Identifying sources of measurement error in assessing dietary intakes - Results of a multi-country ring-trial.

BACKGROUND AND AIMS: Epidemiological investigations include dietary intakes as primary exposures or potential confounders. To reduce bias, data collection protocols include the administration of questionnaires together with measurements of biomarkers. Some error, however, remains and needs to be considered in the analysis and interpretation of results. The European Food Safety Authority supported a ring-trial to compare the precision and reproducibility of dietary assessment methods applied in Europe. METHODS AND RESULTS: Software applications used to collect 24-hour recalls and food records in six countries (Estonia, Italy, Latvia, Portugal, Spain, and Sweden) were assessed. The intake of 256 foods was identically reported to each method. Experienced interviewers participated and were instructed to repeat national protocols closely. The error in recording quantities, compared with reference values, was variable but in about 60% of recorded quantities was in the range of ±20%. Errors were however unsystematic and independent of the food type or quantification method used - although food pictures performed better. The reproducibility of some tools was limited. The methods generally captured additional ingredients (usually flavoring agents), but not sweetening agents or fortification and failed to record packaging information in about 60% of the cases. CONCLUSION: In a design that eliminated respondent bias, this study indicates that softwares, supporting databases and interviewers generally introduce random error in dietary assessments. The inclusion of large sample sizes and food pictures to quantify portions, together with enhanced attention on interviewers' training, standardisation of procedures and regular tool upgrades are essential in assuring a study's quality and comparability.

Sodium in the Finnish diet: II trends in dietary sodium intake and comparison between intake and 24-h excretion of sodium.

OBJECTIVE: To estimate cross-sectional and long-term dietary sodium intakes and sources in Finland, and to evaluate the validity of 48-h recall to assess sodium intake. DESIGN: Cross-sectional dietary surveys and food availability data (Food Balance Sheets). SETTING: Dietary surveys were carried out in Finland in 1992, 1997 and 2002. Food availability data were collected from 1980 to 1999. SUBJECTS: A stratified random sample was drawn from the population register. The total number of participants in the three dietary surveys was 6730. In the subsample for urine collection, the number of participants was 879. INTERVENTIONS: Nutrient intakes were estimated on the basis of a 3-day food diary in 1992, a 24-h recall in 1997 and a 48-h recall in 2002. The 24-h urinary excretion of sodium was used to validate sodium intake. In addition, salt intake was estimated based on Food Balance Sheets. RESULTS: Sodium intake has slowly decreased since the early 1980s. Reported daily sodium intake correlated significantly with sodium excretion. CONCLUSIONS: Sodium intake has decreased during the last two decades, but is still higher than the recommended daily intake. Sodium intake estimation based on dietary surveys and food availability data is a valid method provided that the food composition database is up to date and of good quality. SPONSORSHIP: All surveys were funded by the National Public Health Institute in Finland and the Ministry of Social Affairs and Health.

Meat fats in nutrition.

This article reviews the fat content and fatty acid composition of meats in the human diet and discusses nutritional facts related to meat, meat products and other meat-containing foods as sources of dietary fats. Meat is an increasingly important source of high-value animal protein worldwide. Meat fat comprises mostly monounsaturated and saturated fatty acids, with oleic (C18:1), palmitic (C16:0), and stearic acid (C18:0) being the most ubiquitous. Meat and meat products are considerable sources of cholesterol in the diet. In most industrialized countries, a high meat intake contributes to a higher than recommended total and saturated fat and cholesterol intake. Another concern is that meat may replace sources of other important nutrients in the diet. Therefore, the advice to consumers is to prefer lean meats and low-fat meat products and use meat in moderation only.

Vitamin D deficiency and bone health in healthy adults in Finland: could this be a concern in other parts of Europe?

