Intestinal absorption and 25-hydroxylation of vitamin D in patients with primary biliary cirrhosis

A comparative absorption study of sucrosomial® orodispersible vitamin D3 supplementation vs. a reference chewable tablet and soft gel capsule vitamin D3 in improving circulatory 25(OH)D levels in healthy adults with vitamin D deficiency-Results from a prospective randomized clinical trial

Background

Vitamin D (Vit D) deficiency (VDD), associated with diverse health conditions, is commonly treated with Vit D3 supplements. However, the gastrointestinal (GI) absorption of Vit D3 in different formulations has not been well studied.

Objective

We aimed to compare the absorption of an innovative phospholipids-sucrester matrix biodelivery vehicle-based (sucrosomial®) orodispersible Vit D3 preparation against a reference chewable tablet and soft gel capsule (SGC) Vit D3 formulations in Vit D-deficient healthy adults.

Methods

In study 1, 25 subjects were randomized to receive a weekly single dose of 200,000 IU of sucrosomial® Vit D3 (n = 12) or chewable tablet Vit D3 (n = 13) for 3 weeks. In study 2, 20 subjects were randomized to receive a single dose of 200,000 IU every other week of sucrosomial® Vit D3 (n = 10) or SGC Vit D3 (n = 10) for 6 weeks. Circulatory 25-hydroxyvitamin D3 [25(OH)D] levels were reassessed after 2, 3, and 6 weeks in study 1 and after 4 and 6 weeks in study 2.

Results

In study 1, after 2 weeks, circulatory 25(OH)D levels increased significantly in both Vit D3 treatment groups (p < 0.0001) but improved markedly in the sucrosomial® Vit D3 group, with no further considerable change after 3 and 6 weeks in both groups. Overall, at all three follow-ups, sucrosomial® Vit D3 treatment achieved significantly higher and sustained 25(OH)D levels (p < 0.001). In study 2, after 4 weeks, both Vit D3 treatment groups showed significant improvement in circulatory 25(OH)D levels (p < 0.0001) but substantially higher in the sucrosomial® group with statistically significant differences between the two treatment groups (p = 0.02). At the 6-week follow-up, only subjects in the sucrosomial® Vit D3 group showed a further increase in circulatory 25(OH)D levels (p = 0.049), but no further significant changes in the levels of the SGC Vit D3 group (p = 0.062), showing a statistically significant difference between the two treatment groups (p = 0.002). The Vit D3 treatment was well tolerated by all participants, and no treatment-emergent effects or serious adverse events were reported.

Conclusion

Our results suggest that the sucrosomial® Vit D3 preparation absorbs efficiently in the GI system, achieving adequately higher and sustained circulatory Vit D levels in VDD, and thus can effectively contribute to the body protection against VDD-associated health conditions.

Clinical trial registration

clinicaltrials.gov, identifier: NCT05706259.

Using food fortification to improve vitamin D bioaccessibility and intakes

Vitamin D intakes and status are low in many countries due to seasonal UVB exposure variation and the fact that few foods are naturally vitamin D rich. Data modelling studies show that vitamin D intakes increase with food fortification, and countries with mandatory fortification policies have higher vitamin D intakes and status compared to countries without. While many foods can be vitamin D fortified, vitamin D bioavailability differs depending on fortification methods, food structure and composition. Randomised controlled trials (RCT) report that vitamin D2 bioavailability varies between foods, whereas vitamin D3 is bioavailable from many foods. In vitro studies suggest that altering the lipid composition of fortified foods increases vitamin D3 absorption. Olive oil increased vitamin D3 absorption during in vitro digestion compared to other dietary oils. Additionally, when vitamin D3 was incorporated into micelles formed from in vitro digestion of olive oil, more vitamin D3 was absorbed compared to other dietary oils. However, in a human postprandial study, a preformed vitamin D3 micelle dairy drink did not increase vitamin D3 absorption, and a vitamin D3 olive dairy drink increased vitamin D3 absorption in vitamin D insufficient participants only. Action is urgently needed to improve vitamin D intakes and status worldwide. Food fortification improves vitamin D intakes; however, fortification strategies unique to each country are needed. This review will synthesise the literature describing data modelling and intervention trials that assess the safety and efficacy of vitamin D fortification strategies, and those manipulating food composition to alter vitamin D bioavailability from fortified foods. Additionally, RCT examining the impact of vitamin D fortification strategies on vitamin D intakes and status over time are reviewed.

