Salad dressing: the fat is what gets the salad into you

Fat-free dressing makes a salad cheaper in calories and poorer in what you absorb from it. In 7 adults eating salads of spinach, romaine, cherry tomatoes and carrots, the appearance of alpha-carotene, beta-carotene and lycopene in chylomicrons was negligible with fat-free dressing, higher with 6 g of canola oil, P < 0.04, and higher again with 28 g, P < 0.02. A dose-response version in 12 women went further. Absorption of every carotenoid and fat-soluble vitamin measured was highest with 32 g of soybean oil, P < 0.002, and the rise was linear from 0 to 32 g for alpha-carotene, lycopene, phylloquinone and retinyl palmitate. Both studies used single meals, and carotenoids in chylomicrons are a short-term absorption marker rather than a health outcome. The spread between people was wide enough that some of those 12 women showed a negligible response even at 32 g of oil, and that is the part nobody has explained.

The numbers, per 100 g

How much is actually in it

• Swapping the base oil of 20 g of daily mayonnaise from palm olein to soybean lowered total cholesterol by 0.25 mmol/L in 34 adults, and lowered HDL by 0.12 at the same time. — 34 healthy Malaysians (16 men, 18 women, mean age 23), 4 weeks per arm with a 2-week washout (n = 34) Evidence B source
  Total cholesterol -0.25 mmol/L (P = 0.001), LDL -0.17 mmol/L (P = 0.016) and HDL -0.12 mmol/L (P < 0.001) on soybean against palm olein, with the LDL to HDL ratio unchanged
• Swapping the dressings, oils and mayonnaise of a military canteen for lower omega-6 versions raised diners' omega-3 index from 2.95 to 3.66 in eight weeks without them noticing a loss of taste. — 77 diners in a military dining facility choosing freely from conventional or reformulated foods, 8 weeks (n = 77) Evidence C source
  Omega-3 index 3.66 plus or minus 0.71 against 2.95 plus or minus 0.77 (p < 0.05); total omega-6 10.1 against 15.3 micrograms per mL; EPA 5.0 against 4.05 micrograms per mL

What a real portion looks like

• When 5004 women were coached to cut fat, added fats such as dressings, butter and oils gave up 9.1 g a day, more than meats at 4.6 g and desserts at 3.9 g. — 5004 intervention and 7426 control postmenopausal women in the Women's Health Initiative low-fat trial, 1 year (n = 12430) Evidence B source
  Total fat down 24.3 g/day against controls in year 1, of which added fats 9.1 g/day, meats 4.6 g/day and desserts 3.9 g/day; added fats were 25% of baseline fat intake

What your body absorbs

• Salad eaten with fat-free dressing put essentially no carotenoids into the blood of 7 adults, while 6 g and then 28 g of canola oil in the dressing raised absorption step by step. — 7 adults, three salads of spinach, romaine, cherry tomatoes and carrots with 0, 6 or 28 g canola oil, washout of at least 2 weeks (n = 7) Evidence B source
  Alpha-carotene, beta-carotene and lycopene in chylomicrons negligible with fat-free dressing; higher with reduced-fat (P < 0.04) and higher again with full-fat (P < 0.02)
• Beta-carotene given in salad dressing oil was absorbed at 30% against 16% from a diet of carotene-rich vegetables and fruits, measured by faecal balance in 17 people with an ileostomy. — 17 healthy adults with an ileostomy, two 2-week diets in crossover (n = 17) Evidence C source
  Apparent beta-carotene absorption 30% on the oil diet against 16% on the mixed diet, a 1.9-fold difference; vitamin A equivalency of beta-carotene in oil 3.6 to 1 (95% CI 2.8 to 4.6)

What it does to your health

• In a dietary index built to predict lower blood urate, salad dressing ranked among the foods pushing urate up, and people scoring high on the index had roughly half the gout risk. — Nurses' Health Study and Health Professionals Follow-up Study with replication in NHANES and UK Biobank Evidence C source
  Hazard ratio for gout comparing extreme quintiles 0.48 (95% CI 0.42 to 0.55) in NHS and HPFS and 0.65 (0.48 to 0.88) in UK Biobank; salad dressing listed among positive predictors of urate

