Shortening in the US: the trans fat is gone, the saturated fat is not

Shortening earned its bad name from trans fat, and the trans fat in the US version has been legally removed. In 2015 the FDA ruled that partially hydrogenated oils are no longer generally recognized as safe, and after June 18, 2018 manufacturers could not add them to most foods. The partially hydrogenated shortenings still listed in the USDA table below describe the product before that ruling. What replaced it is mostly palm. In randomized trials of at least 2 weeks, palm oil raised LDL cholesterol by 12 mg/dL (95% CI 7.7 to 16; metric: 0.31 mmol/L, 0.20 to 0.42) against vegetable oils low in saturated fat. That is palm oil as an ingredient, not shortening as sold. A tablespoon of generic shortening weighs 12 g and carries about 106 calories and 3 g of saturated fat.

The numbers, per 3.5 oz (100 g)

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

How much is actually in it

• USDA lists generic shortening at 884 calories, 24.98 g of saturated fat and 6.13 mg of vitamin E per 3.5 oz (100 g). — national food composition database entry Evidence E source
  Per 100 g: 884 calories, saturated fat 24.98 g, alpha-tocopherol 6.13 mg

What a real portion looks like

• One tablespoon of shortening weighs 12 g and carries about 106 calories and 3 g of saturated fat. — US dietary survey portion Evidence E source
  1 tablespoon 12 g: 106.1 calories, 3.0 g saturated fat; 1 cup 192 g: 1697 calories, 48.0 g saturated fat

What your body absorbs

• In 20 adults, interesterifying a palm stearin and palm kernel fat did not change how a 50 g fat meal was digested or cleared over 8 hours. — 20 healthy adults aged 45-75, 50 g fat test meals, double-blind 3-phase crossover (n = 20) Evidence B source
  No difference between interesterified and non-interesterified fat in postprandial triacylglycerol or [13C]palmitic acid appearance; both gave smaller LDL particles than rapeseed oil

What cooking and storage change

• Heating edible oils below 200 C barely changed their trans fat, but between 200 and 240 C total trans fat rose by 0.38% for every 10 C. — 33 experimental studies on 21 edible oils (n = 33 studies) Evidence D source
  Total TFA +0.38% per 10 C rise (95% CI 0.20 to 0.55) between 200 and 240 C; further rise with prolonged heating

What it does to your health

• Over 6 weeks, palmitic-rich and stearic-rich interesterified hard fats at 10% of energy gave the same total to HDL cholesterol ratio, a difference of 0.05. — 51 healthy adults aged 35-65 (47 completed), fats in muffins and spreads, 6 weeks per arm (n = 47) Evidence B source
  Total:HDL cholesterol ratio mean difference 0.05 (95% CI -0.08 to 0.18); IL-10 -0.14 ng/L with palmitic
• In randomized trials palm oil, the main base of trans-free shortening, raised LDL cholesterol by 12 mg/dL (0.31 mmol/L) compared with oils low in saturated fat. — clinical trials of at least 2 weeks comparing palm oil with other cooking oils Evidence A source
  LDL +9.3 mg/dL (0.24 mmol/L) overall (95% CI 0.13 to 0.35), +0.31 (0.20 to 0.42) in randomized trials; HDL +3.5 mg/dL (0.09 mmol/L) vs trans-fat oils
• Observational data link industrial trans fat, which older partially hydrogenated shortenings carried, with 42% more coronary heart disease, while ruminant trans fat showed no link. — prospective cohort studies, 12,942 to 230,135 participants per trans fat association Evidence C source
  Industrial trans fat: CHD RR 1.42 (95% CI 1.05 to 1.92), CHD mortality 1.18 (1.04 to 1.33); ruminant CHD 0.93 (0.73 to 1.18)

Safety, limits and interactions

• WHO advises adults to keep trans fat below 1% of energy, under 2.2 g a day on 2000 calories, and attributes more than 278,000 deaths a year to industrial trans fat. — adults worldwide Evidence E source
  Limit <1% of energy (<2.2 g/day at 2000 calories); >278,000 deaths/year attributed