Intestinal absorption of vitamin D: a systematic review

Context

Vitamin D is frequently prescribed as a supplement, yet its absorption remains poorly understood.

Objective

This systematic review was performed to evaluate data on mechanisms involved in the intestinal absorption of vitamin D.

Data Sources

PubMed, Embase, and Cochrane Library databases were searched.

Study Selection

The following studies were included: experimental laboratory studies of vitamin D absorption through the enterocyte brush-border membrane; absorption tests that used radiolabeled vitamin D; and clinical trials in adults that investigated a single dose of cholecalciferol or ergocalciferol and reported at least 2 measurements of serum cholecalciferol, ergocalciferol, or 25-hydroxyvitamin D.

Data Extraction

From 2069 articles identified, 46 met the inclusion criteria.

Results

Different methods were employed to evaluate vitamin D absorption. Recent research suggests that vitamin D absorption is not an exclusive simple diffusion process. Vitamin D was better absorbed when it was consumed with fat-containing meals, but absorption also occurred without fat or oily vehicles. Factors that modified cholesterol absorption also altered vitamin D absorption.

Conclusion

Vitamin D is probably absorbed through passive diffusion and a mechanism involving membrane carriers, especially cholesterol transporters, although data remain scarce. Some data suggest that fat, when consumed concomitantly with vitamin D, improves vitamin D absorption.

A randomized two way cross over study for comparison of absorption of vitamin D3 buccal spray and soft gelatin capsule formulation in healthy subjects and in patients with intestinal malabsorption

BACKGROUND

Vitamin D deficiency has been proposed to contribute to the development of malabsorption diseases. Despite this, the vitamin D status of these patients is often neglected. The objective of the present work was to compare the absorption of vitamin D3 through the oral route by comparing a 1000 IU soft gelatin capsule and a 500 IU buccal spray (delivering 1000 IU in two spray shots) in healthy subjects and in patients with malabsorption disease.

METHODS

An open label, randomized, two-periods, two-way cross over study was conducted, first in healthy subjects (n = 20) and then in patients with malabsorption syndrome (n = 20). The study participants were equally divided and received either of the treatments (buccal spray, n = 7; soft gelatin capsule, n = 7; control, n = 6) in Period I for 30 days. After washout of another 30 days, the treatments were changed in crossover fashion in Period II. Fasting blood samples were collected to measure baseline 25-hydroxyvitamin D [25(OH)D] levels in all participants at day 0 (Screening visit), day 30 (completion of period I), day 60 (end of wash out and initiation of period II) and day 90 (completion of period II). Safety was evaluated by hematology and biochemistry analyses. Statistical analyses was performed using differences of mean and percentage change from baseline of 25(OH)D levels between two formulation by two tailed Paired t-test with 95% confidence interval.

RESULTS

In healthy subjects, the mean increase in serum 25(OH)D concentration was 4.06 (95% CI 3.41, 4.71) ng/ml in soft gelatin capsule group and 8.0 (95% CI 6.86, 9.13) ng/ml in buccal spray group after 30 days treatment (p < 0.0001). In patients with malabsorption disease, the mean increase in serum 25(OH)D concentration was 3.96 (95% CI 2.37, 5.56) ng/ml in soft gelatin capsule group and 10.46 (95% CI 6.89, 14.03) ng/ml in buccal spray group (p < 0.0001).

CONCLUSION

It can be concluded from the results that the buccal spray produced a significantly higher mean serum 25(OH)D concentration as compared to the soft gelatin capsule, in both healthy subjects as well as in patients with malabsorption syndrome over a period of 30 days administration in a two way cross over study. Treatments were well tolerated by both subject groups

TRIAL REGISTRATION

CTRI/2013/06/003770.