A low vitamin D status could be a concern not only in children and the elderly in Europe, but also in adults. We do not know the effect of mild vitamin D deficiency on bone in this age group. The aim of this study was to detect the prevalence of low serum 25-hydroxyvitamin D [S-25(OH)D] and elevated serum intact parathyroid hormone (S-iPTH) concentrations in healthy young adults in the winter in northern Europe and to characterize the determinants of these variables. In addition, we studied the association between vitamin D status and forearm bone mineral density (BMD) in this population group. Three hundred and twenty-eight healthy adults (202 women and 126 men, 31-43 years) from southern Finland (60 degrees N) participated in this study conducted in February through March 1998. Fasting overnight blood samples were collected in the morning. Forearm BMD was measured by dual-energy X-ray absorptiometry (DXA). The mean daily vitamin D intake met the recommendations in the men (5.6 +/- 3.2 microg) and almost met it in the women (4.7 +/- 2.5 microg). The mean S-25(OH)D concentrations did not differ between genders (women, 47 +/- 34 nM; men, 45 +/- 35 nM; mean +/- SD), but the women had significantly higher mean S-iPTH levels than the men (women, 30 +/- 13 ng/liter; men, 24 +/- 12 ng/liter; p < 0.001). Low S-25(OH)D concentrations (<25 nM) were found in 26.2% of the women (53 women) and 28.6% of the men (36 men), respectively. Based on nonlinear regression analysis between S-25(OH)D and S-iPTH concentration, the S-iPTH concentration started to increase with S-25(OH)D concentrations lower than approximately 80 nM in the women and lower than approximately 40 nM in the men. Based on this relation between S-25(OH)D and S-iPTH concentrations, 86% of the women and 56% of the men had an insufficient vitamin D status. In linear regression analysis, the main positive determinants of S-25(OH)D were dietary vitamin D intake (p < 0.02), the use of supplements (p < 0.005), alcohol intake (p < 0.05), and age (p < 0.005). Smoking associated negatively with the S-25(OH)D concentration (p < 0.03). The main determinants of S-iPTH were S-25(OH)D (p < 0.01), dietary calcium intake (p < 0.02), and body mass index (BMI; p < 0.01). In addition, female gender was associated with higher S-iPTH concentration. The mean daily dietary calcium intake was 1,037 +/- 489 mg and 962 +/- 423 mg, in the men and women, respectively. Significantly lower forearm BMD was found in the men (p = 0.01) but not in the women (p = 0.14) with higher S-iPTH concentrations. Low vitamin D status was prevalent in these young adults in northern Europe in winter, although the vitamin D intake met the recommendation. This probably is not a local problem for northern Europe, because the natural sources of vitamin D are scarce and fortification is not very common in Europe, and with the exception of the southern part of Europe, sunshine is not very abundant in this part of the world. Thus, the results of this study indicate that more attention should be focused on vitamin D status and the sources of vitamin D in these countries.

Determinants of serum enterolactone concentration.

BACKGROUND: The lignan enterolactone, which is produced by the intestinal microflora from dietary precursors, may protect against hormone-dependent cancers and cardiovascular diseases. OBJECTIVE: We examined the cross-sectional associations between the serum enterolactone concentration and variables related to diet and health in Finnish adults. DESIGN: Serum enterolactone was measured by using time-resolved fluoroimmunoassay in 2380 Finnish men and women aged 25-64 y who were participating in a cross-sectional national survey in 1997. Background information was collected with self-administered questionnaires and the diet was assessed with a food-frequency questionnaire. RESULTS: The median serum enterolactone concentration was 13.8 nmol/L (range: 0-95.6 nmol/L) in men and 16.6 nmol/L (range: 0-182.6 nmol/L) in women. Multiple regression analyses showed positive associations in men between the serum enterolactone concentration and constipation, consumption of whole-grain products, and intake of fruit and berries. In women, the serum enterolactone concentration was positively and independently associated with consumption of vegetables, subject age, and constipation and was negatively associated with smoking. Furthermore, female subjects of normal weight had significantly higher serum enterolactone concentrations than did their underweight or obese peers. CONCLUSIONS: The serum enterolactone concentration varies widely in the population. Of the variables we examined, the most important determinants of the serum enterolactone concentration were consumption of lignan-containing foods and constipation; however, these appeared to explain only a small part of the variation. Therefore, the role of gut microflora in the metabolism of lignans might be very important. Further studies will also be needed to determine the bioavailability and absorption rate of lignans.

High dietary omega-6 polyunsaturated fatty acids drastically increase the formation of etheno-DNA base adducts in white blood cells of female subjects.

