Italian dressing: the oil in it is what the salad needs

In a controlled feeding trial, 53 adults with mildly high cholesterol ate two servings a day of Italian or ranch dressing for 3 weeks each, and the choice made no difference to blood lipids, carotenoids or fat-soluble vitamins. The trial compared the two dressings with each other and had no arm without dressing. Where a dressing does change something is the salad under it. In 7 adults, salads eaten with fat-free dressing gave almost no carotenoid absorption, and dressings with 6 g and then 0.99 oz (28 g) of canola oil gave progressively more. In 12 women given 0 to 1.1 oz (0 to 32 g) of soybean oil in the dressing, every carotenoid and fat-soluble vitamin measured was absorbed best at 32 g. Both were single-meal studies with other oils than a typical Italian bottle, and in the second some women barely responded to added oil at all.

As people eat it, per 3.5 oz (100 g)

How much is actually in it

• Across 8 commercial Italian dressing samples analyzed by USDA, monounsaturated fat ranged from 4.61 to 25.54 g per 3.5 oz (100 g), a more than fivefold spread between products. — 8 commercial Italian dressing samples, USDA Foundation Foods (n = 8) Evidence E source
  Total MUFA mean 8.51 g/100 g, median 6.21, range 4.61-25.54; water 51.1-70.6 g/100 g

What a real portion looks like

• USDA dietary survey data count one tablespoon of light Italian dressing as 14 g and one packet as 44 g. — US dietary recall portion weights Evidence E source
  1 tablespoon 14 g; 1 packet 44 g; 1 dipping-size container 57 g; 1 cup 216 g

What your body absorbs

• In a randomized crossover trial in 7 adults, salads eaten with a fat-free dressing gave almost no carotenoid absorption, while dressings with 6 g and then 0.99 oz (28 g) of canola oil gave progressively more. — 7 adults, three salads (spinach, romaine, tomato, carrot) with dressings of 0, 6 or 28 g canola oil, washout of 2 weeks or more (n = 7) Evidence B source
  Chylomicron carotenoids negligible at 0 g oil; higher at 6 g (P < 0.04); higher again at 28 g (P < 0.02)
• In 12 women eating salads with dressings holding 0, 2, 4, 8 or 32 g soybean oil, absorption of every carotenoid and fat-soluble vitamin measured was highest with 1.1 oz (32 g) of oil. — 12 women, five vegetable salads with soybean-oil dressings of 0 to 32 g (n = 12) Evidence B source
  Linear dose response for alpha-carotene, lycopene, phylloquinone and retinyl palmitate across 0-32 g; beta-carotene linear across 0-8 g; highest absorption at 32 g (P < 0.002)

What cooking and storage change

• In 13 healthy adults, boiled potatoes stored cold for 24 h and served with a vinaigrette of 8 g olive oil and 28 g vinegar had a glycemic index 43% lower than freshly boiled potatoes. — 13 healthy adults, test breakfasts with 50 g available carbohydrate, served in random order (n = 13) Evidence C source
  GI 96 vs 168 (-43%), insulinemic index 128 vs 185 (-31%)

What it does to your health

• In a controlled-diet crossover trial in 53 adults with mildly high cholesterol, eating Italian or ranch dressing twice a day for 3 weeks made no difference to blood lipids or carotenoids. — 26 men and 27 women with mild hypercholesterolemia, controlled isocaloric diets, 3 weeks per diet, two servings of dressing per day (n = 53) Evidence B source
  No effect of dressing type on plasma lipids, lipoproteins, carotenoids or fat-soluble vitamins (P > 0.05)
• Adding 3.6 g a day of plant sterol esters to Italian or ranch dressing lowered LDL cholesterol by a further 9.7% and triglycerides by 7.3% over 3 weeks in 53 adults. — 26 men and 27 women with mild hypercholesterolemia, controlled diets, 3 weeks per diet (n = 53) Evidence B source
  LDL -9.7%, triglycerides -7.3%, no additional change in HDL; total plasma carotenoids -9.6%
• Across four small randomized crossover trials, about 10 g of vinegar taken with a complex-carbohydrate meal lowered the 2-hour blood glucose rise by 20% versus placebo. — adults with or without type 2 diabetes, 9 to 10 per trial, four crossover trials with a bagel and juice or dextrose test meal (n = 9-10 per trial) Evidence B source
  Postprandial glycemia -20% vs placebo with complex carbohydrates; no effect with monosaccharides

