Flaxseed oil or olive oil: different fats, no blood pressure effect

Against a control, neither oil taken as a supplement has shown an effect on blood pressure. A meta-analysis of 17 randomized trials found no change in systolic pressure, a mean difference of -0.48 mmHg with a 95% CI of -1.76 to 0.80, and only three of those trials tested flaxseed oil, so for flaxseed the answer is weak. Each oil was compared with a control there, never with the other oil. The two are built very differently. In USDA survey tables flaxseed oil has 53.4 g of the plant omega-3 ALA per 3.5 oz (100 g) against 0.64 g in olive oil, and olive oil has 68.4 g of monounsaturated fat against 18.4 g, one value per oil with no spread. A 14 g tablespoon of flaxseed oil works out at about 7.5 g of ALA, more than twice the 3 g a day tested in the trial that follows. In 56 mostly African-American adults with chronic illness, 3 g of ALA a day from flaxseed oil capsules raised plasma EPA by 60% over 12 weeks, and DHA did not change.

How much is actually in it

• In the USDA survey food table flaxseed oil carries 53.4 g of ALA per 3.5 oz (100 g) against 0.64 g in olive oil, while olive oil carries 68.4 g of monounsaturated fat against 18.4 g in flaxseed oil. — USDA FNDDS survey foods Flaxseed oil food code 82103500 and Olive oil food code 82104000, WWEIA category Salad dressings and vegetable oils Evidence E source
  PUFA 18:3 53.368 vs 0.638 g/100 g, total monounsaturated 18.438 vs 68.42 g/100 g
• The UK composition table gives olive oil 73.0 g of monounsaturated fat and 0.70 g of omega-3 fat per 3.5 oz (100 g), a second figure next to the USDA value. — CoFID 2021 food Oil, olive, code 17-038 Evidence E source
  Monounsaturated 73.00 g/100 g, n-3 polyunsaturated 0.70 g/100 g, saturated 14.30 g/100 g, energy 899 calories

What a real portion looks like

• In the USDA survey food table one tablespoon of either flaxseed or olive oil weighs 14 g, so a tablespoon of flaxseed oil carries about 7.5 g of ALA and about 124 calories. — USDA FNDDS survey foods Flaxseed oil food code 82103500 and Olive oil food code 82104000 Evidence E source
  1 tablespoon 14 g for both oils, flaxseed oil ALA 7.5 g and energy 123.8 calories per tablespoon

What your body absorbs

• In an RCT of 56 adults, 3 g a day of ALA from flaxseed oil raised plasma EPA by 60% in 12 weeks while DHA did not change, and olive oil capsules changed neither. — predominantly African-American adults with chronic illness, 31 on flaxseed oil and 25 on olive oil placebo capsules (n = 56) Evidence B source
  Plasma EPA +60% (24.09 to 38.56 micromol/L), DPA +25%, DHA unchanged, no change with olive oil
• In trials of young women, 14 days of flaxseed oil at about 6 g a day raised plasma ALA, EPA and DPA, while DHA stayed unchanged. — 303 young healthy women randomized across fish oil doses or flaxseed oil 5.90 to 6.60 g/d (n = 303) Evidence B source
  Significant increases in ALA, EPA and DPA (P < 0.01), DHA unchanged
• In a crossover trial of 16 adults, a salad eaten with 0.99 oz (28 g) of olive oil gave 55.2% higher total carotenoid absorption than the same salad with coconut oil. — 16 subjects eating an identical carotenoid-rich salad with each of 4 test fats (n = 16) Evidence B source
  Positive iAUC over 10 h of total carotenoids +55.2%, alpha-carotene +110.8%, lycopene +45.8% with olive oil vs coconut oil

What cooking and storage change

• A systematic review of 23 publications found no support for the belief that frying generally raises cardiovascular risk, and noted a large trial that advised virgin olive oil also for frying. — 23 publications on vegetable oil or fried food consumption and obesity, type 2 diabetes, metabolic syndrome or CVD (n = 23 publications) Evidence C source
  Qualitative synthesis, no pooled estimate

