Riitta Freese

Dietary determinants of serum paraoxonase activity in healthy humans

The associations between habitual diet and a variety of markers of lipid peroxidation or oxidative stress in a group of 95 healthy comparatively young Finnish volunteers (24 male and 71 females) were investigated. The habitual diet of the subjects was evaluated with a 3-day food record. The following biochemical parameters related to lipid peroxidation or oxidative stress were measured: lagtime of Cu2+ induced LDL oxidation in vitro, lipid hydroperoxides and Schiff bases produced during the LDL oxidation test, malondialdehyde measured as thiobarbituric acid-reactive substances from native LDL and Cu2+ oxidized LDL, serum paraoxonase (PON) activity. Serum PON activity showed most constantly associations with habitual diet. PON activity correlated negatively (r=-0.31 to -0.37) with intake of vegetables, total and water-soluble fiber, as well as intake of beta-carotene. Highly significant difference (P=0.005) in PON activity between lowest (<135 g/day) and highest (>256 g/day) vegetable intake quartiles was found. Malondialdehyde levels showed conflicting associations with diet. The results suggest that the significantly lower PON activity associated with high vegetable intake needs to be studied further.

Bioavailability of Quercetin From Berries and the Diet

Abstract: Berries are a rich source of various polyphenols, including the flavonoid quercetin. In this article, the results of three intervention studies investigating the bioavailability of quercetin from berries are reviewed. In the first study, we investigated the short-term kinetics of quercetin after consumption of black currant juice and showed that quercetin is rapidly absorbed from it. In the second study, we showed that plasma quercetin levels increase up to 50% in subjects consuming 100 g/day of bilberries, black currants, and lingonberries as a part of their normal diets for 2 mo. In the third study, healthy subjects consumed a diet high or low in vegetables, berries, and other fruit for 6 wk. Quercetin concentrations nearly doubled in the high-vegetable, -berry, and -other fruit group and decreased by 30% in subjects consuming less of these foods than normally. The results showed that plasma quercetin is bioavailable from a diet containing berries and indicate that it may be a good biomarker of fruit and vegetable intake in general.

Fats, lipids and blood coagulation.

Saturated and n-3 fatty acids, postprandial lipaemia, and the combined effects of fatty acids and lipid-lowering drugs have been of principal interest in recent studies in the field of dietary fats, lipids and haemostasis. The sex-specific effect of individual saturated fatty acids on coagulation factor VII activity has been discovered, and the significant effect of factor VII R353Q polymorphism on the postprandial response has also been found. An increased intake of n-3 fatty acids or fat reduction when combined with intensive lifestyle interventions may lead to reduced thrombotic potential in type 2 diabetic patients and obese individuals. Furthermore, positive effects on haemostasis by combined treatment with long-chain n-3 fatty acids and simvastatin indicate that n-3 fatty acids may be of some relevance with lipid-lowering drugs. The possible unfavourable effect of n-3 fatty acids on plasminogen activator inhibitor-1 activity is still a matter of dispute, but recent studies suggest that n-3 fatty acids, including α-linolenic acid, may have antithrombotic effects by enhancing protein C activity.

Many patients with Type 1 diabetes estimate their prandial insulin need inappropriately

Background:  Many factors contribute to the need for prandial insulin in Type 1 diabetes. However, patients’ success in achieving normal postprandial glucose concentration is understudied. The aim of the present study was to determine how often patients with Type 1 diabetes achieve normal postprandial glucose concentrations and to evaluate factors associated with postprandial hypo‐ and hyperglycemia.

Lipid peroxidation status, somatic mutations and micronuclei in peripheral lymphocytes : a case observation on a possible interrelationship

A controlled dietary study was conducted in healthy female volunteers and reported elsewhere [1]. In a subset of samples four different biomarkers were analyzed: plasma malondialdehyde (MDA) levels and urinary 8-isoprostaglandin-F(2alpha) were measured as markers for lipid peroxidation. The frequency of hprt (hypoxanthine guanine phosphoribosyl transferase) mutants and micronuclei in peripheral blood lymphocytes were analyzed as indicators of genotoxic effects. One of the ten individuals showed extremely high background levels in all of the four endpoints measured. This case observation raises the possibility that life style factors and dietary habits affect the level of DNA reactive lipid peroxidation products, which in turn increase mutagenic and cytogenetic effects. A possible association between these biomarkers, particularly in relation to dietary fat intake and antioxidant status, should now be studied in a larger trial.

Energy and nutrient intakes and adherence to dietary guidelines among Finnish adults with type 1 diabetes

Abstract Background. Patients with type 1 diabetes are instructed to eat a healthy, balanced diet. Implementation of diet is an under-studied phenomenon. We aimed to describe the nutrient intake of a large sample of adult Finnish patients with type 1 diabetes and assess whether they meet the recommendations. Methods. Cross-sectional data from a total of 817 patients are presented. Data on food intake were collected with a 3-day food record completed twice with a 2–3-month interval. Compliance with dietary guidance was self-reported. Results. Patients frequently reported a diet low in carbohydrates and fibre but high in fat. Only 28% restricted saturated fatty acid to less than 10% of their daily energy intake. One-fourth of the patients reported higher than recommended sucrose intake. Salt recommendations were frequently exceeded. Of the micronutrients, the recommendations for vitamin A, vitamin D, folate, and iron were most frequently unmet. Although self-reported compliance was associated with a higher frequency of meeting the recommendations for some of the macronutrients, the actual frequencies were modest. In general, those compliant were observed to consume more vitamin and mineral-dense food. Conclusion. Dietary intake among patients with type 1 diabetes does not, for many nutrients, meet the recommendations.