Safety, limits and interactions

• In a double-blind trial in 84 adults, plant sterol esters up to 9 g a day in spread and salad dressing for 8 weeks caused no product-related serious adverse events, though 9 g lowered alpha- and beta-carotene within normal ranges. — 84 free-living men and women, reduced-fat spread and salad dressing with 0, 3, 6 or 9 g/day phytosterols for 8 weeks (n = 84) Evidence B source
  No product-related serious adverse events; alpha- and trans-beta-carotene reduced at 9 g/day vs control (p < 0.05), values within normal ranges

What people believe that the data does not support

• The EU refused to authorize the claim that apple cider vinegar helps control and normalize body weight, and none of the six vinegar claims in the register is authorized. — EU health claim assessment Evidence E source
  Claim status non-authorized; 0 of 6 vinegar claims authorized

Who this works differently for

• In the same 12-woman dose trial of 0 to 32 g soybean oil in dressing, the boost in carotenoid and vitamin absorption varied widely between people and some barely responded. — 12 women, five salads with 0, 2, 4, 8 or 32 g soybean oil in the dressing (n = 12) Evidence B source
  Wide interindividual variation; some individuals showed a negligible response to added oil
• In 16 people with type 2 diabetes, adding vinegar to a high-glycemic meal cut the 2-hour glucose rise from 311 to 181 mmol min/l, but it did nothing with a low-glycemic meal. — 16 patients with type 2 diabetes in two matched groups of a high-GI or low-GI meal, with and without vinegar (n = 16) Evidence B source
  Glucose iAUC 181 vs 311 mmol min/l with high-GI meal (P=0.04); 229 vs 238 with low-GI meal (P=0.56)

The bottom line

Bottles differ more than the name suggests. Across 8 commercial Italian dressings analyzed by USDA, monounsaturated fat ran from 4.61 to 25.54 g per 3.5 oz (100 g), with a median of 6.21 g. The layer has no sodium or total fat spread, so the label is your only guide there. USDA survey data count a tablespoon of the light version as 14 g and a packet as 44 g, so one packet is about three tablespoons. The vinegar in the bottle has its own small trials. Across four crossover trials of 9 to 10 adults, about 10 g of vinegar with a starchy meal lowered the 2 hour glucose rise by 20% against placebo, and did nothing with simple sugars. In 16 people with type 2 diabetes, vinegar cut the glucose area after a high-glycemic meal from 311 to 181 mmol min/l and left a low-glycemic meal unchanged (229 with vinegar against 238 without). Both used plain vinegar in single meals. They tested a meal, not a treatment, and our cards hold nothing on vinegar taken alongside diabetes medicines or insulin, so these results are no basis for changing how either is used. In 13 healthy adults, potatoes boiled, chilled for 24 h and dressed with 8 g olive oil and 28 g vinegar had a glycemic index of 96 against 168 for fresh ones. Chilling and vinegar were tested together, so the study cannot split them. The EU has authorized none of its six vinegar claims, including the one that apple cider vinegar helps control body weight. Cholesterol-lowering dressings are a different product. Adding 3.6 g a day of plant sterol esters to Italian or ranch dressing cut LDL by a further 9.7% and triglycerides by 7.3% over 3 weeks in the same 53 adults, and total plasma carotenoids fell 9.6%. The safety evidence also concerns sterol products. In 84 adults taking up to 9 g a day of sterols in spread and dressing for 8 weeks, there were no product-related serious adverse events, and 9 g lowered alpha- and beta-carotene while keeping them in the normal range. Both trials were in adults, and our cards hold nothing on sterol products for children, in pregnancy or alongside cholesterol medicines, so they are not a substitute for any treatment. We have no data on allergens, pregnancy or medicines for ordinary Italian dressing, and no study of it on weight, heart disease or diabetes.