What it does to your health

• In a crossover trial of 37 healthy young adults, 1 tbsp (15 mL) a day of flaxseed oil for 6 weeks gave no difference from the same amount of olive oil in inflammatory markers, glucose or blood lipids. — normal weight, apparently healthy young adults who traditionally use olive oil, 37 completers (n = 37) Evidence B source
  No between-treatment difference in adiponectin, TNF alpha, hs-CRP, glucose or lipid profile
• In a 26 week RCT of 56 adults, 3 g a day of ALA from flaxseed oil did not lower LDL or HDL cholesterol compared with olive oil, and adjusted total cholesterol ended 17 mg/dL (0.45 mmol/L) higher in the flaxseed group. — 56 adults, 31 on flaxseed oil capsules and 25 on olive oil placebo capsules (n = 56) Evidence B source
  Total cholesterol 210 vs 200 mg/dL (5.43 vs 5.17 mmol/L) at 26 weeks (P = 0.026), no difference in LDL, HDL or triglycerides
• A meta-analysis of 51 randomized trials in 4334 adults found olive oil did not change blood glucose overall. — adults in 51 RCTs of different olive oil types (n = 4334) Evidence A source
  Glucose WMD -0.04 mg/dL (95% CI -0.1 to 0.02), HbA1c WMD 0.02% (95% CI -0.01 to 0.06), HOMA-IR improved only at 25 to 50 g a day in dose-response analysis
• A network meta-analysis of 13 trials found virgin olive oils, high or low in phenols, lowered systolic blood pressure by about 3 mmHg compared with refined olive oil. — 611 mainly healthy participants aged 26 to 70 in 13 RCTs of at least 3 weeks (n = 611) Evidence A source
  SBP MD -2.99 to -2.87 mmHg vs refined olive oil, LDL-C MD -5.4 mg/dL (95% CI -11 to -0.39; metric: -0.14 mmol/L, -0.28 to -0.01) high vs low phenolic

What people believe that the data does not support

• The European Union refused the label claim that flaxseed oil or its alpha-linolenic acid promotes heart health. — EU Register on nutrition and health claims, snapshot of 21 September 2026, three refused and no authorized claims under flaxseed oil Evidence E source
  Claim POL-HC-7106 carries the status Non-authorized
• The European Union also refused the label claim that olive oil promotes heart health. — EU Register on nutrition and health claims, snapshot of 21 September 2026, one authorized and eight refused claims under olive oil Evidence E source
  Claim POL-HC-7679 carries the status Non-authorized
• The European Union refused the label claim that flaxseed oil stabilizes moods. — EU Register on nutrition and health claims, snapshot of 21 September 2026 Evidence E source
  Claim POL-HC-7105 carries the status Non-authorized

Who this works differently for

• A systematic review of 45 studies found vegetarian diets raise ALA intake but leave EPA and DHA levels significantly lower, especially in vegans. — vegetarians and vegans in 45 studies, including pregnancy and growth (n = 45 studies) Evidence C source
  Higher LA and ALA intake, significantly reduced EPA and DHA concentrations

What is still unknown

• A meta-analysis of 17 randomized trials found that neither olive oil nor flaxseed oil supplements changed systolic blood pressure, mean difference -0.48 mmHg with a confidence interval crossing zero. — normotensive adults and adults at risk of hypertension, 17 RCTs, 14 on olive oil and 3 on flaxseed oil (n = 17 RCTs) Evidence A source
  SBP MD -0.48 mmHg (95% CI -1.76 to 0.80), DBP MD -0.47 mmHg (95% CI -1.33 to 0.39), CRP, IL6 and TNF alpha not significant

