Pia Knuthsen

Carotenoids: Actual knowledge on food sources, intakes, stability and bioavailability and their protective role in humans

Carotenoids are one of the major food micronutrients in human diets and the overall objective of this review is to re-examine the role of carotenoids in human nutrition. We have emphasized the attention on the following carotenoids present in food and human tissues: beta-carotene, beta-cryptoxanthin, alpha-carotene, lycopene, lutein and zeaxanthin; we have reported the major food sources and dietary intake of these compounds. We have tried to summarize positive and negative effects of food processing, storage, cooking on carotenoid content and carotenoid bioavailability. In particular, we have evidenced the possibility to improve carotenoids bioavailability in accordance with changes and variations of technology procedures.

Composition of flavonoids in fresh herbs and calculation of flavonoid intake by use of herbs in traditional Danish dishes

Abstract Many herbs are known as excellent sources of natural antioxidants, and consumption of fresh herbs in the diet may therefore contribute to the daily antioxidant intake. The present study was performed in order to quantify flavonoids in commonly eaten fresh herbs. Fifteen fresh herbs (basil, chives, coriander, cress, dill, lemon balm, lovage, oregano, parsley, rosemary, sage, spearmint, tarragon, thyme, and watercress) were analysed by HPLC and mass spectrometry. Five major flavonoid aglycones were detected and quantified by HPLC after acid hydrolysis: apigenin, isorhamnetin, kaempferol, luteolin, and quercetin. The highest levels of flavonoids were found in parsley (510–630 mg apigenin /100 g), lovage (170 mg quercetin/100g), mint (18–100 mg apigenin/100 g), and dill (48–110 mg quercetin/100 g). Mass spectrometric detection, using atmospheric pressure chemical ionisation (APCI), was used to verify the presence of flavonoids in the hydrolysed extracts of herbs. Some traditional Danish dishes contain herbs, particularly parsley, dill, cress and chives, and the contribution to the flavonoid intake by consumption of these dishes was calculated.

Effects of Organic and Conventional Growth Systems on the Content of Flavonoids in Onions and Phenolic Acids in Carrots and Potatoes

The demand for organic food products is steadily increasing partly due to the expected health benefits of organic food consumption. Polyphenols, such as flavonoids and phenolic acids, are a group of secondary plant metabolites with presumably beneficial health effects, and contents in plants are affected by, for example, plant nutrient availability, climate, pathogen infection, and pest attack. In the current study, onions, carrots, and potatoes were cultivated in two-year field trials in three different geographical locations, comprising one conventional and two organic agricultural systems. The contents of flavonoids and phenolic acids in plants were analyzed by pressurized liquid extraction and high-performance liquid chromatography-ultraviolet quantification. In onions and carrots, no statistically significant differences between growth systems were found for any of the analyzed polyphenols. On the basis of the present study carried out under well-controlled conditions, it cannot be concluded that organically grown onions, carrots, and potatoes generally have higher contents of health-promoting secondary metabolites in comparison with the conventionally cultivated ones.

Evaluation of Web-based Dietary Assessment Software for Children: comparing reported fruit, juice and vegetable intakes with plasma carotenoid concentration and school lunch observations

Web-based Dietary Assessment Software for Children (WebDASC) was developed to estimate dietary intake in a school meal intervention study among 8- to 11-year-old Danish children. The present study validates self-reported fruit, juice and vegetable (FJV) intakes in 8- to 11-year-old children by comparing intake with plasma carotenoid concentration, and by comparing the reported FJV intake to actually eaten FJV, as observed by a photographic method. A total of eighty-one children, assisted by parents, reported their diet for seven consecutive days. For the same five schooldays as they reported their diet, the childrens school lunch was photographed and weighed before and after eating. In the week after the diet reporting, fasting blood samples were taken. Self-reported intake of FJV and estimated intake of carotenoids were compared with plasma carotenoid concentration. Accuracy of self-reported food and FJV consumption at school lunch was measured in terms of matches, intrusion, omission and faults, when compared with images and weights of lunch intake. Self-reported intake of FJV was significantly correlated with the total carotenoid concentration (0·58) (P< 0·01). Fruit and juice consumption showed higher correlations than vegetables with plasma carotenoid concentration (0·38 and 0·42 v. 0·33) (P< 0·01). A total of 82 % of the participants fell into the same or adjacent quartiles when cross-classified by FJV intake and carotenoids biomarkers. WebDASC attained 82 % reporting matches overall and a higher percentage match for reporting fruits compared with beverages. The present study indicated that WebDASC can be used to rank 8- to 11-year-old Danish children according to their intake of FJV overall and at school meals.

Comparison of polyacetylene content in organically and conventionally grown carrots using a fast ultrasonic liquid extraction method.

A rapid and sensitive analytical method for quantification of polyacetylenes in carrot roots was developed. The traditional extraction method (stirring) was compared to a new ultrasonic liquid processor (ULP)-based methodology using high-performance liquid chromatography-ultraviolet (HPLC-UV) and mass spectrometry (MS) for identification and quantification of three polyacetylenes. ULP was superior because a significant reduction in extraction time and improved extraction efficiencies were obtained. After optimization, the ULP method showed good selectivity, precision [relative standard deviations (RSDs) of 2.3-3.6%], and recovery (93% of falcarindiol) of the polyacetylenes. The applicability of the method was documented by comparative analyses of carrots grown organically or conventionally in a 2 year field trial study. The average concentrations of falcarindiol, falcarindiol-3-acetate, and falcarinol in year 1 were 222, 30, and 94 mug of falcarindiol equiv/g of dry weight, respectively, and 3-15% lower in year 2. The concentrations were not significantly influenced by the growth system, but a significant year-year variation was observed for falcarindiol-3-acetate.

