The inverse association between relative abundances of oleic acid and arachidonic acid: a case of distribution dependent regulation?

BACKGROUND: Since oleic acid (OA, 18:1 c9) and arachidonic acid (AA, 20:4 n6) may have antagonistic actions, it is of interest to assess their relative abundances. We previously reported an inverse correlation between % OA and %AA. However, percentages of the same sum may be correlated without involving biology. We now investigate whether random numbers, generated within the true concentration distributions for OA and AA, may be correlated. METHODS: We reanalysed data from a previous diet trial in chickens. Breast muscle was collected, and the concentration of fatty acids in muscle lipids was determined using gas chromatography. We computed R = S - OA - AA, where S is the sum of all fatty acids (g/kg) and R is concentration of all fatty acids, except OA and AA. From histograms we found physiological distributions of OA, AA and R. Then we generated random numbers for each of 3 variables (n = 163), within the distributions (g/kg) for OA (1-7), AA (0.25-0.39), and R (4-10). Next we made scatterplots of % OA vs. % AA, and studied how a narrowing or broadening of distributions might change the relationship. RESULTS: Also with random numbers, generated within true concentration distributions for OA and AA, we found an inverse relationship between their percentages (r = - 0.356, p < 0.001; r = 163); however, the points were not close to the regression line. The %OA vs. %AA relationship changed appreciably in response to slightly altering concentration distributions of OA and AA, and a negative association could be changed to become positive. CONCLUSION: Using random numbers, generated within the biological distributions for OA, AA, and sum of the remaining fatty acids, we found an inverse relationship between "% OA" and "% AA", but the scatterplot was poor compared with that obtained with real values. The association between relative abundances of random numbers of OA and AA was very sensitive to changes in distributions, and a negative association could be changed to become positive by slightly altering the distributions. Thus, the association between relative abundances of OA and AA could be partly caused by the particular distribution of the fatty acid concentration: a Distribution Dependent Correlation.

The inverse association between relative abundances of oleic acid and arachidonic acid is related to alpha -linolenic acid.

BACKGROUND: Many health effects of oils rich in oleic acid (OA, 18:1 n9) seem to be opposite those of arachidonic acid (AA, 20:4 n6), i.e. concerning cardiovascular risk. In recent studies in humans and in the rat we observed that percentages of OA and AA were inversely related, raising the question of whether the inverse association is a general one, and how it might be explained. In the present work we examine whether percentages of OA and AA are inversely associated in breast muscle lipids of chickens, and whether alpha-linolenic acid (ALA) may be related to the OA/AA ratio. METHODS: The study group consisted of 163 chickens. Breast muscle was collected, and the concentration of fatty acids in muscle lipids was determined using gas chromatography. We studied association between fatty acids using bivariate correlations (Pearson) and linear regression. Synthesis of OA from stearic acid (Stear) was estimated using the OA/Stear ratio, and formation of AA from linoleic acid (LA) was estimated by the AA/LA ratio. RESULTS: We found a strong inverse relationship (r = -0.942, p < 0.001; n = 163) between % OA and % AA in breast muscle lipids of the chickens. There was an inverse association (r = -0.887, p < 0.001) between the OA/Stearic acid ratio, estimating Delta9 desaturase, and the AA/LA ratio, estimating desaturases/elongase activities. Furthermore, there was a strong negative association between % AA and the OA/Stearic acid ratio (r = -0.925, p < 0.001), and % OA correlated negatively (r = -0.914, p < 0.001) with the AA/LA ratio. ALA was positively associated (r = 0.956, p < 0.001) with the OA/AA ratio, and this association prevailed when controlling for the other fatty acids. ALA was positively associated (r = 0.857, p < 0.001) with the OA/Stear ratio, but was negatively related (r = -0.827, p < 0.001) to the AA/LA ratio. CONCLUSIONS: The relative abundances of OA and AA that are inversely related in muscle lipids of chickens may be explained by a feedback regulation between the synthesis of OA and AA, and related to ALA, which seems to stimulate formation of OA, and inhibit synthesis of AA, but further studies are required to clarify whether this hypothesis is valid.

