In this article
Hydrogenated fat is the fat that made margarine spreadable, shortening solid and fried food crisp — and it is also the only food ingredient with a death toll attached to it by the World Health Organization. Partial hydrogenation turns liquid vegetable oil into a solid fat, but it also creates trans fat: on average, a quarter to nearly half of a partially hydrogenated oil is trans fat. In a landmark 1990 feeding trial, swapping in trans fat raised LDL cholesterol and lowered HDL cholesterol at the same time — a double hit no other fat delivers — and pooled cohort data put coronary heart disease risk about 23 percent higher for each 2 percent of energy from trans fat. The WHO attributes more than 278,000 deaths a year to industrially produced trans fat and wants intake below 1 percent of energy. The response has been unusually decisive for a food ingredient: Denmark limited it in 2003, the United States removed its generally-recognised-as-safe status in 2015, Canada banned it in 2018 and the European Union capped it in 2019. This article lays out what hydrogenation is, what the trials actually show, what each regulator did, the honest arguments on both sides — and how to spot what is left on a label.
What hydrogenated fats are
Hydrogenation adds hydrogen to the unsaturated fatty-acid chains of a liquid oil — usually a vegetable oil, with a nickel catalyst, heat and pressure — turning it into a more solid, shelf-stable fat. Partial hydrogenation stops part-way, and some remaining double bonds flip from the natural cis configuration to the trans configuration: that is how industrial trans fat is created. The US Food and Drug Administration defines partially hydrogenated oils as fats "that have been hydrogenated, but not to complete or near complete saturation, and with an iodine value greater than 4". On average, the World Health Organization says, trans fat makes up 25 to 45 percent of a partially hydrogenated oil — roughly a third of it is trans fat.
There are two kinds. Industrial trans fat comes from partial hydrogenation; its dominant form is elaidic acid. Ruminant trans fat is made by bacteria in the stomachs of cows, sheep and goats and occurs naturally in meat and dairy; its dominant form is trans-vaccenic acid. The WHO's fact sheet states that both are "equally harmful" — a position the observational literature sits uneasily with, as the debate section explains. Frying oil at high temperature also creates trans fat, but only up to 2 to 3 percent, against the 25 to 45 percent in a partially hydrogenated oil.
The label trap is the word "hydrogenated" on its own. It does not say whether the oil is partially or fully hydrogenated. Full hydrogenation saturates essentially all the double bonds, leaving no trans molecules — the result is a hard, waxy, stearic-acid-rich saturated fat. Fully hydrogenated oils are therefore not a source of trans fat, though they are almost entirely saturated fat, and they remain legal and in use, for example as the hard stock in some peanut butters. The words that mean trans fat is present are "partially hydrogenated oil".
Why manufacturers use them
Manufacturers reached for partially hydrogenated oils for practical reasons: a liquid oil that is solid at room temperature gives margarine its spread, pastry its flake, and biscuits their crisp texture; it keeps for months without going rancid, and it stands up to repeated frying. For most of the twentieth century it was also cheap — the solid fat that let a bakery or a fast-food kitchen work at scale without butter or lard.
But the story since then runs the other way. Once trans fat had to be declared on American labels in 2006, the industry moved fast: the Grocery Manufacturers Association said in 2015 that food companies had already voluntarily lowered the amount of trans fat added to food by more than 86 percent, and FDA figures quoted in the trade press put the fall in US trans-fat consumption at about 78 percent between 2003 and 2012. The industry says that proves voluntary reformulation was working; the regulators say it proves labelling and the prospect of regulation were working.
Where you will find them
- Margarine and vegetable shortening — the solid fats that replaced butter and lard in baking and factory recipes
- Vanaspati ghee — the hydrogenated vegetable ghee used widely in South Asian cooking, and one of the largest remaining sources of industrial trans fat
- Fried foods — fast-food frying and fried street and restaurant food, where partially hydrogenated frying fats were the workhorse oil
- Baked goods such as crackers, biscuits and pies — where a solid fat gives flake and shelf life, along with popcorn, frostings, doughnuts and snack cakes
- Imported products and small producers — in regulated countries, the remaining exposure is concentrated in imported food and food-service settings
- Meat and dairy — the ruminant kind: naturally occurring trans fat in beef, lamb, milk and cheese, which no jurisdiction bans
A Polish market study that checked 1,224 products before the European Union's cap took effect found partially hydrogenated oils listed on 6.9 percent of them in 2017–2019. In the United States and Canada, where the ingredient itself was removed from the food supply, mainstream packaged foods no longer list it at all. What remains is the geography of inaction: the WHO's main sources — margarine, vegetable shortening, Vanaspati ghee, fried foods, and baked goods such as crackers, biscuits and pies — are foods from countries without a best-practice policy, plus the street and restaurant food that escapes even a good policy.
Related: High Fructose Corn Syrup: The Corn Sweetener Behind the 'Worse Than Sugar' Debate — another ingredient whose argument turns on a small chemical difference and a large dose, and whose regulators reached the opposite conclusion.