The bottom line

The same 56 adults were followed to 26 weeks. Flaxseed oil capsules did not lower LDL or HDL cholesterol compared with olive oil capsules, and adjusted total cholesterol ended 17 mg/dL (0.45 mmol/L) higher on flaxseed oil. In a small 6 week crossover trial of 37 healthy young adults who usually use olive oil, 1 tbsp (15 mL) a day of flaxseed oil made no difference against the same amount of olive oil in inflammation markers, glucose or blood lipids. In trials of young women, about 6 g a day of flaxseed oil for 14 days raised plasma ALA, EPA and DPA while DHA stayed flat. A systematic review of 45 studies found vegetarian diets raise ALA intake and leave EPA and DHA significantly lower, most of all in vegans, and in the trials above flaxseed oil did not raise DHA either. Olive oil is not one product. A network meta-analysis of 13 trials in 611 mostly healthy people found virgin olive oils lowered systolic pressure by about 3 mmHg compared with refined olive oil, with low to moderate certainty. A meta-analysis of 51 trials in 4334 adults found olive oil did not change blood glucose overall. In a crossover trial of 16 people, a salad eaten with 0.99 oz (28 g) of olive oil gave 55.2% more carotenoid absorption than with coconut oil, and flaxseed oil was not tested. A review of 23 publications found no support for the belief that frying in general raises cardiovascular risk, and we found no data on frying with flaxseed oil. The EU has refused heart health label claims for both oils and a mood claim for flaxseed oil. We found no card on allergy, pregnancy, children or medicines for either oil, so this page has no safety section.

