correspondence to the valid definition of the BMI. Women in particular seem to model themselves more on the current beauty ideal than men. Women seem to be more influenced by the current ideal of slenderness than their male counterparts. Women are more frequently dissatisfied with their weight, and see themselves as considerably heavier than they actually are. Because of this perception, women attempt to reduce weight more often than men. This type of dissatisfaction with one's body weight and excessive attention paid to body image, particularly weight, are considered as risk factors for the development of eating disorders. Not surprisingly, women are significantly more prone to these conditions than are men.

Nocturnal sleep-disturbing nicotine craving: a newly described symptom of extreme nicotine dependence

In our research on smoking and nicotine dependence we have noticed a sleep disturbance, which is a further symptom of extreme nicotine dependence. We call this symptom "nocturnal sleep-disturbing nicotine craving" (NSDNC). NSDNC is characterised by craving for cigarettes during the individual sleep times. The smoker awakes (one or several times per week) during his regular sleep time, and has to smoke a cigarette before he/she continues sleeping. This symptom can be explained by the decreasing nicotine levels during the sleep time, which results in nicotine craving. However, NSDNC should be carefully separated from other sleep disturbances, or sleep disturbing events (nycturia, medication side effects), when nicotine craving is not the main reason for awakening.

[Treatment of coronary risk factors by general practitioners in Austria]

Aim of the study was to investigate attitudes and practice of coronary prevention in offices of general practitioners and internists. 67 Austrian physicians took part in a mail survey focussing on hyperlipidemia. 96.6% of participating physicians recommend dietary intervention at least at total cholesterol levels of 250 mg/dl, 98.0% prescribe lipid-lowering drugs at least at total cholesterol levels of 300 mg/dl. At corresponding levels of total/HDL cholesterol ratios and especially at corresponding levels of LDL-cholesterol the proportion was lower. On average 37.9% of physicians spend up to 5 minutes for patients with hyperlipidemia, 10.3% spend more than 15 minutes. The time frame is similar in overweight patients, and bigger in patients with hypertension and diabetes. Dietary therapy is estimated similarly successful in patients with hyperlipidemia and overweight, but estimated more successful in patients with hypertension and diabetes. Drug therapy of hyperlipidemia is estimated more successful than in overweight and diabetes, and worse compared with hypertension. Main measures for improving prevention are more time and specific postgraduate education. The majority of physicians feel that within the last five years quality has improved both in the outpatient and the inpatient care.

N-CPAP rejecters--a specific group of noncompliant patients with obstructive sleep apnea syndrome

A large number of studies have been focused on patients with severe obstructive sleep apnea syndrome (OSAS) being non-compliant with N-CPAP therapy, but data concerning patients who reject N-CPAP therapy from the very start, without a day of N-CPAP home therapy, do not exist. The purpose of the study was to determine differences, if any, in the quality of life (QoL) between patients rejecting N-CPAP therapy from the start, untreated patients with severe OSAS waiting for N-CPAP titration, and controls. Qol was measured in terms of life satisfaction on the basis of the Munich life quality dimension list (MLDL), an instrument for cognitive assessment of elementary components (physical condition, psyche, social life, everyday life) of QoL. Untreated patients (n = 16) with severe OSAS have a significantly worse QoL in the dimension of psyche (p = 0.00022), social life (p = 0.00582) and everyday life (p = 0.01633) than do rejecters of therapy (n = 19). In the dimension of physical condition, no significant difference was seen (p = 0.47138). Compared with controls (n = 113), rejecters of therapy have a significantly lower QoL score in regard of physical condition (p = 0.00014) but not in terms of psyche, social life and everyday life. We conclude that a good QoL and the absence of the stress of suffering is one reason why patients with severe OSAS reject N-CPAP therapy in spite of physical impairment.

[Primary prevention from the viewpoint of social medicine--examples of prevention projects]

Life style factors play an essential role in etiology and prognosis of cardiovascular diseases; therefore, from a public health point of view, primary preventive measures are of especial importance. Health reports in the form of specific health reports (such as the Viennese Men's Health Report, the Lower Austrian Public Health Report) represent an important foundation for the matter of health promoting projects. In Austria, various preventive projects were suggested and successfully carried out because of these reports. Furthermore, the introduction of the WEBS organisation (scientific dietary counselling service) has shown that professional dietary counselling can indeed induce a change for the better in dietary behaviour and selection of foodstuffs. By the establishment of the first Austrian Institute for the Treatment of Tobacco and Nicotine Addiction (Nicotine Institute Vienna) not only is the diagnosis and treatment of tobacco addiction ensured, but it also provides information for the populace and those active in the health sector. These social public projects provide a valuable contribution to the prevention of cardiovascular diseases.

