The genetics of serum lipid responsiveness to dietary interventions

Metabolic pathways in sporadic colorectal carcinogenesis: A new proposal

Given the reports made about geographical differences in Colorectal Cancer (CRC) occurrence, suggesting a link between dietary habits, genes and cancer risk, we hypothesise that there are four fundamental metabolic pathways involved in diet-genes interactions, directly implicated in colorectal carcinogenesis: folate metabolism; lipid metabolism; oxidative stress response; and inflammatory response. Supporting this hypothesis are the evidence given by the significant associations between several diet-genes polymorphisms and CRC, namely: MTHFR, MTR, MTRR and TS (involved in folate metabolism); NPY, APOA1, APOB, APOC3, APOE, CETP, LPL and PON1 (involved in lipid metabolism); MNSOD, SOD3, CAT, GSTP1, GSTT1 and GSTM1 (involved in oxidative stress response); and IL-1, IL-6, TNF-α, and TGF-β (involved in inflammatory response). We also highlight the association between some foods/nutrients/nutraceuticals that are important in CRC prevention or treatment and the four metabolic pathways proposed, and the recent results of genome-wide association studies, both assisting our hypothesis. Finally, we propose a new line of investigation with larger studies, using accurate dietary biomarkers and investigating the four metabolic pathways genes simultaneously. This line of investigation will be essential to understand the full complexity of the association between nature and nurture in CRC and perhaps in other types of cancers. Only with this in-depth knowledge will it be possible to make personalised nutrition recommendations for disease prevention and management.

Ketogenic Diet-induced Elevated Cholesterol, Elevated Liver Enzymes and Potential Non-alcoholic Fatty Liver Disease

A 57-year-old woman with class I obesity (BMI = 31.42 kg/m2) and a medical history significant for binge-eating disorder with emotionally-triggered eating, post-traumatic stress disorder, and untreated depression and anxiety, presented for follow-up of weight management with laboratory values revealing acutely-worsened hyperlipidemia and elevated liver enzymes. Abdominal ultrasound showed a mildly heterogenous and echogenic liver, without focal lesions, suggestive of non-alcoholic fatty liver disease. The only significant change from previous consultation four months prior was introduction of a ketogenic diet consisting of eggs, cheese, butter, oil, nuts, leafy green vegetables and milk (almond and coconut). The patient reported a reduction in hunger on this diet. Immediate discontinuation of the diet resulted in modest reduction of low-density lipoprotein cholesterol (LDL-C) and liver enzymes two weeks later. Resolution of liver enzymes was seen within eight months and LDL-C levels normalized one year later. This case report discusses the rationale, benefits and risks of a ketogenic diet and encourages increased vigilance and monitoring of patients on such a diet.

Nutrigenetics of cholesterol metabolism: observational and dietary intervention studies in the postgenomic era

Cholesterol metabolism is a well-defined responder to dietary intakes and a classic biomarker of cardiovascular health. For this reason, circulating cholesterol levels have become key in shaping nutritional recommendations by health authorities worldwide for better management of cardiovascular disease, a leading cause of mortality and one of the most costly health problems globally. Data from observational and dietary intervention studies, however, highlight a marked between-individual variability in the response of cholesterol metabolism to similar dietary protocols, a phenomenon linked to genetic heterogeneity. This review summarizes the postgenomic evidence of polymorphisms within cholesterol-associated genes relative to fasting circulating cholesterol levels under diverse nutritional conditions. A number of cholesterol-related gene-diet interactions are confirmed, which may have clinical importance, supporting a deeper look into the rapidly emerging field of nutrigenetics for meaningful conclusions that may eventually lead to genetically targeted dietary recommendations in the era of personalized nutrition.

Association of height and pubertal timing with lipoprotein subclass profile: exploring the role of genetic and environmental effects

OBJECTIVES

Little is known about the relationship between growth and lipoprotein profile. We aimed to analyze common genetic and environmental factors in the association of height from late childhood to adulthood and pubertal timing with serum lipid and lipoprotein subclass profile.

METHODS

A longitudinal cohort of Finnish twin pairs (FinnTwin12) was analyzed using self-reported height at 11-12, 14, 17 years and measured stature at adult age (21-24 years). Data were available for 719 individual twins including 298 complete pairs. Serum lipids and lipoprotein subclasses were measured by proton nuclear magnetic resonance spectroscopy. Multivariate variance component models for twin data were fitted. Cholesky decomposition was used to partition the phenotypic covariation among traits into additive genetic and unique environmental correlations.

RESULTS

In men, the strongest associations for both adult height and puberty were observed with total cholesterol, low-density lipoprotein cholesterol, intermediate-density lipoprotein cholesterol, and low-density lipoprotein particle subclasses (max. r = -0.19). In women, the magnitude of the correlations was weaker (max. r = -0.13). Few associations were detected between height during adolescence and adult lipid profile. Early onset of puberty was related to an adverse lipid profile, but delayed pubertal development in girls was associated with an unfavorable profile, as well. All associations were mediated mainly by additive genetic factors, but unique environmental effects cannot be disregarded.

CONCLUSIONS

Early puberty and shorter adult height relate to higher concentrations of atherogenic lipids and lipoprotein particles in early adulthood. Common genetic effects behind these phenotypes substantially contribute to the observed associations.

Molecular mechanisms involved in the bidirectional relationship between diabetes mellitus and periodontal disease

Both diabetes and periodontitis are chronic diseases. Diabetes has many adverse effects on the periodontium, and conversely periodontitis may have deleterious effects further aggravating the condition in diabetics. The potential common pathophysiologic pathways include those associated with inflammation, altered host responses, altered tissue homeostasis, and insulin resistance. This review examines the relationship that exists between periodontal diseases and diabetes mellitus with a focus on potential common pathophysiologic mechanisms.

The effect of whole grain wheat sourdough bread consumption on serum lipids in healthy normoglycemic/normoinsulinemic and hyperglycemic/hyperinsulinemic adults depends on presence of the APOE E3/E3 genotype: a randomized controlled trial

Background

Epidemiological studies associate consumption of whole grain foods, including breads, with reduced cardiovascular disease (CVD) risk; however, few studies have compared wheat whole grains with wheat refined grains.

Methods

This study investigated effects of 6-week consumption of whole grain wheat sourdough bread in comparison to white bread on fasting serum lipids in normoglycemic/normoinsulinemic (NGI; n = 14) and hyperglycemic/hyperinsulinemic (HGI; n = 14) adults. The influence of single-nucleotide polymorphisms, 3 within the APOE gene (E2, E3, E4) and 2 within the hepatic lipase gene promoter (LIPC -514C>T, LIPC -250G>A) were considered.

Results

At baseline, HGI participants had significantly higher body weight, waist circumference, body fat, and fasted glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), glucagon, triacylglycerols (TAG) and TAG:HDL-cholesterol, compared to NGI participants; however, none of these in addition to none of the other serum lipids, differed between bread treatments, within either participant group. For participants with the APOE E3/E3 genotype, LDL-cholesterol (P = 0.02) increased in the NGI group (n = 7), and TAG (P = 0.03) and TAG:HDL-cholesterol (P = 0.04) increased in the HGI group (n = 10), following consumption of whole grain wheat sourdough compared to white bread.

Conclusions

In summary, 6-week consumption of whole grain wheat sourdough bread did not significantly modulate serum lipids in NGI or HGI adults; however, it significantly increased LDL-cholesterol, TAG and TAG:HDL-cholesterol in participants with the APOE E3/E3 genotype. These data add to limited literature comparing wheat whole grains to wheat refined grains on CVD risk and highlight the need to consider genetic variation in relation to lipoprotein lipid content and CVD risk.

Selection on alleles affecting human longevity and late-life disease: the example of apolipoprotein E

It is often claimed that genes affecting health in old age, such as cardiovascular and Alzheimer diseases, are beyond the reach of natural selection. We show in a simulation study based on known genetic (apolipoprotein E) and non-genetic risk factors (gender, diet, smoking, alcohol, exercise) that, because there is a statistical distribution of ages at which these genes exert their influence on morbidity and mortality, the effects of selection are in fact non-negligible. A gradual increase with each generation of the ε2 and ε3 alleles of the gene at the expense of the ε4 allele was predicted from the model. The ε2 allele frequency was found to increase slightly more rapidly than that for ε3, although there was no statistically significant difference between the two. Our result may explain the recent evolutionary history of the epsilon 2, 3 and 4 alleles of the apolipoprotein E gene and has wider relevance for genes affecting human longevity.