Sources

1. itdr-daily-r6-11 · food composition data
   Salad dressing, Italian dressing, commercial; Fatty acids, total monounsaturated; 8.511 g; range 4.61-25.54 (median 6.205); samples 8
   USDA FoodData Central, Foundation Foods, release 2026-04-30 (Salad dressing, Italian dressing, commercial) · checked 2026-09-30
2. itdr-daily-r6-12 · food portion data
   Italian dressing, light; FNDDS 83205450; 1 tablespoon 14 g; 1 packet 44 g; 1 dipping-size container 57 g; 1 cup 216 g
   USDA FNDDS, Italian dressing, light, food code 83205450 (FDC 2710224) · checked 2026-09-30
3. itdr-daily-r6-01 · RCT (crossover)
   Essentially no absorption of carotenoids was observed when salads with fat-free salad dressing were consumed. A substantially greater absorption of carotenoids was observed when salads were consumed with full-fat than with reduced-fat salad dressing.
   Am J Clin Nutr, 2004 · checked 2026-09-30
4. itdr-daily-r6-02 · RCT (dose-response)
   Absorption of all carotenoids and fat-soluble vitamins was highest with 32 g oil (P < 0.002).
   Am J Clin Nutr, 2017 · checked 2026-09-30
5. itdr-daily-r6-07 · controlled trial (meal test)
   GI and II of cold potatoes added with vinegar (GI/II=96/128) were significantly reduced by 43 and 31%, respectively, compared with GI/II of freshly boiled potatoes (168/185).
   Eur J Clin Nutr, 2005 · checked 2026-09-30
6. itdr-daily-r6-04 · RCT (crossover)
   Dressings contained 8 g (ranch) or 4 g (Italian) of fat per serving. PSE (3.6 g/d) were provided in two servings/d of one of the dressings. Diets with ranch or Italian dressing without and with PSE were fed for 3 wk/diet and crossed over randomly within dressings. Diets were adjusted to similar fat and fatty acid concentrations. Type of salad dressing did not affect plasma lipids, lipoproteins, carotenoids, or fat-soluble vitamins (P > 0.05).
   Lipids, 2002 · checked 2026-09-30
7. itdr-daily-r6-05 · RCT (crossover)
   Consumption of 3.6 g of PSE resulted in further decreases in LDL cholesterol (9.7%) and TG (7.3%) but no additional change in HDL cholesterol. Total plasma carotenoids decreased 9.6% with PSE.
   Lipids, 2002 · checked 2026-09-30
8. itdr-daily-r6-09 · RCT (crossover)
   The antiglycemic properties of vinegar are evident when small amounts of vinegar are ingested with meals composed of complex carbohydrates. In these situations, vinegar attenuated PPG by 20% compared to placebo.
   Ann Nutr Metab, 2010 · checked 2026-09-30
9. itdr-daily-r6-06 · RCT
   Alpha- and trans-beta-carotene levels were reduced in the 9.0 g/day group vs. control (p < 0.05), but all carotenoid values remained within normal ranges throughout the study.
   J Am Coll Nutr, 2001 · checked 2026-09-30
10. itdr-daily-r6-10 · regulatory decision
    POL-HC-6626 Apple cider vinegar Helps control and normalize body weight. Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-6626, snapshot 2026-09-21 · checked 2026-09-30
11. itdr-daily-r6-03 · RCT (dose-response)
    However, the effect varied widely, and some individuals showed a negligible response.
    Am J Clin Nutr, 2017 · checked 2026-09-30
12. itdr-daily-r6-08 · RCT (meal test)
    We conclude that the addition of vinegar reduces postprandial glycaemia in patients with T2D only when it is added to a high-GI meal.
    Eur J Clin Nutr, 2010 · checked 2026-09-30