The concern: LDL up, HDL down
The case against trans fat rests on a feeding trial that has never really been overturned. In 1990, Mensink and Katan fed 59 healthy volunteers three diets identical except that 10 percent of energy came from oleic acid, from trans isomers of oleic acid, or from saturated fat, each for three weeks. Against the oleic-acid diet, the trans-fat diet raised LDL cholesterol by 0.37 mmol/L (14 mg/dL) and lowered HDL cholesterol by 0.17 mmol/L (7 mg/dL); saturated fat raised LDL by a similar amount (0.47 mmol/L) but left HDL unchanged. The authors concluded that "the effect of trans fatty acids on the serum lipoprotein profile is at least as unfavorable as that of the cholesterol-raising saturated fatty acids, because they not only raise LDL cholesterol levels but also lower HDL cholesterol levels." That is the double hit. A Harvard review put the LDL-to-HDL ratio at 2.58 on the trans diet, against 2.34 on saturated fat and 2.02 on oleic acid — the ratio wording is from the Harvard review, not the 1990 paper.
The cohort data say the cholesterol effect turns into real heart disease. Mozaffarian and colleagues pooled the prospective studies in 2006 and found a 2 percent increase in energy from trans fat associated with a 23 percent increase in coronary heart disease (pooled relative risk 1.23), with effects visible even at intakes of about 3 percent of energy. A 2009 review by the same group put the increase at 24, 20, 27 and 32 percent per 2 percent of energy, depending on whether trans fat replaced carbohydrate, saturated fat, cis-monounsaturated fat or cis-polyunsaturated fat. The largest pooling, de Souza and colleagues in 2015, found total trans fat associated with all-cause mortality (1.34), coronary heart disease mortality (1.28) and total coronary heart disease (1.21) — but not ischaemic stroke (1.07) or type 2 diabetes (1.10) — with moderate certainty for the heart outcomes and very low to low certainty for the others.
Inflammation markers move the same way: the 2009 review found higher TNF-alpha activity, interleukin-6 and C-reactive protein among the most consistently seen effects in trials and observational studies — support for the heart-disease mechanism, not proof of a separate disease endpoint, and no solid review links trans fat to cancer, dementia or other outcomes. Diabetes is a plausible but unproven endpoint: the Nurses' Health Study found a 2 percent increase in energy from trans fat associated with a 39 percent higher risk of type 2 diabetes over 14 years (relative risk 1.39), but the pooled analysis in de Souza 2015 found no significant association, and a 2012 meta-analysis of seven randomised trials found no significant effect on glucose or insulin. There is no safe threshold. Feeding trials show a linear dose-response with no kink, which is why the WHO recommends keeping intake below 1 percent of total energy — less than 2.2 grams a day on a 2,000-calorie diet. One honest caveat: the cohort data are dominated by intakes well above today's post-reformulation levels in regulated markets, so the risk at current low intakes is extrapolated, not directly measured.
What regulators say
Denmark was first: its Nutrition Council proposed limits in 2001, and a law limiting industrially produced trans fat was passed in 2003 and took effect in 2004 — the first national limit in the world. The WHO's commentary notes a decrease in mortality from heart disease in Denmark after the regulation came in.
The United States took the longest road. Trans fat had to be declared on Nutrition Facts labels from 1 January 2006, under a final rule of 11 July 2003. In November 2013 the FDA tentatively determined that partially hydrogenated oils are not generally recognised as safe; in June 2015 it made that determination final (80 FR 34650). That did not itself ban trans fat — it removed the oils' safe status, so any use needed pre-market food-additive approval. The compliance date was 18 June 2018, then extended to 1 January 2020 for non-petitioned uses and 18 June 2019 for petitioned uses. The clean-up came in August 2023, with a direct final rule (88 FR 53764) removing partially hydrogenated oils from the standards of identity for peanut butter and canned tuna, revising the safe-status affirmations for menhaden and low-erucic-acid rapeseed oils, deleting the hydrogenated fish oil affirmation, and revoking the pre-1958 authorisations for margarine, shortening and bread, rolls and buns, on the grounds that these uses "may be injurious to health". It took effect on 22 December 2023. The 2015 determination did not change the labelling rules.
The World Health Organization went global. In May 2018 it launched REPLACE, a six-step package to eliminate industrially produced trans fat by 2023 — review sources, promote healthier replacements, legislate, assess and monitor, create awareness, enforce compliance. The 2023 target was not met, by the WHO's own account: its June 2024 milestone report found 53 countries with best-practice policies, covering 3.7 billion people — 46 percent of the world's population, up from 6 percent in 2018 — and estimated those policies could save about 183,000 lives a year. In January 2024 the WHO certified the first five countries — Denmark, Lithuania, Poland, Saudi Arabia and Thailand — and proposed a revised target of virtual elimination by 2025. Whether that target was met has not been reported in the research for this article, and more than 4 billion people remain unprotected. The WHO's two best-practice options are a mandatory limit of 2 grams of industrially produced trans fat per 100 grams of total fat, or a mandatory ban on partially hydrogenated oils.
