Biomedical subjects

Jette Jakobsen

Publications and source records attributed to Jette Jakobsen.

12 recordsLinked to original sources

PubMed2007

Dietary supplementation with an extract of lycopene-rich tomatoes does not reduce atherosclerosis in Watanabe Heritable Hyperlipidemic rabbits.

Tomatoes are rich in lycopene and other carotenoids which have shown beneficial effects on CVD in epidemiological and intervention studies. In the present study the effect of an extract of lycopene-rich tomatoes, Lyc-O-Mato on atherosclerosis was studies in Watanabe Heritable Hyperlipidemic rabbits. The rabbits were fed a control diet, a control diet supplemented with the tomato extract or a control diet supplemented with a mixture of plant oils for 16 weeks. Lycopene was detected only in plasma of rabbits receiving tomato extract. The tomato extract had no effect on cholesterol and triacylglycerol levels measured in total plasma, lipoprotein fractions and on aortic atherosclerosis evaluated biochemically and by microscopy. Oxidation of lipids in unfractionated plasma also was unaffected by the intake of tomato extract. In conclusion, the tomato extract increased plasma levels of lycopene in rabbits, but had no effect on hypercholesterolaemia, oxidation of plasma lipids or aortic atherosclerosis.

Animals↗

PubMed2006

Vitamin D and estrogen receptor-alpha genotype and indices of bone mass and bone turnover in Danish girls.

Peak bone mass is a major determinant of osteoporosis risk in later life. It is under strong genetic control; however, little is known about the identity of the genes involved. In the present study, we investigated the relationship between polymorphisms in the genes encoding the vitamin D receptor (VDR) (FokI, TaqI) and estrogen receptor-alpha (ERalpha) (PvuII, XbaI), and bone mineral density (BMD), bone mineral content (BMC), and markers of bone turnover in 224 Danish girls aged 11-12 years. BMD and BMC were measured by dual-energy X-ray absorptiometry. Serum osteocalcin, 25(OH)D, and parathyroid hormone (PTH) were measured by ELISA assays and urinary pyridinium cross-links by HPLC. Physical activity, dietary calcium, and Tanner stage were assessed by questionnaire. In general, there were no significant differences in anthropometrical variables, physical activity, dietary calcium, serum 25(OH)D, or PTH among genotype groups. BMD or BMC of lumbar spine or whole body (adjusted for body and bone size and pubertal status) were not associated with VDR or ERalpha genotypes or the combination of these genotypes. This lack of association remained even after adjustment for dietary and environmental factors. VDR genotypes had no effect on bone turnover markers. XX and PP ERalpha genotypes were associated (P < 0.05) with reduced levels of urinary pyridinium cross-links, whereas serum osteocalcin was similar among genotypes. These findings suggest that the rate of bone resorption was influenced by ERalpha genotypes, even though these biochemical differences were not evident in bone mass indices.

Absorptiometry, Photon↗

PubMed2006

A seasonal variation of calcitropic hormones, bone turnover and bone mineral density in early and mid-puberty girls - a cross-sectional study.

The importance of the seasonal variation of calcitropic hormones to growing skeleton has not been established. We studied whether there exists a seasonal variation in calcitropic hormones, bone mineral density (BMD) and bone remodelling markers in early puberty girls. One hundred and ninety-six girls, mean age 11.4 (sd 0.4) years, in Tanner stage 2 (early puberty) and 3 (mid-puberty) were studied during September to March. The BMD was measured from the lumbar vertebrae and the left femur by dual-energy X-ray absoptiometry. Their serum 25-hydroxyvitamin D (S-25-OHD), serum intact parathyroid hormone (S-iPTH), serum osteocalcin, urinary pyridinoline and urinary deoxypyridinoline were analysed from fasting samples. The concentration of S-25-OHD and serum osteocalcin differed among months (P < 0.01), reflecting a seasonal variation. The parathyroid hormone correlated negatively with S-25-OHD (r -0.325, P < 0.001). Moreover, the BMD in the femur (P = 0.047) and to a lesser extent in vertebrae (P = 0.057) differed between months in early puberty girls but this was not seen in mid-puberty. Seasonal variation in S-25-OHD and bone remodelling markers accompanied by negative correlation between S-25-OHD and S-iPTH was seen in this cross-sectional study of adolescent girls. In addition, the seasonal rhythm contributed 7.0-7.6 % difference in the BMD of lumbar vertebrae and left femur in early puberty girls. This variation should be avoided since it could hamper peak bone mass attainment.