What people believe that the data does not support

• Not all trans fat behaves alike: in 10 randomized trials, 1.3-13.2 g a day of dairy trans fat left LDL unchanged and lowered HDL by only 1.9 mg/dL (0.05 mmol/L). — 10 RCTs of TFA-enriched vs regular dairy foods, plus 12 prospective cohorts (n = 10 RCTs) Evidence A source
  No significant difference in lipid biomarkers except HDL-C -1.9 mg/dL (-0.05 mmol/L) (CI -0.10 to -0.00)
• FDA determined in 2015 that partially hydrogenated oils, the old source of trans fat in shortening, are no longer generally recognized as safe, with most uses ending in June 2018. — US food supply Evidence E source
  PHOs not GRAS; compliance June 18, 2018 for most uses, extended to 2020-2021 for some

Who this works differently for

• In pregnancy, higher blood levels of industrial trans-18:1 isomers were linked to preeclampsia and poorer fetal growth, while dietary questionnaires showed no consistent link. — 13 studies in pregnant women: 11 observational, 2 randomized (n = 13 studies) Evidence C source
  Consistent association for biomarker-measured industrial trans-18:1 with preeclampsia and reduced fetal growth indicators; no pooled size in the abstract
• In children and adolescents, advice to cut saturated fat lowered LDL cholesterol by 5 mg/dL (0.13 mmol/L) with no sign of harm to growth. — free-living children and young people aged 2 to 19 in RCTs of at least 13 days and cohorts Evidence A source
  LDL MD -5 mg/dL (95% CI -8.5 to -1.2; metric: -0.13 mmol/L, -0.22 to -0.03); total cholesterol -6.2 mg/dL (-0.16 mmol/L); no adverse effects on growth

What is still unknown

• A review of 233 studies found 87 raw materials used to replace industrial trans fats, mostly palm stearin via interesterification, mainly in margarine and shortenings, with limited knowledge of their long-term health effects. — 233 studies (152 original, 81 reviews) on trans fat substitutes in packaged foods (n = 233 studies) Evidence C source
  87 substitute raw materials; interesterification in 46% of studies; at least 690 ingredient-list terms

The bottom line

The old risk was real and specific. Cohort studies link industrial trans fat with 42% more coronary heart disease (RR 1.42, 95% CI 1.05 to 1.92), and trans fat from dairy and meat showed no such link. In 10 randomized trials, 1.3 to 13.2 g a day of dairy trans fat left every lipid marker unchanged except HDL, which fell by 1.9 mg/dL (0.05 mmol/L). The problem was the factory kind. The newer hard fats are less studied. A review of 233 studies counted 87 raw materials used as replacements, mostly palm stearin that is interesterified, mainly in margarine and shortening. In 20 adults, interesterifying a palm fat did not change how a 50 g fat meal was digested over 8 hours. In 47 adults over 6 weeks, a palmitic-rich and a stearic-rich interesterified fat gave the same total to HDL cholesterol ratio, a difference of 0.05. That trial compared two hard fats with each other, and its authors did not look at longer-term effects. Very hot frying adds a little trans fat back. In laboratory heating of 21 oils, trans fat barely moved below 200 C and rose by 0.38% for every 10 C between 200 and 240 C. Those were oils, not shortening. Who should be careful. WHO advises adults to keep trans fat below 1% of energy, under 2.2 g a day on 2000 calories, and attributes more than 278,000 deaths a year to the industrial kind by modeling. In pregnant women, higher blood levels of industrial trans fat isomers were linked to preeclampsia and poorer fetal growth across 13 mostly observational studies, with no pooled size given. For children, the evidence is about saturated fat in general. In trials in ages 2 to 19, advice to eat less of it lowered LDL by 5 mg/dL (0.13 mmol/L).