Safety, limits and interactions

• Plant sterol esters delivered in salad dressing, 3.6 g a day, lowered LDL cholesterol another 9.7% in 53 adults and lowered total plasma carotenoids by 9.6% at the same time. — 26 men and 27 women with mild hypercholesterolaemia on controlled isocaloric diets, 3 weeks per diet in crossover (n = 53) Evidence B source
  LDL cholesterol down a further 9.7% and triglycerides 7.3% with 3.6 g/day sterol esters; total plasma carotenoids down 9.6%, with beta-carotene, alpha-carotene and beta-cryptoxanthin all falling
• Up to 9 g a day of phytosterol esters eaten in reduced-fat spread and salad dressing for 8 weeks caused no adverse effects in 84 adults, though carotene levels fell at the highest dose. — 84 free-living men and women in four parallel arms at 0, 3, 6 or 9 g/day of phytosterol esters, 8 weeks (n = 84) Evidence B source
  No difference in side effects or laboratory values; alpha- and trans-beta-carotene reduced in the 9 g/day arm (p < 0.05) while staying within normal ranges; campesterol up in all treated arms (p < 0.001)
• A dressing carrying 2 g of spirulina powder daily for 8 weeks lowered systolic and diastolic blood pressure in 41 people with hypertension, while the placebo dressing moved nothing. — 48 patients with hypertension enrolled, 41 completed, 8 weeks alongside standard antihypertensive drugs (n = 48 enrolled, 41 completed) Evidence B source
  Systolic blood pressure p = 0.02, diastolic p = 0.03, triglycerides p = 0.01, plus total and LDL cholesterol reductions, against non-significant changes on placebo; total antioxidant capacity and hs-CRP unchanged in both arms

What people believe that the data does not support

• The plant sterol heart health claim waives the usual disqualifying level for total fat per 50 g in dressings for salad and in spreads, so a dressing can carry the claim despite its fat. — United States food labelling, 21 CFR 101.83 plant sterol and stanol ester health claim Evidence E source
  The general health claim requirements of 101.14 apply except the disqualifying level for total fat per 50 g in dressings for salad and spreads, and except 101.14(e)(6) for dressings for salad

Who this works differently for

• Preschoolers genetically sensitive to bitterness ate 80% more raw broccoli when dressing came with it, and the size of the effect differed with whether the dressing was regular or light and served as a dip or a sauce. — 152 mostly Hispanic preschoolers in Head Start classrooms, broccoli offered twice weekly for 7 weeks (n = 152) Evidence C source
  Bitter-sensitive children ate 80% more broccoli with dressing than plain (P < 0.001); no effect among bitter-insensitive children; liking rose in all groups regardless of dip
• Of two maternal eating patterns tracked to age four, the fried food one raised the odds of a child being overweight by 31%, while the pattern that contained salad dressing showed no association at all. — 1257 mother and child pairs in the CANDLE study, maternal diet in the second trimester, growth tracked from birth to age four (n = 1257) Evidence C source
  Fast food pattern odds ratio 1.32 (1.07 to 1.62) for a rising-high BMI trajectory and 1.31 (1.11 to 1.54) for overweight at four, odds rather than risk; processed food pattern including salad dressing not associated

What is still unknown

• Absorption of every carotenoid and fat-soluble vitamin from a salad was highest at 32 g of soybean oil in the dressing, yet some of the 12 women absorbed almost nothing at that dose. — 12 women, each eating 5 salads with dressings containing 0, 2, 4, 8 or 32 g soybean oil (n = 12) Evidence B source
  Chylomicron area under curve highest with 32 g oil (P < 0.002); linear over 0 to 32 g for alpha-carotene, lycopene, phylloquinone and retinyl palmitate; response varied widely between individuals

