Ana Baylin

The use of fatty acid biomarkers to reflect dietary intake.

Purpose of review This review compares fatty acid biomarkers to assess compliance in dietary intervention trials with their application in epidemiological studies. Recent findings Although many studies have used fatty acid biomarkers to assess compliance in short-term dietary intervention trials and habitual diets in observational studies, there is little information on the reliability and comparability of these measures. In this review, we summarize the usefulness and limitations of fatty acid biomarkers in clinical and epidemiological studies. As there are very few recent publications in this area, a complete literature review is provided. Summary Several options are available for the biological assessment of dietary fatty acids. The type of study (short or long-term), the metabolic characteristics and expected variability in the fatty acids of interest are major considerations when determining which tissues reflect a better measure of true intake. Certain fatty acids may not be suitable to assess differences in intake under non-isocaloric conditions and when trying to identify small differences. Serum cholesterol ester is the most suitable serum fraction to assess short-term dietary compliance, but given the multiple factors that affect response, the quantification of compliance should be interpreted with caution. Adipose tissue is the biomarker of choice for long-term intake, but a preferred blood constituent (plasma versus erythrocytes) is difficult to establish given the data available to date. Future studies should explore the use of whole blood as an alternative choice to measure fatty acid intake in epidemiological studies.

Adipose Tissue α-Linolenic Acid and Nonfatal Acute Myocardial Infarction in Costa Rica

Background—&agr;-Linolenic acid may protect against cardiovascular disease. We examined the association between adipose tissue &agr;-linolenic acid and nonfatal acute myocardial infarction (MI) in a population-based case-control study in Costa Rica. Methods and Results—The 482 case patients with a first nonfatal acute MI and 482 population control subjects were matched by age, sex, and area of residence. Fatty acids were assessed by gas-liquid chromatography in adipose tissue samples collected from all subjects. ORs and 95% CIs were calculated from multivariate conditional logistic regression models. Subjects in the top quintiles of adipose tissue &agr;-linolenic acid had a lower risk of MI than those in the lowest quintile: OR (95% CI), 1.00; 0.80 (0.52 to 1.24); 0.53 (0.34 to 0.82); 0.44 (0.28 to 0.67); and 0.37 (0.24 to 0.59); test for trend, P <0.0001. This association was strengthened after adjustment for established MI risk factors, including smoking, physical activity, income, and adipose tissue linoleic acid and trans fatty acids (OR for the top versus lowest quintile, 0.23; 95% CI, 0.10 to 0.50; test for trend, P <0.0001). Further adjustment for the intake of saturated fat, fiber, alcohol, and vitamin E did not change this association (OR for the top versus lowest quintile, 0.23; 95% CI, 0.10 to 0.55; test for trend, P <0.0001). Conclusions—The inverse association observed between &agr;-linolenic acid and nonfatal acute MI suggests that consumption of vegetable oils rich in &agr;-linolenic acid confers important protection against cardiovascular disease.

α-Linolenic Acid and Risk of Nonfatal Acute Myocardial Infarction

Background— Intake of long-chain n-3 fatty acids found in fish is low in many countries worldwide. &agr;-Linolenic acid could be a viable cardioprotective alternative to these fatty acids in these countries. Methods and Results— Cases (n=1819) with a first nonfatal acute myocardial infarction and population-based controls (n=1819) living in Costa Rica matched for age, sex, and area of residence were studied. Fatty acids were assessed by gas chromatography in adipose tissue samples and by a validated food frequency questionnaire specifically designed for this population. Odds ratios and 95% confidence intervals were calculated from multivariate conditional logistic regression models. &agr;-Linolenic acid in adipose tissue ranged from 0.36% in the lowest decile to 1.04% in the highest decile. The corresponding median levels of intake were 0.42% and 0.86% energy. Greater &agr;-linolenic acid (assessed either in adipose or by questionnaire) was associated with lower risk of myocardial infarction. The odds ratios for nonfatal myocardial infarction for the highest compared with the lowest deciles were 0.41 (95% confidence interval, 0.25 to 0.67) for &agr;-linolenic acid in adipose tissue and 0.61 (95% confidence interval, 0.42 to 0.88) for dietary &agr;-linolenic acid. The relationship between &agr;-linolenic acid and myocardial infarction was nonlinear; risk did not decrease with intakes >≈0.65% energy (1.79 g/d). Fish or eicosapentaenoic acid and docosahexaenoic acid intake at the levels found in this population did not modify the observed association. Conclusions— Consumption of vegetable oils rich in &agr;-linolenic acid could confer important cardiovascular protection. The apparent protective effect of &agr;-linolenic acid is most evident among subjects with low intakes.

