Table II.

Key characteristics of randomized controlled trials included to the meta-analysis

Author, year of publication	Country	Study design	Status	Sample size	Gender (% women)	Mean age [years]	Intervention	Supplemented dose of omega-6	Follow-up duration	Reported outcome
Bates et al., 1977 [37]	UK	Parallel, double-blind, randomized controlled trial (RCT)	With chronic progressive multiple sclerosis	152	–	–	Naudicelle oil	Group A: 0.6 ml of oil, 360 mg linolenic, 3.42 g linoleic Group C: 11.5 g/day linoleic	2 years	All-cause mortality
Bates et al., 1978 [38]	UK	Parallel, double-blind RCT	With acute remitting multiple sclerosis	116	Both genders (69%)	–	Naudicelle oil	Group A: 2.92 g linoleic, 0.34 g γ-linolenic Group C: 23 g/day linoleic	2 years	All-cause mortality
Black et al., 1994 [35]	USA	Parallel, double-blind RCT	With nonmelanoma skin cancer	133	Both genders (39%)	51.5	Dietary advice	Total fat 20% (omega-6 and total polyunsaturated fatty acids (PUFAs)	2 years	All-cause mortality, cardiovascular (CV) mortality, body weight
Burr et al., 1989 [39]	UK	RCT (diet and reinfarction trial)	After an MI	2033	Men only	56.6	Dietary advice	Reduce fat intake to 30%, increase polyunsaturated (using polyunsaturated oils and margarine)	2 years	All-cause mortality, CV mortality, any CV event, coronary heart disease (CHD), fatal or non-fatal myocardial infarction (MI), angina, major adverse cardiac and cerebrovascular events (MACCEs), fatal or non-fatal stroke, heart failure (HF), peripheral arterial disease (PAD), total cholesterol (TC), high-density lipoprotein (HDL), other serious events
Houtsmuller et al., 1980 [40]	Netherlands	RCT	With newly diagnosed diabetes	102	Both genders (44%)	–	Dietary advice	Total fat 40%, one-third linoleic acid, increase ~9% energy of LA	72 months	CV mortality, CHD, fatal or non-fatal MI or angina, TC, triglycerides
Morris et al., 1968 [33]	UK	Parallel RCT	Survived a first MI	393	Men only	–	Dietary advice + soya oil	Increase 84 g/day soya oil (50% LA, 58% PUFA), reduce dietary fat to 35 g/day	4 years	All-cause mortality, CV mortality, any CV event, CHD, fatal or non-fatal MI, angina, fatal or non-fatal stroke, sudden cardiac death, HF, body weight, systolic and diastolic blood pressure, TC
Woodhill et al., 1978 [41]	Australia	Parallel RCT	With previous MI	458	Men only	48.9	Dietary advice	Increase 6.6% energy PUFA, most of which omega-6 Saturated fatty acids10%, PUFA 15%	4.3 years	All-cause mortality, CV mortality, any CV event, CHD, fatal or non-fatal MI, angina, fatal or non-fatal stroke, TC, triglycerides, body mass index, systolic and diastolic blood pressure
Dayton et al., 1969 [36]	USA	Parallel RCT	Men living at the veterans administration center	846	Men only	65.5	Dietary advice	Two-third of SFA replaced by unsaturated fats (corn, soybean, safflower, cottonseed oils), 12% energy of PUFA, 4% energy of LA	8 years	All-cause mortality, CV mortality, any CV event, CHD, fatal or non-fatal MI, angina, fatal or non-fatal stroke, MACCEs, sudden cardiac death, PAD, TC
Vijayakamar et al., 2014 [34]	India	Parallel RCT	With stable coronary artery disease	200	Both genders (6.5%)	59.0	Food (cooking oil) provided	15% from sunflower oil 15% energy omega-6	2 years	All-cause mortality, revascularization-angioplasty or coronary artery bypass grafting, TC, triglycerides, HDL, low-density lipoprotein (LDL)