Table 2 Studies outlining the effects of increasing dietary linoleic acid levels (% energy) from baseline on changes in plasma/serum phospholipid arachidonic acid level

King [16]

Randomized parallel intervention

6 weeks

Baseline diet compared to moderate fat diet

13 (10.3%-1.6%)

-3.2 (p < 0.05)

Used modified food items for diets containing different amounts of fat. Reported AA PL as % change.

Thijssen [42]

Randomized multiple crossover

5 weeks

Stearic acid diet to oleic acid diet in food items (using margarines, breads, sponge cakes)

14 (2.1% -2.4%)

-2.24 (N.S.)

No order to diets given. Subjects received all 3 diets with varying amounts of LA.

Oleic Acid to LA food items (margarines, breads, sponge cakes)

287 (2.4%-9.3%)

-1.15 (N.S.)

No order to diets given. Subjects received all 3 diets with varying amounts of LA.

Montoya [43]

Sequential interventions

4 weeks

From palm oil based diet compared to olive oil based diet

16 (3.2%-3.7%)

4.82 (N.S.)

Used nuns and priests. Everyone consumed same sequence of diets. AA did not change among the three test diets. No crossover, subjects were their own controls.

Olive oil based diet to sunflower oil base diet

230 (3.7%-12.2%)

-3.44 (N.S.)

Lichtenstein [35]

Randomized double-blind crossover

35 days

Baseline soybean oil diet compared to low saturated fat-soybean oil diet. The soybean oils varied in LA composition

15.8 (11% -12.7%)

0.89 (N.S.)

Pooled data of men and women. Five diets of random order. Subjects visited metabolic kitchen 3 times week. Varying LA amounts using modified soybean oils.

Baseline high oleic-soybean oil diet to low ALA-soybean oil diet

552 (1.9%-2.5%)

1.27 (N.S.)

Li [39]

Parallel intervention

14 days 14 days

Baseline Western diet to intervention diet increased in LA intake using safflower oil

17.8 (10.1%-11.9%)

6.18 (N.S.)

Used safflower oil/safflower margarine to increase LA in diet to almost twice DRI of LA. AA did not differ among all groups in study.

Baseline Western diet to intervention diet increased in LA intake using safflower oil

82.4 (7.4%-13.5%)

0.96 (N.S.)

Used safflower oil/safflower margarine to increase LA in diet to more than twice DRI of LA. AA did not differ among all groups in study.

Vega-Lopez [36]

Randomized crossover

35 days

Canola oil diet compared to soybean oil diet

64.2 (6.5%-10.7%)

-2.35 (N.S.)

Canola oil in mixed foods was replaced by soybean oil in mixed foods. AA did not change among all three dietary groups. Canola oil diet is baseline because close to the DRI for LA.

Liou [37]

Randomized crossover

4 weeks

Low LA diet (high in oleic acid safflower oil) compared to high LA diet (high in sunflower oil)

176 (3.8%-10.5%)

-0.18 (N.S.)

AA PL content presented as graphs, not numerically. Fish was avoided in all dietary groups. ALA intake was kept constant between low/high diet.

Valsta [19]

Randomized crossover

6 weeks

Habitual diet compared to high LA trisunflower oil diet

86 (4.2%-7.8%)

10 (p < 0.05)

Fish cut in half in all dietary groups. Has a baseline for before each diet. Used trisunflower oil in margarine, food oil, salad dressing, bread, cake and cookies, in place of habitual foods.

Habitual diet compared to high ALA rapeseed oil diet

45 (4.2%-6.1%)

2.77 (N.S.)

Raatz [18]

Randomized crossover

28 days

Low fat diet (20% energy) compared to high fat diet (45% energy).

100 (6%-12%)

-16 (p < 0.05)

Modified foods rich in LA. Random order to diet, so baseline was chosen based on DRI of LA. Used washout period of 21-28 days

Lasserre [17]

Randomized crossover

5 months

Peanut oil diet compared to sunflower oil

111 (6.5%-13.7%)

-20 (p < 0.05)

Used peanut oil group b/c close to DRI for LA.

Innis [13]

Randomized crossover

8 weeks

Low LA diet to high LA diet

176 (3.8%-10.5%)

1.86 (N.S.)

Controlled for dietary AA.