Vitamin D deficiency and anthropometric indicators of adiposity in school-age children: a prospective study.

BACKGROUND Cross-sectional studies have indicated that vitamin D serostatus is inversely associated with adiposity. It is unknown whether vitamin D deficiency is a risk factor for the development of adiposity in children. OBJECTIVE We investigated the associations between vitamin D serostatus and changes in body mass index (BMI; in kg/m²), skinfold-thickness ratio (subscapular-to-triceps), waist circumference, and height in a longitudinal study in children from Bogota, Colombia. DESIGN We quantified plasma 25-hydroxyvitamin D [25(OH)D] concentrations in baseline samples of a randomly selected group of 479 schoolchildren aged 5-12 y and classified vitamin D status as deficient [25(OH)D concentrations < 50 nmol/L], insufficient [25(OH)D concentrations ≥ 50 and < 75 nmol/L], or sufficient [25(OH)D concentrations ≥ 75 nmol/L]. We measured anthropometric variables annually for a median of 30 mo. We estimated the average change in each anthropometric indicator according to baseline vitamin D status by using multivariate mixed linear regression models. RESULTS Vitamin D-deficient children had an adjusted 0.1/y greater change in BMI than did vitamin D-sufficient children (P for trend = 0.05). Similarly, vitamin D-deficient children had a 0.03/y (95% CI: 0.01, 0.05/y) greater change in subscapular-to-triceps skinfold-thickness ratio and a 0.8 cm/y (95% CI: 0.1, 1.6 cm/y) greater change in waist circumference than did vitamin D-sufficient children. Vitamin D deficiency was related to slower linear growth in girls (-0.6 cm/y, P = 0.04) but not in boys (0.3 cm/y, P = 0.34); however, an interaction with sex was not statistically significant. CONCLUSION Vitamin D serostatus was inversely associated with the development of adiposity in school-age children.

Circulating and Dietary Omega-3 and Omega-6 Polyunsaturated Fatty Acids and Incidence of CVD in the Multi-Ethnic Study of Atherosclerosis

Background Dietary guidelines support intake of polyunsaturated fatty acids (PUFAs) in fish and vegetable oils. However, some controversy remains about benefits of PUFAs, and most prior studies have relied on self‐reported dietary assessment in relatively homogeneous populations. Methods and Results In a multiethnic cohort of 2837 US adults (whites, Hispanics, African Americans, Chinese Americans), plasma phospholipid PUFAs were measured at baseline (2000–2002) using gas chromatography and dietary PUFAs estimated using a food frequency questionnaire. Incident cardiovascular disease (CVD) events (including coronary heart disease and stroke; n=189) were prospectively identified through 2010 during 19 778 person‐years of follow‐up. In multivariable‐adjusted Cox models, circulating n‐3 eicosapentaenoic acid and docosahexaenoic acid were inversely associated with incident CVD, with extreme‐quartile hazard ratios (95% CIs) of 0.49 for eicosapentaenoic acid (0.30 to 0.79; Ptrend=0.01) and 0.39 for docosahexaenoic acid (0.22 to 0.67; Ptrend<0.001). n‐3 Docosapentaenoic acid (DPA) was inversely associated with CVD in whites and Chinese, but not in other race/ethnicities (P‐interaction=0.01). No significant associations with CVD were observed for circulating n‐3 alpha‐linolenic acid or n‐6 PUFA (linoleic acid, arachidonic acid). Associations with CVD of self‐reported dietary PUFA were consistent with those of the PUFA biomarkers. All associations were similar across racial‐ethnic groups, except those of docosapentaenoic acid. Conclusions Both dietary and circulating eicosapentaenoic acid and docosahexaenoic acid, but not alpha‐linolenic acid or n‐6 PUFA, were inversely associated with CVD incidence. These findings suggest that increased consumption of n‐3 PUFA from seafood may prevent CVD development in a multiethnic population.