The European Union chose the cap: Regulation (EU) 2019/649 of 24 April 2019 says trans fat, other than that naturally occurring in animal fat, "shall not exceed 2 grams per 100 grams of fat", with non-complying food allowed on the market until 1 April 2021. Canada chose the ban: on 17 September 2018 it became illegal to add partially hydrogenated oils to foods sold in Canada, including imports and food-service food, with a two-year phase-in for products made before that date. Australia and New Zealand have neither: under Standard 1.2.8 of the Food Standards Code, declaring trans fat is voluntary, but mandatory when a claim is made about cholesterol or fatty acids. The George Institute's submission to a 2023 consultation found 38 percent of Australian packaged products that quantify trans fat exceed the WHO's 2 percent limit, and about 3,660 products (13 percent) may contain hidden industrially produced trans fat; the outcome of that consultation was not verified in the research for this article. The United Kingdom kept the same 2-gram limit as retained EU law.
The debate
The case that the ban was the right call
Trans fat is the only fat that raises LDL and lowers HDL at the same time, the pooled cohort data put coronary heart disease about 23 percent higher for each 2 percent of energy from trans fat, with no threshold, and the WHO attributes more than 278,000 deaths a year to it. The ruminant objection does not rescue the ingredient: in the strongest feeding trial on the question, Gebauer and colleagues found vaccenic acid — the main ruminant trans fat — raised LDL just like industrial trans fat at the same 3.3 percent of energy, and a 2010 quantitative review concluded that all trans-configured fatty acids raise the LDL-to-HDL ratio. The observational null for ruminant trans fat is a dose artefact — people eat far less of it — not evidence that the molecule is benign. And the replacement objection is not a reason to keep a known harm: imperfect substitutes are an argument for studying the substitutes, not for leaving trans fat in the food supply while the studies run.
The case that intakes were already low, and the ban went too far
The American Bakers Association told the FDA in March 2014 that voluntary efforts had produced "extremely low levels of industrially produced trans fat in finished foods — lower than the levels presented by FDA", and that a full ban "goes too far", proposing instead to tighten the rounding rule from 0.5 grams to 0.2 grams per serving. The Grocery Manufacturers Association said food companies had already cut the trans fat added to food by more than 86 percent. The Mercatus Center, a free-market think-tank rather than a scientific body, made the sharper point: after labelling, consumption had fallen about 80 percent, and "at the previous levels, there was pretty good evidence that consumption of trans fatty acids at high levels (4 grams) was associated with heart disease. But what about current consumption at lower levels? The evidence is missing." Add the ruminant data — de Souza 2015 found industrial trans fat associated with total coronary heart disease at 1.42, against 0.93 for ruminant — and the replacement data: in Sundram's 2007 trial, the interesterified fat that replaced trans fat raised fasting glucose by almost 20 percent and cut fasting insulin by 22 percent. Ban the known fat, the argument runs, and you may simply be swapping in an unknown one.
The position this site takes follows the size of the evidence, not either slogan. The strongest case for the bans is the dose-response: the harm is measured in feeding trials, it rises with intake, and it has no identified threshold — exactly the pattern that justifies removing an ingredient rather than labelling it. The strongest case for the sceptics is about the present rather than the past: the cohort data come overwhelmingly from intakes well above today's post-reformulation levels in regulated markets, so the risk at current low intakes is extrapolated rather than directly measured, and the long-term data on the replacements genuinely do not exist. Both stories are true at the same time, because the debate is really about which question matters — whether trans fat harmed people at the intakes of the 1990s, which it plainly did, or whether it still harms people at the intakes of today, which the trials have not directly tested.
Who should avoid them
- People with high LDL cholesterol or heart disease — the best-evidenced harm here is the LDL rise and HDL fall, and the heart-disease risk that follows it
- People who eat a lot of fried and baked food — the dose is what matters, and these are the foods where partially hydrogenated oil concentrates
- People eating street food or imports in countries without a ban or cap — that is where industrial trans fat still hides
- People with type 2 diabetes or prediabetes — on precautionary grounds only: the diabetes link is plausible but unproven
- People who eat several servings of "0 g trans fat" foods a day — the rounding rule means small amounts add up, as the label section below shows
- Everyone, in the WHO's view — industrially produced trans fat is not part of a healthy diet and should be avoided, with intake below 1 percent of energy
How to spot them on a label
In the United States, trans fat has been declared on the Nutrition Facts panel since 1 January 2006, on its own line under saturated fat, in grams per serving — to the nearest 0.5-gram increment below 5 grams. The rule that matters is the rounding rule, in the FDA's own words: "If a serving contains less than 0.5 gram, the content, when declared, must be expressed as '0 g.'" So a food with up to 0.49 grams of trans fat per serving can legally declare 0 g trans fat, including a food whose ingredients list still contains partially hydrogenated oil. There is no percentage daily value for trans fat, and no standalone regulated "trans fat free" claim: the closest defined claim, "saturated fat free", requires less than 0.5 grams of saturated fat and less than 0.5 grams of trans fat per serving. A "0 g trans fat" declaration is a rounding rule, not a regulated "free" claim.
