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Phytate in foods and significance for humans: Food sources, intake, processing, bioavailability, protective role and analysis

The article gives an overview of phytic acid in food and of its significance for human nutrition. It summarises phytate sources in foods and discusses problems of phytic acid/phytate contents of food tables. Data on phytic acid intake are evaluated and daily phytic acid intake depending on food habits is assessed. Degradation of phytate during gastro-intestinal passage is summarised, the mechanism of phytate interacting with minerals and trace elements in the gastro-intestinal chyme described and the pathway of inositol phosphate hydrolysis in the gut presented. The present knowledge of phytate absorption is summarised and discussed. Effects of phytate on mineral and trace element bioavailability are reported and phytate degradation during processing and storage is described. Beneficial activities of dietary phytate such as its effects on calcification and kidney stone formation and on lowering blood glucose and lipids are reported. The antioxidative property of phytic acid and its potentional anticancerogenic activities are briefly surveyed. Development of the analysis of phytic acid and other inositol phosphates is described, problems of inositol phosphate determination and detection discussed and the need for standardisation of phytic acid analysis in foods argued.

Whole grain foods and health - a Scandinavian perspective

The food-based dietary guidelines in the Scandinavian countries that recommend an intake of minimum 75 g whole grain per 10 MJ (2,388 kcal) per day are mainly derived from prospective cohort studies where quantitative but little qualitative details are available on whole grain products. The objective of the current paper is to clarify possible differences in nutritional and health effects of the types of whole grain grown and consumed in the Scandinavian countries. A further objective is to substantiate how processing may influence the nutritional value and potential health effects of different whole grains and whole grain foods. The most commonly consumed whole grain cereals in the Scandinavian countries are wheat, rye, and oats with a considerable inter-country variation in the consumption patterns and with barley constituting only a minor role. The chemical composition of these different whole grains and thus the whole grain products consumed vary considerably with regard to the content of macro- and micronutrients and bioactive components. A considerable amount of scientific substantiation shows that processing methods of the whole grains are important for the physiological and health effects of the final whole grain products. Future research should consider the specific properties of each cereal and its processing methods to further identify the uniqueness and health potentials of whole grain products. This would enable the authorities to provide more specific food-based dietary guidelines in relation to whole grain to the benefit of both the food industry and the consumer.

Whole grain for whom and why

A definition of whole grain is a critical first step in investigating health claims for whole grain and its products. Today, there is no internationally accepted definition of whole grain. Some existing definitions are broad and commodity-based, including grains with similar end uses, while others are more restricted. Scientific knowledge must be the basis for inclusion of certain grains. It is better to start with a restricted list of grains (a precautionary principle) and extend this as more knowledge becomes available. An exact definition of the raw materials (milled, cracked, crushed, rolled, or flaked) and knowledge of the components providing health effects would appear to be crucial issues for the European authorities when approving health claims. It is important that health claims are evidence-based, sustainable, and officially validated.

Folates in lettuce: a pilot study

Background Leafy vegetables are good sources of folates and food shops nowadays offer an increasing number of lettuce varieties. Objective To obtain data on the folate content and forms in common lettuce varieties and spinach sold in the Nordic countries, and to investigate effects of different storage conditions and preparations in the consumers home or at lunchtime restaurants. Design Folate was analysed in eight different lettuce varieties and spinach using a validated high-performance liquid chromatographic method and the detected forms of folates were confirmed by a mass spectrometric detector [liquid chromatography–mass spectrometry (LC-MS)] following heat extraction, deconjugation with rat serum and purification by solid-phase extraction. Results Folate content, expressed in folic acid equivalents, in the lettuce samples varied six-fold, from 30 to 198 µg 100 g−1 on a fresh weight basis. The folate content was decreased by 14% after storage at 4°C for 8 days and by 2–40% after storage at 22°C for 2–4 h, depending on whether samples were stored as whole leaves, or small torn or cut pieces. LC-MS confirmed the identity of the folate forms: H4folate, 5-CH3-H4folate, 5-HCO-H4folate and 10-HCO-H4folate. Conclusion The considerable variation in folate content between varieties of lettuce in this pilot study, with one variety reaching the level found in spinach, indicates the potential to increase folate intake considerably by choosing folate-rich varieties of lettuce and storing at low temperatures.

