Methodology for adding glycemic index to the National Health and Nutrition Examination Survey nutrient database

Preconception dietary glycemic index and risk for large-for-gestational age births

OBJECTIVES

Diets with a high glycemic index (GI) leading to elevated postprandial glucose levels and hyperinsulinemia during pregnancy have been inconsistently linked to an increased risk for large-for-gestational-age (LGA) births. The effects of prepregnancy dietary GI on LGA risk are, to our knowledge, unknown. We examined the association of prepregnancy dietary GI with LGA births and joint associations of GI and maternal overweight/obesity and infant sex with LGA births among 10 188 infants born without congenital anomalies from 1997 to 2011, using data from the National Birth Defects Prevention Study (NBDPS). The aim of this study was to investigate this association among infants without major congenital anomalies (controls) who participated in the NBDPS and to evaluate how prepregnancy BMI and infant sex may modify this association on the additive scale.

METHODS

Dietary intake was ascertained using a 58-item food frequency questionnaire. We dichotomized dietary GI into high and low categories using spline regression models. Infants with a birth weight at or above the 90th percentile for gestational age and sex, according to a U.S. population reference, were considered LGA. We used logistic regression to obtain odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Of the infants, 859 (9%) had a high dietary GI (cut-point: 59), and 1244 infants (12%) were born LGA. Unadjusted analysis suggested an inverse association between high dietary GI and LGA (OR, 0.79; 95% CI, 0.62-0.99). No association was observed in multivariable models when comparing high dietary GI intake between LGA births and all other births (OR, 0.94; 95% CI, 0.74-1.20) or when excluding small-for-gestational-age (SGA) births (OR, 0.94; 95% CI, 0.73-1.19). No joint associations with maternal overweight/obesity or infant sex were observed.

CONCLUSION

High prepregnancy maternal GI was not associated with LGA births independently of or jointly with other factors.

Higher Glycemic Index and Glycemic Load Diet Is Associated with Slower Disease Progression in Amyotrophic Lateral Sclerosis

OBJECTIVE

High-caloric diets may slow the progression of amyotrophic lateral sclerosis; however, key macronutrients have not been identified. We examined whether dietary macronutrients are associated with the rate of progression and length of survival among the prospective cohort study participants.

METHODS

Participants with a confirmed diagnosis of sporadic amyotrophic lateral sclerosis enrolled in the Multicenter Cohort Study of Oxidative Stress were included (n = 304). We evaluated baseline macronutrient intake assessed by food frequency questionnaire in relation to change in revised amyotrophic lateral sclerosis functional rating scale total-score, and tracheostomy-free survival using linear regression and Cox proportional hazard models. Baseline age, sex, disease duration, diagnostic certainty, body mass index, bulbar onset, revised amyotrophic lateral sclerosis functional rating scale total-score, and forced vital capacity were included as covariates.

RESULTS

Baseline higher glycemic index and load were associated with less decline of revised amyotrophic lateral sclerosis functional rating scale total score at 3-month follow-up (β = -0.13, 95% CI -0.2, -0.01, p = 0.03) and (β = -0.01, 95% CI -0.03, -0.0007, p = 0.04), respectively. Glycemic index second-quartile, third-quartile, and fourth-quartile groups were associated with less decline at 3 months by 1.9 (95% CI -3.3, -0.5, p = 0.008), 2.0 (95% CI -3.3, -0.6, p = 0.006), and 1.6 (95% CI -3.0, -0.2, p = 0.03) points compared with the first-quartile group; the glycemic load fourth-quartile group had 1.4 points less decline compared with the first-quartile group (95% CI -2.8, 0.1, p = 0.07). Higher glycemic index was associated with a trend toward longer tracheostomy-free survival (HR 0.97, 95% CI 0.93, 1.00, p = 0.07).

INTERPRETATION

Higher dietary glycemic index and load are associated with slower disease progression in amyotrophic lateral sclerosis. ANN NEUROL 2024;95:217-229.

Quality of dietary carbohydrate is more important than its quantity in lipid peroxidation

BACKGROUND

High glycemic index (GI) diets have been linked to elevated risk of cardiometabolic diseases. One possible underlying mechanism comes from high GI diet's potential to promote lipid peroxidation.

OBJECTIVES

We aim to evaluate whether and to what extent dietary carbohydrate quality and quantity are associated with systemic levels of lipid peroxidation in females.