[Disorders of calcium metabolism]

The majority of clinical complaints derive from disorders of calcium metabolism and are associated with a wide variety of clinical symptoms caused by numerous diseases with entirely different types of pathophysiology. The prognosis varies from favorable to fatal depending on the pathophysiology of the underlying disorder of calcium metabolism; therefore, the diagnostic work-up aims to quickly identify the underlying disease causing the disturbance in calcium homeostasis. Every clinical situation with a diminished state of calcium absorption is treated with calcium and vitamin D in varying doses whereas every disorder with an increased calcium absorptive or resorptive state is treated with improved diuresis in addition to antiresorptive drugs, such as bisphosphonates. In many situations the management of a disturbed calcium balance requires an interdisciplinary approach in order to treat the underlying disease in parallel with correction of the calcium homeostasis.

The role of vitamin d in primary biliary cirrhosis: possible genetic and cell signaling mechanisms

Primary biliary cirrhosis (PBC) is an immune-mediated chronic inflammatory disease of the liver of unknown etiology. Vitamin D deficiency is highly prevalent in patients with PBC, and many studies have demonstrated the significant effect of calcitriol on liver cell physiology. Vitamin D has antiproliferative and antifibrotic effects on liver fibrosis. Genetic studies have provided an opportunity to determine which proteins link vitamin D to PBC pathology (e.g., the major histocompatibility complex class II molecules, the vitamin D receptor, toll-like receptors, apolipoprotein E, Nramp1, and cytotoxic T lymphocyte antigen-4). Vitamin D also exerts its effect on PBC through cell signaling mechanisms, that is, matrix metalloproteinases, prostaglandins, reactive oxygen species, and the transforming growth factor betas. In conclusion, vitamin D may have a beneficial role in the treatment of PBC. The best form of vitamin D for use in the PBC is calcitriol because it is the active form of vitamin D3 metabolite, and its receptors are present in the sinusoidal endothelial cells, Kupffer cells, and stellate cells of normal livers, as well as in the biliary cell line.

Vitamin d deficiency in patients with chronic liver disease and cirrhosis

Vitamin D is now widely recognized to have multiple extraskeletal health functions. The liver is one of the major organs involved in its metabolism. Recent studies have demonstrated a very high prevalence of vitamin D deficiency and insufficiency in patients with chronic liver disease and cirrhosis. There is an emerging interest to explore the relationship between vitamin D deficiency and prevalence and severity of non-alcoholic liver disease and response to antiviral therapy in hepatitis C. In this review, we discuss the current status of our understanding of vitamin D metabolism and vitamin D deficiency in patients with chronic liver disease and cirrhosis.

Distúrbios do eixo cálcio-PTH-vitamina D nas doenças hepáticas crônicas

Distúrbios no eixo cálcio-PTH-vitamina D são freqüentemente associados às doenças hepáticas crônicas (DHC). Já foi demonstrado que pacientes com DHC apresentam uma tendência à diminuição do cálcio e vitamina D, com aumento compensatório do PTH. Embora a diminuição da hidroxilação da vitamina D em 25 (OH) vitamina D fosse considerada o mecanismo principal destas alterações, estudos recentes vêm demonstrando que, mesmo nos estágios avançados de doença, o fígado ainda consegue manter níveis adequados de 25 (OH) vitamina D. Desta forma, outros fatores (ex: dieta inadequada, diminuição da exposição à luz solar) seriam os responsáveis pelas alterações no eixo cálcio-PTH-vitamina D. Além disso, o tratamento das DHC com glicocorticóides (fibrose cística) e ribavirina (Hepatite C) parece contribuir como agravante destes distúrbios. Por outro lado, parece ser a osteoporose, e não a osteomalácia ou o hiperparatireoidismo secundário, a principal alteração nas DHC. Assim, continua objeto de discussão o papel das alterações do eixo cálcio-PTH-vitamina D na osteodistrofia hepática.

Low body mass index and use of corticosteroids, but not cholestasis, are risk factors for osteoporosis in patients with chronic liver disease

BACKGROUND/AIMS

Metabolic bone disease is known to complicate chronic liver disease. In a cross-sectional, controlled study we have studied the prevalence of osteoporosis in patients with various types of chronic liver disease. We also identified risk factors predisposing to osteoporosis in this patient group.

METHODS

Seventy-two hospitalised patients, 46 females and 26 males, were included. Age- and sex-matched individuals from the background population served as controls. Bone mineral density was measured by dual energy X-ray absorptiometry at the lumbar spine and femoral neck.