Transient exposure to coffee as a trigger of a first nonfatal myocardial infarction

Background: The effects of coffee on myocardial infarction are uncertain. We hypothesize that coffee in the presence of predisposing factors can induce a cascade of events that, through sympathetic nervous activation, can induce the onset of myocardial infarction. Methods: We recruited 503 incident cases of nonfatal myocardial infarction between 1994 and 1998 in Costa Rica. We used a case-crossover design to calculate relative risks (RRs) and 95% confidence intervals (95% CIs). Results: The RR of myocardial infarction in the hour after coffee intake was 1.49 (95% CI = 1.17–1.89). Occasional coffee drinkers (≤1 cup/day, n = 103) had a RR of myocardial infarction of 4.14 (2.03–8.42), moderate coffee drinkers (2–3 cups/day, n = 280) had a RR of 1.60 (1.16–2.21), and heavy coffee drinkers (≥4 cups/d, n = 120) had a RR of 1.06 (0.69–1.63; P = 0.006, test of homogeneity). Patients with 3 or more risk factors (n = 101) had a RR of myocardial infarction of 2.10 (1.30–3.39), whereas patients with fewer than 3 risk factors (n = 396) had a RR of 1.39 (1.04–1.82; P = 0.15, test of homogeneity); and RR was 1.72 (1.30–2.30) among sedentary patients compared with 1.07 (0.66–1.72) among nonsedentary (P = 0.10, test of homogeneity). Conclusions: The findings indicate that coffee intake may trigger myocardial infarction. The association is particularly strong among people with light/occasional intake of coffee (≤1 cup/day), with sedentary lifestyle, or with 3 or more risk factors for coronary heart disease.

Dietary Patterns Are Associated with Metabolic Syndrome in Adult Samoans

The prevalence of metabolic syndrome has reached epidemic levels in the Samoan Islands. In this cross-sectional study conducted in 2002-2003, dietary patterns were described among American Samoan (n = 723) and Samoan (n = 785) adults (> or =18 y) to identify neo-traditional and modern eating patterns and to relate these patterns to the presence of metabolic syndrome using Adult Treatment Panel III criteria. The neo-traditional dietary pattern, similar across both polities, was characterized by high intake of local foods, including crab/lobster, coconut products, and taro, and low intake of processed foods, including potato chips and soda. The modern pattern, also similar across both polities, was characterized by high intake of processed foods such as rice, potato chips, cake, and pancakes and low intake of local foods. The neo-traditional dietary pattern was associated with significantly higher serum HDL-cholesterol in American Samoa (P-trend = 0.05) and a decrease in abdominal circumference in American Samoa and Samoa (P-trend = 0.004 and 0.01, respectively). An inverse association was found with metabolic syndrome, although it did not reach significance (P = 0.23 in American Samoa; P = 0.13 in Samoa). The modern pattern was significantly positively associated with metabolic syndrome in Samoa (prevalence ratio = 1.21 for the fifth compared with first quintile; 95% CI: 0.93.1.57; P-trend = 0.05) and with increased serum triglyceride levels in both polities (P < 0.05). Reduced intake of processed foods high in refined grains and adherence to a neo-traditional eating pattern characterized by plant-based fiber, seafood, and coconut products may help to prevent growth in the prevalence of metabolic syndrome in the Samoan islands.