That is why the ingredients list matters more than the panel. As an illustration — arithmetic from the verified 0.5-gram rule, not a sourced finding — a product with 0.49 grams per serving can say "0 g", and three servings would deliver about 1.5 grams, most of the WHO's 2.2-gram daily limit, from a food that claims to contain none.
- Partially hydrogenated [soybean / cottonseed / palm] oil — trans fat is present; this is the phrase to look for
- Hydrogenated or fully hydrogenated oil — negligible trans fat, but almost entirely saturated fat; a different problem
- Shortening, vegetable shortening, margarine — older formulations were partially hydrogenated; check the ingredients, especially on imports
- Check the products that carry it most — fried foods, crackers, biscuits, pies, popcorn and frostings first, especially imports and food-service food
- In Europe, read the ingredients, not the nutrition table — trans fat is not one of the seven mandatory nutrients, but partially hydrogenated oils must still appear in the ingredients list
- In Australia and New Zealand, trans-fat declaration is voluntary — mandatory only when a claim is made about cholesterol or fatty acids
Alternatives: what replaced them
The straightforward replacement is liquid oil. The WHO's 2023 guideline recommends replacing trans fat with polyunsaturated or monounsaturated fats, primarily from plant sources — olive, canola and sunflower oils for cooking and baking. Where a solid fat is genuinely needed, the industry has turned to three substitutes, and the honest position is that the evidence on them is thinner than the evidence on what they replaced.
Interesterified fats are liquid oils chemically or enzymatically rearranged so fatty acids swap positions on the glycerol backbone, making the fat solid without creating trans bonds. The evidence is mixed and short-term. In Sundram's 2007 trial, 30 volunteers ate diets in which the test fat supplied more than 70 percent of dietary fat for four weeks, and the interesterified fat raised fasting glucose by almost 20 percent and lowered fasting insulin by 22 percent compared with palm olein — but that dose is far above realistic intakes, and one author worked for the Malaysian Palm Oil Board. In the InterSat trial (2025), 47 healthy adults ate interesterified fats providing 10 percent of energy for six weeks per arm and found no significant differences between the two interesterified fats on any cardiometabolic marker — but it compared two interesterified fats against each other, not against unmodified oil. A 2024 acute trial in 50 healthy adults found a commercial interesterified spread produced no different post-meal response from equivalent non-interesterified spreads or butter. The jury is still out; the short-term data at realistic intakes are reassuring, and the long-term data do not exist.
Palm oil is the commonest replacement globally, because it is naturally semi-solid and needs no processing. It replaces partially hydrogenated oil with saturated fat, and the health debate about it is a saturated-fat debate — this article does not quote a palm-oil-specific effect size, because no palm-oil health review was fetched for it. Its environmental cost, deforestation, is real, but it is not a health claim and sits outside this article's scope. Fully hydrogenated oils are the third option: hydrogenation run to completion, so virtually no trans fat remains, but the fat is now mostly saturated, largely stearic acid, which is generally considered neutral for LDL cholesterol. No long-term outcome trials of fully hydrogenated oils exist, and the blend's overall saturated-fat load is what matters. Do not let the label trap catch you in reverse: "hydrogenated" without "partially" is not the same thing as trans fat, and a product that has swapped to fully hydrogenated oil has removed the trans fat without removing the saturated fat.
Related: Added Sugars: The Sweetener Hiding in Plain Sight — and Why the Numbers Disagree — the numbers behind the sugar limits, and why Australia's label only shows total sugars.
Frequently asked questions
What is a hydrogenated fat?
A hydrogenated fat is a vegetable oil that has had hydrogen added to it, with a nickel catalyst, heat and pressure, to make it more solid and shelf-stable. Partial hydrogenation stops part-way, and some of the remaining double bonds flip from the natural cis configuration to the trans configuration — creating industrial trans fat, mainly elaidic acid. On average, a partially hydrogenated oil is 25 to 45 percent trans fat, according to the World Health Organization. Full hydrogenation runs to completion, leaving no trans molecules, but the result is almost entirely saturated fat.
Are trans fats banned in the United States?
Effectively, yes — but the mechanism was not a simple ban. In June 2015 the US Food and Drug Administration determined that partially hydrogenated oils are no longer generally recognised as safe, so any use needed pre-market food-additive approval; the compliance date was extended to 1 January 2020. In August 2023 the FDA issued a direct final rule cleaning up the leftover references — removing partially hydrogenated oils from the standards of identity for peanut butter and canned tuna and revoking older authorisations for margarine, shortening and bread — effective 22 December 2023. Labelling rules did not change: trans fat is still declared on the Nutrition Facts panel, and a serving with less than 0.5 grams can still be listed as 0 grams.