A 12-week worksite health promotion program reduces cardiovascular risk factors in male workers with the apolipoprotein E2 and apolipoprotein E3 genotypes, but not in apolipoprotein E4 genotype

Worksite health promotion programs focusing on diet and lifestyle modification have been shown to improve health outcomes in workers. The purpose of this study was to investigate whether a 12-week worksite health promotion program shows different response of cardiovascular risk factors in subjects according to apolipoprotein E (Apo E) genotype and obesity level in 141 male Korean industrial workers. We hypothesized that the health changes of a 12-week intervention may not be the same within Apo E genotypes in nonobese and obese subjects. They received 5 face-to-face meetings based on their health profiles. In obese group carrying Apo E3 genotype, body mass index, body fat (%), waist circumference, waist-hip ratio, and systolic blood pressure were decreased, as well as intakes of energy (P = .000) and carbohydrate (P = .005). High-density lipoprotein cholesterol (P = .004) level was improved in individuals with the Apo E2 genotype. These beneficial effects were only observed in individuals with the Apo E2 or Apo E3 genotype. Multiple linear regression revealed that obesity was strongly correlated with waist circumference (P = .002), plasma total cholesterol (P = .037), and changes in dietary cholesterol intake (P = .011) in individuals with the Apo E3 genotype, whereas only changes in dietary fat intake (P = .044) was correlated in those with the Apo E4 genotype. Overall, the results of this study suggest that a health promotion program can be a useful method of improving cardiovascular risk factors and dietary intake in industrial workers with certain genotypes only. Therefore, further research is needed to develop a tailored, long-term worksite health promotion program based on genetic background.

APOB-516 T allele homozygous subjects are unresponsive to dietary changes in a three-month primary intervention study targeted to reduce fat intake

Dietary guidelines aim to control fat intake and reduce cardiovascular risk but an important interindividual variability occurs among subjects. The objective was to investigate whether the response of lipid and glucose homeostasis parameters after a three-month diet aimed at reducing cardiovascular risk could be modulated by the -516C/T polymorphism in the apolipoprotein B gene (APOB). Middle-aged men (n = 69) and women (n = 100) with moderate cardiovascular disease risk were advised to reduce total energy and fat intakes and replace saturated dietary fat by monounsaturated and polyunsaturated fat. Subjects were genotyped for APOB-516C/T polymorphism. At the entry and at the end of the three-month period, fasting and postprandial plasma lipid analyses were performed. At entry, subjects homozygous for the APOB-516 T allele exhibited significantly lower fasting plasma concentrations of apolipoprotein B 48, triglycerides and triglyceride-rich lipoproteins-triglycerides compared to C carrier subjects. After the diet period, while C carrier subjects presented a clear improvement of most biological parameters, paradoxically T/T subjects did not modify them. In addition, the apoB 48 postprandial response after a standardized mixed test meal was not improved in T/T subjects after the three-month diet, contrary to C allele carriers. Even though their phenotype at entry does not show any significant increase of risk factors when compared to other groups, subjects homozygous for the APOB-516 T allele are unresponsive to a healthy diet that improves cardiovascular risk status in the whole population.

Metabolic effects of weight loss on a very-low-carbohydrate diet compared with an isocaloric high-carbohydrate diet in abdominally obese subjects

OBJECTIVES

This study was designed to compare the effects of an energy-reduced, isocaloric very-low-carbohydrate, high-fat (VLCHF) diet and a high-carbohydrate, low-fat (HCLF) diet on weight loss and cardiovascular disease (CVD) risk outcomes.

BACKGROUND

Despite the popularity of the VLCHF diet, no studies have compared the chronic effects of weight loss and metabolic change to a conventional HCLF diet under isocaloric conditions.

METHODS

A total of 88 abdominally obese adults were randomly assigned to either an energy-restricted (approximately 6 to 7 MJ, 30% deficit), planned isocaloric VLCHF or HCLF diet for 24 weeks in an outpatient clinical trial. Body weight, blood pressure, fasting glucose, lipids, insulin, apolipoprotein B (apoB), and C-reactive protein (CRP) were measured at weeks 0 and 24.

RESULTS

Weight loss was similar in both groups (VLCHF -11.9 +/- 6.3 kg, HCLF -10.1 +/- 5.7 kg; p = 0.17). Blood pressure, CRP, fasting glucose, and insulin reduced similarly with weight loss in both diets. The VLCHF diet produced greater decreases in triacylglycerols (VLCHF -0.64 +/- 0.62 mmol/l, HCLF -0.35 +/- 0.49 mmol/l; p = 0.01) and increases in high-density lipoprotein cholesterol (HDL-C) (VLCHF 0.25 +/- 0.28 mmol/l, HCLF 0.08 +/- 0.17 mmol/l; p = 0.002). Low-density lipoprotein cholesterol (LDL-C) decreased in the HCLF diet but remained unchanged in the VLCHF diet (VLCHF 0.06 +/- 0.58 mmol/l, HCLF -0.46 +/- 0.71 mmol/l; p < 0.001). However, a high degree of individual variability for the LDL response in the VLCHF diet was observed, with 24% of individuals reporting an increase of at least 10%. The apoB levels remained unchanged in both diet groups.

CONCLUSIONS

Under isocaloric conditions, VLCHF and HCLF diets result in similar weight loss. Overall, although both diets had similar improvements for a number of metabolic risk markers, an HCLF diet had more favorable effects on the blood lipid profile. This suggests that the potential long-term effects of the VLCHF diet for CVD risk remain a concern and that blood lipid levels should be monitored. (Long-term health effects of high and low carbohydrate, weight loss diets in obese subjects with the metabolic syndrome; http://www.anzctr.org.au; ACTR No. 12606000203550).

Association of apolipoprotein A1-C3 gene cluster polymorphisms with gallstone disease

INTRODUCTION

Genetic polymorphisms in apolipoprotein genes may be associated with alteration in lipid profile and susceptibility to gallstone disease.

AIM

To determine the association between apolipoprotein A1 (APOA1) -75 guanine [G] to adenine [A] and +83/84 M2(+/-), MspI) and apolipoprotein C3 (APOC3) (SstI) polymorphisms with gallstone disease.

METHODS

MspI polymorphisms of the APOA1 gene and SstI polymorphisms of APOC3 were analyzed in DNA samples of 214 gallstone patients and 322 age- and sex-matched healthy controls. All statistical analyses were performed using SPSS version 11.5 (SPSS, USA) and Arlequin version 2.0 (Arlequin, Switzerland).

RESULTS

The APOA1 -75 G/A polymorphism was significantly associated with gallstone disease. Patients with the GG genotype (P=0.015) and G allele carriers (P=0.004) had a significantly higher risk of gallstone disease (1.087-fold and 1.561-fold, respectively), whereas patients with AA genotypes (P=0.011) and A allele carriers (P=0.004) were protected (OR 0.230 and 0.641, respectively) against gallstone disease. APOA1 +83 M2(+/-) and APOC3 SstI polymorphisms were not associated with gallstone disease. Case-control analysis of haplotypes showed a significant association in males only. G-M2(+)-S1 conferred risk for gallstone disease (P=0.036; OR 1.593, 95% CI 1.029 to 2.464), while A-M2(+)-S1 was protective (P=0.002; OR 0.370, 95% CI 0.197 to 0.695) against gallstone disease. In APOA1(-75)-APOA1(+83) bilocus haplotypes, G-M2(+) was associated (P=0.0001) with very high risk (OR 3.173, 95% CI 1.774 to 5.674) for gallstone disease in males only. APOA1(-75)-APOC3(SstI) haplotypes also showed significant association while APOA1(+83)-APOC3(SstI) haplotypes showed no association with gallstone disease.

CONCLUSIONS

The APOA1 -75 G/A polymorphism is associated with gallstone disease and shows sex-specific differences. On the other hand, APOA1 M2(+/-) and APOC3 SstI polymorphisms may not be associated with gallstone disease. Haplotype analysis is a better predictor of risk for gallstone disease.