Adolescent↗

PubMed2006

Vitamin D status of 51-75-year-old Irish women: its determinants and impact on biochemical indices of bone turnover.

OBJECTIVES: To assess the vitamin D status of Irish postmenopausal women during wintertime, and to examine its relationship with serum parathyroid hormone (PTH) and biochemical markers of bone turnover. In addition, the determinants of wintertime serum 25-hydroxyvitamin D (25OH-D) levels in these women were investigated. DESIGN: A cross-sectional observational study. SETTING: Cork City, Ireland (52 degrees N). SUBJECTS: Ninety-five apparently healthy, free-living postmenopausal women (aged 51-75 years), not taking any medication and free from any condition likely to affect vitamin D status or calcium/bone metabolism. RESULTS: Forty-eight per cent and 7% of women had serum 25OH-D levels <50 nmol l(-1) and <25 nmol l(-1), respectively. 25OH-D levels in these women were positively associated with dietary calcium intake (P = 0.0002) and use of vitamin D-containing supplements (P = 0.031), and negatively associated with cigarette smoking (P = 0.027) and body mass index (BMI) (P = 0.030). Low serum 25OH-D levels (<50 nmol l(-1)) were associated (P < 0.01) with elevated serum PTH levels. There were no significant differences in urinary pyridinium crosslinks or serum osteocalcin, biochemical indices of bone turnover, between subjects with serum 25OH-D levels above or below 50 nmol l(-1). CONCLUSION: A high proportion of Irish postmenopausal women had low vitamin D status (<50 nmol l(-1)) during late wintertime, which appeared to lead to elevated levels of serum PTH but not of bone turnover markers. Use of regular low-dose supplemental vitamin D, meeting daily calcium recommendations, cessation of smoking and maintaining BMI in the normal range are important factors that could help maintain adequate vitamin D levels during wintertime in these women.

Aged↗

PubMed2006

How much vitamin D3 do the elderly need?

BACKGROUND: Vitamin D insufficiency poses a problem in many parts of the world, the elderly being an especially vulnerable group. This insufficiency results from an inadequate amount of sunshine and a low dietary intake of vitamin D. Typically, insufficiency is accompanied with high intact parathyroid hormone, (S-iPTH) concentrations. AIMS OF THE STUDY: We studied how serum 25-hydroxy vitamin D (S-25-OHD) concentrations respond to different doses of vitamin D3 supplementation. Secondly to determine the smallest efficient dose to maintain serum 25-OHD concentration above the insufficiency level. We also studied which dose would be efficient in decreasing S-iPTH concentration in these subjects. SUBJECTS AND METHODS: Forty-nine 65- to 85-year-old women participated. The women were randomly assigned into one of four groups receiving 0 (placebo), 5, 10 or 20 microg of vitamin D3 daily for 12 weeks. Fasting morning blood was drawn at the beginning of the study, and thereafter every second week. Calciotropic variables were assessed from serum and urine samples. RESULTS: The S-25-OHD concentration increased significantly (p < 0.001) in all supplemented groups [5 microg: by 10.9 (8.5) nmol/L, 10 microg: by 14.4 (6.9) nmol/L, 20 microg: by 23.7 (11.9) nmol/L], whereas it decreased in the placebo group by 8.3 (13.2) nmol/L. Equilibrium in S-25-OHD concentration was reached in all groups after 6 weeks of supplementation at 57.7 (8.9) nmol/L, 59.9 (8.9) nmol/L and 70.9 (8.9) nmol/L in the groups with increasing vitamin D supplementation. The dose-response to supplementation decreased with increasing vitamin D status at baseline, r = -0.513, p = 0.002. S-iPTH tended to decrease in those with highest dose response to supplementation. CONCLUSIONS: A clear dose response was noted in S-25-OHD to different doses of vitamin D3. The recommended dietary intake of 15 microg is adequate to maintain the S-25-OHD concentration around 40-55 nmol/L during winter, but if the optimal S-25-OHD is higher than that even higher vitamin D intakes are needed. Interestingly, subjects with lower vitamin D status at baseline responded more efficiently to supplementation than those with more adequate status.