The bottom line

How much fat and which fat are separate questions. In 17 healthy adults with an ileostomy, beta-carotene from salad dressing oil was absorbed at 30% against 16% from a diet of carotene-rich vegetables and fruits, a 1.9-fold difference, though the two diets differed in beta-carotene dose as well as in matrix. Swapping the base oil of 20 g of daily mayonnaise from palm olein to soybean lowered total cholesterol by 0.25 mmol/L, P = 0.001, and LDL by 0.17 mmol/L, P = 0.016, in 34 healthy Malaysians of mean age 23 over four weeks per arm. HDL fell 0.12 mmol/L at the same time, P < 0.001, and the LDL to HDL ratio did not move, which is the honest way to state that result. In a military dining facility, reformulating the dressings, oils and mayonnaise to lower omega-6 raised the omega-3 index of 77 diners from 2.95 to 3.66 over eight weeks, p < 0.05. Those diners chose their own food and were not randomised, several foods changed at once, and 3.66 is still low against the usual targets. Dressing is also where plant sterols get sold, and their cost is measured in the same trials. Plant sterol esters at 3.6 g a day in salad dressing lowered LDL cholesterol a further 9.7% and triglycerides 7.3% in 53 adults with mild hypercholesterolaemia on controlled isocaloric diets, three weeks per arm, and lowered total plasma carotenoids by 9.6% at the same time. Up to 9 g a day of phytosterol esters in reduced-fat spread and salad dressing for eight weeks produced no difference in side effects or laboratory values across 84 free-living adults. Alpha- and trans-beta-carotene fell in the 9 g arm, p < 0.05, while every carotenoid value stayed inside the normal range. Those two trials are the whole of what this page holds on limits, and eight weeks in about 20 people per arm reads on tolerability rather than on long-term safety. Neither sterol trial included children or pregnant women, no study here was designed to test an interaction with a medicine, and nothing here says what storage or heat does to a dressing. What dressing does to behaviour is better documented than what it does to blood. Among 152 mostly Hispanic preschoolers offered raw broccoli twice a week for seven weeks, the children who were genetically sensitive to bitterness ate 80% more broccoli when dressing came with it than when it was served plain, P < 0.001. No such effect appeared among the bitter-insensitive children. Classrooms rather than children were assigned to condition, the authors call the design quasi-experimental, and 70% of this group were bitter-sensitive, which is higher than in many populations. On the other side of the ledger, when 5004 postmenopausal women were coached to cut fat, added fats such as butter, oils and salad dressings gave up 9.1 g a day. That beat meats at 4.6 g and desserts at 3.9 g, out of a total fat reduction of 24.3 g a day against controls. That came from food frequency questionnaires, which understate fat. Three findings get quoted in both directions, so read them slowly. A dressing carrying 2 g of spirulina powder a day for eight weeks lowered systolic blood pressure, p = 0.02, and diastolic, p = 0.03, in 41 people with hypertension who completed the trial alongside their usual antihypertensive drugs. The placebo dressing changed nothing significantly. Those are within-group p values rather than a between-group effect size, which makes the contrast look sharper than it is. In a dietary index built to predict lower blood urate, salad dressing sits among the twelve foods ranked as positive predictors of urate. People in the top fifth of that index had a hazard ratio for gout of 0.48 (0.42 to 0.55), and that number belongs to the whole index rather than to dressing. In 1257 mother and child pairs, the maternal eating pattern that contained salad dressing showed no association with a child having overweight at four, while the fried food pattern raised those odds 31%, odds rather than risk. A null for a pattern is no evidence that dressing protects. One last sign of what this food is: the plant sterol health claim in 21 CFR 101.83 waives the disqualifying level for total fat per 50 g for dressings for salad and spreads, so that a dressing can carry the claim at all.

