Table 1: Detailed summary of included prospective cohort studies and each study quality scoring.

Quality scores
NOQAS  Critical appraisal —UK (11)
Study author (year)Population of studyYears of followupAscertain of cases (prostate cancer)Omega fatty acid intake determinationFatty acid omega-3/omega-6Comparison of group usedAdjustment variables(C)omparison

Schuurman et al. [9], 199958, 279 men  
55–69 yo
6.3 yearsPathology reports150-item semiquantitative food frequency questionnaire (FFQ)Omega 3 (ALA, EPA, DHA) and Omega 6 (LA, AA)QuintileAge, family history of prostate carcinoma, socioeconomic status, total energy intake4238

Laaksonen et al. [10], 20042,002
42–60 yo
12.6 yearsCancer registries4-day food records nutrition estimated for fatty acidsOmega 6
Tertile Age, dietary intake of energy-adjusted saturated fat, fiber and calcium intake; plasma lipid-standardized tocopherol levels.
BMI, fasting serum insulin and blood glucose levels and nonesterified fatty acid

et al. [11],
44,856 men
40–75 yo
14 years
Self-report and medical/pathology recordEvery 4 years 131-FFQOmega 3 and Omega 6 and ALAQuintileAge, major ancestry, family history of prostate cancer, BMI at age 21 y, height, type 2 diabetes,
history of vasectomy, cigarette smoking, physical activity, intake of total energy, intakes of calcium, supplemental vitamin E, and lycopene.

et al. [12],
29,592 men
55–74 yo
5.1 years (average years)Self-report with medical record Two 24 hr continuing Surveies of Food Intake by Individual over a year using 137 semiquantitative FFQ (ALA composite per food item)Omega 3 (ALA) Quintile Age, current body mass
index, family history of prostate
cancer, history of diabetes,
smoking history, intake of total
energy, lycopene, supplemental
vitamin E, aspirin use, physical
activity, and race

et al. [13], 2007
40–75 yo
16 yearsSelf-report and hospital recordEvery 4 years, 131 item semiquantitative FFQOmega 3 (ALA)Quintile
Age, BMI at age 21 years, height, smoking, physical
activity level, family history of prostate cancer, history of diabetes mellitus, race, and intakes of total calories, processed meat, fish, tomato sauce, and vitamin E supplements

et al. [14], 2007
18,314 smoker
10 yearsCancer registriesEvery 2 years, self-assessment diet FFQOmega 6QuartileAge, race/ethnicity, energy intake, BMI, smoking and family history3238

et al. [15], 2007
82,483 men
>45 yo
8 yearsCancer registriesSelf-administered quantitative FFQ, 180 item 3-day recordOmega 3 (DHA and EPA)
Omega 6
Quintile Age, ethnicity, family history of prostate cancer, education, BMI, smoking status, and energy intake42310

Wallstr m
et al. [16], 2007
10,564 men
45–73 yo
11 yearsCancer registryModified diet history seven-day menu book/168 item questionnaire,
45 min interview
Omega 3 and Omega 6Quintile
Age, diabetes, waist circumference, height, educational level, alcohol habits, BMI, smoking history, birth country, total calcium intake, consumption of fruits,
vegetables, and red meat
All dietary variables were energy adjusted

et al. [17], 2008
20,167 men
40–84 yo
19 years (mean year)Medical record 12 months abbreviated food (fish) frequency questionnaire
Omega 3 (long-chain )Quintile Age, BMI, physical activity, intakes of alcohol, tomato products, dairy products, and meat, smoking, race, use of multivitamins, use of vitamin E supplements3238