The InnvaDiab-DE-PLAN study: a randomised controlled trial with a culturally adapted education programme improved the risk profile for type 2 diabetes in Pakistani immigrant women.

The objective of the present study was to explore whether a culturally adapted lifestyle education programme would improve the risk factor profile for type 2 diabetes (T2D) and the metabolic syndrome (MetS) among Pakistani immigrant women in Oslo, Norway. The randomised controlled trial (the InnvaDiab study), lasting 7 ± 1 months, comprised six educational sessions about blood glucose, physical activity and diet. Participants (age 25-62 years) were randomised into either a control (n 97) or an intervention (n 101) group. Primary outcome variables were fasting and 2 h blood glucose, and secondary outcome variables were fasting levels of insulin, C-peptide, lipids, glycated Hb, BMI, waist circumference and blood pressure, measured 1-3 weeks before and after the intervention. During the intervention period, the mean fasting blood glucose decreased by 0·16 (95 % CI -0·27, -0·05) mmol/l in the intervention group, and remained unchanged in the control group (difference between the groups, P=0·022). Glucose concentration 2 h after the oral glucose tolerance test decreased by 0·53 (95 % CI -0·84, -0·21) mmol/l in the intervention group, but not significantly more than in the control group. A larger reduction in fasting insulin was observed in the intervention group than in the control group (between-group difference, P= 0·036). Among the individuals who attended four or more of the educational sessions (n 59), we found a more pronounced decrease in serum TAG (-0·1 (95 % CI -0·24, 0·07) mmol/l) and BMI (-0·48 (95 % CI -0·78, -0·18) kg/m²) compared with the control group. During the intervention period, there was a significant increase in participants having the MetS in the control group (from 41 to 57 %), which was not seen in the intervention group (from 44 to 42 %). Participation in a culturally adapted education programme may improve risk factors for T2D and prevent the development of the MetS in Pakistani immigrant women.

Percentage oleic acid is inversely related to percentage arachidonic acid in total lipids of rat serum.

BACKGROUND: Since many health effects of oils rich in oleic acid (18:1, n-9) seem to be opposite those of arachidonic acid (20:4, n-6), i.e. concerning cardiovascular risk, we examined whether % 18:1 might be negatively associated with % 20:4. METHODS: Fatty acid separation by gas chromatography was performed in total serum lipids of 36 male rats. Using bivariate correlations and multiple linear regressions we studied the association between oleic acid and arachidonic acid. RESULTS: We found an inverse relationship (r = -0.885, p < 0.001; n = 36) between percentages of 18:1 and 20:4 in total lipids of rat serum, persisting when controlling for the other fatty acids measured. In a multiple linear regression model with % 20:4 as the dependent variable and percentages of the other fatty acids entered simultaneously as independents, oleic acid and linoleic acid contributed most to predict % 20:4. Per cent 20:4 correlated negatively (p< 0.01) with a Delta-9 desaturase index, i.e. the (18:1)/(18:0) ratio, and with the (20:4)/(18:2) ratio, estimating desaturases/elongase. CONCLUSIONS: Percentages of 18:1 and 20:4 seem to be inversely related and desaturase/elongase inhibition could be involved. The results might partly explain positive health effects of foods rich in oleic acid.

Percentages of oleic acid and arachidonic acid are inversely related in phospholipids of human sera.