BMI, lipid profile, physical fitness and smoking habits of young male adults and the association with parental education

BACKGROUND Few studies have focused on the potential relationship between parental educational level and cardiovascular risk factors among young male adults. The aim of this study was to investigate cardiovascular disease risk factors among young men and whether body mass index (BMI), serum lipids, physical fitness and smoking habits were related to paternal and maternal education. METHODS In this cross-sectional study 750 18- to 26-year-old male recruits participated. RESULTS Linear regression analyses showed that the paternal education was inversely associated with BMI (P = 0.035) and the concentration of total cholesterol (P = 0.003) and low-density lipoprotein (LDL) (P = 0.014). Running performance was inversely related to cigarette smoking (P = 0.022) and the concentration of triacylglycerol (P = 0.001). BMI was positively related to the concentration of LDL (P = 0.002), total cholesterol/high-density lipoprotein (HDL) ratio (P < 0.001) and inversely related to the concentration of HDL (P < 0.001), running performance (P < 0.001) and muscular strength (P = 0.011). Recruits with low BMI, both high and low fitness, had a significantly better lipid profile than recruits with high BMI and low fitness (P <or= 0.016). A lower concentration of triacylglycerol (P <or= 0.001) and a higher concentration of HDL (P = 0.034) were further shown among recruits with high BMI/high fit compared to recruits with high BMI/low fit. CONCLUSIONS High paternal educational level was associated with a lower BMI and a better lipid profile among young adult men. Furthermore, men with low BMI, both high and low fit, had a better lipid profile than those with high BMI/low fit. Men with high BMI/high fit had a better lipid profile that those with high BMI/low fit.

Preferences and perceptions of personal vegetable consumption: a study among young men in the Norwegian National Guard.

A survey was developed to assess the intake, main sources and preferences related to vegetables among 578 male recruits (response rate 78%), in addition to perceptions of personal vegetable consumption. The recruits’ average vegetable intake (including potatoes) was 244 g/day. Six per cent of the recruits consumed the recommended 450 g/day or more of vegetables. However, 33% of all recruits stated that they consume enough vegetables. The most important sources of vegetables were potatoes and hot composite dishes for lunch and dinner. High (≥282 g/day) and low (≤182 g/day) consumers had distinctly different patterns of vegetable consumption. The hot dishes were a more important source among low than high vegetable consumers (P<0.01). Several recruits reported liking raw (76%) and cooked (58%) vegetables, and preferences were positively related to the vegetable intake (P<0.02) and (P<0.001). The results suggest some optimistic bias among the recruits regarding their personal vegetable consumption.

A nutrition intervention with a main focus on vegetables and bread consumption among young men in the Norwegian National Guard

Background Young men are difficult to reach with conventional nutrition information and they have a low intake of vegetables and whole grain cereals. Few intervention studies have focused on improving young mens consumption of vegetables and whole grains. Objective A 5-month intervention focusing on a combination of increased availability of healthy foods and nutritional information was developed to stimulate the intake of vegetables and semi-whole grain bread among a group of young men in the Norwegian military. Subjects A total of 376 recruits in the intervention group and 105 recruits in the control group participated in the entire study. Results The average daily increase in consumption of vegetables was 82 g (p<0.001), and semi-whole grain bread 47 g (p<0.001) between baseline and follow-up in the intervention group. No significant changes were observed in the control group. Differences between intervention and control group at follow-up were significant (p<0.001) for vegetables and semi-whole grain bread, when controlling for baseline values, and seasonal variation for vegetables. The recruits in the intervention group received higher scores on the questions concerning nutritional knowledge after the intervention, compared to baseline (p<0.001). There was a significantly higher increase in the intake of vegetables among the recruits who increased the number of correct answers to the knowledge questions (β-value: 0.14, p<0.05) than among the others. There was no significant change in scores of food satisfaction after the intervention. Conclusion The combination of increased availability of healthy food items and nutrition information was an effective way to increase the intake of vegetables and semi-whole grain bread, without a reduction in food satisfaction, among young men in the military.