Lipid peroxidation generates reactive aldehydes such as trans-4-hydroxy-2-nonenal and malonaldehyde, which form promutagenic exocyclic DNA adducts in human cells and may contribute to diet-related cancers. Using ultrasensitive detection methods, analysis of WBC DNA from volunteers in a dietary study revealed that high intake of omega-6 polyunsaturated fatty acids increased malonaldehyde-derived adducts in male and female subjects. In contrast, etheno adducts (1,N6-ethenodeoxyadenosine; 3,N4-ethenodeoxycytidine) were not elevated in males but were, on average, 40 times higher in females, displaying a huge intersubject variation in lipid peroxidation-derived DNA damage. Exocyclic DNA adducts are promising biomarkers for examining the hypothesis of possible links between increased intake of dietary omega-6 polyunsaturated fatty acids, DNA damage, and elevated cancer risk for breast, colon, and prostate.

The effects of the apolipoprotein B signal peptide (ins/del) and XbaI polymorphisms on plasma lipid responses to dietary change.

There is interindividual variation in plasma lipid response to dietary changes. The polymorphisms which are associated with plasma lipid levels could possibly explain part of this variation. Therefore, the apolipoprotein B (apo B) signal peptide insertion/deletion (ins/del) and XbaI restriction fragment length polymorphisms are possible regulators of plasma lipid responses. We examined their role in the regulation of plasma lipid responses in 87 North Karelians (43 men, 44 women). The dietary study consisted of a 2-week baseline period (34-35% of energy from fat), followed by an 8-week low-fat (24 En%), low-cholesterol (279 mg/d) diet period and an 8-week switchback period. In this study population the apo B ins/del and XbaI polymorphisms exhibited mainly similar and partly significant effects on the responses of plasma very low-density lipoprotein (VLDL) and high density lipoprotein2 (HDL2) cholesterol to dietary changes. After consumption of the low saturated fat, low-cholesterol diet, ins/ins X - /X - homozygotes showed the greatest increase in VLDL cholesterol (p < 0.05 for differences between ins/del genotypes) and the greatest fall in HDL2 cholesterol (p = 0.01 for ins/del and p = 0.05 for XbaI), while only minimal alterations were seen in the del/del and X + /X + groups. After returning to the original diet, the changes of these lipids were reversed, ins/ins and X -/X - homozygotes having the greatest reductions in VLDL cholesterol (p < 0.05 for XbaI) and the greatest increases in HLDL2 cholesterol (p < 0.001 for XbaI). The findings suggest that plasma VLDL and HDL2 cholesterol responsiveness to diet may be partly explained by variation at the apo B gene.

Rapeseed oil and sunflower oil diets enhance platelet in vitro aggregation and thromboxane production in healthy men when compared with milk fat or habitual diets.

In this highly controlled trial, 26 normolipidemic men (average age 28 years, range 18 to 60) were fed a baseline diet high in milk fat (MF) (fat 36% of energy, saturates 19%, monounsaturates 11%, polyunsaturates 4%), followed by a diet high in sunflower oil (SO) (fat 38% of energy, saturates 13%, monounsaturates 10%, polyunsaturates 13%) and another diet high in low erucic-acid rapeseed oil (RO) (fat 38% of energy, saturates 12%, monounsaturates 16%, polyunsaturates 8%). All diets were mixed natural diets with the same cholesterol contents. The baseline milk fat diet was given for 14 days and the oil diets for 24 days in a blind cross-over design. The platelet in vitro aggregation (slope %/min) induced by 1, 2 and 3 microM ADP and collagen (25 micrograms/ml PRP) was highly significantly (p less than 0.001) increased after both oil diets when compared with the results from the milk fat diet. The aggregation pattern determined by threshold collagen concentration confirmed increased collagen sensitivity of the platelets after the rapeseed oil diet (p less than 0.001). The enhancement of platelet aggregation was associated with increased in vitro platelet thromboxane production after the oil diets vs. the milk fat diet (p less than 0.05 after the sunflower oil diet and p less than 0.001 after the rapeseed oil diet).

Comparison of the effects of two diets rich in monounsaturated fatty acids differing in their linoleic/alpha-linolenic acid ratio on platelet aggregation.

