Erica M. Holt, MPH : University of Minnesota (UM) Lyn M. Steffen, PhD, MPH, RD: UM

Fruit and Vegetable Consumption and its Relation to Markers of Inflammation and

Oxidative Stress in Adolescentsand Oxidative Stress in Adolescents

Erica M. Holt, MPH : University of Minnesota (UM)Lyn M. Steffen, PhD, MPH, RD: UM

Antoinette Moran, MD: UMSamar Basu, PhD: Uppsala University

Julia Steinberger, MD: UMJulie A. Ross, PhD: UM

Ching-Ping Hong, MS: UMAlan R. Sinaiko, MD: UM

Holt E, et al. J Am Diet Assoc. 2009; 109 (Mar).

JOURNAL OF THEAMERICAN DIETETICASSOCIATION



Fruit and Vegetable Consumption and its Relation to Markers of Inflammation and Oxidative Stress in Adolescents

Background

• Fruits and vegetables, foods rich in flavonoids and antioxidants, have been associated with lower risk of stroke, coronary heart disease, and markers of inflammation and oxidative stress in adults

• Markers of inflammation and oxidative stress are predictors of coronary heart disease risk

• It is unknown whether these markers are related to dietary flavonoid and antioxidant intake in youth.




Study Objective

To determine whether greater intakes of fruit and vegetables, antioxidants, and total flavonoids are inversely associated with

markers of inflammation and oxidative stress in adolescent boys and girls.




Study Methods

• Study Design

– Cross-sectional study conducted in 1996-2000

• Study Population

– 304 adolescent girls and boys

– Exclusions for analysis:

• 19 students without dietary data

– 285 adolescents included in analysis




Data Collection

• Tanner stage assessed (I, II, III, IV, V)• Height and weight measured

– Body mass index (BMI) calculated kg/m2

• Fasting blood sample obtained– Analyzed for markers of inflammation (C-reactive protein

[CRP], tumor necrosis factor-alpha [TNF-a], interleukin-6 [IL-6], 15-keto-dihydro-PGF2a [PGF2a] and oxidative stress, 8-iso-F2a [F2-isoprostane])

• Dietary intake assessment – Willett 127-item food frequency questionnaire




Food Groups

• Food intakes were grouped into selected food categories for these analyses

– Fruit: 10 different fruits

– Fruit juice: apple, orange, grapefruit juice

– Vegetables: 24 vegetables

– French fried potatoes

– Legumes




Statistical Methods

• All analyses were conducted using SAS, version 9.1• Variables with skewed distributions were log transformed to

achieve normality; means were back transformed and reported as geometric means.

• Spearman partial correlation analyses evaluated the relation of dietary intake with markers of inflammation and oxidative stress, adjusting for age, sex, race, Tanner stage, energy intake, and body mass index.




Results

Characteristic Boys

(n=155)

Girls

(n=130)

p-value

Age 15.1 (1.2) 14.9 (1.2) 0.13

Tanner Stage, n (%) 4.5 (0.8) 4.6 (0.6) 0.22

BMI, kg/m2 23.3 (5.0) 24.0 (5.3) 0.21

SD = standard deviation BMI = Body mass index

Mean (SD) physical and clinical characteristics of adolescent boys and girls, N=285




Mean (SD) markers of inflammation and oxidative stress among adolescent boys and girls, N=285

Characteristic Boys

(n=155)

Girls

(n=130)

p-value

CRP 0.77 (1.9) 0.85 (1.9) 0.12

TNF-a 4.01 (1.9) 4.33 (2.2) 0.33

IL-6 2.16 (2.1) 2.41 (1.9) 0.17

PGF2-a 0.17 (1.4) 0.20 (1.4) 0.003

F2isoprostane 0.3 (1.6) 0.4 (1.5) 0.004CRP = c-reactive protein TNF-a = Tumor necrosis factor-á IL-6 = Interleukin-6 F2-iso = F2-isoprostane