Polymorphisms in the APOA1/C3/A4/A5 gene cluster and cholesterol responsiveness to dietary change

BACKGROUND

The relationship between dietary composition and plasma lipids is to some extent genetically determined. It has been found that variants of some genes (e.g., apolipoprotein E and cholesterol 7-alpha hydroxylase) play an important role in changes in plasma lipid levels in response to dietary intervention. We analyzed the effect of variation in the apolipoprotein (APO) APOA1/C3/A4/A5 gene cluster on decreases in plasma cholesterol levels over an 8-year follow-up study.

METHODS

Men (n=133) from the Czech population, for which dietary composition has markedly changed (red meat 80-->68 kg/person/year, animal fat 16-->9 kg/person/year, fruits and vegetables 133-->150 kg/person/year) were recruited. APOA1 (G-75>A and C83>T), APOC3 (C-482>T and C3238>G), APOA4 (Thr347>Ser and Gln360His) and APOA5 (T-1131>C, Ser19>Trp and Val153>Met) variants were analyzed by PCR and restriction analysis. Lipid levels were analyzed in 1988 and 1996. Dietary information was obtained from the Institute of Agricultural Economy.

RESULTS

In APOA5 Ser19Ser homozygotes (n=105), plasma cholesterol was relatively stable over the years (6.1+/-1.3 and 5.6+/-1.0 mmol/L in 1988 and 1996), but the decrease was much higher in Trp19 carriers (n=27; 6.5+/-1.6 vs. 5.1+/-1.1 mmol/L). This difference in change is significant at p<0.005. Similarly, a better response to dietary changes was detected in carriers of the common APOA4 haplotypes Thr-347Thr/Gln360Gln and Thr347Ser/Gln360Gln (n=102; 6.3+/-1.3 and 5.5+/-1.1 mmol/L in 1988 and 1996, p<0.001). Total cholesterol was relatively stable over time in carriers (n=18) of at least one His360 allele and/or two Ser347 alleles (5.7+/-1.1 and 5.5+/-0.9 mmol/L in 1988 and 1996, n.s.). Other variants analyzed did not influence the change in lipid measurements over time.

CONCLUSIONS

APOA4 and APOA5 variants may play an important role in the individual sensitivity of lipid parameters to dietary composition in men.

Apolipoprotein E polymorphism and changes in serum lipids during a family-based counselling intervention

OBJECTIVE

To compare serum lipids and their changes during a family-based health education in children aged 6-17 years with or without the epsilon4 allele of the gene encoding apolipoprotein E (apoE).

DESIGN

An intervention study.

SETTING

A family-based prevention of risk factors of coronary heart disease in Eastern Finland. The programme consisted of two counselling meetings at children's schools and three at children's homes.

SUBJECTS

Four hundred and thirty-nine children with a family history of cardiovascular diseases (CVD) participated in a family-based health education. The children were divided into two groups according to apoE genotype. The risk group consisted of 143 children having apoE epsilon4 allele (genotype epsilon3/4 or epsilon4/4) and the non-risk group of 296 children without apoE epsilon4 allele (epsilon2/3 or epsilon3/3). The final sample of the follow-up study included 354 (81%) children (114 and 240, respectively).

RESULTS

Baseline differences were found in low-density lipoprotein cholesterol (LDL-C) (P=0.007) and LDL-C/high-density lipoprotein cholesterol (HDL-C) ratio (P=0.030) among boys and in total cholesterol (TC)/HDL-C (P=0.008) and LDL-C/HDL-C ratios (P=0.006) among girls. Differences between groups in changes during the follow-up were observed only for TC/HDL-C ratio (P-value adjusted for age=0.049) among boys.

CONCLUSIONS

At baseline, children with apoE epsilon4 allele had on average a more unfavourable lipid profile than those without apoE epsilon4 allele. However, the effect of about 33 months' family-based health education on plasma lipids did not depend on apoE genotype in children with a family history of CVD.

Moderate increase in dietary sucrose does not influence fasting or postprandial serum lipids regardless of the presence of apolipoprotein E2 allele in healthy subjects

OBJECTIVE

To investigate whether a moderate increase in dietary sucrose intake induces different serum lipid responses in normolipidemic subjects with the epsilon 2 allele compared with subjects without the epsilon 2 allele.

DESIGN

Controlled, parallel study.

SUBJECTS

There were 15 subjects with the apolipoprotein E (APOE)3/2 genotype and 19 subjects with the APOE 3/3 or 3/4 genotype, whose mean+/-s.d. age was 48+/-14 and 35+/-10 years, respectively. All subjects had normal glucose metabolism.

INTERVENTIONS

The subjects were instructed to increase their sucrose intake by 40 g/day for 8 weeks and to decrease the intake of saturated and unsaturated fat to maintain energy balance. Dietary adherence was monitored using food records and the actual increase in sucrose intake was 39.8+/-18.4 g/day. Sixteen subjects (nine with APOE 3/2 genotype, seven with APOE 3/3 or 3/4 genotypes) participated also in an 8 h oral fat tolerance test at the beginning and at the end of the intervention.

RESULTS

Body weight remained stable during the intervention. Sucrose intake did not have a significant effect on fasting concentrations of serum total and lipoprotein lipids, plasma glucose, serum insulin, squalene and non-cholesterol sterols in either genotype group. Neither were there any changes in postprandial lipid or insulin responses.

CONCLUSIONS

Moderate increase in sucrose intake does not affect fasting or postprandial serum lipid responses in healthy subjects with or without the epsilon 2 allele.

Personalized genomic medicine: a future prerequisite for the prevention of coronary artery disease

Within the next 10-15 years, medicine will be personalized in large part on the basis of the individual's genomic variants. Coronary artery disease remains the number one cause of morbidity and mortality in the Western world and is predicted to become the number one cause worldwide by 2010. It has been stated that treating the risk factors of coronary artery disease has made it a preventable disease that should be eliminated in the 21st century. It is postulated that about 50% of susceptibility to coronary artery disease is genetic, involving known and occult risk factors. Thus, comprehensive prevention will require identification of genetic susceptibility. The recent technology of a chip with 500,000 DNA markers makes genome-wide scanning to identify the genes contributing to coronary artery disease possible. Multislice CT will provide the high-throughput coronary arteriograms required for this research and for prevention in asymptomatic individuals with a family history of heart disease.

Variation in the cholesteryl ester transfer protein (CETP) gene does not influence individual plasma cholesterol response to changes in the nature of dietary fat

BACKGROUND AND AIMS

Some individuals respond to a greater extent than others to changes in dietary fat and cholesterol even when dietary intake is consistent. A prospective study has been undertaken in which two groups of individuals according to cholesteryl ester transfer protein (CETP) genotype were compared in terms of plasma lipid response to altering the nature of dietary fat in a free-living situation.

METHODS AND RESULTS

Following genotyping, 35 individuals with the CETP Taq1 B1B1 genotype were paired with age and sex-matched individuals with one or two CETP B2 alleles, to undertake a single crossover trial with a diet high in saturated fat and a diet high in polyunsaturated fat. There was no washout period between the two 4-week phases. Plasma lipoproteins were measured at the beginning and end of each phase. The difference (95% CI) in plasma LDL-cholesterol concentration at the end of the PUFA and SAFA diets was 0.95 (0.71, 1.19) mmol/l in the CETP B1B1 group and 0.80 (0.57, 1.04) mmol/l in the group with at least one CETP B2 allele. The dietary induced changes in the two genotype groups were not significantly different (p=0.38) from each other. Comparable results were observed for plasma total cholesterol. The high PUFA and SAFA diets did not significantly alter plasma HDL concentration in either of the CETP genotype groups. Response was also similar according to apolipoprotein E genotype (E3E3 vs E4+) and lipoprotein lipase genotype (S447X).

CONCLUSIONS

The results of this study do not support previous studies in which CETP genotype predicted plasma LDL-cholesterol response to diet. CETP genotype does not significantly affect the change in plasma total and LDL-cholesterol concentrations that occur when altering the nature of dietary fat. These data suggest that the influence of genetic factors on total and LDL-cholesterol may be relatively small in comparison with the effect of dietary manipulation.