Association between folate intake from different food sources in Norway and homocysteine status in a dietary intervention among young male adults

The aim of the present investigation was to study the effect of a dietary intervention which combined nutrition information with increased availability of vegetables, fruits and wholegrain bread. The effect of the intervention was determined by changes in the intake of vegetables, fruits, wholegrain bread and estimated nutrients. Furthermore, the study investigated whether changes in relative contribution from different food sources of folate were related to changes in the concentration of plasma total homocysteine (p-tHcy). The 5-month intervention study included 376 male recruits from the Norwegian National Guard, Vaernes (intervention group) and 105 male recruits from the Norwegian National Guard, Heggelia (control group). The study resulted in an increase in the total consumption of vegetables, fruits, berries and juice (P < 0.001) and of wholegrain bread (P < 0.001). The participants in the intervention group showed a higher increase in the intake of dietary fibre (P < 0.001) and folate (P < 0.001) compared with the control group. The relative contribution of folate intake from fruits, vegetables and wholegrain bread was higher in the intervention group compared with the control group (P < 0.001 for all). The increased intake of folate from wholegrain bread was inversely associated with a reduced concentration of p-tHcy (P = 0.017). In summary, the dietary intervention resulted in an increased intake of vegetables, fruits and wholegrain bread and a subsequent increase in folate intake from these food components. Reduction in the concentration of p-tHcy was significantly related to an increased folate intake due to an increased consumption of wholegrain bread.

Effect of a nutrition intervention on intake of vegetables, fruits, and semi whole grain bread among low and high consumers in the Norwegian National Guard.

BACKGROUND Nutritional information seldom reaches individuals with the most unhealthful dietary habits. OBJECTIVE To explore whether an intervention focusing on a combination of nutritional information and increased availability of vegetables, fruits, and semi whole grain bread was effective to raise the intake, and knowledge, of these foods among recruits in the military with low as well as high baseline intake. METHODS Intervention study, including 479 recruits, in intervention and control military camps. The participants were divided into three groups (low, medium, and high) according to their baseline intake of vegetables, fruits, and semi whole grain bread. RESULTS Those with low/medium baseline intake in the intervention camp had a significant increase in the intake of vegetables, fruits, and semi whole grain bread at follow-up. All three intake groups in the intervention camp also had significantly higher intake of these foods compared to those in the control camp at follow-up. The knowledge scores increased significantly among both high and low consumers in the intervention camp, but not in the control camp. CONCLUSION The intervention led to increased intake of vegetables, fruits, and semi whole grain bread among those recruits in the intervention camp, who were most in need to change their diet.

Risk assessment of folic acid in food supplements.