Aged↗

PubMed2006

Bread fortified with cholecalciferol increases the serum 25-hydroxyvitamin D concentration in women as effectively as a cholecalciferol supplement.

Fortification of foods is a feasible way of preventing low vitamin D status. Bread could be a suitable vehicle for fortification because it is a common part of diets worldwide. The bioavailability of cholecalciferol from bread is not known. We studied cholecalciferol stability, the concentration of the added cholecalciferol, the dispersion of cholecalciferol in bread, and the bioavailability of cholecalciferol from fortified bread. Three batches of fortified low-fiber wheat and high-fiber rye breads were baked; from each batch, 3 samples of dough and bread were analyzed for their cholecalciferol content. In a single-blind bioavailability study, 41 healthy women, 25-45 y old, with mean serum 25-hydroxyvitamin D concentration 29 nmol/L (range 12-45 nmol/L), were randomly assigned to 4 study groups. Each group consumed fortified wheat bread, fortified rye bread, regular wheat bread (control), or regular wheat bread and a cholecalciferol supplement (vitamin D control) daily for 3 wk. The daily dose of vitamin D was 10 mug in all groups except the control group. The vitamin dispersed evenly in the breads and was stable. Both fortified breads increased serum 25-hydroxyvitamin D concentration as effectively as the cholecalciferol supplement. Supplementation or fortification did not affect serum intact parathyroid hormone concentration or urinary calcium excretion. In conclusion, fortified bread is a safe and feasible way to improve vitamin D nutrition.

Adult↗

PubMed2006

A positive dose-response effect of vitamin D supplementation on site-specific bone mineral augmentation in adolescent girls: a double-blinded randomized placebo-controlled 1-year intervention.

UNLABELLED: The effect of vitamin D supplementation on bone mineral augmentation in 212 adolescent girls with adequate calcium intake was studied in a randomized placebo-controlled setting. Bone mineral augmentation determined by DXA increased with supplementation both in the femur and the lumbar vertebrae in a dose-responsive manner. Supplementation decreased the urinary excretion of resorption markers, but had no impact on formation markers. INTRODUCTION: Adequate vitamin D intake protects the elderly against osteoporosis, but there exists no indisputable evidence that vitamin D supplementation would benefit bone mineral augmentation. The aim of this 1-year study was to determine in a randomized double-blinded trial the effect of 5 and 10 microg vitamin D3 supplementation on bone mineral augmentation in adolescent girls with adequate dietary calcium intake. MATERIALS AND METHODS: Altogether, 228 girls (mean age, 11.4 +/- 0.4 years) participated. Their BMC was measured by DXA from the femur and lumbar spine. Serum 25-hydroxyvitamin D [S-25(OH)D], intact PTH (S-iPTH), osteocalcin (S-OC), and urinary pyridinoline (U-Pyr) and deoxypyridinoline (U-Dpyr) were measured. Statistical analysis was performed both with the intention-to-treat (IT) and compliance-based (CB) method. RESULTS: In the CB analysis, vitamin D supplementation increased femoral BMC augmentation by 14.3% with 5 microg and by 17.2% with 10 microg compared with the placebo group (ANCOVA, p = 0.012). A dose-response effect was observed in the vertebrae (ANCOVA, p = 0.039), although only with the highest dose. The mean concentration of S-25(OH)D increased (p < 0.001) in the 5-microg group by 5.7 +/- 15.7 nM and in the 10-microg group by 12.4 +/- 13.7 nM, whereas it decreased by 6.7 +/- 11.3 nM in the placebo group. Supplementation had no effect on S-iPTH or S-OC, but it decreased U-DPyr (p = 0.042). CONCLUSIONS: Bone mineral augmentation in the femur was 14.3% and 17.2% higher in the groups receiving 5 and 10 microg of vitamin D, respectively, compared with the placebo group, but only 10 mug increased lumbar spine BMC augmentation significantly. Vitamin D supplementation decreased the concentration of bone resorption markers, but had no impact on bone formation markers, thus explaining increased bone mineral augmentation. However, the positive effects were noted with the CB method but not with IT.