Stability of vitamin D in foodstuffs during cooking

We investigated the retention of vitamin D3 and 25-hydroxyvitamin D3 in eggs, vitamin D3 in margarine, and vitamin D3 and vitamin D2 in bread. Our set-up illustrated the cooking methods usually performed in households i.e. boiling, frying in pan and oven, and baking. All experiments were performed three times independently of one another. The retention of vitamin D compounds in eggs and margarine during heat treatment in an oven for 40 min at normal cooking temperature showed retention at 39-45%, while frying resulted in retention at 82-84%. Boiled eggs were found to have a similar level of retention (86-88%). For bread baked, as recommended in the recipe, the retention of vitamin D3 in rye bread at 69% was lower than the retention in wheat bread at 85%. A similar observation was made for vitamin D2, although the retention was slightly higher, 73% and 89%. No difference between retention of vitamin D3 and 25-hydroxyvitamin D3 in eggs was shown. Cooking may cause detrimental loss of vitamin D, but it depends on the actual foodstuffs and the heating process. Further research is needed to optimise cooking procedures to enhance retention of vitamin D. Vitamin D retention should be taken into account in future calculations of dietary intake of vitamin D.

Pressurised liquid extraction of flavonoids in onions. Method development and validation.

A rapid and reliable analytical method for quantification of flavonoids in onions was developed and validated. Five extraction methods were tested on freeze-dried onions and subsequently high performance liquid chromatography (HPLC) with UV detection was used for quantification of seven flavonoids. The extraction efficiencies were lowest for the conventional water bath extraction compared to pressurized liquid extraction (PLE), ultrasonication, ultrasonic liquid processor, and microwave extraction, which yielded similar efficiencies. The reproducibility was in the same range (RSD: 1-11%) for all tested extraction methods. However, PLE was the preferred extraction method because the method can be highly automated, use only small amounts of solvents, provide the cleanest extracts, and allow the extraction of light and oxygen-sensitive flavonoids to be carried out in an inert atmosphere protected from light. The method parameters: extraction temperature, sample weight, flush volume and solvent type were optimised, and a clean-up step was integrated in the PLE procedure by in-cell addition of C18-material to the extraction cells, which slightly improved the recovery and reproducibility of the method. The one-step PLE method showed good selectivity, precision (RSDs=3.1-11%) and recovery of the extractable flavonoids (98-99%). The method also appeared to be a multi-method, i.e. generally applicable to, e.g. phenolic acids in potatoes and carrots.

Effects of organic and conventional growth systems on the content of carotenoids in carrot roots, and on intake and plasma status of carotenoids in humans.

BACKGROUNDnThe demand for organic food products has increased during the last decades due to their probable health effects, among others. A higher content of secondary metabolites such as carotenoids in organic food products has been claimed, though not documented, to contribute to increased health effects of organic foods. The aim was to study the impact of organic and conventional agricultural systems on the content of carotenoids in carrots and human diets. In addition, a human cross-over study was performed, measuring the plasma status of carotenoids in humans consuming diets made from crops from these agricultural systems.nnnRESULTSnThe content of carotenoids in carrot roots and human diets was not significantly affected by the agricultural production system or year, despite differences in fertilisation strategy and levels. The plasma status of carotenoids increased significantly after consumption of the organic and conventional diets, but no systematic differences between the agricultural production systems were observed.nnnCONCLUSIONnThe expected higher content of presumed health-promoting carotenoids in organic food products was not documented in this study.

Seasonal and regional variations of iodine in Danish dairy products determined by inductively coupled plasma mass spectrometry

The content of iodine in 72 samples of Danish dairy products was determined by direct flow injection (FI) sample introduction of whole milk into the ICP-MS instrument, or by bomb ashing of cream and cheese samples prior to the ICP-MS measurement. The performance of the FI-based method was superior to the bomb ashing method in terms of the limit of detection which was 9 ng g n –1 n and 60 ng g n –1 n for the two methods, respectively, and in repeatability which was 8.4 and 45 ng g n –1 n, respectively. Both methods of analysis were accurate as demonstrated by analyses of the CRM 063R Skim Milk Powder. The iodine content of the milk samples varied between 42-162 ng g n –1 n. A geographical difference in the iodine content showed that milk from Jutland contained less iodine than milk from Sealand. This can be explained by the lower natural iodine content in the drinking water resources in Jutland. A temporal difference showed a general increase in iodine concentration in milk from all regions during the winter months over the summer months. This can be explained by the use of iodine-enriched fodder during the winter months. The poorer repeatability of the analyses of cream and cheese samples obscured any possible geographical and temporal variation of iodine in these samples.

Iodine content in bread and salt in Denmark after iodization and the influence on iodine intake

Objective To measure the iodine content in bread and household salt in Denmark after mandatory iodine fortification was introduced and to estimate the increase in iodine intake due to the fortification. Design The iodine content in rye breads, wheat breads and salt samples was assessed. The increase in iodine intake from fortification of bread and the increase in total iodine intake after fortification were estimated. Subjects Iodine intake before and after fortification was estimated based on dietary intake data from 4,124 randomly selected Danish subjects. Main results Approximately 98% of the rye breads and 90% of the wheat breads were iodized. The median iodine intake from bread increased by 25 (13–43) µg/day and the total median iodine intake increased by 63 (36–104) µg/day. Conclusions The fortification of bread and salt has resulted in a desirable increase in iodine intake, and the current fortification level of salt (13 ppm) seems reasonable.