Association of apolipoprotein E genotype with early onset of coronary heart disease in Greek men

Apolipoprotein (apo) E polymorphism has been associated with coronary heart disease (CHD) although its relation to the age of CHD onset is still not defined. The age of onset of established CHD was obtained from 502 Greek men and compared to 103 healthy men. The age grouping was based on the age of CHD onset (earlier < or =44 years, n = 73, intermediate 45-64 years, n = 321, and later > or =65 years, n = 108). Apo E genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and the lipid profile was assessed. No differences in genotype and allele frequencies were found within the CHD groups. The apo epsilon3/4 genotype and the apo epsilon4 allele were less frequent in the earlier-onset group than in healthy men (11.0 % vs 22.3%, Pearson Chi-Square p = 0.028 and 6.8% vs 13.6%, Pearson Chi-Square p = 0.023, respectively). The lipid profile was similar in all genotypes of all groups except for high-density lipoprotein cholesterol levels, which were higher in epsilon2 carriers compared to non-epsilon2 carriers (in mg/dL [+/-SD]; 44 [9] vs 39 [10], in mmol/L [+/-SD]; 1.1 [0.2] vs 1.0 [0.3] p = 0.005). There is an association between apo E genotype and early onset of CHD in Greek men. In the earlier CHD onset group, the apo epsilon3/4 genotype was less frequent compared to healthy men. This supports that the apo epsilon3/4 genotype is associated with decreased risk of premature CHD. Because the results of similar studies are not consistent, it may be that the relationship between apo E genotype and CHD is related to ethnicity rather than a universal phenomenon.

Influence of dietary carbohydrate and fat on LDL and HDL particle distributions

Variations in the size and density distributions of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) particles have been related to risk for cardiovascular disease. In particular, increased levels of small, dense LDL particles, together with reduced levels of large HDL and increases in small HDL, are integral features of the atherogenic dyslipidemia found in patients with insulin resistance, obesity, and metabolic syndrome. Increased dietary carbohydrates, particularly simple sugars and starches with high glycemic index, can increase levels of small, dense LDL and HDL, primarily by mechanisms that involve increasing plasma triglyceride concentrations. Low-carbohydrate diets may have the opposite effects. Diets with differing fatty acid composition can also influence LDL and HDL particle distributions.

Apolipoprotein E genotype in dyslipidemic patients and response of blood lipids and inflammatory markers to alpha-linolenic Acid

The objective of this study was to determine the effect of alpha-linolenic acid (ALA) supplementation on blood lipids and inflammatory markers, in relation to apolipoprotein (apo) E genotype. The diets of 50 dyslipidemic male patients were supplemented with 15 mL of flaxseed oil per day for 12 weeks. Retrospectively, 3 apo E genotype variants were found (epsilon2/epsilon3, n=7; epsilon3/epsilon3, n=33; epsilon3/epsilon4, n=10). No significant differences were found among apo E genotypes in any variables at baseline. ALA supplementation produced a small but significant decrease in high-density lipoprotein cholesterol (from 1.12 to 1.08 mmol/L, 43 to 42 mg/dL; p=0.008) and apo A-I levels (from 1.28 to 1.24 g/L, p=0.036) in the epsilon3/epsilon3 homozygotes. In addition, ALA supplementation resulted in a significant decrease in the serum concentration of serum amyloid A (SAA) (p=0.014), C-reactive protein (CRP) (p=0.013), macrophage colony-stimulating factor (MCSF) (p<0.001), and interleukin (IL)-6 (p=0.028). Serum SAA and MCSF were also significantly decreased in the epsilon3/epsilon4 group (p=0.005 and p=0.017, respectively). In contrast, ALA produced no effects on any of the inflammatory markers in the epsilon2/epsilon3 group. ALA may have beneficial effects on inflammation in dyslipidemic carriers of the apo epsilon3/epsilon3 and epsilon3/epsilon4 genotypes, but not in carriers of the epsilon2 allele.

The peroxisome proliferator-activated receptor alpha Leu162Val polymorphism influences the metabolic response to a dietary intervention altering fatty acid proportions in healthy men

BACKGROUND

Serum lipid responses to dietary modification are partly determined by genetic factors.

OBJECTIVE

We tested whether plasma lipoprotein and lipid responsiveness to a modification in the dietary ratio of polyunsaturated to saturated fatty acids (P:S) is influenced by the peroxisome proliferator-activated receptor alpha (PPARalpha) Leu162Val polymorphism in healthy men.

DESIGN

Ten carriers of the V162 allele and 10 L162 homozygotes were matched according to age and body mass index (BMI). During the protocol, all subjects followed the National Cholesterol Education Program Step I diet, but intake of saturated and polyunsaturated fatty acids was adjusted to obtain a P:S of 0.3 for the first 4-wk period (low-P:S diet) and a P:S of 1.0 for the next 4-wk period (high-P:S diet).

RESULTS

At screening, the PPARalpha Leu162Val polymorphism was not associated with anthropometric indexes or plasma lipoprotein and lipid concentrations. After the high-P:S diet, a significant gene-by-diet interaction was observed for changes in plasma total cholesterol, apolipoprotein (apo) A-I, and cholesterol concentrations in small LDL particles (P <or= 0.05). Mean differences after the high-P:S diet were observed between genotype groups for plasma apo A-I concentrations (P<0.05). Changes in BMI, waist circumference, and concentrations of triacylglycerol, phospholipid, and apo B did not differ significantly between groups.

CONCLUSION

The PPARalpha Leu162Val polymorphism may contribute to interindividual variability in plasma lipoprotein and lipid response after modification of the dietary P:S ratio.

Pharmacogenetics of lipid diseases

The genetic basis for most of the rare lipid monogenic disorders have been elucidated, but the challenge remains in determining the combination of genes that contribute to the genetic variability in lipid levels in the general population; this has been estimated to be in the range of 40-60 per cent of the total variability. Therefore, the effect of common polymorphisms on lipid phenotypes will be greatly modulated by gene-gene and gene-environment interactions. This approach can also be used to characterise the individuality of the response to lipid-lowering therapies, whether using drugs (pharmacogenetics) or dietary interventions (nutrigenetics). In this regard, multiple studies have already described significant interactions between candidate genes for lipid and drug metabolism that modulate therapeutic response--although the outcomes of these studies have been controversial and call for more rigorous experimental design and analytical approaches. Once solid evidence about the predictive value of genetic panels is obtained, risk and therapeutic algorithms can begin to be generated that should provide an accurate measure of genetic predisposition, as well as targeted behavioural modifications or drugs of choice and personalised dosages of these drugs.

High carbohydrate diets and Alzheimer's disease

Alzheimer's disease (AD) is a common, progressive, neurodegenerative disease that primarily afflicts the elderly. A well-defined risk factor for late onset AD is possession of one or more alleles of the epsilon-4 variant (E4) of the apolipoprotein E gene. Meta-analysis of allele frequencies has found that E4 is rare in populations with long historical exposure to agriculture, suggesting that consumption of a high carbohydrate (HC) diet may have selected against E4 carriers. The apoE4 protein alters lipid metabolism in a manner similar to a HC diet, suggesting a common mechanism for the etiology of AD. Evolutionarily discordant HC diets are proposed to be the primary cause of AD by two general mechanisms. (1) Disturbances in lipid metabolism within the central nervous system inhibits the function of membrane proteins such as glucose transporters and the amyloid precursor protein. (2) Prolonged excessive insulin/IGF signaling accelerates cellular damage in cerebral neurons. These two factors ultimately lead to the clinical and pathological course of AD. This hypothesis also suggests several preventative and treatment strategies. A change in diet emphasizing decreasing dietary carbohydrates and increasing essential fatty acids (EFA) may effectively prevent AD. Interventions that restore lipid homeostasis may treat the disease, including drugs that increase fatty acid metabolism, EFA repletion therapy, and ketone body treatment.