METHODS

In this cross-sectional analysis of 2163 middle-aged women, a subset of the Shanghai Women's Health Study, we measured lipid peroxidation biomarkers F2-isoprostanes (F2-IsoPs) and its metabolite, 2,3-dinor-5,6-dihydro-15-F2t-IsoP (F2-IsoP-M), in urine. The quality of carbohydrate was defined by dietary GI, assessed using a validated FFQ via in-person interviews. A multivariable linear regression model with restricted cubic spline functions was used to evaluate the association of measured biomarkers with carbohydrate intake and dietary GI.

RESULTS

After adjustment for potential confounding factors such as cigarette smoking, BMI, and comorbidities, among others, we found that F2-IsoP-M concentrations were positively associated with both carbohydrate intake and dietary GI. Carbohydrate intake and dietary GI were weakly correlated (r = 0.12). When further mutually adjusted for the 2 factors, the positive association with F2-IsoP-M remained statistically significant for GI (P = 0.004) but not for carbohydrate intake (P = 0.50). Compared with those in the 10th percentile of dietary GI, fold increases (95% CI) in F2-IsoP-M concentrations for those in the 30th, 50th, 70th, and 90th percentiles were 1.03 (1.00, 1.07), 1.06 (1.01, 1.10), 1.09 (1.03, 1.14), and 1.13 (1.05, 1.21), respectively. Moreover, there appeared a threshold regarding the association between dietary GI and F2-IsoP-M concentrations, with the dose-effect slope of GI being 2.3 times greater when GI was ≥75 relative to GI <75.

CONCLUSIONS

This study provides evidence that the quality of dietary carbohydrate may be more important than the quantity of the intake with regard to systemic lipid peroxidation.

Glycaemic index, glycaemic load and cancer risk: results from the prospective NutriNet-Santé cohort

BACKGROUND

Evidence is accumulating that high dietary glycaemic index (GI) and glycaemic load (GL) are potential risk factors for several metabolic disorders (e.g. type-2 diabetes, cardiovascular diseases), but remains limited concerning cancer risk. Although, mechanistic data suggest that consuming high-GI foods may contribute to carcinogenesis through elevated blood glucose levels, insulin resistance or obesity-related mechanisms. Our objective was to study the associations between dietary GI/GL and cancer.

METHODS

In total, 103 020 French adults (median age = 40.2 years) from the NutriNet-Santé cohort (2009-2020) with no cancer or diabetes at baseline were included (705 137 person-years, median follow-up time = 7.7 years). Repeated 24-h dietary records linked with a detailed food-composition table (>3500 food/beverage items). We computed the average dietary GI and GL at the individual level. Associations between GI, GL, contribution of low- and medium/high-GI foods to energy and carbohydrate intake and cancer risk (overall, breast, prostate and colorectal) were assessed using multivariable Cox proportional-hazard models.

RESULTS

Higher dietary GL was associated with higher overall cancer risk [n = 3131 cases, hazard ratios (HRs) for sex-specific quintile 5 vs 1 = 1.25, 95% confidence interval (CI) = 1.03-1.52; Ptrend = 0.008] and specifically postmenopausal breast cancer (n = 924, HRQ5vs.Q1 = 1.64, 95% CI = 1.06-2.55; Ptrend = 0.03). A higher contribution of low-GI food/beverages to energy intake was associated with lower cancer risk whereas a higher contribution of medium/high-GI items to energy intake was positively associated with higher risk of overall, breast and postmenopausal breast cancers (Ptrend ≤ 0.02).

CONCLUSIONS

These results support a possible impact of GI/GL on cancer risk. If confirmed in other populations and settings, dietary GI/GL could be considered as modifiable risk factors for primary cancer prevention.

TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT03335644.

A bilingual dietary intervention early in treatment is feasible and prevents weight gain in childhood acute lymphoblastic leukemia

BACKGROUND

Childhood acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. The onset of obesity during childhood ALL has been well established and is associated with inferior survival rates and increased treatment-related toxicities. This pilot study sought to determine if a dietary intervention is feasible and minimizes weight gain during the initial phases of treatment for ALL.

METHODS

Participants were recruited from four institutions, fluent in English or Spanish, between 5 and 21 years old, and enrolled within 3 days of starting induction therapy. Participants were counseled for 6 months to follow a low glycemic diet. Dietary and anthropometric data were collected at diagnosis, end of induction, and end of month 6 (NCT03157323).