BACKGROUND: Many health effects of oils rich in oleic acid (18:1 n9) seem to be opposite those of arachidonic acid (20:4 n6), i.e. concerning cardiovascular risk. In recent study in rats we observed that percentages of oleic acid and arachidonic acid were inversely related in total serum lipids. In the present work we investigate whether an inverse relationship between this couple of fatty acids also exists in the phospholipid fraction of human sera. METHODS: The study group consisted of 11 men and 35 women. Mean age was 23.8 ± 2.5 years (mean ± SD), and the body mass index was 23.5 ± 3.2 kg/m2. After fasting overnight, blood was drawn and the concentration of fatty acids in serum phospholipids was determined, using gas chromatography. We studied the association between percentages of oleic acid and arachidonic acid using bivariate correlations (Pearson), and multiple linear regressions. RESULTS: We found an inverse relationship (r = -0.563, p < 0.001; n = 46) between % oleic acid and % arachidonic acid in the serum phosholipid fraction of the 46 fasting subjects. By multiple linear regression, and % 20:4 n6 as the dependent variable, the inverse association with % 18:1 n9 persisted when controlling for sex, age, body mass index, and percentages of the other fatty acids measured (t = -17.6, p < 0.001). Per cent 20:4 n6 seemed to correlate negatively (r = -0.289, p = 0.05) with the (18:1 n9)/(18:0) ratio, estimating Delta9 desaturase activity, and % oleic acid correlated negatively (r = -0.321, p = 0.029) with the (20:4)/(18:2) ratio, estimating desaturases/elongase activities. CONCLUSIONS: In a group of healthy human subjects, percentages of oleic acid and arachidonic acid were inversely related, and the inverse association persisted when controlling for possible confounding variables. The findings might contribute to explain positive health effects of foods rich in oleic acid.

Increased serum triglycerides and reduced HDL cholesterol in male rats after intake of ammonium chloride for 3 weeks.

BACKGROUND: Previous data suggested that intake of sodas and other acid beverages might be associated with increased levels of serum triglycerides, lowered HDL cholesterol, and increased formation of mono unsaturated fatty acids, which are the preferred ones for triglyceride synthesis. The present work is an extension of these studies. METHODS: Thirty male rats were divided into 3 groups. All groups were given the same food, but various beverages: water (W), ammonium chloride, 200 mmol/L (AC), or sodium bicarbonate, 200 mmol/L (SB). Serum triglycerides, HDL cholesterol, and the fatty acid distribution in total serum lipids were determined. Delta9-desaturase in serum lipids was estimated by the ratio of palmitoleic to palmitic acid, and by the oleic/stearic acid ratio. Correlation and ANOVA were used to study associations and group differences. RESULTS: After 3 weeks, the AC group had higher triglyceride concentration and higher Delta9 desaturase indexes, but lower serum HDL and body weight as compared with the SB and W groups. In each of the groups, the oleic acid/stearic acid ratio correlated positively with serum triglycerides; in the pooled group the correlation coefficient was r = 0.963, p<0.01. CONCLUSIONS: Rats ingesting ammonium chloride as compared with sodium bicarbonate responded with increased desaturase indexes, increased serum triglycerides, and lowered HDL cholesterol concentration, thereby possibly contributing to explain the increased triglyceride concentration previously observed in subjects with a frequent intake of acid beverages, such as sodas containing carbonic acid, citric acid, and phosphoric acid.

Intended Ranges and Correlations between Percentages of Variables Like Oleic Acid, Eicosapentaenoic Acid, and Arachidonic Acid.

In chicken muscle, we previously showed that ranges of oleic acid (OA), arachidonic acid (AA), and eicosapentaenoic acid (EPA) might explain why %OA was inversely related to %AA, and that %EPA correlated positively with %AA. We here try to clarify further how ranges of the fatty acids could make strong associations between their relative amounts, utilizing published data from chicken muscle and human sera. We generated random number variables (OA', AA', EPA') in lieu of the true variables, and we studied effects of altering their ranges upon scatterplots of %OA' vs. %AA' (%EPA'), and %AA' vs. %EPA'. To explain the results, we first applied the equation OA' + AA' + EPA' = S, i.e., %OA' + %AA' + %EPA' = 100. Next, we considered how the OA' (AA', EPA') fractions of S related to S. Increasing the OA' range towards higher values improved the positive association between %AA' and %EPA'. Thus, increased intake of OA could improve the positive correlations between percentages of eicosanoid precursors, raising the question of whether "intended ranges" of some fatty acids represent a case of evolutionary selection to, e.g., achieve balance between eicosanoids.

