Content and Bioaccessibility of Minerals and Proteins in Fish-Bone Containing Side-Streams from Seafood Industries.

With the aim to upcycle fish side-streams, enzymatic hydrolysis is often applied to produce protein hydrolysates with bioactive properties or just as a protein source for food and feed. However, the production of hydrolysates generates a side-stream. For underutilized fish and fish backbone this side-stream will contain fish bones and make it rich in minerals. The aim of this study was to assess the relative bioaccessibility (using the standardized in vitro model INFOGEST 2.0) of minerals in a dietary supplement compared to bone powder generated after enzymatic hydrolysis of three different fish side-streams: undersized whole hake, cod and salmon backbones consisting of insoluble protein and bones. Differences in the bioaccessibility of protein between the powders were also investigated. The enzyme hydrolysis was carried out using different enzymes and hydrolysis conditions for the different fish side-streams. The content and bioaccessibility of protein and the minerals phosphorus (P), calcium (Ca), potassium (K) and magnesium (Mg) were measured to evaluate the potential of the powder as an ingredient in, e.g., dietary supplements. The bone powders contained bioaccessible proteins and minerals. Thus, new side-streams generated from enzymatic hydrolysis can have possible applications in the food sector due to bioaccessible proteins and minerals.

High Oral Vitamin D3 Intake Does Not Protect Against UVR-induced Squamous Cell Carcinoma in Mice.

BACKGROUND/AIM: The effect of vitamin D on skin carcinogenesis is unclear. Vitamin D derivatives may protect against ultraviolet radiation (UVR)-induced DNA damage, immune suppression, and skin carcinogenesis. However, some epidemiological studies have reported an increased incidence of skin cancer associated with high serum vitamin D levels. We investigated the effect of vitamin D supplementation on serum, skin, and tumor vitamin D levels and on skin cancer development in hairless immunocompetent mice. MATERIALS AND METHODS: Female C3.Cg-Hrhr/TifBomTac immunocompetent mice (n=125) were randomly separated into five groups. Two groups received a high vitamin D3 diet (4.5 µg/day/mouse). One group received a medium vitamin D3 diet (2.3 µg/day/mouse). Two groups received a standard diet (0.045 µg/day/mouse). Three standard erythema doses of UVR were given three times per week to three groups. RESULTS: Animals on a high vitamin D3 diet had ~150-fold higher serum vitamin D3 levels (p=0.00016) and 3-fold higher serum 25-hydroxyvitamin D3 [25(OH)D3] levels (p=0.00016) than those on a standard diet. For mice on the medium vitamin D3 diet, serum vitamin D3 and 25(OH)D3 levels were 18-fold and 2.3-fold higher than for the standard diet, respectively (p=0.00016). All UVR-exposed mice developed tumors. Vitamin D3 levels were lower in the tumor than the skin (p<0.0001). High and medium supplementation with vitamin D3 did not affect tumor development (p>0.05). CONCLUSION: In mice, vitamin D levels in the serum, skin, and tumors were augmented by supplementation, but this did not affect the development of UVR-induced skin tumors.

Treatment of Vitamin K Deficiency in Hemodialysis Patients - A Pilot Study Comparing Menaquinone-7 Tablets and a Vitamin K Rich Diet.