RESULTS

Twenty-three of 28 participants (82.1%) were evaluable and included in the analysis. Dietary changes targeted by the nutrition intervention were successful; sugar intake declined (P = .003), whereas vegetable intake increased (P = .033). The majority of participants were able to adhere to the dietary principles prescribed: ≥70.0% reduced glycemic load and ≥60.0% increased fiber intake and decreased sugar intake. Importantly, we did not observe an increase in body mass index z-score during induction or over the 6-month intervention period. Most families found the nutrition intervention easy to follow (60%) and affordable (95%) despite simultaneous initiation of treatment for ALL.

CONCLUSIONS

A 6-month nutrition intervention initiated during the initial phase of treatment for childhood ALL is feasible and may prevent weight gain. Our preliminary findings need to be confirmed in a larger clinical trial.

Rice and Prevention of Type 2 Diabetes: Narrative Review of Epidemiologic Evidene

Inspite that rice is a main staple and heaviliy consumed in most of Asian populations, health effect of rice has been less examined in nutritional epidemiologic studies compared to those of foods such as fruits, vegetables, meats and fish. Some recent meta-analyses that collected prospective cohort studies reported the associations between rice intake and incidence of and mortality from some chronic diseases especially type 2 diabetes. Concerning type 2 diabetes, the results are remarkably different between white (polished) rice and brown (unpolished) rice: the former increased and the latter decreased the risk. This difference may partly be explained by the different types and amounts of dietary fiber and different scores of dietary glycemic index. However, the results on dietary fiber and dietary glycemic index were not necessarily consistent. Indirect effect of rice intake has been examined through the studies on association of dietary patterns and breakfast skipping to type 2 diabetes. However, most of the results were inconclusive. Simple and straightforward judgement on the effect of rice to type 2 diabete should be avoided, and more nutritional epidemiologic studies with high research quality, including basic studies on dietary assessment, are needed, especially in Asian populations.

Healthy Eating and Active Living for Diabetes-Glycemic Index (HEALD-GI): Protocol for a Pragmatic Randomized Controlled Trial

BACKGROUND

Rigorous evidence is needed regarding the best approach for increasing the uptake of Diabetes Canada's evidence-based recommendations to include low-glycemic index (GI) foods in daily meal planning as an effective dietary self-care strategy for glycemic control among people with type 2 diabetes (T2D).

OBJECTIVE

This study aims to present the study design and baseline data from the Healthy Eating and Active Living for Diabetes-Glycemic Index (HEALD-GI) trial, which was designed to evaluate the effectiveness of an enhanced GI-targeted nutrition education on GI-related knowledge and mean daily GI among adults with T2D in Edmonton, Alberta.

METHODS

We used a pragmatic randomized controlled trial design and allocated 67 adults (aged ≥18 years) with T2D living in Edmonton, Alberta, Canada, to a control group that received standard printed copies of Canada's Food Guide and Diabetes Canada's GI resources or to an intervention group that received the same materials, plus a customized Web-based platform with 6 self-directed learning modules and print material. Each module included videos, links to reliable websites, chat rooms, and quizzes. Evidence-based GI concept information included GI values of foods and low-GI shopping, recipes, and cooking tips by a registered dietitian. In addition, support through email, text messaging (short message service), phone calls, or postal mail was provided to reinforce participants' learning. The primary outcome, average dietary GI, was assessed using 3-day food records. Additional measures including GI knowledge and self-efficacy, glycated hemoglobin (HbA_1c), lipids, systolic blood pressure, body mass index (BMI; weight, height), waist circumference, and computer proficiency were assessed at baseline and at 3-month postintervention.

RESULTS

Between November 2017 and February 2018, we contacted adults (aged ≥18 years) with T2D living in Edmonton, Alberta, screened and recruited eligible participants into the study. All data collection ended in June 2018. Overall, 64% (43/67) participants were males; mean age was 69.5 (SD 9.3) years, with a mean diabetes duration of 19.0 (SD 13.7) years. Mean BMI was 30.1 (SD 5.7) kg/m², and mean HbA_1c value was 7.1% (SD 1.2%). Data analysis was completed in December 2018.

CONCLUSIONS

The GI concept is often difficult to teach. The HEALD-GI study aims to provide evidence in support of an alternative approach to translating the GI concept to adults with T2D. Findings from this study may help registered dietitians to better disseminate low-GI dietary recommendations using efficient and cost-effective, patient-centered approaches. Furthermore, evidence generated will contribute to addressing some of the controversies regarding the clinical usefulness of the GI concept.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/11707.