Long-term effects of daily postprandial physical activity on blood glucose: a randomized controlled trial.

Previous studies have shown that a bout of moderate or light postprandial physical activity effectively blunts the postprandial increase in blood glucose. The objective of this study was to test whether regular light postprandial physical activity can improve glycemia in persons with hyperglycemia or with a high risk of hyperglycemia. We randomized 56 participants to an intervention or a control group. They were diagnosed as hyperglycemic, not using antidiabetics, or were categorized as high-risk individuals for type 2 diabetes. The intervention group was instructed to undertake a minimum 30 min of daily light physical activity, starting a maximum of 30 min after a meal in addition to their usual physical activity for 12 weeks. The control group maintained their usual lifestyle. Blood samples were taken pre- and post-test. Forty participants completed the study and are included in the results. The self-reported increase in daily physical activity from before to within the study period was higher in the intervention group compared with control (41 ± 25 vs. 2 ± 16 min, p < 0.001). Activity diaries and accelerometer recordings supported this observation. The activity in the intervention group started earlier after the last meal compared with control (30 ± 13 vs. 100 ± 57 min, p = 0.001). There were no within- or between-group differences in any glycemic variable from pre- to post-test. In conclusion, the present study does not seem to support the notion that regular light postprandial physical activity improves blood glucose in the long term in persons with hyperglycemia or with high risk of hyperglycemia.

Effect of a high intake of cheese on cholesterol and metabolic syndrome: results of a randomized trial.

BACKGROUND: Cheese is generally rich in saturated fat, which is associated with increased risk for cardiovascular diseases. Nevertheless, recent reports suggest that cheese may be antiatherogenic. OBJECTIVE: The goal of this study was to assess whether intake of two types of Norwegian cheese, with widely varying fat and calcium content, might influence factors of the metabolic syndrome and serum cholesterol levels differently. DESIGN: A total of 153 participants were randomized to one of three groups: Gamalost(®), a traditional fat- and salt-free Norwegian cheese (50 g/day), Gouda-type cheese with 27% fat (80 g/day), and a control group with a limited cheese intake. Blood samples, anthropometric measurements, blood pressure, and questionnaires about lifestyle and diet were obtained at inclusion and end. RESULTS: At baseline, there were no differences between the groups in relevant baseline characteristics, mean age 43, 52.3% female. After 8 weeks' intervention, there were no changes in any of the metabolic syndrome factors between the intervention groups compared with the control group. There were no increases in total- or LDL cholesterol in the cheese groups compared with the control. Stratified analysis showed that those in the Gouda group with metabolic syndrome at baseline had significant reductions in total cholesterol at the end of the trial compared with control (-0.70 mmol/L, p=0.013), and a significantly higher reduction in mean triglycerides. In the Gamalost group, those who had high total cholesterol at baseline had a significant reduction in total cholesterol compared with control (-0.40 mmol/L, p=0.035). CONCLUSIONS: In conclusion, cholesterol levels did not increase after high intake of 27% fat Gouda-type cheese over 8 weeks' intervention, and stratified analysis showed that participants with metabolic syndrome had reduced cholesterol at the end of the trial.

Does cheese intake blunt the association between soft drink intake and risk of the metabolic syndrome? Results from the cross-sectional Oslo Health Study.