Purpose: Vitamin K deficiency and hence a high level of plasma dephosphorylated undercarboxylated matrix Gla protein (dp-ucMGP) is frequent in patients on hemodialysis. This group is recommended to restrict their potassium intake which often leads to restriction of vitamin K rich foods. A menaquinone-7 (MK-7) supplement has been shown to decrease dp-ucMGP, but it has yet to be examined if a vitamin K rich diet could be equally effective. Patients and Methods: A prospective randomized crossover intervention trial with two arms; 6 weeks of 360 µg MK-7 tablet/day and 6 weeks of a vitamin K rich diet with a 3-week washout period in between. Participants were 10 patients in hemodialysis and the primary outcome measures were changes in dp-ucMGP, total MGP (tMGP), and undercarboxylated osteocalcin (ucOC). Furthermore, the level of potassium and phylloquinone in broccoli was determined after different durations of boiling. Results: During the MK-7 intervention the dp-ucMGP and ucOC decreased significantly compared to baseline (-0.42 [-0.93; -0.22] nmol/L (p=<0.01) and -1.85 [-2.91; -1.30] nmol/L (p<0.01)), while these were unchanged during the dietary intervention (0.03 [-0.64; 0.37] nmol/L (p=1.00) and 0.30 [-1.71; 1.41] nmol/L (p=0.77)). Between the two interventions there was a greater decrease in ucOC (p=0.02) during the MK-7 compared to the dietary period. No significant changes in the total MGP levels were found in any of the periods. The retention of potassium following boiling for 2 minutes and 8 minutes was 76% and 49%, respectively, while for phylloquinone the retention was 92%, and independent of duration of boiling. Conclusion: A daily MK-7 supplement for 6 weeks lowered dp-ucMGP and ucOC significantly, while a vitamin K rich diet was not able to induce any significant effect. Boiled broccoli maintains a reasonable content of phylloquinone while potassium is extracted and is a reasonable source of phylloquinone for patients on hemodialysis.

In vitro bioaccessibility of vitamin K (phylloquinone and menaquinones) in food and supplements assessed by INFOGEST 2.0 - vit K.

Vitamin K describes a group of fat-soluble vitamers namely phylloquinone and menaquinones. The growing evidence for vitamin K's role beyond blood coagulation, and the possible differences between the vitamers are emerging. Knowledge of the content of menaquinones in different food matrixes and the potential differences in bioaccessibility between the vitamin K vitamers and food matrixes are limited. In this study, the bioaccessibility was assessed using the INFOGEST 2.0 static in vitro digestion model optimised by including a Danish standard meal. The presence of the standard meal was crucial to obtaining a robust and stable digestion model. The bioaccessibility of the Danish standard meal, water, vitamin K standards, vitamin K supplements, broccoli, spinach, natto, pasteurised whole egg and canola oil was assessed by three replications. The bioaccessibility was in the range 30%-102%. The lowest bioaccessibility was observed in broccoli while the highest bioaccessibility was found in egg and canola oil. No competition in the bioaccessibility between vitamin K vitamers and vitamin D was observed.

Vitamin D Levels in Sows from Five Danish Outdoor Herds.

Vitamin D is essential for sow health and productivity. Standard sow feed is therefore supplemented with vitamin D3 or 25-hydroxyvitamin D3 (25(OH)D3). However, it is uncertain whether the levels achieved are adequate for optimal performance. Currently, information on serum levels of vitamin D in pigs reared under both indoor and outdoor conditions is lacking. In August 2020, we obtained blood samples from 97 organic newly weaned sows housed outdoors during pregnancy and farrowing and used these to test for vitamin D in serum. The average concentration was 67 ± 16 ng 25(OH)D3/mL with a range of 32 to 134 ng 25(OH)D3/mL. The vitamin D3 content was 21 ± 7 ng/mL, ranging from 9 to 48 ng/mL. The average number of hours of sun from June to August was 7.0 ± 0.5 h/day. Parity, farm and body condition score did not significantly affect serum levels of 25(OH)D3.

Causes of Vitamin K Deficiency in Patients on Haemodialysis.

Background: A low vitamin K status is common in patients on haemodialysis, and this is considered one of the reasons for the accelerated atherosclerosis in these patients. The vitamin is essential in activation of the protein Matrix Gla Protein (MGP), and the inactive form, dp-ucMGP, is used to measure vitamin K status. The purpose of this study was to investigate possible underlying causes of low vitamin K status, which could potentially be low intake, washout during dialysis or inhibited absorption capacity. Moreover, the aim was to investigate whether the biomarker dp-ucMGP is affected in these patients. Method: Vitamin K intake was assessed by a Food Frequency Questionnaire (FFQ) and absorption capacity by means of D-xylose testing. dp-ucMGP was measured in plasma before and after dialysis, and phylloquinine (vitamin K1) and dp-ucMGP were measured in the dialysate. Changes in dp-ucMGP were measured after 14 days of protein supplementation. Results: All patients had plasma dp-ucMGP above 750 pmol/L, and a low intake of vitamin K. The absorption capacity was normal. The difference in dp-ucMGP before and after dialysis was -1022 pmol/L (p < 0.001). Vitamin K1 was not present in the dialysate but dp-ucMGP was at a high concentration. The change in dp-ucMGP before and after protein supplementation was -165 pmol/L (p = 0.06). Conclusion: All patients had vitamin K deficiency. The reason for the low vitamin K status is not due to removal of vitamin K during dialysis or decreased absorption but is plausibly due to a low intake of vitamin K in food. dp-ucMGP is washed out during dialysis, but not affected by protein intake to a clinically relevant degree.