RESULTS

Bone mineral density was significantly lower in patients with chronic liver disease than in controls at the lumbar spine (Z-score: -0.35 SD+/-1.36 vs. 0.26 SD+/-1.19, p<0.01) but not at the femoral neck (Z-score: -0.18 SD+/-1.48 vs. 0.17 SD+/-1.08, NS). Patients with cholestatic chronic liver disease did not have lower bone mineral density compared with patients with non-cholestatic chronic liver disease (Z-score: -0.35 SD+/-1.30 vs. -0.34 SD+/-1.45). Osteoporosis was found in 30% of the patients and 15% of the controls, respectively. In a multivariate regression analysis on risk factors in the patient group, the following factors were associated with osteoporosis: use of corticosteroids (odds ratio=18.9; p<0.01), low body mass index (odds ratio=14.1; p=0.001), high age and female sex.

CONCLUSION

Patients with chronic liver disease are at risk of developing osteoporosis. Risk factors for osteoporosis in chronic liver disease are low body mass index and corticosteroid therapy, in addition to high age and female sex. Cholestatic liver disease per se is not associated with an increased risk for osteoporosis.

Osteopenia in primary biliary cirrhosis and cirrhosis of the liver in women, evaluated by dual-energy X-ray absorptiometry

To study bone involvement in primary biliary cirrhosis (PBC), we used dual-energy X-ray absorptiometry to measure bone mineral density (BMD) in Japanese women with PBC and with cirrhosis of the liver. In both groups, in each decade up to 60 years of age, the mean BMD of the lumbar spine was not significantly different from that in healthy Japanese women; however, in patients aged 60 years or more, the level was significantly lower both in the patients with PBC (P < 0.001) and in those with cirrhosis of the liver (P < 0.01). Patients with PBC were also examined by single-photon absorptiometry. The BMD of the radius in the patients with PBC was less changed than that of the lumbar vertebrae; thus, the bone changes in PBC seem to be greater in spongy than in cortical bone.

Fat soluble vitamins in liposomes: studies on incorporation efficiency and bile salt induced vesicle disintegration

A systematic investigation has been undertaken to study the possible role of liposomes in facilitating the absorption of fat soluble vitamins (FSV) after oral administration in situations where FSV absorption is impaired. Conditions for the optimal incorporation of vitamins A, D3 and E individually or in combination, into multilamellar liposomes composed of egg phosphatidylcholine, dipalmitoyl phosphatidylcholine or distearoyl phosphatidylcholine (total vitamin to phospholipid molar ratios of 0.5:1, 0.75:1 and 0.9:1) have been studied. When two or three FSVs were incorporated simultaneously, FSV molar ratios used were based on the daily allowances (RDA) recommended for human males by the US Food and Nutrition Board. [Monitoring of FSV incorporation was carried out by the assay of 3H radioactivity (vitamins D3 or E, incorporated either individually or together with vitamin A), fluorometrically (vitamin A) or by an HPLC method developed in the present study for the assay of all three FSV simultaneously.] Incorporation yield of FSV used alone or in combination was found to decrease with increasing total vitamin to phospholipid molar ratio and to broadly depend on the phospholipid used. Although a vitamin to phospholipid molar ratio of 0.5:1 was found optimal in terms of percent vitamin incorporation (up to about 94% of the amount used), greater absolute amounts of FSV were recovered in most of the formulations with higher molar ratios. Moreover, when two or three FSV were incorporated simultaneously, amounts recovered with liposomes were reasonably similar to the RDA used initially.(ABSTRACT TRUNCATED AT 250 WORDS)

Has smoking changed the epidemiology of ulcerative colitis?

The influence of smoking on the risk of developing ulcerative colitis is well documented. Compared with lifetime non-smokers, the risk is reduced in smokers and increased in ex-smokers. During the past 50 years general smoking habits have changed considerably. The proportions of smokers and ex-smokers among men and women have undergone significant changes and, consequently, probably also their risk of ulcerative colitis. A review of 56 earlier epidemiologic studies of ulcerative colitis from 1930 to 1990 showed that the sex distribution in ulcerative colitis has changed from an earlier female predominance that has now been replaced by a male predominance. In contemporary pediatric studies no such changes were seen. We propose that these changes in adults are not related to the disease per se but to an extrinsic factor affecting adults but not children--namely smoking.