PGF 2a = Prostaglandin F2a SD = standard deviation




Mean (SE) daily nutrient intake of adolescent 155 boys and 130 girls, N=285

Nutrient intakea Boys Girls p-value

Energy, kcal 2532 (83) 2234 (94) 0.01

Fiber, g 21.4 (0.4) 22.9 (0.5) 0.03

Vitamin C, mgb 250 (15.2) 251 (17.1) 0.96

Beta-carotene, IU 9047 (565) 9047 (589) 0.31

Folate, mcgb 471 (15.2) 463 (17.3) 0.71

aaAdjusted for age, race, Tanner stage, energy intake b nutrients include food + supplement intake

SE = standard error




Mean (SE) daily fruit and vegetable intake of adolescent 155 boys and 130 girls, N=285

Food Intake, servingsa Boys Girls p-value

Fruit 1.4 (0.1) 1.4 (0.1) 0.90

Fruit juice 1.7 (0.1) 1.2 (0.1) 0.02

Vegetablesb 2.3 (0.1) 2.6 (0.1) 0.14

French fries 0.5 (0.2) 0.5 (0.3) 0.43

Legumes 0.2 (0.03) 0.2 (0.03) 0.89

Total fruit/vegetable 5.6 (0.3) 5.5 (0.3) 0.79

aaAdjusted for age, race, Tanner stage, energy intake bVegetables exclude french fries

SE = standard error




Mean (SE) daily flavonoid intake of adolescent 155 boys and 130 girls,

N=285Flavonoid intakea Boys Girls p-value

Myricetin, mg 0.92 (0.07) 1.03 (0.08) 0.27

Kaempferol, mg 2.51 (0.28) 3.06 (0.33) 0.21

Quercetin, mg 10.2 (0.33) 10.8 (0.38) 0.23

Luteolin, mg 0.08 (0.04) 0.04 (0.04) 0.43

Total flavonoids, mg 14.2 (0.58) 15.4 (0.66) 0.16

aaAdjusted for age, race, Tanner stage, energy intake SE = standard error




Dietary Intakea CRP TNF-a IL-6 PG F2

Vitamin C, mg b -0.13* NS -0.14* NS -0.16*

Beta-carotene, IU NS -0.14* -0.15* NS NS

Folate, mcgb -0.18* NS NS NS -0.21*

Kaempferol, mg NS NS NS NS -0.15*

Quercetin, mg NS NS NS NS -0.15*

Total flavonoids NS NS NS NS -0.14*

Correlation of dietary antioxidants with markers of inflammation and Oxidative Stress in Adolescents, N=285

a = models adjusted for age, sex, race, Tanner stage, energy intake, Body Mass Index

b= nutrients include food and vitamin supplement intake*p<0.05

CRP = c-reactive protein TNF-a = Tumor necrosis factor-á IL-6 = Interleukin-6 F2-iso = F2-isoprostane

PGF 2a = Prostaglandin F2a




Correlation of food intake with markers of inflammation and oxidative stress in adolescents, N=285

Food Intakea CRP TNF-a IL-6 PG F2

Fruit -0.19* NS -0.13* NS NS

Vegetables NS -0.13* -0.15* NS NS

Legumes NS NS -0.16* NS NS

Fruit and vegetablesb* -0.15* -0.13* -0.16* NS -0.13*

*p<0.05

a = models adjusted for age, sex, race, Tanner stage, energy intake, Body Mass Index (BMI)b = total fruit and vegetables include fruit juice and French fried potatoesCRP = c-reactive protein TNF-a = Tumor necrosis factor-á IL-6 = Interleukin-6 F2-iso = F2-isoprostane

PGF 2a = Prostaglandin F2a




Conclusions

• The beneficial effects of fruit and vegetable intake on markers of inflammation and oxidative stress are already present by early adolescence.

• These findings provide support for the United States Dietary Guideline “to consume five or more servings per day” of fruits and vegetables, which is beneficial for cardiovascular health.

Documents

Erica M. Holt, MPH : University of Minnesota (UM) Lyn M. Steffen, PhD, MPH, RD: UM