Non-pharmacological Treatment Options in the Management of Diabetes Mellitus

The global prevalence of diabetes, especially type 2 diabetes mellitus, has reached epidemic proportions in the last few decades of the 20th century because of the obesity pandemic resulting from adverse lifestyles. Diabetes as a consequence of obesity (diabesity), continues to increase exponentially in the 21st century. Although there are a multitude of drugs for the effective management of diabesity with modest benefits, most patients will require insulin for control of diabetes at some stage that would worsen obesity, and thereby diabesity. Therefore, effective non-pharmacological therapy needs to be expedited in all patients with diabesity. These measures include medical nutrition interventions, change of lifestyles and bariatric surgery. Non-pharmacological interventions are also useful for the effective management of even type 1 diabetes mellitus when used along with insulin therapy especially in those with obesity. This review summarises the current evidence base for the non-pharmacological interventions in the management of diabetes.

Lower Dietary Inflammatory Index Scores Are Associated with Lower Glycemic Index Scores among College Students

The association between the Dietary Inflammatory Index (DII^®), the glycemic index (GI), and the glycemic load (GL) is not known, although it is known that carbohydrates are pro-inflammatory. We aimed to measure the association between the DII and both GI and GL among college students. In this cross-sectional study, 110 college students completed a 3-day food diary, which was used to calculate the DII, the GI, the GL, and the healthy eating index (HEI)-2010. Least square means and 95% confidence intervals of the GI, the GL, and the HEI-2010 were presented per DII tertile using generalized linear mixed models. Participants in tertile 1 of DII scores had lower GI and GL scores, but higher HEI-2010 scores than those in tertile 3. Pearson correlations showed that DII score was positively correlated with the GI score (r = 0.30, p < 0.01), but negatively correlated with the HEI-2010 (r = −0.56, p < 0.001). DII score was not correlated with GL score. Results from this study suggest that increased inflammatory potential of diet, as represented by higher DII scores, was associated with increased GI scores and lower quality of diet on the HEI-2010. Use of the DII suggests new directions for dietary approaches for preventing chronic diseases that moves beyond convention by decreasing systemic inflammation.

Examining sex differences in glycemic index knowledge and intake among individuals with type 2 diabetes

AIM

We examined self-reported dietary behaviours and actual food intakes among adult men and women with type 2 diabetes participating in Alberta's Caring for Diabetes (ABCD) Study.

METHODS

Participants completed 3-day food records and questions about glycemic index (GI) concept knowledge and dietary behaviours. Daily average GI and glycemic load (GL) were calculated for all carbohydrates consumed. Dietary intake was analyzed using ESHA FoodPro (version 10.13.1). Sex differences in nutrient intakes were explored across categories of GI knowledge and dietary practices.

RESULTS

Participants (N=170) mean (SD) age 65.8 (9.6) years were 46.5% women, 90.6% Caucasian with a mean BMI of 31.3 (7.0)kg/m² and diabetes duration of 13.4 (8.6) years. Overall, 60% of men versus 40% of women consumed carbohydrates in quantities below Acceptable Macronutrient Distribution Ranges (AMDR). About 80% of men versus 90% of women consumed proteins above AMDR whereas 60% versus 65% of women consumed fats above AMDR. Fibre intake among men was lower than recommended (p<0.01). Men who reported having knowledge of the GI-concept also reported lower GI intake versus men who did not (p=0.03).

CONCLUSION

Sex differences exist in low-GI diabetes self-care dietary behaviours among adults with type 2 diabetes participating in this study. Gender-sensitive approaches for enhancing diabetes self-care low-GI dietary behaviour should be explored.