Nutritional genomics

Nutritional genomics has tremendous potential to change the future of dietary guidelines and personal recommendations. Nutrigenetics will provide the basis for personalized dietary recommendations based on the individual's genetic make up. This approach has been used for decades for certain monogenic diseases; however, the challenge is to implement a similar concept for common multifactorial disorders and to develop tools to detect genetic predisposition and to prevent common disorders decades before their manifestation. The preliminary results involving gene-diet interactions for cardiovascular diseases and cancer are promising, but mostly inconclusive. Success in this area will require the integration of different disciplines and investigators working on large population studies designed to adequately investigate gene-environment interactions. Despite the current difficulties, preliminary evidence strongly suggests that the concept should work and that we will be able to harness the information contained in our genomes to achieve successful aging using behavioral changes; nutrition will be the cornerstone of this endeavor.

Apolipoprotein E gene promoter -219G->T polymorphism increases LDL-cholesterol concentrations and susceptibility to oxidation in response to a diet rich in saturated fat

BACKGROUND

The apolipoprotein E (APOE) gene promoter polymorphism (-219G-->T) has been associated with increased risk of myocardial infarction, premature coronary artery disease, and decreased plasma apolipoprotein E concentrations.

OBJECTIVE

We aimed to determine in healthy subjects whether this polymorphism modifies the susceptibility of LDL to oxidation and the lipid response to the content and quality of dietary fat.

DESIGN

Fifty-five healthy men with the APOE3/E3 genotype (7 GG, 38 GT, and 10 TT) completed 3 dietary periods, each lasting 4 wk. The first was a saturated fatty acid (SFA)-rich diet [38% fat-20% SFA and 12% monounsaturated fatty acid (MUFA)-and 47% carbohydrates (CHO)], which was followed by a CHO-rich diet (30% fat-<10% SFA and 12% MUFA-and 55% CHO) or a MUFA-rich diet (38% fat-<10% SFA and 22% MUFA-and 47% CHO) in a randomized crossover design. At the end of each dietary period, LDL oxidation susceptibility, lipids, and lipoproteins were measured.

RESULTS

Compared with carriers of the G allele, TT subjects had a significantly (P < 0.05) shorter lag time after the SFA diet. The replacement of the SFA diet by the CHO or MUFA diet induced a greater increase (P < 0.05) in lag time in the TT subjects than in the GG or GT subjects. Carriers of the T allele had higher LDL-cholesterol (P < 0.05) and apolipoprotein B (P < 0.05) plasma concentrations after the SFA diet than did GG subjects. Compared with GG subjects, carriers of the T allele had a significantly (P < 0.05) greater decrease in LDL cholesterol and apolipoprotein B when they changed from the SFA to the CHO diet.

CONCLUSION

The -219G-->T polymorphism may partially explain differences in individual responses to diet.

Dietary cholesterol does not increase biomarkers for chronic disease in a pediatric population from northern Mexico

BACKGROUND

An increased incidence of coronary artery disease (CAD) is prevalent in northern Mexico. Effects of specific dietary components on risk factors for CAD have not been evaluated in children.

OBJECTIVE

The purpose was to evaluate the effects of dietary cholesterol provided by whole eggs on the lipoprotein profile, LDL size, and phenotype in children from this region.

DESIGN

Children (29 girls and 25 boys aged 8-12 y) were randomly assigned to either 2 eggs/d (EGG period; 518 additional mg cholesterol) or the equivalent amount of egg whites (SUB period; 0 additional mg cholesterol) for 30 d. After a 3-wk washout period, the children were assigned to the alternate treatment.

RESULTS

Subjects were classified as hyporesponders (no increase or </=0.05 mmol/L increase in plasma cholesterol for 100 mg additional cholesterol) or hyperresponders (>/=0.06 mmol/L increase). During the EGG period, the hyperresponders (n = 18) had an elevation in both LDL cholesterol (from 1.54 +/- 0.38 to 1.93 +/- 0.36 mmol/L) and HDL cholesterol (from 1.23 +/- 0.26 to 1.35 +/- 0.29 mmol/L) with no changes in LDL:HDL. In contrast, hyporesponders (n = 36) had no significant alterations in plasma LDL or HDL cholesterol. All subjects had an increase in LDL peak diameter during the EGG period (P < 0.01) and a decrease (P < 0.01) in the smaller LDL subfractions. In addition, 5 of the children having LDL phenotype B (15%) shifted from this high-risk pattern to pattern A after the EGG treatment.

CONCLUSIONS

Intake of 2 eggs/d results in the maintenance of LDL:HDL and in the generation of a less atherogenic LDL in this population of Mexican children.

Double-blind, randomized feedback control fails to improve the hypocholesterolemic effect of a plant-based low-fat diet in patients with moderately elevated total cholesterol levels

OBJECTIVE

To determine whether the cholesterol-lowering effect of a plant-based low-fat diet can be improved by a flexible control design that controls the extent of fat reduction based on the individual response of blood cholesterol.

DESIGN

Randomized, double-blind intervention study.

SETTING

A hotel in Prerow, Germany.

SUBJECTS

A total of 32 participants (21 female and 11 male participants) with total cholesterol level > 5.7 mmol/l.

INTERVENTION

The control group consumed a plant-based low-fat diet with constantly 20% of energy as fat; the intervention group received a diet with either 20 or 15% of energy as fat, depending on the serum cholesterol response of the preceding week. A flexible control design based on the individual cholesterol response during a run-in period of 1 week was used within a low-fat intervention.

RESULTS

During the run-in period, the consumption of a plant-based low-fat diet led to a reduction in total cholesterol by 18+/-6 mmol/l (P < 0.001), in LDL cholesterol by 19+/-9 mmol/l (P < 0.001) and triglycerides by 13+/-3 mmol/l (P < 0.001). During the feedback control period, an additional reduction in total cholesterol by 13+/-8 (P < 0.001) and in LDL cholesterol by 17+/-11 (P < 0.001) was observed compared to 15+/-15 and 7+/-18 in the control group. The effect of an additional feedback control was only marginal and not statistically significant compared to the effect of the low-fat diet alone.

CONCLUSIONS

On a level of fat intake already reduced to 20% of energy, the use of a feedback control to adapt the fat content of the diet depending on the individual serum cholesterol response was not more effective in reducing blood cholesterol levels than a plant-based low-fat diet alone.

Very low-carbohydrate and low-fat diets affect fasting lipids and postprandial lipemia differently in overweight men

Hypoenergetic very low-carbohydrate and low-fat diets are both commonly used for short-term weight loss; however, few studies have directly compared their effect on blood lipids, with no studies to our knowledge comparing postprandial lipemia, an important independently identified cardiovascular risk factor. The primary purpose of this study was to compare the effects of a very low-carbohydrate and a low-fat diet on fasting blood lipids and postprandial lipemia in overweight men. In a balanced, randomized, crossover design, overweight men (n = 15; body fat >25%; BMI, 34 kg/m(2)) consumed 2 experimental diets for 2 consecutive 6-wk periods. One was a very low-carbohydrate (<10% energy as carbohydrate) diet and the other a low-fat (<30% energy as fat) diet. Blood was drawn from fasting subjects on separate days and an oral fat tolerance test was performed at baseline, after the very low-carbohydrate diet period, and after the low-fat diet period. Both diets had the same effect on serum total cholesterol, serum insulin, and homeostasis model analysis-insulin resistance (HOMA-IR). Neither diet affected serum HDL cholesterol (HDL-C) or oxidized LDL (oxLDL) concentrations. Serum LDL cholesterol (LDL-C) was reduced (P < 0.05) only by the low-fat diet (-18%). Fasting serum triacylglycerol (TAG), the TAG/HDL-C ratio, and glucose were significantly reduced only by the very low-carbohydrate diet (-44, -42, and -6%, respectively). Postprandial lipemia was significantly reduced when the men consumed both diets compared with baseline, but the reduction was significantly greater after intake of the very low-carbohydrate diet. Mean and peak LDL particle size increased only after the very low-carbohydrate diet. The short-term hypoenergetic low-fat diet was more effective at lowering serum LDL-C, but the very low-carbohydrate diet was more effective at improving characteristics of the metabolic syndrome as shown by a decrease in fasting serum TAG, the TAG/HDL-C ratio, postprandial lipemia, serum glucose, an increase in LDL particle size, and also greater weight loss (P < 0.05).