Is trans fat worse than saturated fat?
Gram for gram, yes — on blood cholesterol, which is the best-measured effect. In the landmark 1990 feeding trial by Mensink and Katan, trans fat raised LDL cholesterol by 0.37 mmol/L and lowered HDL cholesterol by 0.17 mmol/L compared with oleic acid, while saturated fat raised LDL by a similar amount but left HDL unchanged. The net effect on the LDL to HDL ratio was about double that of saturated fat, according to a Harvard review of the trial. For heart disease itself, a 2006 pooled analysis found each 2 percent of energy from trans fat was associated with a 23 percent higher incidence of coronary heart disease. The nuance is dose: people eat far more saturated fat than trans fat, so saturated fat still accounts for a larger share of the population burden.
Does trans fat cause type 2 diabetes?
That is not established. One large cohort study, the Nurses' Health Study, found a 2 percent increase in energy from trans fat was associated with a 39 percent higher risk of type 2 diabetes over 14 years. But when de Souza and colleagues pooled the cohort studies in 2015, they found no significant association between total trans fat and type 2 diabetes, and a 2012 meta-analysis of seven randomised trials found no significant effect of higher trans-fat intake on glucose or insulin concentrations. The honest verdict is plausible but unproven: a real signal in one large cohort that did not survive pooling, and no support from trials.
Is there a safe level of trans fat intake?
No threshold has been identified below which the risk disappears. The World Health Organization recommends keeping total trans-fat intake below 1 percent of total energy — less than 2.2 grams a day on a 2,000-calorie diet — and says industrially produced trans fat should be avoided. The European Food Safety Authority's position is that intakes should be as low as possible within a nutritionally adequate diet, and the US Institute of Medicine's advice, quoted in the FDA's own guidance, was to keep trans-fat consumption as low as possible while eating a nutritionally adequate diet. The risk rises with dose, and the cohort data are dominated by intakes well above today's post-reformulation levels in regulated markets, so the risk at current low intakes is extrapolated rather than directly measured.
How do I avoid trans fat?
Read the ingredients list, not just the Nutrition Facts panel. In the United States, look for the words partially hydrogenated followed by an oil — soybean, cottonseed or palm. A product can legally declare 0 grams of trans fat if a serving contains less than 0.5 grams, so the panel alone can miss it. In Europe, partially hydrogenated oils must still appear in the ingredients list, even though trans fat is not a mandatory line on the nutrition declaration. For cooking and baking, liquid vegetable oils such as olive, canola or sunflower oil are the straightforward replacement, and the World Health Organization recommends replacing trans fat with polyunsaturated or monounsaturated fats from plant sources. Ruminant trans fat in meat and dairy will not appear as partially hydrogenated on a label — it shows only in the trans-fat grams line, where one is printed.
Checked against the FDA's 2024 PHO revocation guide, the WHO's 2024 trans fat fact sheet, Regulation (EU) 2019/649, Health Canada's 2018 ban notice and the Mensink & Katan, Mozaffarian and de Souza studies · Last updated 2026-11-09 · How we assess ingredients
Sources (39)
- US Food and Drug Administration — "Revocation of Uses of Partially Hydrogenated Oils in Foods: Small Entity Compliance Guide" (April 2024): the 2015 final determination (80 FR 34650), the original 18 June 2018 compliance date, the extensions to 1 January 2020 for non-petitioned uses and 18 June 2019 for petitioned uses (83 FR 23358), and the 2023 direct final rule (88 FR 53764)
- US Food and Drug Administration — Direct Final Rule: Revocation of Uses of Partially Hydrogenated Oils in Foods: the 2023 rule's scope — removing partially hydrogenated oils from the standards of identity for peanut butter and canned tuna, revising the safe-status affirmations for menhaden oil and low-erucic-acid rapeseed oil, deleting the hydrogenated fish oil affirmation, and revoking prior sanctions for margarine, shortening and bread, rolls and buns
- Federal Register 88 FR 86580 (14 December 2023) — confirmation of the effective date of 22 December 2023 for the direct final rule, no significant adverse comment having been received
- World Health Organization — Trans fat fact sheet (24 January 2024): total trans-fat intake below 1 percent of total energy, less than 2.2 grams a day on a 2,000-calorie diet; more than 278,000 deaths a year attributed to industrially produced trans fat; high intake associated with 34 percent higher risk of death from any cause, 28 percent higher coronary heart disease deaths and 21 percent higher coronary heart disease; partially hydrogenated oil is on average 25–45 percent trans fat; frying oil at high temperature generates up to 2–3 percent; the two best-practice policy options; "both industrially produced and naturally occurring trans fat are equally harmful"
- World Health Organization — 5-year milestone report on global trans-fat elimination (24 June 2024): the 2023 target was not met; 53 countries had best-practice policies in effect, covering 3.7 billion people (46 percent of world population), up from 6 percent in 2018; those policies could save about 183,000 lives a year; seven countries added best-practice policies in 2023; the first five countries certified under the validation programme were Denmark, Lithuania, Poland, Saudi Arabia and Thailand