Biomarkers↗

PubMed2004

The effect of a high-protein, high-sodium diet on calcium and bone metabolism in postmenopausal women and its interaction with vitamin D receptor genotype.

The influence of a high-Na, high-protein (calciuric) diet on Ca and bone metabolism was investigated in postmenopausal women (aged 50-67 years) who were stratified by vitamin D receptor (VDR) genotype. In a crossover trial, twenty-four women were randomly assigned to a diet high in protein (90 g/d) and Na (180 mmol/d) or a diet adequate in protein (70 g/d) and low in Na (65 mmol/d) for 4 weeks, followed by crossover to the alternative dietary regimen for a further 4 weeks. Dietary Ca intake was maintained at usual intakes (about 20 mmol (800 mg)/d). Urinary Na, K, Ca, N and type I collagen cross-linked N-telopeptide (NTx; a marker of bone resorption), plasma parathyroid hormone (PTH), serum 25-hydroxycholecalciferol (25(OH)D3), 1,25-dihydroxycholecalciferol (1,25(OH)2D3), osteocalcin and bone-specific alkaline phosphatase (B-Alkphase) were measured in 24 h urine samples and fasting blood samples collected at the end of each dietary period. The calciuric diet significantly (P<0.05) increased mean urinary Na, N, K, Ca and NTx (by 19 %) compared with the basal diet, but had no effect on circulating 25(OH)D3, 1,25(OH)2D3, PTH, osteocalcin or B-Alkphase in the total group (n 24). There were no differences in serum markers or urinary minerals between the basal and calciuric diet in either VDR genotype groups. While the calciuric diet significantly increased urinary NTx (by 25.6 %, P<0.01) in the f+ VDR group (n 10; carrying one or more (f) Fok I alleles), it had no effect in the f- VDR group (n 14; not carrying any Fok I alleles). It is concluded that the Na- and protein-induced urinary Ca loss is compensated for by increased bone resorption and that this response may be influenced by VDR genotype.

Aged↗

PubMed2004

The 6-a-day study: effects of fruit and vegetables on markers of oxidative stress and antioxidative defense in healthy nonsmokers.

BACKGROUND: Fruit and vegetables contain both nutritive and nonnutritive factors that might contribute to redox (antioxidant and prooxidant) actions. OBJECTIVE: We investigated the relative influence of nutritive and nonnutritive factors in fruit and vegetables on oxidative damage and enzymatic defense. DESIGN: A 25-d intervention study with complete control of dietary intake was performed in 43 healthy male and female nonsmokers who were randomly assigned to 1 of 3 groups. In addition to a basic diet devoid of fruit and vegetables, the fruit and vegetables (Fruveg) group received 600 g fruit and vegetables/d; the placebo group received a placebo pill, and the supplement group received a vitamin pill designed to contain vitamins and minerals corresponding to those in 600 g fruit and vegetables. Biomarkers of oxidative damage to protein and lipids and of antioxidant nutrients and defense enzymes were determined before and during intervention. RESULTS: Plasma lipid oxidation lag times increased during intervention in the Fruveg and supplement groups, and the increase was significantly higher in the former. Plasma protein carbonyl formation at lysine residues also increased in both of these groups. Glutathione peroxidase activity increased in the Fruveg group only. Other markers of oxidative damage, oxidative capacity, or antioxidant defense were largely unaffected by the intervention. CONCLUSIONS: Fruit and vegetables increase erythrocyte glutathione peroxidase activity and resistance of plasma lipoproteins to oxidation more efficiently than do the vitamins and minerals that fruit and vegetables are known to contain. Plasma protein carbonyl formation at lysine residues increases because of the vitamins and minerals in fruit and vegetables.