Nutrigenomics and nutrigenetics

PURPOSE OF REVIEW

Nutritional genomics has tremendous potential to change the future of dietary guidelines and personal recommendations. Nutritional genomics covers nutrigenomics, which explores the effects of nutrients on the genome, proteome and metabolome, and nutrigenetics, the major goal of which is to elucidate the effect of genetic variation on the interaction between diet and disease. Nutrigenetics has been used for decades in certain rare monogenic diseases such as phenylketonuria, and it has the potential to provide a basis for personalized dietary recommendations based on the individual's genetic makeup in order to prevent common multifactorial disorders decades before their clinical manifestation.

RECENT FINDINGS

Preliminary results regarding gene-diet interactions in cardiovascular diseases are for the most part inconclusive because of the limitations of current experimental designs. Success in this area will require the integration of various disciplines, and will require investigators to work on large population studies that are designed to investigate gene-environment interactions.

SUMMARY

Based on the current knowledge, we anticipate that in the future we will be able to harness the information contained in our genomes to achieve successful aging using behavioral changes, with nutrition being the cornerstone of this endeavor.

Comparison between the effects of soy milk and non-fat cow milk on lipid profile and lipid peroxidation in patients with primary hypercholesterolemia

OBJECTIVE

This study assessed whether the consumption of soy milk could add significantly to the lipid profile and lipid peroxidation in comparison with non-fat milk.

METHODS

A double-blind, randomized, crossover study was conducted on 60 outpatients with primary hypercholesterolemia following a lipid-lowering diet for at least 6 wk. Lipid profile was obtained at baseline and at 6 and 12 wk, with the patients randomly assigned to receive initially 1 L/d of soy milk or non-fat cow milk for 6 wk. Lipid peroxidation was estimated by plasma thiobarbituric reactive substances. Apolipoprotein E genotypes were examined by polymerase chain reaction restriction fragment length polymorphism.

RESULTS

The soy milk diet was associated with low-density lipoprotein cholesterol reduction (baseline = 157 +/- 5 mg/dL; soy milk = 148 +/- 4 mg/dL; non-fat cow milk = 158 +/- 4 mg/dL; P < 0.05, soy milk versus other treatments) and with high-density lipoprotein cholesterol increase (baseline = 58 +/- 2 mg/dL; soy milk = 62 +/- 2 mg/dL; non-fat cow milk = 57 +/- 2 mg/dL; P < 0.05, soy milk versus other treatments). In addition, plasma thiobarbituric reactive substances were reduced by the soy milk diet (baseline = 1.82 +/- 0.12 nM/L; soy milk = 1.49 +/- 0.09 nM/L; non-fat cow milk = 1.91 +/- 0.11 nM/mL; P < 0.05, soy milk versus non-fat cow milk). Changes in lipid profile were not influenced by APOE genotypes.

CONCLUSIONS

These results indicate that soy milk as part of a lipid-lowering diet has beneficial effects in improving lipid profile and reducing lipid peroxidation.

Association of apolipoprotein E polymorphism with blood lipids and maximal oxygen uptake in the sedentary state and after exercise training in the HERITAGE family study

The relationship of apolipoprotein E (apo E) genotypes to plasma lipid and maximal oxygen uptake (Vo(2max)) was studied in the sedentary state and after a supervised exercise training program in black and white men and women. At baseline, the apo E 2/3 genotype was associated with the lowest, and apo E 3/4 and E4/4 with the highest low-density liporpotein (LDL) cholesterol and apo B levels in men and women of both races, while female (not male) carriers of apo E3 had higher high-density lipoprotein (HDL) cholesterol levels than carriers of other genotypes. Very-low-density lipoprotein (VLDL) cholesterol and triglyceride levels were significantly higher in carriers of both apo E2 and apo E4 in white men only. Racial and sex differences were noted in lipid responses to exercise training across genotypes with a significantly greater increase in HDL cholesterol observed only in white female carriers of apo E 2/3 and E3/3, as compared to apo E4/4. Apo E polymorphism was not found to be associated with Vo(2max) levels either in the sedentary state nor the Vo(2max) response to exercise training, contrary to previous reports.

APOE polymorphism and lipid profile in three ethnic groups in the Singapore population

BACKGROUND

Serum lipid concentrations are modulated by environmental factors such as exercise, alcohol intake, smoking, obesity and dietary intake and genetic factors. Polymorphisms at the Apolipoprotein E (APOE) locus have consistently shown a significant association with total and LDL-cholesterol (LDL-C). However, their impact on HDL-cholesterol (HDL-C) may be population dependent. Having three major ethnic groups within a similar social environment allows us to study the role of genetics and their interactions with lifestyle factors on the serum lipid profile and coronary risk in Asians.

METHODS

This study included 1740 males (1146 Chinese, 327 Malays and 267 Asian Indians) and 1950 females (1329 Chinese, 360 Malays and 261 Asian Indians) with complete data on anthropometric indices, fasting lipids, smoking status, alcohol consumption, exercise frequency and genotype at the APOE locus.

RESULTS

Malays and Asian Indians were more obese compared with the Chinese. Smoking was uncommon in all females but Malay males had significantly higher prevalence of smokers. Malays had the highest LDL-C whilst Indians had the lowest HDL-C, The epsilon 3 allele was the most frequent allele in all three ethnic groups. Malays had the highest frequency of epsilon 4 (0.180 and 0.152) compared with Chinese (0.085 and 0.087) and Indians (0.108 and 0.075) in males and females, respectively. The epsilon 2 allele was the least common in Asian Indians. Total cholesterol (TC) and LDL-C was highest in epsilon 4 carriers and lowest in epsilon 2 carriers. The reverse was seen in HDL-C with the highest levels seen in epsilon 2 subjects. The association between ethnic group and HDL-C differed according to APOE genotype and gender. Asian Indians had the lowest HDL-C for each APOE genotype except in Asian Indian males with epsilon 2, where HDL-C concentrations were intermediate between Chinese and Malays.

CONCLUSION

Ethnic differences in lipid profile could be explained in part by the higher prevalence of epsilon 4 in the Malays. Ethnicity may influence the association between APOE genotypes and HDL-C. APOE genotype showed no correlation with HDL-C in Malay males whereas the association in Asian Indians was particularly marked. Further studies of interactions between genes and environmental factors will contribute to the understanding of differences of coronary risk amongst ethnic groups.

Effects of Greek Orthodox Christian Church fasting on serum lipids and obesity

BACKGROUND

No study to date has focused on the impact of Greek Orthodox Christian fasting on serum lipoproteins and obesity yet.

METHODS

120 Greek adults were followed longitudinally for one year. Sixty fasted regularly in all fasting periods (fasters) and 60 did not fast at all (controls). The three major fasting periods under study were: Christmas (40 days), Lent (48 days) and Assumption (August, 15 days). A total of 6 measurements were made during one year including pre- and end-fasting blood collection, serum lipoprotein analyses and anthropometric measurements.

RESULTS

Statistically significant end-fasting total and LDL cholesterol differences were found in fasters. Fasters compared to controls presented 12.5% lower end-total cholesterol (p < 0.001), 15.9% lower end-LDL cholesterol (p < 0.001) and 1.5% lower end-BMI (p < 0.001). The end- LDL/HDL ratio was lower in fasters (6.5%, p < 0.05) while the change in end- HDL cholesterol in fasters (4.6% decline) was not significant. Similar results were found when the pre- and end-fasting values of fasters were compared. No change was found in control subjects.

CONCLUSIONS

Adherence to Greek Orthodox fasting periods contributes to a reduction in the blood lipid profile including a non-significant reduction in HDL cholesterol and possible impact on obesity.