- World Health Organization — "A recipe for good health: banish trans fat to history's dust bin" (3 February 2023): Denmark's 2004 regulation and the decrease in mortality from heart disease after its introduction — this article uses the current 278,000 figure from the 2024 fact sheet
- Hippocratic Post (January 2024) — WHO awards for eliminating trans fats: the first five countries certified, and the WHO's revised target of virtual elimination by 2025, with best-practice policies in countries accounting for at least 90 percent of the global trans-fat burden — whether that target was met has not been reported in the research for this article
- Commission Regulation (EU) 2019/649 of 24 April 2019 (OJ L 110/17, 25 April 2019): the content of trans fat, other than trans fat naturally occurring in fat of animal origin, in food intended for the final consumer "shall not exceed 2 grams per 100 grams of fat"; food not complying could continue to be placed on the market until 1 April 2021
- Health Canada — "Canadian ban on trans fats comes into force today" (17 September 2018): it is now illegal for manufacturers to add partially hydrogenated oils to foods sold in Canada, including imported foods and foods prepared in all food-service establishments; a two-year phase-in applied to products manufactured before 17 September 2018; naturally occurring trans fats in milk, cheese, beef and lamb are not covered
- US Food and Drug Administration — Small Entity Compliance Guide: Trans Fatty Acids in Nutrition Labeling, Nutrient Content Claims, and Health Claims (docket FDA-2003-D-0035): the 2003 final rule (68 FR 41434), effective 1 January 2006; trans fat declared in grams per serving to the nearest 0.5-gram increment below 5 grams, and "if a serving contains less than 0.5 gram, the content, when declared, must be expressed as '0 g'"; no percentage daily value; the Institute of Medicine wording that trans-fat consumption should be "as low as possible while consuming a nutritionally adequate diet"
- US Code of Federal Regulations, Title 21, §101.62 — Nutrient content claims: there is no standalone defined "trans fat free" claim; the "saturated fat free" claim requires less than 0.5 grams of saturated fat and less than 0.5 grams of trans fat per reference amount customarily consumed and per labelled serving
- Food Standards Australia New Zealand — Australia New Zealand Food Standards Code, Standard 1.2.8: trans-fat declaration is voluntary, but required when a nutrition content or health claim is made about cholesterol or saturated, trans, polyunsaturated or monounsaturated fatty acids
- The George Institute — Submission on options for improving the composition of the food supply in relation to industrially produced trans fats (21 November 2023): 38 percent of packaged products that quantify trans fat in Australia exceed the WHO 2 percent limit, and about 3,660 packaged products (13 percent) may contain hidden industrially produced trans fat identifiable only from ingredients lists; recommends a complete ban on partially hydrogenated oils, with the WHO limit as a backup; voluntary reformulation "will not be effective" — the outcome of the 2023 consultation was not verified in the research for this article
- Retained EU Regulation 2019/649 (legislation.gov.uk): the 2-gram industrially produced trans fat per 100 grams of fat limit as retained law in Great Britain — verified from the retained-regulation text; no UK government press release was fetched for this article
- Regulation (EU) No 1169/2011 on the provision of food information to consumers: the mandatory nutrition declaration is energy, fat, saturates, carbohydrate, sugars, protein and salt per 100 grams or millilitres — trans fat is not among the mandatory nutrients, while partially hydrogenated oils must still appear in the ingredients list
- Tufts Health & Nutrition Letter — fully versus partially hydrogenated oil (updated 17 September 2019): "when oils are fully hydrogenated, all their bonds get changed to hydrogen-carbon and there are no more trans molecules"; fully hydrogenated oil is a hard, waxy, stearic-acid-rich saturated fat, used for example in reduced-fat peanut butter
- K&L Gates — "FDA Announces Final Determination That Partially Hydrogenated Oils Are Not GRAS" (2015): partially hydrogenated oils are "those fats and oils that have been hydrogenated, but not to complete or near complete saturation, and with an iodine value (IV) greater than 4"; the three-year phase-out; the determination did not change labelling requirements
- US Government Accountability Office — Report B-335722 (17 November 2023): corroborates the 2023 direct final rule's scope and its effective date of 22 December 2023
- Assessment of the Presence of Partially Hydrogenated Oils (PHOs) as a Food Ingredient in the Polish Market (The Free Library): partially hydrogenated oils listed on 6.9 percent of 1,224 products in 2017–2019, before the EU regulation took effect
- Frontiers in Animal Science (2023) — review of ruminant trans fats: "in contrast to industrial TFA, which have undisputed adverse health effects, ruminant TFA such as trans vaccenic acid (TVA), rumenic acid (RA) and trans palmitoleic acid (TPA) have been associated with reduced risk for some diseases such as type 2 diabetes" in observational studies — but "the same benefits have not been observed in other animal studies or in human clinical trials" and "additional clinical and mechanistic studies are needed"