The effect of dietary linoleic/alpha-linolenic acid ratio on human platelet aggregation in vitro was investigated using low-erucic acid rapeseed oil and high-oleic acid sunflower oil as the major fat sources. In a cross-over study 20 healthy male subjects, average age 29 year (range 20-46 yr), followed experimental rapeseed oil (RO) and Trisun-sunflower oil (TSO) diets after their habitual diet for six weeks. Subjects were provided most of the fat containing foods but were allowed to eat other foods almost freely. Fatty acid compositions of the diets calculated from dietary records were as follows (saturated/monounsaturated/polyunsaturated fatty acids): RO diet 12.4/18.6/8.9% of total energy (en%) (linoleic/alpha-linolenic acid ratio 2.8) and TSO diet 11.8/17.8/8.3 en% (linoleic/alpha-linolenic acid ratio 28), respectively. Plasma cholesterol ester fatty acid composition proved compliance to the experimental diets. Platelet aggregations induced by ADP (1, 2 and 3 microM) or thrombin (0.12, 0.15 and 0.18 NIH/ml) were significantly enhanced and collagen-(1.5, 2.5 and 5.0 micrograms/ml) induced aggregation tended to be enhanced after the TSO diet compared with the RO diet. After the TSO diet platelet aggregation was enhanced from the level of the habitual diets by one thrombin (0.18 NIH/ml), one collagen (1.5 micrograms/ml) and all three ADP concentrations. The diets had no effect on antithrombin III activity. Results show that platelet aggregation in vitro decreases as the ratio of linoleic acid to alpha-linolenic acid decreases in diets rich in monounsaturated fatty acids.

Lack of effect on blood pressure by low fat diets with different fatty acid compositions.

We compared the effects on blood pressure (BP) of three isocaloric diets with reduced total fat and saturated fatty acid (SAFA) contents but with different proportions of monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA). Diet LF (low fat) provided 20 en% fat (7.9% SAFA, 7.8% MUFA, 3.0% PUFA); diet HP (high PUFA) 26 en% fat (7.5% SAFA, 8.2% MUFA, 8.1% PUFA), and diet HM (high MUFA) 26 en% fat (7.3% SAFA, 14.1% MUFA, 3.2% PUFA). The diets were consumed for 8 weeks (intervention) preceded by 2 weeks and followed by 8 weeks on a habitual diet (baseline/ switchback) with 33-34 en% fat (13-14% SAFA, 12% MUFA, 6% PUFA). Forty-five free-living couples were randomly allocated into the three diet groups, and 43 men and 44 women completed the study. BP was measured weekly with an automatic device. Compliance to diet was monitored by repeated food records, serum fatty acid compositions, and weekly visits to a nutritionist. Both systolic BP (SBP) and diastolic BP (DBP) remained unchanged throughout the study in all three groups. The weight-adjusted mean (s.e.m.) BP values showed changes in SBP of +1.7 (1.8), -0.4 (1.7), and +1.9 (1.9) mm Hg on the LF, HP, and HM diets, respectively (difference NS), and DBP of +0.1 (1.0), +0.6 (1.0), and -0.3 (1.0) mm Hg, respectively (difference NS) between the last 2 weeks of the baseline and intervention periods. The expected fatty acid intakes were achieved, and there were no between-group differences in change of body weight, intake of dietary fibre and potassium, and 24-h sodium excretion. A reduction in total fat and SAFA intake and changes in the proportions of dietary MUFA and PUFA did not affect the BP levels of this normotensive population with an adequate intake of PUFA at baseline.

Alpha-linolenic acid in rapeseed oil partly compensates for the effect of fish restriction on plasma long chain n-3 fatty acids.