Adult↗

PubMed2003

Geographical differences in vitamin D status, with particular reference to European countries.

Vitamin D is produced endogenously when the skin is exposed to sunlight and can be obtained exogenously from a few natural food sources, from food fortification and from supplements. Generally, vitamin D intake is low < or = 2-3 microg/d in Europe. Casual exposure to sunlight is thought to provide most of the vitamin D requirement of the human population. However, skin synthesis of vitamin D may not compensate for the low nutritional intake in Europe, even in countries with high supplies from food fortification and supplements. For assessment of vitamin D nutritional status the concentration of 25-hydroxyvitamin D (25(OH)D) in serum is considered to be an accurate integrative measure reflecting an individual's dietary intake and cutaneous production. A substantial percentage of the elderly and adolescents in Europe have a low concentration of 25(OH)D; in the elderly this percentage ranges from approximately 10 in the Nordic countries to approximately 40 in France. Low vitamin D status seems to be aggravated by disease and immobility, and by a low frequency of supplement use.

Adolescent↗

PubMed2003

Food contents and biological activity of 25-hydroxyvitamin D: a vitamin D metabolite to be reckoned with?

Only a limited number of foods naturally contain vitamin D such as fish, meat and offal, and eggs, and milk and dairy products. However, all these foods in addition contain the metabolite 25-hydroxyvitamin D (25OHD). From the few systematic studies which have been performed the food contents of 25OHD in animal foods are usually low but vary. Contents are typically very low in milk and fish (<0.1 microg/100 g), somewhat higher in meat and offal (0.2-0.4 microg/100 g) and up to 1 microg/100 g in egg yolk. It has been demonstrated that 25OHD is absorbed better and faster from the diet than native vitamin D and has metabolic effects of its own in regulating cell growth and calcium metabolism. Thus, the biological activity of 25OHD is greater than that of native vitamin D. However, there is as yet no consensus on the conversion factor that should be used for 25OHD to calculate vitamin D activity. Depending on the testing system used the factor varies from 1.5 to 5. If food contents and the higher potency of 25OHD are not included in dietary intake surveys, true vitamin D intake will be underestimated.

Animals↗

PubMed2002

High vitamin A content in some small indigenous fish species in Bangladesh: perspectives for food-based strategies to reduce vitamin A deficiency.

Recognising the importance of fish in the Bangladeshi diet, the objective of the present study was to screen commonly consumed fish species for vitamin A content to evaluate the potential of fish as a vitamin A source in food-based strategies to combat vitamin A deficiency. Samples of 26 commonly consumed fish species and one crustacean were collected in Kishoreganj and Mymensingh, Bangladesh. To obtain edible parts, the fish were cleaned by Bangladeshi women according to traditional practices. Distribution of vitamin A in parts of the fish and the effect of the cleaning practices on the vitamin A content in#10; edible parts were assessed. The content of vitamin A compounds was analysed by high-performance liquid chromatography. The vitamin A content in small fish ranged from 2680 retinol equivalents (RE)/100 g raw edible parts in mola (Amblypharyngodon mola) to 20 RE/100 g raw edible parts in chata (Colisa lalia; an alternative scientific name is Colisa lalius). The vitamin A content in cultured species, silver carp (Hypophthalmichthys molitrix), rui (Labeo rohita), mrigal (Cirrhinus mrigala) and tilapia (Oreochromis niloticus) was low, <30 RE/100 g raw edible parts. In mola, 90% of the vitamin A was found in the eyes and viscera. The vitamin A content in the screened fish species was highly variable, by more than a factor of 100. The existence of commonly consumed fish in Bangladesh belonging to the categories of very high and high vitamin A content offers a great unexploited potential for food-based strategies to improve the vitamin A intake by promoting the production and consumption of these species.

Animals↗