OBJECTIVES: A high soft drink intake may promote, whereas intake of cheese may reduce risk of the metabolic syndrome (MetS), but will cheese intake blunt the soft drink versus MetS association? DESIGN: Cross-sectional study. SETTING: The Oslo Health Study. PARTICIPANTS: Among the 18 770 participants of the Oslo Health Study there were 5344 men and 6150 women having data on cheese and soft drink intake and on risk factors for MetS, except for fasting glucose. The MetSRisk index=the weighted sum of triglycerides (TG), systolic blood pressure, diastolic blood pressure, waist circumference and body mass index (BMI) divided by high-density lipoprotein (HDL) were used as a combined risk estimate to examine the cheese/soft drink versus MetS interaction, and the SumRisk index was used to assess whether increasing intake of soft drinks/cheese would include an increasing number of MetS factors being above the cut-off values. We analysed the data using non-parametric correlation and analysis of covariance (ANCOVA). RESULTS: In all three groups of soft drink intake (seldom/rarely, 1-6 glasses/week, ≥1 glass/day), there was a negative cheese versus MetSRisk correlation (p≤0.003), but in the highest intake group the influence of cheese seemed to level off, suggesting interaction. However, there was no interaction between cheese and soft drinks within the fully adjusted models. Conversely, at all four levels of cheese intake, MetSRisk increased with an increasing intake of soft drinks (p≤0.001 at all cheese levels). Similar associations were found with the SumRisk index. When controlling for a large number of covariates (eg, sex, age group, smoking, education, physical activity, intake of fruits/berries and vegetables), the above associations prevailed. CONCLUSIONS: Cheese intake blunted the association between soft drink intake and MetS, an influence possibly related to fatty acid desaturation, or to undetected covariates.

The oslo health study: a dietary index estimating frequent intake of soft drinks and rare intake of fruit and vegetables is negatively associated with bone mineral density.

Background. Since nutritional factors may affect bone mineral density (BMD), we have investigated whether BMD is associated with an index estimating the intake of soft drinks, fruits, and vegetables. Methods. BMD was measured in distal forearm in a subsample of the population-based Oslo Health Study. 2126 subjects had both valid BMD measurements and answered all the questions required for calculating a Dietary Index = the sum of intake estimates of colas and non-cola beverages divided by the sum of intake estimates of fruits and vegetables. We did linear regression analyses to study whether the Dietary Index and the single food items included in the index were associated with BMD. Results. There was a consistent negative association between the Dietary Index and forearm BMD. Among the single index components, colas and non-cola soft drinks were negatively associated with BMD. The negative association between the Dietary Index and BMD prevailed after adjusting for gender, age, and body mass index, length of education, smoking, alcohol intake, and physical activity. Conclusion. An index reflecting frequent intake of soft drinks and rare intake of fruit and vegetables was inversely related to distal forearm bone mineral density.

The Oslo Health Study: a Dietary Index estimating high intake of soft drinks and low intake of fruits and vegetables was positively associated with components of the metabolic syndrome.

A previous finding that soft drink intake is associated with increased serum triglycerides and decreased high-density-lipoprotein (HDL) cholesterol, both components of the metabolic syndrome (MetS), raises the question of whether other aspects of an unhealthy diet might be associated with MetS. Main MetS requirements are central obesity and 2 of the following: increased triglycerides, low HDL, increased systolic or diastolic blood pressure, and elevated fasting blood glucose. Of the 18 770 participants in the Oslo Health Study, there were 13 170 respondents (5997 men and 7173 women) with data on MetS factors (except fasting glucose) and on the components used to determine the Dietary Index score (calculated as the intake estimate of soft drinks divided by the sum of intake estimates of fruits and vegetables). MetSRisk was calculated as the sum of arbitrarily weighted factors positively associated with MetS divided by HDL cholesterol. Using regression analyses, the association of the Dietary Index with MetSRisk, with the number of MetS requirements present, and with the complete MetS was studied. In young, middle-aged, and senior men and women, there was, in general, a positive association (p < 0.001) between the Dietary Index and the MetS estimates, which persisted in regression models adjusted for sex, age, time since the last meal, intake of cheese, intake of fatty fish, intake of coffee, intake of alcohol, smoking, physical activity, education, and birthplace. Thus, an index reflecting a high intake of soft drinks and a low intake of fruit and vegetables was positively and independently associated with aspects of MetS.

The Oslo health study: soft drink intake is associated with the metabolic syndrome.