OBJECTIVE: To examine the ability of alpha-linolenic acid (ALA) in low erucic acid rapeseed oil (RO) to compensate for the effects of a restriction in fish intake on plasma fatty acid composition. DESIGN AND SUBJECTS: Two times 6 weeks' randomized dietary intervention was used with blind crossover design in 40 healthy unconfined women and men (age 20-46y). INTERVENTIONS: Subjects were assigned to two fish restricted diets, namely RO diet and Trisun-sunflower oil (TSO) diet, with similar proportions of saturated : monounsaturated : polyunsaturated fatty acids (11.5:17.5:8.5% of total energy, En%), but differing in their ALA content (2.2 and 0.3 En%) and n-6 : n-3-ratio (3 : 1 and 23 : 1, respectively). The fatty acid compositions of plasma triglycerides (TG), cholesterol esters (CE), and phospholipids (PL) were analyzed by gas chromatography. Dietary intake was evaluated based on 3- to 7-day food records. RESULTS: The proportion of TG and CE ALA decreased on the TSO diet (from 1.6% to 0.9% and from 0.9% to 0.4%, respectively, P < 0.001) and increased on the RO diet (from 1.7% to 3.4% and from 0.9% to 1.3%, respectively, P < 0.001) compared to the baseline level. The proportion of eicosapentaenoic acid (EPA) in all three plasma fractions decreased on the TSO diet but not on the RO diet. The proportions of docosa-hexaenoic acid (DHA) decreased on both experimental diets and there was no difference in CE DHA between the diets. PL docosa-pentaenoic acid (DPA) and PL DHA remained at a higher level on the RO diet compared to the TSO diet (P < 0.001 and P < 0.05, respectively). CONCLUSIONS: ALA is metabolized to EPA in humans to a significant extent. The degree to which rapeseed oil (ca 50g/day) affects the proportion of EPA resembled the effect of a weekly portion (50-100g) of fatty fish depending on the fat content of the fish.

Lack of effect on blood pressure by polyunsaturated and monounsaturated fat diets.

We carried out a blind highly controlled study to investigate the effects of a sunflower-oil-rich diet and a rapeseed-oil-rich diet on the blood pressure of normotensive subjects. Twenty-nine men and 30 women, average age 30 years (range 18-65) were first fed a baseline diet high in saturated fatty acids (19 E% (percentage of total energy), total fat 36 E%) for 2 weeks. According to the crossover design 30 subjects then received a sunflower oil diet high in polyunsaturated fatty acids (13 E%, total fat 38 E%) followed by a low erucic acid rapeseed oil diet high in monounsaturated fatty acids (16 E%, total fat 38 E%) for 3.5 weeks each. The other 29 subjects had the same diets in reverse order. At the end of the saturated fat period systolic blood pressure was 122.6 +/- 11.5(mean +/- SD) mmHg and diastolic blood pressure 75.4 +/- 7.5 mmHg; during the sunflower oil diet the figures were 119.6 +/- 10.3 and 73.9 +/- 7.4 mmHg, and during the rapeseed oil diet 120.1 +/- 11.2 and 72.6 +/- 6.4 mmHg, respectively. There was a significant difference in diastolic blood pressure only between the two oil diets (P less than 0.01). At the end of a 4 weeks' recovery period the systolic and diastolic blood pressures of the subjects were even lower (118.6 +/- 10.6 and 72.3 +/- 8.3 mmHg, respectively) than during the study. These results suggest that the dietary changes had only minor effects - if any at all - on blood pressure in healthy normotensive subjects.

Effect of extreme fish consumption on dietary and plasma antioxidant levels and fatty acid composition.

OBJECTIVE: To assess the effects of high-fish and low-fish diets on plasma concentrations of fatty acids and selected antioxidants. DESIGN AND SUBJECTS: The effects of fish consumption on dietary and plasma antioxidant levels and fatty acid composition were studied as part of a large dietary survey of Finnish adults (n = 1861). High-fish consumers were matched with low-fish consumers and 41 pairs were identified. The members of each pair were of the same sex, from the same 10 y age group, and from the same or adjacent areas. There were 21 men and 20 women in each group, with a mean age of 54.3 y. METHODS: The fish consumption of the subjects was investigated with a qualitative food questionnaire. Additionally, a 3 d food record was used to estimate the diet. Two indices were defined to describe the oxidation potential of the diets. The plasma alpha-tocopherol, gamma-tocopherol, and beta-carotene concentrations and various fatty acids were analysed. RESULTS: The mean fish intake was 103 g/d in the high-fish and 5 g/d in the low-fish group. The dietary intakes of vitamin C, protein, total n-3 polyunsaturated fatty acids (PUFA), eicosapentaenoic acid, docosahexaenoic acid, mercury, selenium, and salt and the theoretical oxidative potential were higher (P < 0.05) and the saturated fatty acid intake lower (P < 0.01) in the high-fish than in the low-fish group. The dietary vitamin E intake was similar in both groups but the ratio of dietary vitamin E/PUFA was higher (P < 0.01) in the high-fish than in the low-fish group (0.85 and 0.75, respectively). The plasma n-3 PUFAs were higher (P < 0.001) and n-6 PUFAs lower (P < 0.001) in the high-fish than in the low-fish group. There were no differences in plasma antioxidant levels between the groups. CONCLUSION: This study shows that extreme fish consumption does not affect plasma antioxidant levels.