Plasma F2-isoprostanes Are Positively Associated with Glycemic Load, but Inversely Associated with Dietary Polyunsaturated Fatty Acids and Insoluble Fiber in Postmenopausal Women

Background: Dietary factors, such as antioxidant nutrients, contribute significantly to the maintenance of an appropriate balance between antioxidant defense and free radical production in the body.Objective: The objective of this study was to examine the relation between oxidative stress as assessed by plasma F₂-isoprostane (IsoP) concentration, glycemic load (GL), glycemic index (GI), intake of antioxidant nutrients, dietary fiber, and polyunsaturated fatty acids (PUFAs).Methods: This study was a cross-sectional secondary analysis of baseline data collected from a random sample of 269 postmenopausal women participating in the Minnesota Green Tea Trial. GL, GI, and dietary variables were calculated from the diet history questionnaire. Subjects filled out surveys about the use of anti-inflammatory drugs and physical activity. Plasma IsoP concentration was assessed by GC-mass spectrometry. IsoP concentrations were compared across quartiles of GL, GI, insoluble fiber, PUFAs, and antioxidant nutrients with the use of linear regression.Results: Antioxidant supplement intake, including zinc, copper, vitamin C and vitamin E, was reported by >60% of the participants. Mean intake of PUFAs was 12.5 g. Mean plasma IsoP concentrations increased from 34 to 36.7 pg/mL in the lowest quartiles of GL and GI, respectively, to 45.2 and 41.6 pg/mL, respectively, in the highest quartiles (P-trend = 0.0014 for GL and P-trend = 0.0379 for GI), whereas mean IsoP concentrations decreased from 41.8 pg/mL in the lowest quartile of PUFAs to 34.9 pg/mL in the highest quartile (P-trend = 0.0416). Similarly, mean IsoP concentrations decreased from 44.4 pg/mL in the lowest quartile of insoluble fiber to 36 pg/mL in the highest quartile (P-trend = 0.0243) after adjustment for potential confounders.Conclusions: We concluded that dietary PUFAs and insoluble fiber are inversely associated with oxidative stress whereas GL and GI are positively associated with oxidative stress in postmenopausal women. This trial was registered at clinicaltrials.gov as NCT00917735.

Calorically restricted diets decrease PCSK9 in overweight adolescents

BACKGROUND AND AIMS

Nutritional therapy is the first line approach to treatment of hyperlipidemia in childhood. Proprotein convertase subtilisin kexin type 9 (PCSK9) is a key regulator of plasma cholesterol levels and a target of novel lipid-lowering pharmacotherapies. We examined the effects of an intensive nutritional intervention on PCSK9 levels in overweight adolescents with cardiovascular disease (CVD) risk factors.

METHODS AND RESULTS

Twenty seven obese and overweight adolescents with CVD risk factors were assigned to either a low fat or low glycemic load diet. During an 8-week "Intensive Phase," assigned meals were delivered to the home, and all participants received weekly in-person home nutrition counseling and phone calls. The subjects then underwent a 4-month "Maintenance Phase" without food provision and with no in-person contact. Anthropometric measurements, laboratory data, and serum PCSK9 protein levels were measured at baseline, 8 weeks, and 6 months. PCSK9 decreased by 16.5% at 8 weeks (201.2 ± 56.3 vs 165.6 ± 58.4 ng/mL; p < 0.001); PCSK9 levels returned to baseline levels at 6 months, after the Maintenance Phase. Change in PCSK9 was associated with change in fasting insulin, HOMA-IR, and AUC insulin, independent of weight loss.

CONCLUSIONS

PCSK9 decreased in youth participating in an intensive dietary intervention. Change in HOMA-IR was associated with change in PCSK9, independent of weight loss, suggesting an important relationship with insulin sensitivity. ClinicalTrials.gov Identifier: NCT01080339.

Dietary glycaemic index and glycaemic load among Australian adults - results from the 2011-2012 Australian Health Survey

This study aimed to determine the major food groups contributing to dietary glycaemic load (GL). Plausible food intake data collected using a multiple-pass 24 hour recall from a weighted sample of 6326 adult respondents (52% male) of the 2011-2012 Australian Health Survey dataset (AHS) were analysed. The GI of foods was estimated based on a previously published step-wise method. Descriptive statistics were calculated for dietary glycaemic index (GI), GL and contribution to GL by major food groups, stratified by age and sex. Trends across age groups were assessed using linear regression. Pearson's χ² was used to test for differences between age groups for categorical demographics variables. The mean (SD) dietary GI and GL was 54 (7) and 135 (59) respectively and the top 3 contributors to dietary GL were breads (14.4%), cereal-based dishes (10.3%) and breakfast cereals (ready to eat) (6.6%). There were small but significant differences in the GL contribution pattern between the sexes. The findings indicate that the average dietary GI of Australian adults is similar to that of other population groups, with a large proportion of starchy and energy-dense nutrient-poor foods that contribute to a high GL.