- Mensink RP, Katan MB (1990). Effect of dietary trans fatty acids on high-density and low-density lipoprotein cholesterol levels in healthy subjects. New England Journal of Medicine 323(7):439–445: 59 healthy subjects, three diets of identical composition for three weeks each, differing only in that 10 percent of energy came from oleic acid, trans isomers of oleic acid, or saturated fat; on the trans-fat diet, HDL cholesterol 0.17 mmol/L lower and LDL cholesterol 0.37 mmol/L higher than on the oleic-acid diet; on the saturated-fat diet, LDL 0.47 mmol/L higher with HDL unchanged
- Mozaffarian D, Katan MB, Ascherio A, Stampfer MJ, Willett WC (2006). Trans fatty acids and cardiovascular disease. New England Journal of Medicine 354:1601–1613 — figures verified from the BMJ editorial summarising it (BMJ 2006; 333:214), not from the paywalled NEJM full text: a 2 percent increase in energy from trans fat was associated with a 23 percent increase in coronary heart disease incidence (pooled relative risk 1.23; 95% CI 1.11–1.37); adverse effects were seen even at intakes of about 3 percent of energy; "on a per-calorie basis, trans fats appear to increase the risk of CHD more than any other macronutrient"
- Mozaffarian D, Aro A, Willett WC (2009). Health effects of trans-fatty acids: experimental and observational evidence. European Journal of Clinical Nutrition 63 Suppl 2:S5–21: meta-analysis of prospective studies — 24, 20, 27 and 32 percent higher risk of myocardial infarction or coronary heart disease death for every 2 percent of energy from trans fat, replacing carbohydrate, saturated fat, cis-monounsaturated fat and cis-polyunsaturated fat respectively; the most consistent effects were adverse lipids, pro-inflammatory effects (higher TNF-alpha activity, interleukin-6 and C-reactive protein) and endothelial dysfunction; "the limited data suggest that the experimental effects of ruminant and industrial TFA are similar when consumed in similar quantities, but very few persons consume such high levels of ruminant TFA"
- de Souza RJ et al. (2015). Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies. BMJ 351:h3978: total trans fat associated with all-cause mortality (relative risk 1.34), coronary heart disease mortality (1.28) and total coronary heart disease (1.21), but not ischaemic stroke (1.07) or type 2 diabetes (1.10); total coronary heart disease — industrial trans fat 1.42 against ruminant trans fat 0.93; coronary heart disease mortality — industrial 1.18 against ruminant 1.01; ruminant trans-palmitoleic acid inversely associated with type 2 diabetes (0.58); GRADE certainty "moderate" for heart outcomes and "very low" to "low" for other associations
- Bendsen NT, Christensen R, Bartels EM, Astrup A (2011). Consumption of industrial and ruminant trans fatty acids and risk of coronary heart disease: a systematic review and meta-analysis of cohort studies. European Journal of Clinical Nutrition 65(7):773–783: total trans fat associated with coronary heart disease events (relative risk 1.22) and fatal coronary heart disease (1.24); ruminant trans fat not significantly associated (0.92); industrial trans fat showed a trend to a positive association (1.21, P=0.09) that was not statistically significant — the authors note the limited number of studies "prohibits any firm conclusions concerning whether the source of TFA is important"
- World Health Organization (2023). Saturated Fatty Acid and Trans-Fatty Acid Intake for Adults and Children: WHO Guideline: "WHO recommends that adults and children reduce trans-fatty acid intake to 1% of total energy intake (strong recommendation)"; "WHO suggests further reducing trans-fatty acid intake to less than 1% of total energy intake (conditional recommendation)"; "WHO recommends replacing trans-fatty acids in the diet with polyunsaturated fatty acids or monounsaturated fatty acids primarily from plant sources (conditional recommendation)"
- European Food Safety Authority (2004). Trans fatty acids — EFSA Panel reviews dietary intakes and health effects: "at equivalent dietary levels, the effect of trans fatty acids on heart health may be greater than that of saturated fatty acids. However, current intakes of trans fatty acids are generally more than 10-fold lower than those of saturated fatty acids"; EU mean intakes then were 0.5–2.0 percent of energy; the "as low as possible" position is the EFSA position as quoted in the European Commission's Joint Research Centre 2014 report, and the 2018 EFSA opinion document itself was not fetched for this article
- Sundram K, Karupaiah T, Hayes KC (2007). Stearic acid-rich interesterified fat and trans-rich fat raise the LDL/HDL ratio and plasma glucose relative to palm olein in humans. Nutrition & Metabolism 4:3: 30 healthy volunteers, three four-week controlled diets with more than 70 percent of dietary fat from the test fat; both partially hydrogenated soybean oil and interesterified fat significantly elevated the LDL/HDL ratio and fasting blood glucose — fasting glucose almost 20 percent higher in the interesterified group, fasting insulin 22 percent lower after the interesterified diet; one author was nutrition director at the Malaysian Palm Oil Board, and the test-fat dose is far above realistic intakes