Collaborative study: Quantification of total folate in food using an efficient single-enzyme extraction combined with LC-MS/MS.

Quantification of the specific folate vitamers to estimate total folate in foods is not standardized. A collaborative study, including eight European laboratories, was conducted in order to determine the repeatability and reproducibility of the method for folate quantification in foods using the plant-origin γ-glutamyl hydrolase as part of the extraction procedure. The seven food samples analyzed represent the food groups; fruits, vegetables, dairy products, legumes, offal, fish, and fortified infant formula. The homogenization step was included, and six folate vitamers were analyzed using LC-MS/MS. Total folate content, expressed as folic acid equivalent, was 17-490 µg/100 g in all samples. Horwitz ratio values were within the acceptable range (0.60-1.94), except for fish. The results for fortified infant formula, a certified reference material (NIST 1869), confirmed the trueness of the method. The collaborative study is part of a standardization project within the Nordic Committee on Food Analysis (NMKL).

Vitamin D-fortified foods improve wintertime vitamin D status in women of Danish and Pakistani origin living in Denmark: a randomized controlled trial.

PURPOSE: Low vitamin D status is prevalent worldwide. We aim to investigate the effect of vitamin D fortification on serum 25-hydroxyvitamin D (25(OH)D) concentration in women of Danish and Pakistani origin at risk of vitamin D deficiency. METHODS: A 12-week randomized, double-blinded, placebo-controlled intervention trial during winter time, designed to provide 20 µg vitamin D3/day through fortified yoghurt, cheese, eggs and crisp bread, and assess the change in serum 25(OH)D. Participants were 143 women of Danish and Pakistani origin, living in Denmark, randomized into four groups, stratified by ethnicity. RESULTS: Mean (SD) baseline 25(OH)D concentrations among women of Danish and Pakistani origin were 49.6 (18) and 46.9 (22) nmol/L, respectively (P = 0.4). While 9% of Danish women had 25(OH)D < 30 nmol/L, the prevalence among women of Pakistani origin was 24%. Median (IQR) vitamin D intake among Danish and Pakistani women at endpoint was 32.0 (27.0, 34.4) µg/day and 24.2 (19.2, 30.8) µg/day, respectively. Endpoint serum 25(OH)D increased in fortified groups to 77.8 (14) nmol/L among Danish women and 54.7 (18) nmol/L among women of Pakistani origin (P < 0.01). At endpoint, 0% in the Danish-fortified group and 3% in the Pakistani-fortified group had 25(OH)D < 30 nmol/L, compared with 23 % and 34% in their respective control groups. CONCLUSIONS: Vitamin D fortification of four different foods for 12 weeks during winter was effective in increasing serum 25(OH)D and reducing the prevalence of very low vitamin D status among women of Danish and Pakistani origin. CLINICALTRIALS. GOV WITH IDENTIFIER: NCT02631629.

Challenges to Quantify Total Vitamin Activity: How to Combine the Contribution of Diverse Vitamers?