It has been reported that the frequency of cola intake (COLA) is positively associated with serum triglycerides and negatively associated with high-density-lioprotein (HDL) cholesterol, both components of the metabolic syndrome (MetS). The question now is whether noncola soft drink intake (NCOLA) is associated with MetS. Among the 18 770 participants in the Oslo Health Study, 5373 men and 6181 women had data on COLA and NCOLA and risk factors for MetS (except fasting glucose). Main MetS requirements are central obesity and 2 of the following: increased triglycerides, low HDL cholesterol, increased systolic or diastolic blood pressure, and elevated fasting blood glucose. The MetSRisk index was calculated to estimate many MetS components. Using regression analyses, the association between COLA (NCOLA) and MetS (MetSRisk) was studied. In young (aged 30 years), middle-aged (aged 40 and 45 years), and senior (aged 59 and 60 years) men and women, there was, in general, a positive correlation between COLA and MetSRisk, and between COLA and single MetS risk factors, except HDL cholesterol, which was negatively correlated. A less consistent picture was found for NCOLA. By regression analyses, after adjustment for sex, age, time since last meal, and use of sugar-sweetened soft drinks, a positive association between COLA (NCOLA) and MetSRisk (MetS) was still found. However, when also controlling for cheese, fatty fish, coffee, alcohol, smoking, physical activity, education, and birthplace, only the association with COLA remained significant, irrespective of the presence or absence of sugar. In conclusion, the self-reported intake frequency of soft drinks can be positively associated with MetS.

Cola intake and serum lipids in the Oslo Health Study.

Soft drinks can be a major source of sucrose, which may influence serum lipid concentration. We have examined the association between intake frequency of various types of soft drinks and the concentration of serum triglycerides (TG) and high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol in the cross-sectional Oslo Health Study. A total of 14 188 subjects of the altogether 18,770 participants of the study had data on intake frequency of colas and non-colas, with or without sugar. The population sample consisted of both sexes and 3 age groups: group 1 (30 years of age), group 2 (40 and 45 years of age), and group 3 (59-60 years of age). In both sexes, HDL decreased and TG increased significantly (p < 0.001) with increasing intake frequency of colas. In contrast, no consistent associations were found between the reported intake of non-cola soft drinks and the serum lipids. We found no significant differences related to the reported presence or absence of sugar in the soft drinks. In multiple linear regression analyses, the colas vs. serum lipid associations prevailed (p < 0.001) after including 13 possible confounders: sex; age group; time since last meal; physical activity; intake of alcohol, coffee, cheese, fruit and (or) berries, and fatty fish; smoking; length of education; use of cholesterol-lowering drugs; and intake of non-colas. Thus, the self-reported intake frequency of colas, but not other soft drinks, was negatively associated with serum HDL, and positively associated with TG and LDL.

Slow postmeal walking reduces postprandial glycemia in middle-aged women.

Postprandial blood glucose concentration is a risk factor for the development of cardiovascular diseases and diabetes, even at states well below hyperglycemic levels. A previous study has shown that postmeal exercise of moderate intensity blunts the blood glucose increase after carbohydrate intake (Høstmark et al. Prev. Med. 42(5): 369-371). The objective of the present study was to examine whether even postmeal slow walking would have a similar effect. Fourteen healthy women aged >50 years participated in 3 experiments in a random crossover design: after a carbohydrate-rich meal, either they were seated (control experiment) or they performed slow postmeal walking for 15 min (W15) or 40 min (W40). Blood glucose concentration was determined prior to the meal (fasting), and at 11 time points throughout each experiment. The W15 trial lowered the blood glucose values during walking and delayed the peak blood glucose value (p = 0.003). In W40, the postmeal blood glucose increase during walking was blunted, the peak glucose value was delayed (p = 0.001), and the incremental area under the 2-h blood glucose curve (IAUC) was reduced (p = 0.014). There was a negative relationship between IAUC and walking time (p = 0.016). The individual reducing effect of walking on IAUC correlated strongly with IAUC on the control day (p < 0.001). We conclude that even slow postmeal walking can reduce the blood glucose response to a carbohydrate-rich meal. The magnitude of this effect seems to be related to the duration of walking and to the magnitude of the postprandial blood glucose response when resting after a carbohydrate-rich meal.