POLYUNSATURATED FATTY ACIDS AND PLATELET AGGREGATION

Platelets take part in haemostasis and thrombosis, and studies have been carried out to try to understand how dietary fatty acids could reduce platelet activation and thus the risk of cardiovascular disease. Unfortunately, many of these studies had serious methodological flaws, and the shortcomings in their study designs are probably the main reason for contradictory results in humans. The evidence concerning linoleic acid is not consistent, but intervention studies show increased platelet aggregation to various agonists after high-linoleic-acid diets. On the other hand, intake of alpha-linoleic acid either has no effect or leads to decreased platelet aggregation when compared with linoleic acid. High intake of long-chain n-3 fatty acids of fish or fish oils seems to usually decrease platelet aggregation. To date, there have not been many studies on the effect of platelet aggregation of small or reasonable amounts of n-3 fatty acids.

Sense of coherence, food selection and leisure time physical activity in type 1 diabetes.

Background: Successful management of type 1 diabetes depends on the self-care practices. Sense of coherence has been associated with various measures of lifestyle choices. We aimed to study the associations between sense of coherence and self-care practices in patients with type 1 diabetes. We hypothesized that patients with weak sense of coherence have less prudent food choices and lower physical activity. Methods: Cross-sectional data from 1104 patients (44% men, mean age 45±12 years) from the FinnDiane Study were available. Sense of coherence, dietary intake, and leisure time physical activity were evaluated using self-reported questionnaires. Diet score was calculated based on the degree to which food choices complied with dietary guidelines. Weekly metabolic equivalent hours were calculated by multiplying the activity duration by the activity- and intensity-specific metabolic equivalent. Results: The sense of coherence score correlated positively both with the diet score and the weekly metabolic equivalent hours. Those in the lowest sense of coherence tertile had both the lowest diet scores and the lowest weekly metabolic equivalent hours values. Among women, the sense of coherence score was associated with the diet score when adjusted for age, socioeconomic status, received dietary guidance, and nephropathy status. The sense of coherence score independently predicted the metabolic equivalent hours value in men. Conclusions : A higher sense of coherence score predicted more prudent food choices in women and higher physical activity in men. In the future, the health consequences associated with a weak sense of coherence should be studied prospectively. Also, the possibility to use the sense of coherence questionnaire as a screening instrument to identify patients who could benefit from intensified counseling should be investigated.

Effects of conjugated linoleic acid on linoleic and linolenic acid metabolism in man.

Evidence from animal studies suggests that conjugated linoleic acid (CLA) modulates plasma and tissue appearance of newly synthesized PUFA. The effects of a 1.2g (0.5 % energy) daily intake of the cis-9,trans-11 (c9,t11) isomer of CLA, trans-10,cis-12 (t10,c12) isomer of CLA or olive oil (placebo) on linoleic acid (LA) and linolenic acid (LNA) metabolism in healthy human volunteers was investigated. Fifteen subjects were fed an experimental diet and supplemented with c9,t11-CLA, t10,c12-CLA or placebo for 7 d before consuming a tracer dose of U-[(13)C]LA (50 mg) and U-[(13)C]LNA (50 mg). Blood samples were taken at 0, 2, 4, 6, 8, 24, 48, 72 and 168 h and analysed using high-precision MS. No differences between the groups in peak plasma [(13)C]LA (10.3-11.6 % of dose), [(13)C]LNA (2.5-2.9 % of dose), [(13)C]arachidonic acid (0.09-0.12 % of dose), [(13)C]EPA (0.04-0.06 % of dose) or [(13)C]DHA (0.06-0.10 % of dose) were detected. Concentration v. time curves (area under the curve) also showed no significant differences between groups. This suggests that, in healthy human subjects consuming a diet with adequate intake of essential fatty acids, CLA does not affect metabolism of LA or LNA.

No effect on oxidative stress biomarkers by modified intakes of polyunsaturated fatty acids or vegetables and fruit.

Diet may both increase and decrease oxidative stress in the body. We compared the effects of four strictly controlled isocaloric diets with different intakes of polyunsaturated fatty acids (PUFA, 11 or 3% of energy) and vegetables and fruit (total amount of vegetables and fruit 516 or 1059 g/10 MJ) on markers associated with oxidative stress in 77 healthy volunteers (19–52 years). Plasma protein carbonyls (2-aminoadipic semialdehyde residues) and whole-body DNA and nucleotide oxidation (urinary 8-oxo-7,8-dihydro-2′-deoxyguanosine excretion) tended to decrease in all treatment groups with no differences between the diets. The diets did not differ in their effects on red blood cell antioxidative enzyme activities, either. The results suggest that in healthy volunteers with adequate nutrient intakes, 6-week diets differing markedly in the amount of PUFA or vegetables and fruit do not differ in their effects on markers associated with oxidative stress.