Table 2.

Randomised controlled trials (RCT) with fatty and lean fish on insulin sensitivity

Author	Subjects	Health	Design	Background diet	Intervention meals	Duration	Results
Dunstan et al. (1997)( 137 )	n 49 37 M 12 F Mean age: 53 (sd 7·7) years Age range: 30–65 years	Type 2 diabetes (no insulin) Mean BMI: 29·6 (sd 3·5) kg/m2	RCT, parallel	4 weeks baseline period – normal diet	(1) Fish + moderate exercise (2) Fish and + light exercise (3) No fish + moderate exercise (4) Control (no fish + light exercise) Fish: 7 d/week (turbot, sardines, tuna, salmon)=3·65 g n-3 PUFA/d	8 weeks	Fish groups elevated levels of glycated Hb and blood glucose compared with controls
Mori et al. (1997)( 30 )	n 63 42 M 21 F Mean age: 54·1 (sd 1·8) years Age range: 40–70 years	Hypertension Mean BMI: 31·6 (sd 1·05) kg/m2	RCT, parallel	4 weeks baseline period – normal diet	(1) Control (weight-maintaining diet) (2) Fish (weight-maintaining diet + fish daily) (3) Weight loss (energy-restricted diet) (4) Fish + weight loss (energy-restricted diet + fish daily) Fish: 7 d/week (turbot, sardines, tuna, salmon)=3·65 g n-3 PUFA/d	16 weeks	Fish + weight loss group improved glucose and insulin metabolism
Balfego et al. (2016)( 138 )	n 32 14 M 18 F Mean age: 60·6 (sem 2·1) years Age range: 40–70 years	Type 2 diabetes (no insulin) Mean BMI: 29·7 (sem 0·9) kg/m2	RCT, parallel, pilot	2 weeks lead-in period	(1) Control (standard diet, no sardines) (2) Sardine (standard diet + sardines 100 g for 5 d per week)	6 months	Both groups reduced fasting insulin + HOMA-IR to comparable levels (NS group differences). Glycated Hb reduced in the control group
Hallund et al. (2010)( 139 )	n 68 68 M Mean age: 53 (sd 8·3) years Age range: 40–70 years	Healthy Mean BMI: 24·7 (sd 2·3) kg/m2	RCT, parallel	Normal diet	(1) Farmed trout – marine diet (2) Farmed trout – vegetable diet (3) Chicken 150 g for 3–4 d per week	8 weeks	NS diet effects on fasting glucose, insulin or HOMA-IR
Zhang et al. (2012)( 141 )	n 126 126 F Mean age: 55·8 (sd 6·7) years Age range: 35–70 years	Hypertriacylglycerolaemia Mean BMI: 26·7 (sd 3·3) kg/m2	RCT, parallel	2 weeks run-in (normal diet)	(1) Salmon (2) Herring (3) Pompano (4) Control (meat). Fish/meat: 80 g for 5 d per week	8 weeks	NS diet effects on fasting glucose, insulin or HOMA-IR
Raatz et al. (2013)( 9 )	n 19 8 M 11 F Mean age: 51·6 (sem 1·5) years Age range: 40–65 years	Healthy Mean BMI: 29·2 (sem 0·6) kg/m2 BMI range: 25–35 kg/m2	RCT, cross-over	Normal diet	Different doses of farmed salmon: 90, 180, 270 g 2 x/week	3 × 4 weeks, 4–8 weeks washout	NS diet effects on fasting glucose, insulin or HOMA-IR
Jacques et al. (1992)( 169 )	n 15 15 F Mean age: 62·5 (sem 0·3) years Age range: 53–79 years	Healthy Postmenopausal Mean BMI: 26 (sem 1) kg/m2	RCT, cross-over	Pre-experimental diet (similar to normal diet)	(1) Lean white fish (cod, sole, haddock, halibut, pollock) (2) Non-fish (lean beef, pork, egg, milk) 70–75 % of daily protein replaced with protein from the intervention meals	2 × 4 weeks, 5 weeks washout	Elevated serum sex hormone-binding globulin and higher HDL-cholesterol in lean fish compared with non-fish group (related to improved insulin sensitivity)
Lacaille et al. (2000)( 168 )	n 11 11 M Age range: 19–27 years	Healthy Mean BMI: 24·0 (sem 1·0) kg/m2	RCT, cross-over	Pre-experimental diet (similar to normal diet)	(1) Lean fish (cod and sole) (2) Non-fish (lean beef, pork, veal, eggs, skimmed milk, milk products)	2 × 4 weeks, 5 weeks washout	Elevated serum sex hormone-binding globulin and higher HDL-cholesterol in lean fish compared with non-fish group (related to improved insulin sensitivity)
Gascon et al. (1996)( 171 )	n 14 14 F Mean age: 22·4 (sem 0·9) years	Premenopausal Mean BMI: 22 (sem 1·0) kg/m2	RCT, cross-over	Pre-experimental diet (similar to normal diet)	(1) Lean fish (cod and sole) (2) Non-fish (lean beef, pork, veal, eggs, skimmed milk, milk products)	2 × 4 weeks, 5 weeks washout	No effects on insulin sensitivity
Aadland et al. (2016)( 76 )	n 20 7 M 13 F Mean age: 50·6 (sem 3·4) years	Healthy Mean BMI: 25·6 (sem 0·7) kg/m2	RCT, cross-over	3 weeks run-in period with diet in accordance with Norwegian recommendations	(1) Lean seafood 7 d/week (2) Non-seafood 7 d/week Fish: cod, pollock, saithe, scallops	2 × 4 weeks, 5 weeks washout	Reduced postprandial C-peptide + lactate, no effect on glucose + insulin concentrations in seafood compared with non-seafood group, but reduction in TAG (early markers of improved insulin sensitivity)

M, male; F, female; HOMA-IR, homeostasis model of assessment insulin resistance.