Genetic variation and the lipid response to dietary intervention: a systematic review

There is wide interindividual variation in the lipid and lipoprotein responses to dietary change, and the existence of consistent hypo- and hyperresponders supports the hypothesis that responsiveness is related to genetic variation. Many studies have investigated the possibility that the heterogeneity in responsiveness to changes in dietary fat, cholesterol, and fiber intake is explained by variation in genes whose products affect lipoprotein metabolism, eg, apolipoproteins, enzymes, and receptors. A systematic review of the literature was carried out to investigate the effect of genetic variation on the lipid response to dietary intervention. A search strategy for the MEDLINE database retrieved 2540 articles from 1966 to February 2002. This strategy was adapted and performed on the EMBASE database, which retrieved 2473 articles from 1980 to week 9, 2002. Reference lists from relevant journal articles were also checked. This is the first systematic review of the literature, and it summarizes results available from 74 relevant articles. There is evidence to suggest that variation in the genes for apolipoprotein (apo) A-I, apo A-IV, apo B, and apo E contributes to the heterogeneity in the lipid response to dietary intervention. However, the effects of genetic variation are not consistently seen and are sometimes conflicting. Future studies need to have much larger sample sizes based on power calculations and carefully controlled dietary interventions and should investigate the effects of polymorphisms in multiple genes instead of the effects of polymorphisms in single genes.

Impact of the Pro12Ala polymorphism of the PPAR-gamma2 gene on serum triacylglycerol response to n-3 fatty acid supplementation

Serum lipid responses to dietary modification are partly determined by genetic factors. The objective of the present study was to investigate the influence of the Pro12Ala polymorphism of the peroxisome proliferator-activated receptor-gamma2 (PPAR-gamma2) gene on serum lipid and lipoprotein responses to n-3 fatty acid supplementation. A total of 76 men and 74 women (age 49+/-8 years, body mass index 26.5+/-3.0 kg/m(2)) participated in a controlled multi-center study. Subjects were randomly assigned to consume either fish oil supplements (3.6g n-3 fatty acids/day containing 2.4 g of EPA and DHA) or placebo capsules containing olive oil for 3 months. At baseline, the Pro12Ala polymorphism was not associated with serum total and lipoprotein lipid concentrations or lipoprotein lipase activity in the fasting state. After the 3-month study period, carriers of the Ala12 allele presented a greater decrease in serum triacylglycerol concentration in response to n-3 fatty acid supplementation than did subjects with the Pro12Pro genotype when the total dietary fat intake was below 37 E% (p=0.003) or the intake of saturated fatty acids was below 10 E% (p=0.006). Changes in serum total cholesterol, serum LDL cholesterol and HDL cholesterol concentrations were similar among the genotypes in the n-3 fatty acid supplementation group and in the placebo group. In conclusion, the Pro12Ala polymorphism of the PPAR-gamma2 gene may modify the inter-individual variability in serum triacylglycerol response to n-3 fatty acid supplementation.

KLOTHO allele status and the risk of early-onset occult coronary artery disease

We previously identified a functional variant of KLOTHO (termed "KL-VS"), which harbors two amino acid substitutions in complete linkage disequilibrium and is associated with reduced human longevity when in homozygosity. Klotho-deficient mice display extensive arteriosclerosis when fed a normal diet, suggesting a potent genetic predisposition. To determine whether klotho influences atherosclerotic risk in humans, we performed cross-sectional studies to assess the association between the KL-VS allele and occult coronary artery disease (CAD) in two independent samples of apparently healthy siblings of individuals with early-onset (age <60 years) CAD (SIBS-I [N=520] and SIBS-II [N=436]). Occult CAD was defined as the occurrence of a reversible perfusion defect during exercise thallium scintigraphy and/or as an abnormal result of an exercise electrocardiogram (SIBS-I, n=97; SIBS-II, n=56). In SIBS-I, the KL-VS allele conferred a relative odds of 1.90 (95% confidence interval 1.21-2.98) for occult CAD, after adjusting for familial intraclass correlations (P<.005). Logistic regression modeling, incorporating known CAD risk factors, demonstrated that the KL-VS allele is an independent risk factor (P<.019) and that the imposed risk of KL-VS allele status is influenced by modifiable risk factors. Hypertension (P<.022) and increasing high-density lipoprotein cholesterol (HDL-C) levels (P<.022) mask or reduce the risk conferred by the KL-VS allele, respectively, whereas current smoking (P<.004) increases the risk. Remarkably concordant effects of the KL-VS allele and modifying factors on the risk of occult CAD were seen in SIBS-II. These results demonstrate that the KL-VS allele is an independent risk factor for occult CAD in two independent high-risk samples. Modifiable risk factors, including hypertension, smoking status, and HDL-C level, appear to influence the risk imposed by this allele.

Lipids, lipoproteins, and exercise

PURPOSE

Dose-response relationships between exercise training volume and blood lipid changes suggest that exercise can favorably alter blood lipids at low training volumes, although the effects may not be observable until certain exercise thresholds are met.

METHODS AND RESULTS

Plasma triglyceride reductions are often observed after exercise training regimens requiring energy expenditures similar to those characterized to increase high-density lipoprotein cholesterol (HDL-C). Thresholds established from cross-sectional and longitudinal exercise training studies indicate that 15 to 20 miles/week of brisk walking or jogging, which elicit between 1,200 to 2,200 kcals of energy expenditure per week, is associated with triglyceride reductions of 5 to 38 mg/dL and HDL-C increases of 2 to 8 mg/dL. Exercise training seldom alters total cholesterol and low-density lipoprotein cholesterol (LDL-C) unless dietary fat intake is reduced and body weight loss is associated with the exercise training program, or both. Thus, for most individuals, the positive effects of regular exercise are exerted on blood lipids at low training volumes and accrue so that noticeable differences frequently occur with energy expenditures of 1,200 to 2,200 kcals/week.

CONCLUSIONS

It appears that weekly exercise caloric expenditures that meet or exceed the higher end of this range are more likely to produce the desired lipid changes. Regarding hyperlipidemic disorders, the primary means for intervention is pharmacologic, whereas diet modification, weight loss, and exercise, although important, are viewed as adjunctive therapies. Because much is known about the exercise training-induced plasma lipid and lipoprotein modifications as well as the mechanisms responsible for these changes, rehabilitation professionals can better develop a comprehensive medical management plan that optimizes pharmacologic, reduced dietary fat intake, weight loss, and exercise interventions.

A ketogenic diet favorably affects serum biomarkers for cardiovascular disease in normal-weight men

Very low-carbohydrate (ketogenic) diets are popular yet little is known regarding the effects on serum biomarkers for cardiovascular disease (CVD). This study examined the effects of a 6-wk ketogenic diet on fasting and postprandial serum biomarkers in 20 normal-weight, normolipidemic men. Twelve men switched from their habitual diet (17% protein, 47% carbohydrate and 32% fat) to a ketogenic diet (30% protein, 8% carbohydrate and 61% fat) and eight control subjects consumed their habitual diet for 6 wk. Fasting blood lipids, insulin, LDL particle size, oxidized LDL and postprandial triacylglycerol (TAG) and insulin responses to a fat-rich meal were determined before and after treatment. There were significant decreases in fasting serum TAG (-33%), postprandial lipemia after a fat-rich meal (-29%), and fasting serum insulin concentrations (-34%) after men consumed the ketogenic diet. Fasting serum total and LDL cholesterol and oxidized LDL were unaffected and HDL cholesterol tended to increase with the ketogenic diet (+11.5%; P = 0.066). In subjects with a predominance of small LDL particles pattern B, there were significant increases in mean and peak LDL particle diameter and the percentage of LDL-1 after the ketogenic diet. There were no significant changes in blood lipids in the control group. To our knowledge this is the first study to document the effects of a ketogenic diet on fasting and postprandial CVD biomarkers independent of weight loss. The results suggest that a short-term ketogenic diet does not have a deleterious effect on CVD risk profile and may improve the lipid disorders characteristic of atherogenic dyslipidemia.

Apolipoprotein E and diets: a case of gene-nutrient interaction?

Apolipoprotein E has key functions in lipoprotein metabolism, and polymorphisms in the apolipoprotein E gene are associated with distinct lipoprotein patterns. The possibility of gene-nutrient interactions for apolipoprotein E has been addressed in many studies. Although results have generally been mixed, the indications for such an interaction have been more common in studies employing a metabolic challenge. Studies directly designed to examine apolipoprotein E gene-nutrient interactions are needed.