The Norwegian Scientific Committee for Food Safety (VKM) received a request from the Norwegian Food Safety Authority to assess whether the Tolerable Upper Intake Level (UL) of folic acid should be amended in light of new scientific evidence suggesting a possible link between high intake levels of folic acid and risk of cancer. Folic acid obtained from both food supplements and fortified foods should be assessed. Folic acid is a synthetic form of folate and is commonly used in food supplements and in food fortification because of its stability and bioavailability. Folic acid is reduced, methylated and released into the circulation. Natural folates occur in reduced forms, e.g. as tetrahydrofolate (THF), which are unstable and may thus loose biochemical activity during harvesting, storage, processing, and preparation. Folate is cofactor for enzymes in one-carbon metabolism where it provides one-carbon units for the formation of RNA and DNA. Folate is also essential for the normal functioning of the methionine cycle, which is responsible for both the conversion of homocysteine to methionine and the production of the universal methyl donor S-adenosylmethionine (SAM). SAM donates its methyl group to more than 100 methyltransferases for a wide range of substrates such as DNA, hormones, proteins, neurotransmitters and membrane phospholipids. While no Tolerable Upper Intake Level (UL) has been derived for natural dietary folates, the Scientific Committee on Food (SCF, 2000) set an UL of 1000 μg folic acid per day in 2000. The UL was set because it was found that high intakes of folic acid could correct megaloblastic anemia, which is the hallmark manifestation of vitamin B12 deficiency. In this way folic acid may mask vitamin B12 deficiency which again may cause irreversible neurological damage. The ULs for Grey Literature Haugen et al.; EJNFS, 5(4): 305-307, 2015; Article no.EJNFS.2015.028 306 children and adolescents (1-17 years) were adjusted on the basis of body weight and range from 200 to 800 μg/day. The UL for folic acid has been reassessed by other authorities, most recently in 2009 by EFSA (EFSA, 2009), who upheld an UL of 1000 μg/day. In 2009, Ebbing et al. published results from combined analyses of two randomised, placebocontrolled trials with B-vitamin supplementation in patients with ischemic heart disease. They found an increased risk of cancer in those who were randomised to receive folic acid in combination with vitamin B12 (Ebbing et al. 2009). Folates are important for cell division. It is therefore possible that tumor growth or growth of premalignant cells may be stimulated by high concentrations of folate in the blood. Another concern with use of folic acid is circulating unmetabolised folic acid (UMFA) which is often found at intakes of more than 200 μg per day (Kelly et al. 1997). It has been argued that UMFA could affect homeostatic regulation of folate (Smith et al. 2008), and that it may reduce natural-killer cell cytotoxicity (Troen et al. 2006). In vitro studies have also demonstrated that folic acid can down-regulate tumor suppressor genes (Lubecka-Pietruszewska et al. 2013). This opinion addresses the question whether the current UL for folic acid should be amended based on new scientific evidence. Furthermore, VKM has been requested to estimate folic acid intake from food supplements and from foods that are fortified with folic acid, in all age groups in the population above 1 year. In addition, possible consequences of amending the maximum limit for folic acid in food supplements should be discussed. In the literature search for this opinion (articles published from 2009 to 15 October 2014 were obtained), we found eight meta-analyses and five single studies where the aims were to study the relation between folic acid supplementation and incidence of cancer. Meta-analyses including studies in which folic acid was used in combination with other supplements were not included in the final evaluation, as the effect of folic acid could not be distinguished from the effect of the other substances. Only one meta-analysis was therefore considered relevant for the evaluation of UL for folic acid; a meta-analysis of patients with colorectal adenomas who received 1 mg folic acid per day for 3-6 years (Figueiredo et al. 2011). No increased risk of colorectal adenomas or cancer was found in this meta-analysis. Nor did the included single studies report increased risk of colorectal cancer following folic acid supplementation (Gao et al. 2013; Wu et al. 2009). Brain tumor and childhood leukemia were investigated in two case-control studies in offspring of women using folic acid supplementation during pregnancy (Amigou et al. 2012; Milne et al. 2012). Both studies indicated no negative effects of folic acid supplementation during pregnancy. A secondary analysis of one of the single studies on colorectal adenomas found a statistically significant increased risk of prostate cancer following folic acid supplementation (Figueiredo et al. 2009). However, the small number of prostate cancer cases in this single study does not make this result robust. In six studies circulating UMFA was reported among subjects who used folic acid supplements or who were subjected to folic acid food fortification. Whether UMFA contributes to the development of cancer or other undesirable health effects is not known. These studies do not provide new evidence for amending the existing UL for folic acid. About 26% of women and 18% of men aged 18-70 years participating in the nationwide dietary survey Norkost 3, reported to take folic acid supplements. The mean intake of folic acid among users was149 μg/day among women and 172 μg/day among men. Among pregnant women participating in The Norwegian Mother and Child Cohort Study, 62% reported use of folic acid supplements in 2008. Mean folic acid intake was 388 μg/day, and the 95 th percentile was 800 μg/day. Information on intake of folic acid from supplements for other age groups is not available. Intake of folic acid from fortified foods is not available in the national food consumption surveys for any age groups. However, according to a Norwegian model for food fortification from 2006 and later updates (last update in 2013), 53 μg folic acid per 100 kcal can be added to food and drinks Haugen et al.; EJNFS, 5(4): 305-307, 2015; Article no.EJNFS.2015.028 307 without exceeding the UL for folic acid in any age groups. With the current levels of folic acid in food supplements and current levels in fortified products, the UL for folic acid will not be exceeded. VKM was also requested to assess the impact of any increase of the current maximum limit of 200 μg for folic acid in supplements. Increasing the maximum limits in food supplements to 400 μg will imply exceedance of UL for children younger than 6 years and an intake close to UL in children 7-10 years. An increase in the maximum limits in food supplements to 600 μg will imply exceedance of UL for children younger than 10 years and an intake close to UL in children 11-14 years. Increasing the maximum limits in food supplements to 400 μg or 600 μg will not imply exceedance of UL among adults as evaluated in the Norwegian food fortification model (VKM, 2013). No new evidence for increased risk of cancer related to folic acid was found in the reviewed literature. Studies in subjects who had a history of colorectal adenomas, a group considered particularly vulnerable to develop cancer, reported no increased risk of colon cancer or adenomas after 3-5 years of treatment with 1000 μg of folic acid per day. VKM therefore concludes that studies published after 2009 and until 15 October 2014 examining cancer do not provide support to alter the existing UL for folic acid.