Sources

1. fxoo-r2-11 · reference dataset
   Flaxseed oil | FNDDS 82103500 | fdc_id 2710185 | PUFA 18:3 53.368 g/100 g | Fatty acids, total monounsaturated 18.438 g/100 g || Olive oil | FNDDS 82104000 | fdc_id 2710186 | PUFA 18:3 0.638 g/100 g | Fatty acids, total monounsaturated 68.42 g/100 g
   USDA FNDDS (FoodData Central survey 2024-10-31), food codes 82103500 and 82104000 · checked 2026-10-02
2. fxoo-r2-12 · reference dataset
   Oil, olive | CoFID 17-038 | Mono FA /100g food 73.00 g | n-3 poly /100g food 0.70 g | Satd FA /100g fd 14.30 g | Energy 899 kcal
   CoFID 2021, Public Health England, Oil, olive, code 17-038 (OGL v3.0) · checked 2026-10-02
3. fxoo-r2-13 · reference dataset
   Flaxseed oil | FNDDS 82103500 | fdc_id 2710185 | 1 tablespoon 21000 = 14 g | PUFA 18:3 7.5 g per tablespoon | Energy 123.8 kcal per tablespoon || Olive oil | FNDDS 82104000 | fdc_id 2710186 | 1 tablespoon 21000 = 14 g
   USDA FNDDS (FoodData Central survey 2024-10-31), food codes 82103500 and 82104000 · checked 2026-10-02
4. fxoo-r2-03 · randomized controlled trial
   In a randomized, double-blind trial, 56 participants were given 3 g ALA/d from flaxseed oil capsules (n = 31) or olive oil placebo capsules (n = 25). Plasma EPA levels at 12 wk in the flaxseed oil group increased by 60%, from 24.09 +/- 16.71 to 38.56 +/- 28.92 micromol/L (P = 0.004), whereas no change occurred in the olive oil group. ... Plasma DHA levels did not change in either group.
   J Nutr, 2006 · checked 2026-10-02
5. fxoo-r2-04 · randomized trial
   A total of 303 young women were randomised to intakes ranging between 0.33 and 4.50 g EPA+DHA/day from fish oil (not all doses used in each year) or flaxseed oil (5.90-6.60 g/d) daily for 14 days in a series of trials, over 5 years. ... Flaxseed oil supplementation for 14 day resulted in significant (P < 0.01) increases in ALA, EPA and DPA, whilst DHA remained unchanged.
   Eur J Clin Nutr, 2018 · checked 2026-10-02
6. fxoo-r2-06 · randomized crossover trial
   Sixteen subjects consumed salad with 4 test fats in random order ... Similarly, the positive iAUC1-10h of TC, α-carotene, and lycopene were 55.2%, 110.8%, and 45.8%, respectively, higher with olive oil than with coconut oil.
   Am J Clin Nutr, 2023 · checked 2026-10-02
7. fxoo-r2-09 · systematic review
   we conclude that (1) the myth that frying foods is generally associated with a higher risk of CVD is not supported by the available evidence; (2) virgin olive oil significantly reduces the risk of CVD clinical events, based on the results of a large randomised trial that included as part of the intervention the recommendation to use high amounts of virgin olive oil, also for frying foods
   Br J Nutr, 2015 · checked 2026-10-02
8. fxoo-r2-02 · randomized crossover trial
   Participants were supplied with 15 mL/day of either FO or OO. Each intervention and the wash-out period lasted 6 weeks. ... Thirty seven participants completed the study. No difference between the two interventions was observed in adiponectin, TNF-α, high sensitivity-CRP or glucose levels and lipid profile.
   Metabolism, 2013 · checked 2026-10-02
9. fxoo-r2-05 · randomized controlled trial
   In a randomized double-blind trial, 56 participants were given 3 g/d of ALA from flaxseed oil in capsules (n = 31) or olive oil containing placebo capsules (n = 25) for 26 wk. Changes in plasma HDL cholesterol, LDL cholesterol, and triglyceride concentrations did not differ between the 2 groups at 26 wk. The adjusted plasma total cholesterol concentration at 26 wk was 0.45 mmol/L higher in the flaxseed oil group (5.43 +/- 0.03 mmol/L) compared with the olive oil group (5.17 +/- 0.07 mmol/L) (P = 0.026).
   J Nutr, 2006 · checked 2026-10-02
10. fxoo-r2-07 · meta-analysis of RCTs
    51 trials (n = 4334 participants) were included in the meta-analysis. We found the consumption of olive oil was not associated with statistically significant changes in blood glucose (WMD = -0.04 mg dL-1; 95% CI, -0.1 to 0.02; P = .18; I2 = 27.05%)
    Nutr Rev, 2026 · checked 2026-10-02
11. fxoo-r2-08 · network meta-analysis of RCTs
    Thirteen RCTs (16 reports) with 611 mainly healthy participants (mean age: 26-70 years) were identified. ... Both, HP(E)VOO and LP(E)VOO reduces SBP compared to ROO (range of MD: -2.99 to -2.87 mmHg)
    Nutr Metab Cardiovasc Dis, 2019 · checked 2026-10-02
12. fxoo-r2-14 · regulatory register
    POL-HC-7106 Flaxseed oil/alpha-linoleic acid Promotes heart health Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-7106, snapshot 2026-09-21 · checked 2026-10-02
13. fxoo-r2-15 · regulatory register
    POL-HC-7679 Olive Oil Olive Oil promotes your heart health Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-7679, snapshot 2026-09-21 · checked 2026-10-02
14. fxoo-r2-16 · regulatory register
    POL-HC-7105 Flaxseed oil Stabilises moods. Non-authorised
    EU Register on nutrition and health claims, claim POL-HC-7105, snapshot 2026-09-21 · checked 2026-10-02
15. fxoo-r2-10 · systematic review
    the review found that vegetarian diets increased linoleic acid (C18:2 n-6, LA) and alpha-linolenic acid (C18:3 n-3, ALA) intake but resulted in significantly reduced concentrations of eicosapentaenoic acid (C20:5 n-3, EPA) and docosahexaenoic acid (C22:6 n-3, DHA), particularly in vegan diets.
    Lipids, 2026 · checked 2026-10-02
16. fxoo-r2-01 · meta-analysis of RCTs
    Seventeen RCTs, comprising 14 studies on OO and 3 on FLO, met the inclusion criteria. Meta-analysis using a random-effects model reported no significant effect on SBP n=17 mean difference (MD) -0.48; 95% CI: -1.76, 0.80; p=0.65, I2 =0%) and DBP (n=16, MD -0.47; 95% CI: -1.33, 0.39; p=0.65, I2 =0%)
    Curr Hypertens Rev, 2024 · checked 2026-10-02