In micronodular cirrhosis, hepatocytes retain a normal C-25 hydroxylation capacity toward vitamin D3: a study using the rat carbon tetrachloride-induced cirrhotic model

To test further the competence of the cirrhotic liver to metabolize vitamin D3 at C-25, hepatocytes were isolated from controls and from CCl4-induced cirrhotic rat livers, as well as from partially hepatectomized rats. The transformation of D3 into 25-hydroxyvitamin D3 was studied in the presence of 10(7) hepatocytes at D3 concentrations of 20 nmol/L to 15.4 mumol/L. Histologically, micronodular cirrhosis was present in all CCl4-treated rats, whereas controls had normal livers; portal venous pressure (p less than 0.008) and intrahepatic collagen content (p less than 0.0001) were significantly increased in CCl4-treated rats, whereas no difference was found between the two groups in the total and ionized serum calcium, D3 metabolites, ALT, AST and alkaline phosphatase. Cytochrome P-450 was 0.27 +/- 0.02 and 0.25 +/- 0.02 nmol/10(6) hepatocytes in controls and cirrhotic rats (N.S.), and it significantly increased in both groups after phenobarbital or 3-methylcholanthrene administration (p less than 0.0001). 25-Hydroxyvitamin D3 formation was best described by power law equations and varied between 0.02 +/- 0.0004 and 29.57 +/- 2.8 in controls, and 0.024 +/- 0.0004 and 32.0 +/- 7.0 pmol.hr-1.10(6) hepatocytes-1 in cirrhotic rats. No statistically significant difference was found in the slopes of the 25-hydroxyvitamin D3 formation, but the y-axis intercept was found to be lower in cirrhotic rats under basal resting conditions (p less than 0.005). Inducers of the mixed function oxidases significantly increased 25-hydroxyvitamin D3 formation in controls as well as in cirrhotic rats (p less than 0.005). Moreover, both groups were found to respond similarly to the addition of modulators of the enzyme such as the calcium ionophore A23187 and parathyroid hormone. Partial hepatectomy was also without effect on the activation of D3. Furthermore, the cell sequestration of D3 was also found to be unperturbed in hepatocytes obtained from either cirrhotic or partially hepatectomized livers. The data indicate that in well-compensated micronodular cirrhosis, the C-25 hydroxylation of D3 is generally intrinsically normal at the cellular level and that it also remains fully responsive to in vivo and in vitro modulators of its activity.

Absorption of a pharmacological dose of vitamin D3 from two different lipid vehicles in man: comparison of peanut oil and a medium chain triglyceride

The absorption of a pharmacological dose of vitamin D3 from two different lipid vehicles, peanut oil, containing long chain fatty acids, and a medium chain triglyceride was compared. Serial measurements of the serum concentration of vitamin D3 after dosage were made. The serum levels of 25-hydroxyvitamin D3, the major circulating vitamin D3 metabolite, were also determined. The analytical methods used were based on HPLC. In the fasting state, the serum levels of vitamin D3 were significantly higher after administration in peanut oil than after administration in the medium chain triglyceride. When the vitamin D3 dose was ingested together with food no difference between the two formulations was observed. Only small inter-formulation differences in serum 25-hydroxyvitamin D3 levels were detected. The results indicate that the presence of long chain fatty acids facilitates the absorption of vitamin D3.

Vitamin D, parathyroid hormone, and bone mineral content of lumbar spine and femur in primary biliary cirrhosis

In order to elucidate the pathogenesis and degree of osteopoenia in primary biliary cirrhosis (PBC) we conducted a cross-sectional study of 47 non-selected female patients with biopsy-proven PBC. Bone mineral content (BMC) of the lumbar spine, femoral neck and femoral shaft was determined using dual photon absorptiometry. Compared to healthy females of corresponding decades the PBC patients exhibited significantly decreased mean BMC-values in lumbar spine (88%, P less than 0.05) and femoral neck (92%, P less than 0.05) but not in femoral shaft (96%, NS). Bone mineral content was not significantly associated with duration of liver disease, impairment of liver function (serum concentrations of albumin, clotting factors II + VII + X, bilirubin, alkaline phosphatase galactose elimination capacity or histology), variables reflecting calcium homeostasis (serum concentrations of ionized calcium, parathyroid hormone, vitamin D binding protein, 25-hydroxy vitamin D3 and 1,25-dihydroxy vitamin D3) or previous treatment with glucocorticosteroids. In view of our negative findings we suggest that future studies in this field should focus on physical activity and female sex hormones as determinants for the prevention of osteopoenia in females with primary biliary cirrhosis.