- Hall WL et al. (InterSat, 2025). The effects of consumption of interesterified fats rich in palmitic acid compared with stearic acid on intermediary markers of cardiometabolic disease risk: a randomized controlled trial in healthy adults. American Journal of Clinical Nutrition 122(5):1361–1373: randomised double-blind crossover, 47 healthy adults, interesterified fats providing 10 percent of energy for six weeks per arm; no significant differences between the two interesterified fats for the total-to-HDL cholesterol ratio or for total, HDL or LDL cholesterol, triglycerides, insulin sensitivity, inflammation markers, liver fat or blood-vessel function; the trial compared two interesterified fats against each other, not against unmodified oil, and was funded by the Malaysian Palm Oil Board
- Food & Function (2024). Acute trial of a commercial interesterified spread versus equivalent non-interesterified spreads and butter in 50 healthy adults: no different postprandial triacylglycerol, lipoprotein, inflammatory or endothelial response — verified from the abstract
- Salmerón J et al. (2001). Dietary fat intake and risk of type 2 diabetes in women. American Journal of Clinical Nutrition 73(6):1019–1026: Nurses' Health Study, 84,204 women, 14 years' follow-up, 2,507 incident cases; a 2 percent increase in energy from trans fat was associated with a relative risk of 1.39 for type 2 diabetes (95% CI 1.15–1.67); total fat, saturated and monounsaturated fat were not associated with diabetes risk
- Gebauer SK et al. (2015). Vaccenic acid and trans fatty acid isomers from partially hydrogenated oil both adversely affect LDL cholesterol: a double-blind, randomized controlled trial. American Journal of Clinical Nutrition 102:1339–1346 — verified via the USDA Agricultural Research Service record: 106 healthy adults, four 24-day controlled diets; vaccenic acid at 3.3 percent of energy and industrial trans fat at 3.3 percent of energy both increased total cholesterol, LDL cholesterol, apolipoprotein B and the total-to-HDL and LDL-to-HDL ratios compared with the control diet; vaccenic acid also increased HDL cholesterol and apolipoprotein AI and lowered fibrinogen; conjugated linoleic acid had neutral effects on total cholesterol
- Chardigny JM et al. (TRANSFACT, 2008). Trans fatty acids from industrial and natural sources: effects on lipid and lipoprotein profiles. American Journal of Clinical Nutrition 87:558–566 — verified via the FAO AGRIS record: 46 healthy subjects, crossover, about 11–12 grams a day (about 5 percent of energy) of trans fat from industrial versus natural sources; natural-source trans fat increased HDL cholesterol in women but not men, and increased LDL in women only; "the HDL cholesterol-lowering property of TFAs seems to be specific to industrial sources"
- Brouwer IA et al. (2010). Effect of trans-fatty acid intake on blood lipids and lipoproteins: a systematic review and meta-regression analysis. PLoS One 5:e9434: "all fatty acids with a double bond in the trans configuration raise the ratio of plasma LDL to HDL cholesterol" — verified via a secondary summary of the review, not from the full text
- Harvard School of Public Health review of trans fats (reproduced): the LDL-to-HDL ratio on the Mensink and Katan diets was 2.58 on the trans diet, 2.34 on the saturated-fat diet and 2.02 on the oleic-acid diet, and the net effect of trans fat on the ratio was approximately double that of saturated fat — this ratio wording is from the Harvard review, not from the 1990 paper itself
- Effects of trans fatty acids on glucose homeostasis: a meta-analysis of randomized, placebo-controlled clinical trials. American Journal of Clinical Nutrition (2012) 96:1093–1099 — verified via the Epistemonikos record: seven randomised trials; increased trans-fat intake did not result in significant changes in glucose or insulin concentrations; the lipid effects were confirmed
- American Bakers Association, comments to the FDA (March 2014), reported via Associations Now: voluntary efforts had produced "extremely low levels of industrially produced trans fat in finished foods — lower than the levels presented by FDA"; "consumption of trans fat in the U.S. has dramatically decreased and will continue to decrease as industry continues to develop alternatives"; a full ban "goes too far"; the association proposed tightening the rounding rule from 0.5 grams to 0.2 grams per serving
- Grocery Manufacturers Association (2015), reported via Progressive Grocer: food companies had "already voluntarily lowered the amount of trans fat added to food products by more than 86 percent" and would petition the FDA to approve low levels of partially hydrogenated oils, "as safe as the naturally occurring trans fat present in the normal diet"; FDA figures quoted in the same report put the fall in US trans-fat consumption at about 78 percent between 2003 and 2012
- Mercatus Center (2013–2014). "Trans Fat Ban Just a Swing in the Dark": after labelling, consumption fell 80 percent; "at the previous levels, there was pretty good evidence that consumption of trans fatty acids at high levels (4 grams) was associated with heart disease. But what about current consumption at lower levels? The evidence is missing… We don't know if there are levels of trans fatty acids that are benign or perhaps even good for you." Labelled here as a free-market think-tank argument, not a scientific review