This state-of-the-art review aims to highlight the challenges in quantifying vitamin activity in foods that contain several vitamers of a group, using as examples the fat-soluble vitamins A and D as well as the water-soluble folate. The absorption, metabolism, and physiology of these examples are described along with the current analytical methodology, with an emphasis on approaches to standardization. Moreover, the major food sources for the vitamins are numerated. The article focuses particularly on outlining the so-called SLAMENGHI factors influencing a vitamer's' ability to act as a vitamin, that is, molecular species, linkage, amount, matrix, effectors of absorption, nutrition status, genetics, host-related factors, and the interaction of these. After summarizing the current approaches to estimating the total content of each vitamin group, the review concludes by outlining the research gaps and future perspectives in vitamin analysis. There are no standardized methods for the quantification of the vitamers of vitamin A, vitamin D, and folate in foods. For folate and ß-carotene, a difference in vitamer activity between foods and supplements has been confirmed, whereas no difference has been observed for vitamin D. For differences in vitamer activity between provitamin A carotenoids and retinol, and between 25-hydroxyvitamin D and vitamin D, international consensus is lacking. The challenges facing each of the specific vitamin communities are the gaps in knowledge about bioaccessibility and bioavailability for each of the various vitamers. The differences between the vitamins make it difficult to formulate a common strategy for assessing the quantitative differences between the vitamers. In the future, optimized stationary digestive models and the more advanced dynamic digestive models combined with in vitro models for bioavailability could more closely resemble in vivo results. New knowledge will enable us to transfer nutrient recommendations into improved dietary advice to increase public health throughout the human life cycle.

The use of synthetic and natural vitamin D sources in pig diets to improve meat quality and vitamin D content.

This study investigated the effects of synthetic and natural sources of vitamin D biofortification in pig diets on pork vitamin D activity and pork quality. One hundred and twenty pigs (60 male, 60 female) were assigned to one of four dietary treatments for a 55 d feeding period. The dietary treatments were (1)50 µg vitamin D3/kg of feed; (2)50 µg of 25-hydroxvitamin D3/kg of feed (25-OH-D3); (3)50 µg vitamin D2/kg of feed; (4)50 µg vitamin D2-enriched mushrooms/kg of feed (Mushroom D2). The pigs offered the 25-OH-D3 diet exhibited the highest (P < 0.001) serum total 25-hydroxyvitamin D concentration and subsequently exhibited the highest (P < 0.05) Longissimus thoracis (LT) total vitamin D activity. Mushroom D2 and 25-OH-D3 supplementation increased pork antioxidant status. The vitamin D2-enriched mushrooms improved (P < 0.05) pig performance, carcass weight and LT colour. In conclusion, 25-OH-D3 is the most successful source for increasing pork vitamin D activity, while Mushroom D2 may be a new avenue to improve animal performance and pork quality.

Vitamin D-biofortified beef: A comparison of cholecalciferol with synthetic versus UVB-mushroom-derived ergosterol as feed source.

This study investigates dietary fortification of heifer feeds with cholecalciferol and ergocalciferol sources and effects on beef total vitamin D activity, vitamer, respective 25-hydroxymetabolite contents, and meat quality. Thirty heifers were allocated to one of three dietary treatments [(1) basal diet + 4000 IU of vitamin D3 (Vit D3); (2) basal diet + 4000 IU of vitamin D2 (Vit D2); and (3) basal diet + 4000 IU of vitamin D2-enriched mushrooms (Mushroom D2)] for a 30 day pre-slaughter period. Supplementation of heifer diets with Vit D3 yielded higher (p < 0.001) Longissimus thoracis (LT) total vitamin D activity (by 38-56%; p < 0.05) and serum 25-OH-D concentration (by 20-36%; p < 0.05), compared to that from Vit D2 and Mushroom D2 supplemented animals. Irrespective of vitamin D source, carcass characteristics, sensory and meat quality parameter were unaffected (p > 0.05) by the dietary treatments. In conclusion, vitamin D3 biofortification of cattle diets is the most efficacious way to enhance total beef vitamin D activity.

Stability of vitamin D3 and vitamin D2 in oil, fish and mushrooms after household cooking.

Information on the retention of vitamin D in food following household cooking is scarce. So far the retention of its metabolites vitamin D3, vitamin D2, and 25-hydroxyvitamin D3 has shown that the type of food and the cooking method are the essential determinants, and there is no significant difference between the metabolites. We investigated the retention of vitamin D3 and vitamin D2 in sunflower oil, vitamin D3 in rainbow trout, and vitamin D2 in button mushrooms. The investigated cooking methods were boiling at different pH, steam cooking, microwave cooking, pan-frying, and oven baking. There was no difference between the retention of vitamin D3 and vitamin D2 added to sunflower oil, which ranged from 70 to 99%. In rainbow trout, the retention of vitamin D3 at 85-114% was not significantly different from 100%, except for panfrying at 85%. However, the retention of vitamin D2 in mushrooms at 62-88% was significantly different from 100% (p ≤ 0.05).