Metabolic disturbances in plasma as biomarkers for Huntington's disease

Huntington's disease (HD), caused by expanded CAG repeats encoding a polyglutamine tract in the huntingtin protein, presents with a predominant degeneration of neurons in the striatum and cortex. Although a few studies have identified substantial metabolite alterations in plasma, the picture of plasma metabolomics of HD has not been clearly depicted yet. Using a global metabolomics screening for plasma from 15 HD patients and 17 controls, HD patient group was separated from the control group by a panel of metabolites belonging to carnitine, amino acid and phosphatidylcholine species. The quantification of 184 related metabolites (including carnitine, amino acid and phosphatidylcholine species) in 29 HD patients, 9 presymptomatic HD carriers and 44 controls further showed one up-regulated (glycine) and 9 down-regulated metabolites (taurine, serotonin, valine, isoleucine, phosphatidylcholine acyl-alkyl C36:0 and C34:0 and lysophosphatidylcholine acyl C20:3). To understand the biosynthetic alterations of phosphatidylcholine in HD, we examined the expression levels and activities of a panel of key enzymes responsible for phosphatidylcholine metabolism. The results showed down-regulation of PCYT1A and increased activity of phospholipase A2 in HD leukocytes. These metabolic profiles strongly indicate that disturbed metabolism is involved in pathogenesis of HD and provide clue for the development of novel treatment strategies for HD.

Providing food to treat adolescents at risk for cardiovascular disease

OBJECTIVE

Diet modification is recommended to treat childhood cardiovascular (CV) risk factors; however, the optimal dietary strategy is unknown.

METHODS

In a randomized trial, the effect of a low-fat (LF) and a low-glycemic-load (LGL) reduced-calorie diet were examined in youth with overweight/obesity with CV risk factors. Using a novel intervention, we delivered LF or LGL meals and nutrition education to the home for 8 weeks (Intensive Phase), followed by 4 months Maintenance without food provision. Between-group differences in the change in insulin area under the curve (InsAUC) by oral glucose tolerance test and other risk factors were analyzed.

RESULTS

Overall, participants (n = 27) showed substantial improvement during the Intensive Phase, including InsAUC (-59 ± 18.2 µU/ml × 120 min, P = 0.004), total cholesterol (-9.9 ± 3.6 mg/dl, P = 0.01), weight (-2.7 ± 0.5 kg, P < 0.001), waist circumference (-3.1 ± 0.8 cm, P < 0.001), HOMA-IR (-1.7 ± 0.4, P < 0.001), systolic blood pressure (-5 ± 1.4 mm Hg, P = 0.002), and CRP (-0.1 ± 0.1 mg/dl, P = 0.04). There were minimal between-group differences; the LF group showed greater declines in HDL (P = 0.005) and fasting glucose (P = 0.01) compared to the LGL group. Improvements waned during Maintenance.

CONCLUSIONS

Home delivery of LF or LGL diets resulted in rapid and clinically important improvements in CV risk factors that diminished without food delivery and did not differ based on dietary intervention. If scalable, food provision may represent an alternative nutrition treatment strategy.

Consumption of a high glycemic load but not a high glycemic index diet is marginally associated with oxidative stress in young women

Research studies have suggested that chronic consumption of high glycemic index foods may lead to chronically high oxidative stress. This is important because oxidative stress is suspected to be an early event in the etiology of many disease processes. We hypothesized that dietary glycemic index and glycemic load were positively associated with oxidative stress assessed by plasma F2-isoprostanes in healthy, premenopausal women (body mass index [BMI] = 24.7 ± 4.8 kg/m(2) and age 25.3 ± 3.5 years, mean ± SD). We measured plasma F2-isoprostanes in 306 healthy premenopausal women at the baseline visit for the Women In Steady Exercise Research study, using gas chromatography-mass spectrometry. Dietary glycemic index and load were calculated from the National Cancer Institute Diet History Questionnaire, and participants were divided into quartiles of dietary glycemic index and of glycemic load. Plasma F2-isoprostanes were compared across quartile groups of dietary glycemic index and glycemic load using linear regression models. Plasma F2-isoprostanes (pg/mL) increased with quartile of glycemic load (test for linear trend, P = .033), and also increased with quartile of glycemic index in participants with BMI ≥ 25 (P = .035) but not in those with BMI <25 (P = .924). After adjustment for BMI, alcohol consumption and total energy intake, both these positive trends remained marginally significant (P = .123 for quartiles of glycemic index and P = .065 for quartiles of glycemic load).