Sources

1. sldr-daily-r1-06 · randomised crossover trial
   Treatments resulted in significant reductions in TC (diff = -0.25 mmol/L; P = 0.001), LDL-C (diff = -0.17 mmol/L; P = 0.016) and HDL-C (diff = -0.12 mmol/L; P < 0.001) in SB-mayo compared to PO-mayo without affecting LDL-C:HDL-C ratio (P > 0.05).
   Lipids Health Dis, 2016 · checked 2026-09-24
2. sldr-daily-r1-12 · prospective parallel-arm study
   The intervention group achieved a higher omega-3 index score (3.66 ± 0.71 vs. 2.95 ± 0.77; p < 0.05), lower total n-6 (10.1 ± 4.6 vs. 15.3 ± 6.7 µg/mL; p < 0.05), and higher serum concentration of EPA (5.0 ± 1.31 vs. 4.05 ± 1.56 µg/mL; p < 0.05) vs. controls.
   Nutrients, 2022 · checked 2026-09-24
3. sldr-daily-r1-09 · randomised controlled trial
   At baseline, the major sources of fat were added fats, such as butter, oils, and salad dressings (25%); meats (21%); and desserts (13%)...Reductions came primarily from added fats (9.1 g/day), meats (4.6 g/day), and desserts (3.9 g/day).
   J Am Diet Assoc, 2003 · checked 2026-09-24
4. sldr-daily-r1-01 · randomised crossover trial
   After ingestion of the salads with fat-free salad dressing, the appearance of alpha-carotene, beta-carotene, and lycopene in chylomicrons was negligible...Essentially no absorption of carotenoids was observed when salads with fat-free salad dressing were consumed.
   Am J Clin Nutr, 2004 · checked 2026-09-24
5. sldr-daily-r1-03 · controlled clinical trial
   The apparent absorption of (labelled and dietary) beta-carotene from the 'oil diet' (30 %) was 1.9-fold higher than from the 'mixed diet' (16 %).
   Br J Nutr, 2010 · checked 2026-09-24
6. sldr-daily-r1-10 · prospective cohort study
   The EDINU positively ranks low-fat milk, blueberries, grapes, and cheese as negative predictors of urate and negatively ranks mixed vegetables, liquor, red meat, liver, artificially sweetened beverages, tomato products, wine, and salad dressing as positive predictors.
   Am J Clin Nutr, 2025 · checked 2026-09-24
7. sldr-daily-r1-04 · randomised controlled trial
   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 2026-09-24
8. sldr-daily-r1-05 · randomised controlled trial
   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 2026-09-24
9. sldr-daily-r1-07 · randomised controlled trial
   We observed that the consumption of spirulina dressing significantly reduced systolic blood pressure (p = .02), diastolic blood pressure (p = .03), serum triglyceride (p = .01), total cholesterol, and low-density lipoprotein (LDL) levels, compared to nonsignificant changes in the placebo group.
   Phytother Res, 2021 · checked 2026-09-24
10. sldr-daily-r1-13 · regulation
    All requirements set forth in § 101.14 shall be met, except § 101.14(a)(4) with respect to the disqualifying level for total fat per 50 grams (g) in dressings for salad and spreads and § 101.14(e)(6) with respect to dressings for salad.
    21 CFR 101.83, health claims: plant sterol/stanol esters and risk of coronary heart disease · checked 2026-09-24
11. sldr-daily-r1-08 · quasi-experimental classroom study
    Bitter-sensitive children, however, ate 80% more broccoli with dressing than when served plain (P<0.001); effects did vary based on whether regular or light dressing was provided as a dip or sauce.
    J Acad Nutr Diet, 2012 · checked 2026-09-24
12. sldr-daily-r1-11 · prospective cohort study
    Women with greater adherence to the fast food pattern were more likely to have children in the rising-high BMI trajectory group [OR (95% CI) = 1.32 (1.07-1.62); p = 0.008] or having overweight/obesity at age four [OR (95% CI) = 1.31 (1.11-1.54); p = 0.001]. The processed food pattern was not associated with these outcomes.
    Nutrients, 2020 · checked 2026-09-24
13. sldr-daily-r1-02 · randomised dose-response trial
    Absorption of all carotenoids and fat-soluble vitamins was highest with 32 g oil (P < 0.002)...However, the effect varied widely, and some individuals showed a negligible response.
    Am J Clin Nutr, 2017 · checked 2026-09-24