Vitamin D Stored in Fat Tissue During a 5-Year Intervention Affects Serum 25-Hydroxyvitamin D Levels the Following Year.

Context: Vitamin D and 25-hydroxyvitamin D [25(OH)D] are stored in adipose tissue, but the clinical relevance is uncertain. Objective: To evaluate changes in serum 25(OH)D and adipose tissue vitamin D levels after stopping vitamin D supplementation. Design: A prospective, double-blind cohort follow-up study. Setting: Clinical Research Unit at University Hospital of North Norway. Patients: Seventy-six subjects were included after participation in a 3- to 5-year prevention of type 2 diabetes study and were administered 20,000 IU of vitamin D or placebo per week. Intervention: During the 12-month follow-up period, blood samples were drawn at the beginning and after 1, 3, 6, 9, and 12 months. Fat biopsies were taken at the start and end. Main Outcome Measures: Changes in 25(OH)D level in serum and 25(OH)D and vitamin D levels in adipose tissue. Results: Forty-one of 42 subjects who were given vitamin D and 33 of 34 subjects who were given placebo completed the study. At the inclusion, mean serum 25(OH)D levels were 122 and 71 nmol/L in the vitamin D and placebo groups, respectively. Serum 25(OH)D levels were significantly higher in the vitamin D group than in the placebo group throughout and were 84.5 and 73.1 nmol/L, respectively, after 12 months. In the vitamin D group, adipose tissue vitamin D levels decreased by 52% over 12 months. Conclusion: Vitamin D and 25(OH)D stored in adipose tissue after 3 to 5 years of vitamin D supplementation may have a clinically relevant effect on serum 25(OH)D level the following year.

Vitamin D Vitamers Affect Vitamin D Status Differently in Young Healthy Males.

Dietary intake of vitamin D includes vitamin D3 (vitD3), 25-hydroxyvitamin D3 (25OH-D3), and vitamin D2 (vitD2). However, the bioactivity of the different species has not been scientifically established. The hypothesis in this study was that vitD3, 25OH-D3, and vitD2 have an equal effect on 25-hydroxyvitamin D in serum (vitamin D status). To test our hypothesis, we performed a randomized, crossover study. Twelve young males consumed 10 µg/day vitD3 during a four-week run-in period, followed by 3 × 6 weeks of 10 µg/day vitD3, 10 µg/day 25OH-D3, and 10 µg/day vitD2. The content of vitD3, vitD2, 25OH-D3, and 25-hydroxyvitamin D2 (25OH-D2) in serum was quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The hypothesis that the three sources of vitamin D affect vitamin D status equally was rejected. Based on the assumption that 1 µg vitD3/day will show an increase in vitamin D status of 1.96 nmol/L, the results showed that 23 µg vitD2 and 6.8 µg 25OH-D3 was similar to 10 µg vitD3. These results demonstrate that further investigations are necessary to determine how to quantify the total vitamin D activity based on chemical quantification of the individual vitamin D metabolites to replace the total vitamin D activity assessed in biological rat models.

Investigation of the effect of UV-LED exposure conditions on the production of vitamin D in pig skin.

The dietary intake of vitamin D is currently below the recommended intake of 10-20µg vitamin D/day. Foods with increased content of vitamin D or new products with enhanced vitamin D are warranted. Light-emitting diodes (LEDs) are a potential new resource in food production lines. In the present study the exposure conditions with ultraviolet (UV) LEDs were systematically investigated in the wavelength range 280-340nm for achieving optimal vitamin D bio-fortification in pig skin. A wavelength of 296nm was found to be optimal for vitamin D3 production. The maximum dose of 20kJ/m(2) produced 3.5-4µg vitamin D3/cm(2) pig skin. Vitamin D3 produced was independent on the combination of time and intensity of the LED source. The increased UV exposure by UV-LEDs may be readily implemented in existing food production facilities, without major modifications to the process or processing equipment, for bio-fortifying food products containing pork skin.