Comparison of 3 Methods for Identifying Dietary Patterns Associated With Risk of Disease

Reduced rank regression and partial least-squares regression (PLS) are proposed alternatives to principal component analysis (PCA). Using all 3 methods, the authors derived dietary patterns in Costa Rican data collected on 3,574 cases and controls in 1994-2004 and related the resulting patterns to risk of first incident myocardial infarction. Four dietary patterns associated with myocardial infarction were identified. Factor 1, characterized by high intakes of lean chicken, vegetables, fruit, and polyunsaturated oil, was generated by all 3 dietary pattern methods and was associated with a significantly decreased adjusted risk of myocardial infarction (28%-46%, depending on the method used). PCA and PLS also each yielded a pattern associated with a significantly decreased risk of myocardial infarction (31% and 23%, respectively); this pattern was characterized by moderate intake of alcohol and polyunsaturated oil and low intake of high-fat dairy products. The fourth factor derived from PCA was significantly associated with a 38% increased risk of myocardial infarction and was characterized by high intakes of coffee and palm oil. Contrary to previous studies, the authors found PCA and PLS to produce more patterns associated with cardiovascular disease than reduced rank regression. The most effective method for deriving dietary patterns related to disease may vary depending on the study goals.

Individual saturated fatty acids and nonfatal acute myocardial infarction in Costa Rica.

Background: Epidemiological studies on the effect of individual saturated fatty acids (SFAs) on cardiovascular disease, especially in developing countries with different dietary patterns, are scarce.Objective: To determine the risk of nonfatal acute myocardial infarction (MI) associated with consumption of individual SFAs and their food sources in Costa Rica.Design: The cases (n=485) were survivors of a first acute MI and were matched by age, sex and area of residence to population controls (n=508). Data on anthropometrical measurements, lifestyle and diet were collected using interviewer-administered questionnaires.Results: In analyses adjusted for confounders, consumption of total and individual SFAs was associated with an increased risk of MI. The odds ratio (OR) (95% confidence intervals) for 1% increase in energy from total saturated fat was 1.12 (1.03–1.21) while it was 1.51 (1.03–2.22) for lauric acid+myristic acid, 1.14 (1.01–1.30) for palmitic acid and 2.00 (1.34–3.00) for stearic acid. Although lauric and myristic acids were associated with increased risk of MI, they were consumed in small amounts and most of the saturated fat (87%) came from palmitic and stearic acids, which derived mainly from red meat and fried foods. Consumption of cheese (1–2 vs 0 servings/day) was associated with increased risk of MI (OR=3.07; 95% confidence interval: 1.74–5.39; P for trend <0.0001), while consumption of low-fat milk was not.Conclusions: Increased consumption of total and individual SFAs is associated with increased risk of MI. Lauric, myristic and stearic acids were more potent than palmitic acid.Sponsorship: National Institutes of Health Grant HL 49086 and HL 60692.

Adipose tissue palmitoleic acid and obesity in humans: does it behave as a lipokine

BACKGROUND Animal models have shown that adipose-derived palmitoleic acid may serve as a lipokine that contributes to resistance to diet-induced obesity. Studies in humans have evaluated only plasma palmitoleic acid concentrations, which reflect stearoyl-coenzyme A desaturase 1 (SCD1) activity in the liver and are associated with increased risk of obesity. These apparent opposite effects of palmitoleic acid deserve further research in humans. Because carbohydrate intake can increase hepatic SCD1 activity, it could be used as a stratifying variable to disentangle the effects of adipose tissue SCD1 compared with the effects of liver SCD1 activity on obesity. OBJECTIVE We examined whether the effects of adipose tissue palmitoleic acid and SCD1 activity were associated with decreased obesity prevalence and whether this association was modified by carbohydrate intake. DESIGN Prevalence ratios (PRs) of obesity [body mass index (in kg/m²) > 30] were examined in a cross-sectional study in 1926 adults in Costa Rica. Two desaturation indexes (16:1/16:0 and 18:1/18:0) were used as surrogate measures of adipose tissue SCD1 activity. RESULTS We observed a positive association between adipose tissue palmitoleic acid concentrations and obesity (PR for lowest compared with highest quintiles of palmitoleic acid: 2.27; 95% CI: 1.52, 3.38; P for trend < 0.0001). A significant association was also observed between obesity and adipose desaturation indexes. The association between adipose tissue palmitoleic acid concentrations and obesity was attenuated in persons with low carbohydrate intake. CONCLUSIONS There is no direct evidence that adipose tissue palmitoleic acid behaves as a lipokine to reduce obesity occurrence in humans. However, the attenuation of the association by low carbohydrate intake warrants further research on adipose-derived palmitoleic acid and obesity risk.