Bone disease in chronic childhood cholestasis. I. Vitamin D absorption and metabolism

Metabolic bone disease is common in children and adults with chronic cholestasis. We evaluated baseline vitamin D (vitamin D2 and D3), 25-OH vitamin D2 and D3, 1,25(OH)2 vitamin D, vitamin D-binding protein, bone mineral content and dietary mineral content in six children (mean age: 12.1 years) with cholestasis since infancy. Absorption of 25-OH vitamin D3 and vitamin D2 was evaluated by measuring serial serum concentrations after a test dose. Bone mineral content was reduced by greater than 2 S.D. in five of six subjects compared to age-specific controls; none had radiographic evidence of rickets but all had osteopenia. Dietary Ca and P content in the subjects was comparable to the recommended daily allowance for age-specific children. Baseline serum vitamin D2 concentrations were undetectable in all but one cholestatic subject despite oral supplementation with 2,500 to 50,000 IU per day vitamin D2. Baseline serum 25-OH vitamin D was 33.2 +/- 6.0 ng per ml (mean +/- S.E.) and comparable to our laboratory norms (15 to 50 ng per ml). Serum 1,25(OH)2 vitamin D and "free" 1,25(OH)2 vitamin D were both significantly (p less than 0.05) reduced compared to controls. A significantly blunted rise and reduced area under the absorption curve (both p less than 0.001) after 1,000 IU per kg vitamin D2 was found in cholestatic children (0.8 ng +/- 0.5 ng per ml and 18.0 +/- 14.3 ng hr per ml, respectively) compared to controls (59.5 +/- 10.0 ng per ml and 1,780 +/- 253 ng hr per ml, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Severe cholestasis leads to vitamin D depletion without perturbing its C-25 hydroxylation in the dog

The role of the liver as a contributory factor in the vitamin D deficiency of cholestatic liver disease has been studied in vivo in dogs with chronic bile duct ligation, whereas controls underwent diversion of the bile flow through the urinary bladder via a choledococystostomy anastomosis. The hepatic extraction of vitamin D3 was evaluated by the multiple indicator dilution technique, and the formation of 25-hydroxyvitamin D3 was assessed by directly sampling the hepatic effluent for up to 150 min after vitamin D3 administration. The serum and hemodynamic data indicate that dogs with chronic bile duct ligation had severe cholestasis and hepatocellular injury; histologically, macronodular cirrhosis was present. Dogs with choledococystostomy anastomosis had normal livers and normal liver function. The data indicate that the absence of normal bile flow into the intestinal lumen led to a progressive depletion of vitamin D reserve in both animals with choledococystostomy anastomosis and those with chronic bile duct ligation. However, neither the hepatic fractional extraction of vitamin D3, its hepatic clearance nor its transformation into 25-hydroxyvitamin D3 was significantly changed by chronic bile duct ligation. The results of the present studies indicate that the hepatic handling of vitamin D3 including its C-25 hydroxylation, is well preserved in the presence of severe cholestasis. They also suggest that the state of vitamin D depletion which often accompanies chronic cholestatic liver disease can largely be accounted for by factors such as secondary malabsorption of the vitamin due to the absence of adequate amounts of bile salts in the intestinal lumen, or by other factors which seem independent of the hepatic metabolism of vitamin D.

Epidemiology of ulcerative colitis in western Norway

The incidence of ulcerative colitis (UC) in the three counties that compose Western Norway was registered in a prospective study during the years 1984 and 1985. Both inpatients and outpatients were included. Five hundred and fifty general practitioners and 12 hospitals participated in the study. A total of 239 patients were diagnosed in this area with 807,000 inhabitants, giving a mean annual incidence of 14.8 per 100,000. For patients between 30 and 35 years of age the age-specific incidence rate was 31.2. The M/F sex ratio was 1.10. Familial occurrence of inflammatory bowel disease was found in 11% of the patients. Patients with rectal involvement only constituted 35% of the patients.