Interlaboratory Trial for Measurement of Vitamin D and 25-Hydroxyvitamin D [25(OH)D] in Foods and a Dietary Supplement Using Liquid Chromatography-Mass Spectrometry.

Assessment of total vitamin D intake from foods and dietary supplements (DSs) may be incomplete if 25-hydroxyvitamin D [25(OH)D] intake is not included. However, 25(OH)D data for such intake assessments are lacking, no food or DS reference materials (RMs) are available, and comparison of laboratory performance has been needed. The primary goal of this study was to evaluate whether vitamin D3 and 25(OH)D3 concentrations in food and DS materials could be measured with acceptable reproducibility. Five experienced laboratories from the United States and other countries participated, all using liquid chromatography tandem-mass spectrometry but no common analytical protocol; however, various methods were used for determining vitamin D3 in the DS. Five animal-based materials (including three commercially available RMs) and one DS were analyzed. Reproducibility results for the materials were acceptable. Thus, it is possible to obtain consistent results among experienced laboratories for vitamin D3 and 25(OH)D3 in foods and a DS.

Effects of vitamin D2-fortified bread v. supplementation with vitamin D2 or D3 on serum 25-hydroxyvitamin D metabolites: an 8-week randomised-controlled trial in young adult Finnish women.

There is a need for food-based solutions for preventing vitamin D deficiency. Vitamin D3 (D3) is mainly used in fortified food products, although the production of vitamin D2 (D2) is more cost-effective, and thus may hold opportunities. We investigated the bioavailability of D2 from UV-irradiated yeast present in bread in an 8-week randomised-controlled trial in healthy 20-37-year-old women (n 33) in Helsinki (60°N) during winter (February-April) 2014. Four study groups were given different study products (placebo pill and regular bread=0 µg D2 or D3/d; D2 supplement and regular bread=25 µg D2/d; D3 supplement and regular bread=25 µg D3/d; and placebo pill and D2-biofortified bread=25 µg D2/d). Serum 25-hydroxyvitamin D2 (S-25(OH)D2) and serum 25-hydroxyvitamin D3 (S-25(OH)D3) concentrations were measured at baseline, midpoint and end point. The mean baseline total serum 25-hydroxyvitamin D (S-25(OH)D=S-25(OH)D2+S-25(OH)D3) concentration was 65·1 nmol/l. In repeated-measures ANCOVA (adjusted for baseline S-25(OH)D as total/D2/D3), D2-bread did not affect total S-25(OH)D (P=0·707) or S-25(OH)D3 (P=0·490), but increased S-25(OH)D2 compared with placebo (P<0·001). However, the D2 supplement was more effective than bread in increasing S-25(OH)D2 (P<0·001). Both D2 and D3 supplementation increased total S-25(OH)D compared with placebo (P=0·030 and P=0·001, respectively), but D2 supplementation resulted in lower S-25(OH)D3 (P<0·001). Thus, D2 from UV-irradiated yeast in bread was not bioavailable in humans. Our results support the evidence that D2 is less potent in increasing total S-25(OH)D concentrations than D3, also indicating a decrease in the percentage contribution of S-25(OH)D3 to the total vitamin D pool.

Tissue content of vitamin D3 and 25-hydroxy vitamin D3 in minipigs after cutaneous synthesis, supplementation and deprivation of vitamin D3.

Information regarding the endogenous storages of vitamin D3 after cutaneous vitamin D synthesis compared to oral vitamin D3 supplementation is sparse. Furthermore it is not known whether vitamin D3 can be stored for later use during periods of shortages of vitamin D3. To investigate the endogenous storages of vitamin D3 two studies were carried out in Göttingen minipigs. In study 1 one group of minipigs (n=2) was daily exposed to UV light corresponding to 10-20 min of midday sun and another group (n=2) of pigs were fed up to 60 µg vitamin D3/day corresponding to 3.7-4.4 µg/kg body weight. Study 1 demonstrated that daily UV-exposure of minipigs stimulated the cutaneous synthesis of vitamin D3 and resulted in increasing serum vitamin D3 and 25-hydroxy vitamin D3, but also carcasses containing vitamin D3 and 25-hydroxy vitamin D3. The vitamin D3 content in adipose tissue from the UV-exposed minipigs was 150-260 ng/g and the content was 90-150 ng/g in the orally supplemented minipigs. In study 2, minipigs were UV-exposed daily for 49 days. Subsequently, one group (n=2) was fed a vitamin D-free diet and another group (n=2) was dosed daily with 13C-labeled vitamin D3. The concentrations of vitamin D3 and 25-hydroxy vitamin D3 in serum and skin- and subcutaneous adipose tissue biopsies were repeatedly monitored. Vitamin D3 and 25-hydroxy vitamin D3 were eliminated from the skin and the adipose tissue after UV-exposure was ceased. Supplementation of 13C-vitamin D3 did not seem to affect the decline in the endogenous vitamin D3 in the adipose tissue formed during UV-exposure.