Folate intake, plasma folate and homocysteine status in a random Finnish population.

OBJECTIVE: To assess the folate status of Finnish adults using plasma folate and homocysteine as biomarkers and to evaluate dietary and supplementary folate intakes. MATERIALS AND METHODS: Plasma folate, vitamin B(12) and total homocysteine (tHcy) were determined in a random sample of 643 subjects aged 25-74 y living in the Helsinki area. The methylenetetrahydrofolate reductase (MTHFR)-genotypes were analyzed from a subsample (n=394). Dietary intake data by 24 h recall and use of vitamin supplements were collected. RESULTS: Plasma folate was normal (>/=5 nmol/l) in 99% of subjects and optimal (>/=8 nmol/l) in terms of a minimum tHcy in 90%. Mean plasma folate of non-supplement users was 13.7 and 12.9 nmol/l and tHcy 11.3 and 9.2 micro mol/l for men and women, respectively. Elevated tHcy (>14 micro mol/l) was found in 11% of subjects. Homozygote frequency for MTHFR genotype TT was 5.0% and their plasma tHcy was 14.8 micro mol/l compared to the mean of the other subjects, 10.5 micro mol/l, P<0.05. The mean dietary folate intake was 241 micro g/day (29 micro g/MJ of energy) for men and 205 micro g/day (33 micro g/MJ) for women, respectively. The main dietary sources of folate were vegetables 12%, wholemeal ryebread 11%, fruits 10%, and potato 10%. Regular supplement users (n=97) received on average 207 micro g folic acid per day from supplements. CONCLUSIONS: The folate status of Finnish adults seems to be adequate according to energy adjusted folate intake, plasma folate and homocysteine. The MTHFR homozygote frequency was low compared to other countries. Regular use of supplementary folic acid less than 300 micro g increased plasma folate, but supplemental folic acid over 300 micro g was required to lower tHcy values significantly.

The significance of glutathione conjugation for aflatoxin B1 metabolism in rainbow trout and coho salmon.

Rainbow trout are known to be more susceptible to aflatoxin B1 (AFB1) hepatocarcinogenesis than coho salmon, or trout pre-fed the carcinogenesis inhibitors beta-naphthoflavone (beta NF), Aroclor 1254 or indole-3-carbinol. The study reported here examined the relationship between AFB1-glutathione (GSH) conjugation and AFB1 carcinogenesis in salmon, trout and trout pre-fed the three inhibitors. The AFB1-glutathione (AFB1-SG) conjugate was not detected in salmon bile and was present in trout bile in amounts representing less than 0.2% of the administered dose 24 hr after injection of [3H]AFB1. The major conjugates were glucuronides of aflatoxicol and aflatoxicol M1. In incubations of isolated liver cell fractions, less than 0.5% of the original AFB1 dose was recovered as AFB1-SG in salmon and trout preparations, compared to 25% in mouse-liver cell preparations. The GSH concentration in livers of the control trout was higher than that for coho salmon but lower than that for trout pre-fed beta NF. Liver GSH-transferase activity in control trout livers was much higher than in the control salmon livers, but was only 62% of that found for trout fed beta NF. There was no apparent relationship among the various groups between liver GSH concentrations, liver GSH-transferase activity, or biliary GSH conjugate, and the degree of carcinogenic response of AFB1. Thus current evidence does not indicate a major role for aflatoxin B1 epoxide-GSH detoxification in coho salmon, or rainbow trout fed any of the three anticarcinogens tested. These results in salmonid fish are contrary to those which suggest AFB1-SG conjugation as a major determinant of AFB1 carcinogenesis and its dietary modulation in rodent models.