Incidence of Crohn's disease in a defined population in northern Sweden, 1974-1981

An epidemiologic study of Crohn's disease, comprising the population of the two most northerly counties of Sweden and covering the 8-year period 1974-1981, was carried out. The basic population was about 510,000, and the area is regarded as rural, with a mean density of 3 inhabitants per km2. In all, 199 patients with a hospital discharge diagnosis of Crohn's disease were identified. A mean annual incidence of 4.9 per 10(5) inhabitants and a peak incidence of 6.7 were found. There was no sex difference and no obvious change in incidence during the time period studied. The highest incidence was observed in young adults, and ileal disease predominated. A significantly higher incidence was observed in the town of Umeå than in the rest of northern Sweden. The increase was confined to the ages between 20 and 40 years. The present study concludes that the incidence of Crohn's disease is high in northern Sweden, even though it is a sparsely populated rural area. The incidence figures are similar to those obtained for other parts of Sweden.

The effects of different vitamin D-states on intestinal absorption of vitamin D3 and its metabolites in rats

Rats were kept on a diet deficient in vitamin D for 2 months and were then randomly assigned to one of three groups with different supplies of vitamin D for 9 days. At the end of this period [3H]-cholecalciferol (5 microCi) was administered intragastrically and the serum radioactivity was recorded after various periods of time. The animals were kept in metabolic cages and urine and faeces were collected. After 3 days the animals were killed and the liver, kidney and fat tissue were investigated for radioactivity. The radioactivity was separated into different fractions of vitamin D by means of chromatography. The animals with vitamin D deficiency displayed higher levels of serum radioactivity, which were to a great extent confined to the fractions of the more polar metabolites (25(OH)D3 and 1,25(OH)2D3). There was significantly less radioactivity in the 3-day faecal collection from these animals. In general, there was a low urinary excretion of radioactivity. In the rats with sufficient vitamin D, most of the radioactivity remained as the parent substance and was also detected in increased amounts in the liver, kidney and fat tissue. The results suggest a discriminatory enterohepatic cycling of vitamin D and its more polar metabolites leading to an increased faecal loss of the pro-hormone in animals with a vitamin D surplus. It is proposed that the selectively effective enterohepatic reabsorption of the different metabolites may serve as a protective mechanism when body stores of vitamin D are overloaded.

Comparison of vitamin E and 25-hydroxyvitamin D absorption during childhood cholestasis

To characterize differences in intestinal absorption of fat-soluble vitamins during cholestasis, intestinal absorption of vitamin E was compared with that of 25-hydroxyvitamin D in eight infants and young children with prolonged neonatal cholestasis. Oral tolerance tests were performed using 100 IU/kg/dose dl-alpha-tocopherol and 10 micrograms/kg/dose 25-hydroxyvitamin D. Mean vitamin E absorption was only 1.0% to 1.9% of that of control children, whereas 25-hydroxyvitamin D absorption was 22.5% to 25.1% of that of controls. Although intestinal absorption of both vitamins is impaired during cholestasis, the severity of vitamin E malabsorption far exceeds that of 25-hydroxyvitamin D.

Unusual sialilation of the serum DBP associated with the Gc 1 allele in alcoholic cirrhosis of the liver

The serum level of the 'vitamin D binding protein' (DBP) or Gc ('group-specific component'), its phenotype distribution and the quantitative estimation of the different electrophoretic isoforms were determined in a sample of healthy individuals (blood donors) and in patients with alcoholic hepatitis. It is shown that the serum DBP levels and the amount of the different electrophoretic isoforms are influenced by the protein phenotypes. In the patients an increased frequency of the Gc 1 allele is noticed. For the first time, an unusual form of the apo DBP protein was detected but only in the sera of the Gc 1 allele carriers. The protein form investigated by analytical procedures presents one more sialic acid residue than the usual Gc 1 protein. This unusual metabolic transformation of the DBP is mostly observed among male patients and is often associated with a deteriorating clinical outcome.