Vitamin D3 increases in abdominal subcutaneous fat tissue after supplementation with vitamin D3.

OBJECTIVE: The objective was to assess the amount of vitamin D3 stored in adipose tissue after long-term supplementation with high dose vitamin D3. DESIGN: A cross-sectional study on 29 subjects with impaired glucose tolerance who had participated in a randomized controlled trial with vitamin D3 20 000 IU (500 µg) per week vs placebo for 3-5 years. METHODS: Abdominal subcutaneous fat tissue was obtained by needle biopsy for the measurements of vitamin D3 and 25-hydroxyvitamin D3 (25(OH)D3). Body fat was measured with dual-energy X-ray absorptiometry, and serum 25(OH)D3 level was quantified. RESULTS: In the subjects given vitamin D3, the median concentrations of serum 25(OH)D3, fat vitamin D3, and fat 25(OH)D3 were 99 nmol/l, 209 ng/g, and 3.8 ng/g, respectively; and correspondingly in the placebo group 62  nmol/l, 32 ng/g, and 2.5 ng/g. If assuming an equal amount of vitamin D3 stored in all adipose tissue in the body, the median body store was 6.6 mg vitamin D3 and 0.12 mg 25(OH)D3 in those given vitamin D3. CONCLUSIONS: Subcutaneous adipose tissue may store large amounts of vitamin D3. The clinical importance of this storage needs to be determined.

Randomized controlled trial of the effects of vitamin D­fortified milk and bread on serum 25-hydroxyvitamin D concentrations in families in Denmark during winter: the VitmaD study.

BACKGROUND: Vitamin D intakes are lower than dietary recommendations in most populations, and thus, a low vitamin D status is widespread, especially during winter. OBJECTIVE: We investigated the effects of increasing vitamin D intake to the recommended amount by fortification of milk and bread on serum 25-hydroxyvitamin D [25(OH)D] concentrations in families during winter in Denmark. DESIGN: The study was a randomized controlled trial in 782 children and adults (4-60 y old) recruited as 201 families. Families were randomly assigned to vitamin D-fortified or nonfortified milk and bread for 6 mo starting in September. The milk and bread replaced the participants' usual consumptions of products. RESULTS: Median (IQR) vitamin D intakes (habitual diet plus fortified products) were 9.4 mg/d (6.5, 12.3 mg/d) and 2.2 mg/d (1.5, 3.0 mg/d) in fortification and control groups, respectively. Geometric mean (IQR) serum 25(OH)D concentrations decreased from 73.1 nmol/L (61.9, 88.5 nmol/L) to 67.6 nmol/L (56.2, 79.4 nmol/L) in the fortification group and from 71.1 nmol/L (61.2, 85.9 nmol/L) to 41.7 nmol/L (29.5, 58.9 nmol/L) in the control group (both P , 0.001). The final 25(OH)D concentration was significantly higher in the fortification group than in the control group (P , 0.001). By the end of the study, ,1% of subjects in the fortification group and 25% of subjects in the control group had 25(OH)D concentrations ,30 nmol/L and 16% and 65% of subjects, respectively, had 25(OH)D concentrations ,50 nmol/L. CONCLUSION: Vitamin D fortification of milk and bread reduces the decrease in serum 25(OH)D concentrations during winter and ensures 25(OH)D concentrations .50 nmol/L in children and adults in Denmark.