Carbohydrate substitution for fat or protein and risk of type 2 diabetes in male smokers.

BACKGROUND/OBJECTIVES: We examined the associations between carbohydrate substitutions (total; low-, medium-, high-glycemic index (GI) carbohydrates) for fat or protein and risk of type 2 diabetes. SUBJECTS/METHODS: The cohort comprised 25,943 male smokers among whom 1098 diabetes cases were identified from a national register during a 12-year follow-up. Diet was assessed by a validated food frequency questionnaire. The relative risks (RR) and confidence intervals (CI) for diabetes were analyzed using Cox proportional hazard modeling, and multivariate nutrient density models were applied to examine the associations between substitutions of macronutrients and diabetes risk. RESULTS: The risk of diabetes was lower when fat or protein was replaced with an isoenergetic amount (2% of energy intake) of carbohydrates, the multivariate RRs were 0.96 (95% CI: 0.94, 0.99) and 0.85 (95% CI: 0.80, 0.90), respectively. The lower risks were due to replacing saturated plus trans fatty acids, and meat, milk or plant protein with carbohydrates, respectively. Low-, medium- or high-GI carbohydrates did not associate with lower diabetes risk when replacing fat or fatty acids, except when total fat was replaced with medium-GI carbohydrates. Low-, medium- and high-GI carbohydrates had similar inverse associations with diabetes risk when they replaced total, meat or milk protein. CONCLUSION: Higher carbohydrate intake at the expense of fat, attributable to trans and saturated fatty acids, or protein was associated with decreased diabetes risk. Replacing fat or protein with lower-GI carbohydrates was not more beneficial than replacing it with higher-GI carbohydrates.

Glycemic load effect on fasting and post-prandial serum glucose, insulin, IGF-1 and IGFBP-3 in a randomized, controlled feeding study.

BACKGROUND/OBJECTIVES: The effect of a low glycemic load (GL) diet on insulin-like growth factor-1 (IGF-1) concentration is still unknown but may contribute to lower chronic disease risk. We aimed to assess the impact of GL on concentrations of IGF-1 and IGF-binding protein-3 (IGFBP-3). SUBJECTS/METHODS: We conducted a randomized, controlled crossover feeding trial in 84 overweight obese and normal weight healthy individuals using two 28-day weight-maintaining high- and low-GL diets. Measures were fasting and post-prandial concentrations of insulin, glucose, IGF-1 and IGFBP-3. In all 80 participants completed the study and 20 participants completed post-prandial testing by consuming a test breakfast at the end of each feeding period. We used paired t-tests for diet component and linear mixed models for biomarker analyses. RESULTS: The 28-day low-GL diet led to 4% lower fasting concentrations of IGF-1 (10.6 ng/ml, P=0.04) and a 4% lower ratio of IGF-1/IGFBP-3 (0.24, P=0.01) compared with the high-GL diet. The low-GL test breakfast led to 43% and 27% lower mean post-prandial glucose and insulin responses, respectively; mean incremental areas under the curve for glucose and insulin, respectively, were 64.3±21.8 (mmol/l/240 min; P<0.01) and 2253±539 (µU/ml/240 min; P<0.01) lower following the low- compared with the high-GL test meal. There was no effect of GL on mean homeostasis model assessment for insulin resistance or on mean integrated post-prandial concentrations of glucose-adjusted insulin, IGF-1 or IGFBP-3. We did not observe modification of the dietary effect by adiposity. CONCLUSIONS: Low-GL diets resulted in 43% and 27% lower post-prandial responses of glucose and insulin, respectively, and modestly lower fasting IGF-1 concentrations. Further intervention studies are needed to weigh the impact of dietary GL on risk for chronic disease.

Glycaemic index values in the Finnish food composition database: an approach to standardised value documentation.