Carbohydrate-induced hypertriglyceridemia: modifying factors and implications for cardiovascular risk

High-carbohydrate/low-fat, isocaloric diets have repeatedly been shown to increase plasma triglyceride concentrations. The present review addresses recent developments relevant to several important unresolved issues. These include the type of dietary carbohydrate that is most likely to induce hypertriglyceridemia, predictors of individual susceptibility, modifiable physiologic factors that may mitigate the plasma triglyceride response, underlying metabolic mechanisms that are responsible for increased plasma triglycerides, and implications of altered serum lipid profiles for atherogenic risk. Although some progress has been made in this field, the central public health issue - the net effect on cardiovascular risk - remains unresolved.

Polyunsaturated fatty acids modulate the effects of the APOA1 G-A polymorphism on HDL-cholesterol concentrations in a sex-specific manner: the Framingham Study

BACKGROUND

A common G-to-A substitution in the promoter area (-75 base pairs) of the apolipoprotein A-I gene (APOA1) has been described. The A allele was shown to be associated with higher HDL-cholesterol concentrations in some studies but not in others.

OBJECTIVE

We examined whether dietary fat modulates the association between this polymorphism and HDL-cholesterol concentrations.

DESIGN

We studied a population-based sample of 755 men and 822 women from the Framingham Offspring Study.

RESULTS

The frequency of the A allele was 0.165. No significant differences were observed between G/G subjects and carriers of the A allele for any lipid variables. In multivariate linear regression models, HDL-cholesterol concentrations in women were associated with a significant interaction between polyunsaturated fatty acid (PUFA) intake as a continuous variable and APOA1 genotype (P = 0.005). By using 3 categories of PUFA intake, we found a significantly different effect of APOA1 genotype across PUFA categories in women. When PUFA intake was <4% of energy, G/G subjects had approximately 14% higher HDL-cholesterol concentrations than did carriers of the A allele (P < 0.05). Conversely, when PUFA intake was >8%, HDL-cholesterol concentrations in carriers of the A allele were 13% higher than those of G/G subjects (P < 0.05). No significant allelic difference was observed for subjects in the range of PUFA intake of 4-8% of energy. These interactions were not significant in men.

CONCLUSIONS

We found a significant gene-diet interaction associated with the APOA1 G-A polymorphism. In women carriers of the A allele, higher PUFA intakes were associated with higher HDL-cholesterol concentrations, whereas the opposite effect was observed in G/G women.

Periodontitis and diabetes interrelationships: role of inflammation

Diabetes mellitus is a systemic disease with several major complications affecting both the quality and length of life. One of these complications is periodontal disease (periodontitis). Periodontitis is much more than a localized oral infection. Recent data indicate that periodontitis may cause changes in systemic physiology. The interrelationships between periodontitis and diabetes provide an example of systemic disease predisposing to oral infection, and once that infection is established, the oral infection exacerbates systemic disease. In this case, it may also be possible for the oral infection to predispose to systemic disease. In order to understand the cellular/molecular mechanisms responsible for such a cyclical association, one must identify common physiological changes associated with diabetes and periodontitis that produce a synergy when the conditions coexist. A potential mechanistic link involves the broad axis of inflammation, specifically immune cell phenotype, serum lipid levels, and tissue homeostasis. Diabetes-induced changes in immune cell function produce an inflammatory immune cell phenotype (upregulation of proinflammatory cytokines from monocytes/polymorphonuclear leukocytes and downregulation of growth factors from macrophages). This predisposes to chronic inflammation, progressive tissue breakdown, and diminished tissue repair capacity. Periodontal tissues frequently manifest these changes because they are constantly wounded by substances emanating from bacterial biofilms. Diabetic patients are prone to elevated low density lipoprotein cholesterol and triglycerides (LDL/TRG) even when blood glucose levels are well controlled. This is significant, as recent studies demonstrate that hyperlipidemia may be one of the factors associated with diabetes-induced immune cell alterations. Recent human studies have established a relationship between high serum lipid levels and periodontitis. Some evidence now suggests that periodontitis itself may lead to elevated LDL/TRG. Periodontitis-induced bacteremia/endotoxemia has been shown to cause elevations of serum proinflammatory cytokines such as interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha), which have been demonstrated to produce alterations in lipid metabolism leading to hyperlipidemia. Within this context, periodontitis may contribute to elevated proinflammatory cytokines/serum lipids and potentially to systemic disease arising from chronic hyperlipidemia and/or increased inflammatory mediators. These cytokines can produce an insulin resistance syndrome similar to that observed in diabetes and initiate destruction of pancreatic beta cells leading to development of diabetes. Thus, there is potential for periodontitis to exacerbate diabetes-induced hyperlipidemia, immune cell alterations, and diminished tissue repair capacity. It may also be possible for chronic periodontitis to induce diabetes.

Treatment approaches: food first for weight management and health

Many genetic, environmental, behavioral, and cultural factors affect health. Diet is as vital as any of them for preventing disease and promoting well-being. We know that what we eat can lead to premature disability and mortality: to obesity, coronary heart disease, type 2 diabetes, degenerative arthritis, sleep apnea, and other illnesses. Now scientific evidence points to links between dietary patterns and illness. The study of these links is a new approach to understanding the role that diet plays in chronic disease. Initial studies include those on eating patterns and risk of colon cancer. More recently, researchers have investigated all-cause mortality and leading causes of chronic disease. Novel epidemiological approaches include factorial analysis to evaluate dietary patterns and cluster analysis to examine nutrient intake, gender, and weight status across food-pattern clusters. These methods work best within groups to identify major dietary patterns, but not necessarily ideal diets. They may also differ across population groups. The success of the Dietary Approaches to Stop Hypertension and Lyon Diet Heart studies supports the value of dietary pattern analysis. At the same time, the relative failure of single-nutrient studies underscores the need for new methodologies and directions in research.

Apolipoprotein E genotype affects plasma lipid response to atorvastatin in a gender specific manner

The response to therapy with hypolipidemic agents shows considerable individual variation. These differences may be due to the interaction of environmental and genetic factors that affect drug bioavailability, receptor function or ligand structure. Our objective was to assess the effect of apolipoprotein (apo) E genotype and gender on lipid-lowering response to the HMG CoA reductase inhibitor, atorvastatin. Genotyping was carried out on DNA from 328 male and female subjects who participated in a multicentric, double-blind clinical trial, and received 10 mg/day of atorvastatin. Our data demonstrate no significant gender differences for LDL cholesterol levels at baseline. Moreover, mean LDL-C lowering was similar in men (-36.2%, range -2.7 to -57.8%) and in women (-38.1%, range -9.5 to -58.5%) as compared to baseline. However, men carrying the epsilon2 allele had a significantly higher mean LDL-C response (-44%) than epsilon3 homozygotes (-37%) and epsilon4 carriers (-34%); P=0.01 for apoE group by treatment interaction. No such gene/treatment interactions were noted in women, with those carrying the epsilon2 allele showing a similar mean response (-34%) as epsilon3 homozygotes (-39%) and epsilon4 carriers (-34%). Mean plasma triglyceride lowering with atorvastatin was 17%. A significant apoE group by treatment interaction (P=0.010) was also observed in men, with epsilon2 carriers being more responsive (-27%) than epsilon3/3 (-13%) and epsilon4 (-22%). This interaction was not observed in women. In summary, atorvastatin treatment had similar effects on plasma lipid levels in both men and women; however, the apoE gene locus was a significant predictor of LDL-C and TG responses to atorvastatin therapy in men, but not in women.

Exercise in the treatment of lipid disorders

As a result of scientific evaluation, we know that exercise has a positive impact on the lipid and lipoprotein profile, and we have a greater understanding for the necessary amount of exercise needed to cause these changes. In the case of hyperlipidemic disorders, we know the primary means for intervention is pharmacological, and that diet, weight loss, and exercise are viewed as adjunctive therapies. Because much is known about the exercise training-induced plasma lipid and lipoprotein modifications as well as the lipoprotein enzyme changes, future research should continue to focus on the molecular basis for these changes. For example by knowing a person's apo E genotype, we gain better comprehension as to why some individuals respond to exercise, while others do not. Another area for further investigation is the assessment of drug and exercise interaction. Presently, little is known regarding the use of lipid-lowering drugs and the impact of exercise. Finally, these investigations could provide new insights for better understanding the exercise CAD protective effects. The future challenge is to better understand the impact that regular exercise participation has in optimizing the lipid and lipoprotein profile with individuals with special lipid disorders.