Sources

1. shrt-r4-01 · national food composition dataset
   FNDDS 2710167 Shortening, NS as to vegetable or animal (81203000, Margarine): Energy 884 KCAL/100 g · Fatty acids, total saturated 24.98 G · Vitamin E (alpha-tocopherol) 6.13 MG
   USDA FNDDS 2021-2023 (FoodData Central), Shortening, NS as to vegetable or animal, food code 81203000, fdc_id 2710167 · checked 2026-09-29
2. shrt-r4-02 · national food composition dataset
   FNDDS 2710167 Shortening, NS: 1 tablespoon 12 g · 1 cup 192 g · Energy 106.1 KCAL/tbsp · Fatty acids, total saturated 3.0 G/tbsp
   USDA FNDDS 2021-2023 (FoodData Central), Shortening, NS as to vegetable or animal, food code 81203000, fdc_id 2710167 · checked 2026-09-29
3. shrt-r4-03 · randomized crossover trial
   Interesterification did not modify fat digestion, postprandial lipemia, or lipid metabolism measured by stable isotope and DGM analysis.
   Am J Clin Nutr, 2021 · checked 2026-09-29
4. shrt-r4-07 · meta-analysis of laboratory studies
   Overall, heating to temperatures <200 °C had no appreciable impact on different TFA levels. Between 200 and 240 °C, levels of C18:2 t (0.05% increase per 10 °C rise in temperature, 95% CI: 0.02 to 0.05%), C18:3t (0.18%, 95% CI: 0.14 to 0.21%), and total TFA (0.38%, 95% CI: 0.20 to 0.55%) increased with temperature.
   Nutrients, 2022 · checked 2026-09-29
5. shrt-r4-04 · randomized crossover trial
   No significant differences were observed in total:HDL cholesterol ratio between interventions (stearic compared with palmitic mean difference: 0.05; 95% confidence interval [CI]: -0.08, 0.18).
   Am J Clin Nutr, 2025 · checked 2026-09-29
6. shrt-r4-05 · meta-analysis of RCTs
   This effect was observed in randomized trials (0.31 mmol/L; 95% CI: 0.20, 0.42 mmol/L) but not in nonrandomized trials (0.03 mmol/L; 95% CI: -0.15, 0.20 mmol/L; P-difference = 0.02).
   J Nutr, 2015 · checked 2026-09-29
7. shrt-r4-06 · meta-analysis of observational studies
   Industrial, but not ruminant, trans fats were associated with CHD mortality (1.18 (1.04 to 1.33) v 1.01 (0.71 to 1.43)) and CHD (1.42 (1.05 to 1.92) v 0.93 (0.73 to 1.18)).
   BMJ, 2015 · checked 2026-09-29
8. shrt-r4-12 · agency position
   WHO's recommendation for adults is to limit consumption of trans fat to less than 1% of total energy intake, which is less than 2.2 g per day for a 2000-calorie diet. ... More than 278 000 deaths each year globally can be attributed to intake of industrially produced trans fat.
   WHO, Trans fat fact sheet · checked 2026-09-29
9. shrt-r4-09 · meta-analysis of RCTs
   Among 10 RCTs, there were no significant differences in mean difference for any lipid biomarkers except for a slight decrease in HDL-C (mean difference: -0.05 mmol/L; confidence interval: -0.10 to -0.00) for TFA-enriched vs. regular dairy foods.
   Nutr Res, 2026 · checked 2026-09-29
10. shrt-r4-11 · agency position
    In 2015, FDA released its final determination that Partially Hydrogenated Oils (PHOs) are not Generally Recognized as Safe (GRAS). ... For the majority of uses of PHOs, June 18, 2018, remains the date after which manufacturers cannot add PHOs to foods.
    FDA, Final Determination Regarding Partially Hydrogenated Oils (Removing Trans Fat) · checked 2026-09-29
11. shrt-r4-08 · systematic review of observational studies
    Biomarker-based studies consistently showed that higher proportions of these isomers were associated with increased preeclampsia risk and reduced fetal growth indicators. In contrast, dietary intake studies showed no consistent associations, likely due to their limited capacity to distinguish iTFAs from ruminant TFAs.
    Nutr Res, 2026 · checked 2026-09-29
12. shrt-r4-10 · meta-analysis of RCTs
    Compared with control diets, there was a highly statistically significant effect of reduced SFA intake on total cholesterol (mean difference (MD) -0.16 mmol/l, [95% confidence interval (CI): -0.25 to -0.07]), LDL cholesterol (MD -0.13 mmol/l [95% CI:-0.22 to -0.03]) and diastolic blood pressure (MD -1.45 mmol/l [95% CI:-2.34 to -0.56]).
    PLoS One, 2017 · checked 2026-09-29
13. shrt-r4-13 · scoping review
    A total of 87 different raw materials were cited as trans fats substitutes in the selected studies, with palm stearin being the most frequent. The processing methods were categorized in 8 groups, with interesterification being the most cited (46% of studies). Food items belonging to 15 food groups were found to contain trans fats substitutes, mainly margarine, shortenings, and spreads.
    Nutr Rev, 2025 · checked 2026-09-29