BACKGROUND/OBJECTIVES: The glycaemic index (GI) is used to describe the blood glucose-raising potential of carbohydrate-containing foods. Only a few descriptions of the addition of GI values to national food composition databases (FCDBs) exist. We tested whether the value documentation framework established within the European Food Information Resource (EuroFIR) Network could be used for GI values when adding them to the Finnish FCDB. METHODS: The list of foods requiring GI values was based on the National FINDIET 2007 Survey data and extended with foods encoded in a food-frequency questionnaire used in other nationally representative studies. The minimum quality of GI measurements was verified when gathering values from various sources, using earlier defined criteria. If a measured GI value for a food was directly available, or could be imputed or estimated, the value was added to the Finnish FCDB and documented using core standard vocabularies of EuroFIR. The GI values of composite foods were calculated using recipe calculation software. RESULTS: A total of 2210 foods required a GI value. GI values for 1322 foods were available and added to the FCDB. The remaining 888 foods were composite foods and received a GI value through recipe calculation. The standard vocabularies describing the origin of the GI values, the methods used in their derivation and their qualitative characteristics were suitable for GI values. CONCLUSIONS: GI values can be added to FCDBs and documented using terms similar to those used for traditional food composition data. Standardised value documentation may provide transparency for GI database compilation processes.

Validity and reproducibility of the NORBAGREEN food frequency questionnaire.

OBJECTIVE: To measure the validity and reproducibility of the NORBAGREEN food frequency questionnaire (FFQ). SUBJECTS/METHODS: In Finland, 125 subjects aged 25-64 years sampled from the five main regions of the FINDIET 2002 Study and in Lithuania, 99 citizens of Kaunas aged 19-75 years participated in the study. Reference methods for the FFQ were two 3-day FFQs in Finland and four 24-h recalls in Lithuania. The FFQ was repeated after 6-8 months in both countries. The outcome of the FFQ1 was correlated with the outcome of the reference methods and with the outcome of repeated FFQ2. Cross-classification of food intakes by FFQ1 and the reference methods was examined in tertiles. RESULTS: Validity correlations (FFQ vs the reference method, Spearman's correlation) were for vegetables, fruit and bread 0.50 (P<0.01), 0.53 (P<0.01) and 0.54 (P<0.01) in Finland; and 0.55 (P<0.01), 0.31 (P<0.01) and 0.51 (P<0.01) in Lithuania, respectively. Correlations were smaller for potatoes and fish. The overall proportion categorized in the same or adjacent intake tertiles with the two instruments was over 83% in both countries. Reproducibility correlations varied between 0.51 and 0.75 in the Finnish study, and between 0.51 and 0.83 in the Lithuanian study. CONCLUSIONS: The NORBAGREEN FFQ can be used to rank subjects according to vegetable, fruit and bread consumption. Questions on fish and potato consumption need to be developed further.

Associations of vitamin D receptor, calcium-sensing receptor and parathyroid hormone gene polymorphisms with calcium homeostasis and peripheral bone density in adult Finns.

BACKGROUND: Thus far the search for osteoporosis candidate genes has focused less attention on the regulation of calcium homeostasis. Associations of vitamin D receptor (VDR) FokI, calcium-sensing receptor (CaSR) A986S and parathyroid hormone (PTH) BstBI polymorphisms with calcium homeostasis and peripheral bone density were investigated in adult Finns. METHODS: The subgroup of the population-based FINRISK survey consists of 339 healthy adults aged 31-43 years. Lifestyle data were assessed with questionnaires and food diaries. DNA was isolated from blood, and biochemical determinants of calcium metabolism were measured from blood and 24-hour urine samples. Bone mineral density (BMD) was measured using the DXA method at the distal forearm and by quantitative ultrasound (broadband ultrasound attenuation and speed of sound) at the calcaneus. Subjects were genotyped for VDR FokI, CaSR A986S and PTH BstBI polymorphisms. RESULTS: The CaSR 986S allele was associated with higher serum ionized calcium (p = 0.014). Forearm BMD was lowest for the PTH BstBI genotype bb in males (p = 0.023). VDR FokI and PTH BstBI polymorphisms showed a significant interaction on serum PTH (p = 0.010). The other gene-gene or diet-gene interactions studied showed no significant results. CONCLUSIONS: VDR, CaSR and PTH contribute to the genetic regulation of calcium homeostasis and peripheral bone density.