Factors delaying treatment of acute myocardial infarction

The study was set up to investigate factors delaying treatment of acute myocardial infarction. Nine hundred and sixty-seven Austrian physicians submitted data on their most recent case of myocardial infarction in a cross-sectional study. Mean time for seeking medical care was 111 min from onset; mean admission time to the hospital was 136 min. The degree of anxiety and fear perceived by the patient was positively associated with an earlier decision. Adjusted means of decision time according to degree of fear ranged from 29 to 133 min, adjusted means of admission time from 77 to 153 min. Decision time and admission time were negatively associated with the presence of typical symptoms and a history of myocardial infarction. Adjusted means of decision time according to symptom-history category ranged from 75 to 134 min, adjusted means of admission time from 110 to 151 min. Admission time was also higher in men when patients lived alone, and if the journey to the hospital was a 40 min or more car drive (i.e. 90th percentile). We conclude that measures that increase awareness in patients at risk are vital to reduce delays in seeking medical care and hospital admission, and thus to improve the prognosis of acute myocardial infarction.

Primary diffuse leptomeningeal gliomatosis (PDLG): a neoplastic cause of chronic meningitis

Cancerous 'chronic meningitis' may be related to subarachnoid space involvement by solid tumors, hematologic malignancies or rarely intraparenchymatous gliomas. Primary leptomeningeal gliomatosis is a rare condition that is attributed to malignant transformation of heterotopic neuroglial tissue. We discuss the clinical and biological features of a patient who died with the diffuse form of primary leptomeningeal gliomatosis (PDLG). A literature search shows that a one to two months long non-specific prodromal phase followed by a fluctuating neurologic downhill course is suggestive of this disease. Cerebro-spinal fluid (CSF) cytology has been diagnostic in only 1 of 8 reported cases. Recent technical progress, including the use of GFAP (glial fibrillary acidic protein) directed antibody, may enhance the sensitivity of CSF cytologies. Diagnosis may require repeated cerebral biopsies, because the hemispheric lesions are often separated by normal tissue. PDLG must be added to the large differential diagnosis of 'chronic meningitis'.

[Factors delaying therapy in myocardial infarct]

The timelag from onset of myocardial infarction to beginning of treatment is significantly correlated with prognosis, especially since introduction of thrombolytic therapy. Based on the last case of 967 Austrian physicians (general practitioners and internists, working in an office or in a hospital) we investigated possible factors delaying the beginning of treatment. On the average it took 111 minutes from onset of symptoms until the patient contacted physicians working in offices. The overall mean from onset of symptoms to hospital admission was 136 minutes. Within the hospital almost no delay was reported. Main factors for delay were repression or suppression and misinterpretation of symptoms. Thus, the biggest potential for an early onset of treatment lies within the patients response to onset of symptoms. Measures improving knowledge about mechanisms of the disease of known or possible coronary heart disease patients are most important. Side-effects, such as over-critical or demanding patients should be avoided. In any case they should not distract from the importance of measures improving patients response.

[Low-dose cytosine arabinoside (ARA-C) in the treatment of acute myeloid leukemia]

Eleven patients over 70 years of age and two patients under 60 years of age with myeloblastic leukemia have been treated with low doses of cytarabine (10 mg per m2 every 12 hours by subcutaneous injection for a median duration of 3 weeks). Four patients of the first group went into complete remission, 2 patients in the older age group and the 2 patients under 60 years of age went into partial remission, while only 3 patients out of 13 (23%) did not respond to this treatment. Sometimes severe cytopenia observed during the induction phase counterbalanced the advantages of treatment (simplicity and absence of systemic toxicity) and suggest an antimitotic effect which is probably associated with differentiation of the malignant clone.

Delay of diethylnitrosamine-induced hepatoma in rats by carrot feeding

Carcinogenesis and death caused by diethylnitrosamine(DENA)-induced hepatomas in Sprague Dawley rats can be significantly delayed by feeding only carrots for several days a week. As this result is not obtained by supplementing food with even higher concentrations of synthetic beta-carotene, there must be several other factors which--together with the carotenoid--contribute to the positive effect. Several other possibilities such as effects of fasting, direct interactions with the carcinogen, resorption, vitamin A storage in the liver, etc., are proposed and discussed.