Trans Fat (Trans Fatty Acids): FSSAI's 2 Per Cent Limit, Vanaspati and Reheated Oil

Trans fat is unsaturated fat whose molecules have been twisted into a straighter shape, which makes an oil firm, slow to turn rancid and cheap to fry in. Most of it has come from partially hydrogenated vegetable oil: vanaspati, margarine and bakery shortening. A smaller amount occurs naturally in milk fat and the meat of cattle, sheep and goats. The body needs none. WHO's ceiling is under 1 per cent of energy, about 2.2 g a day, and since January 2022 FSSAI has allowed no more than 2 per cent industrial trans fat in the fat of any food. This entry belongs to the fats section of the handbook.

What is trans fat, and where does it come from?

It comes from two places. The industrial kind forms when hydrogen is added to liquid vegetable oil to make it semi-solid: ICMR-NIN's 2024 guidelines explain that during this process some of the mono and polyunsaturated fat turns into saturated fat and some into isomers called trans fatty acids. WHO puts the trans fat content of partially hydrogenated oil at 25 to 45 per cent on average. The natural kind is made in the stomachs of ruminant animals, so small amounts turn up in milk, ghee, butter and mutton.

FSSAI's regulations write the distinction into law. They define industrial trans fatty acids by their chemistry and then exclude trans fatty acids from dairy, meat, fish and their products, so the legal limit applies to what a factory or a fryer adds and not to what a cow makes. The nutrition panel follows the same line: it asks for trans fat other than the naturally occurring kind. WHO counts both kinds together in its advice.

How much trans fat is too much?

Any amount is more than you need. ICMR-NIN's 2024 Dietary Guidelines set no allowance and no gram limit; they simply say trans fats are harmful and should be avoided, and that they are more harmful than saturated fat. The working number comes from WHO: less than 1 per cent of total energy from trans fat of every origin, which is under 2.2 g a day on a 2,000 kcal diet. You can find your own energy figure with the calorie calculator.

The 2 per cent limit is measured against the fat in a product, not the product's weight, and it binds the manufacturer. The 2 g on a label is only the yardstick FSSAI uses to turn grams per serving into a percentage, alongside 67 g of total fat and 22 g of saturated fat. Neither is a target to eat up to.

FSSAI's rules for trans fat in Indian food

India tightened the limit in two steps. A regulation issued in December 2020 cut industrial trans fat in oils and fats to 3 per cent by January 2021 and 2 per cent by January 2022. A second, issued in February 2021, extended the 2 per cent ceiling from 1 January 2022 to every food in which edible oils and fats are an ingredient. That matches one of WHO's two best-practice policies, a mandatory limit of 2 g of industrial trans fat per 100 g of total fat; the other is a ban on partially hydrogenated oil. WHO's REPLACE package of 2018 sets out six steps for governments: review the sources, promote healthier oils, legislate, assess, create awareness and enforce.

The label has to tell you the amount. FSSAI's labelling regulations require the nutrition panel to give trans fat in grams, though only where the food has more than 0.5 per cent fat, and they allow the figure to be written as "not more than". Every pack of edible oil, vanaspati, margarine and fat spread, and every food made with them, must declare its trans fat and saturated fat. Since October 2019 a voluntary "Trans Fat Free" logo has been open to outlets and products that meet the 0.2 g per 100 g condition.

Where does trans fat turn up on an Indian plate?

It turns up in vanaspati and the foods made with it, in commercially fried snacks, and in small natural amounts in dairy fat. ICMR-NIN notes that vanaspati stands in for ghee and butter in sweets, snack foods and bakery products, so mithai, namkeen, rusk and biscuits are the foods to think of first. FSSAI's own list adds margarine, bakery shortening, refined oils, baked products and fried foods.

The rows are not like for like. The Indian Food Composition Tables report one trans fatty acid, elaidic acid, and their vanaspati was analysed years before the present limit, so a tin bought today should carry less. The street vendor figures are also from before the regulation. The pages for vanaspati per 100 g and ghee per 100 g show each fat's saturated fat as well: 61 g and 71 g per 100 g.

What have Indian market surveys found?

The largest is FSSAI's own baseline survey with the Quality Council of India, released in September 2021, a few months before the 2 per cent limit took force. It collected 6,245 packaged samples from 419 cities and districts in 34 States and Union Territories. Only 196 samples, 3.14 per cent, had more than 2 per cent trans fat, and 176 of those were in a single category: oils, vanaspati, shortenings and margarine.

The survey covered packaged products only, so it says little about the loose samosa, jalebi or bhatura sold from a cart. A study published in 2015, before the present rule, looked there instead. It analysed 39 street foods and snacks and surveyed low-income households in two villages and an urban slum. Trans fat made up anything from 0.1 to 29.9 per cent of the fat in vendors' oils, and 13 per cent of urban and 4 per cent of rural households were eating more than WHO advises.

Does reheating oil create trans fat?

It creates some, though far less than hydrogenation does. WHO describes the increase from frying at high temperature as modest, up to 2 to 3 per cent, against 25 to 45 per cent in partially hydrogenated oil. An Indian laboratory study in 2016 heated six fats and oils, among them soyabean oil, groundnut oil, ghee and partially hydrogenated fat, at 180 and 220 degrees Celsius. Trans fat rose in all six, by 2.3 to 4.5 g per 100 g in the oils and 2.6 to 5.96 g per 100 g in the fats.

Trans fat is not the main reason to stop reusing oil. ICMR-NIN's guidelines say repeated heating oxidises polyunsaturated fat into harmful compounds, and advise that oil used once for frying at home should be filtered, used for a curry within a day or two, and not used for frying again. For food businesses FSSAI sets a limit on those breakdown products, called total polar compounds, of 25 per cent, beyond which the oil is not fit for use. The site's guide to which cooking oil suits an Indian kitchen covers the choice of oil.

What does the evidence say about trans fat and the heart?

The evidence on heart disease comes from observational studies that follow people for years, not from trials. A systematic review in The BMJ in 2015 pooled prospective cohorts and found that people with the highest trans fat intake had a 34 per cent higher risk of death from any cause, a 28 per cent higher risk of death from coronary heart disease and a 21 per cent higher risk of coronary heart disease. The authors rated the certainty for the coronary outcomes as moderate and the rest as low or very low.

There is a plausible route. FSSAI's survey note states that trans fat raises LDL cholesterol and lowers HDL cholesterol, and ICMR-NIN lists a disturbed lipid profile among its effects: the reverse of what you would want from a blood cholesterol report. On natural trans fat the sources disagree. In the BMJ review industrial trans fat was linked with coronary heart disease and ruminant trans fat was not, which the authors put down to the much lower amounts eaten. WHO's position is that both kinds are equally harmful, and its 1 per cent ceiling counts both.

WHO attributes more than 278,000 deaths a year worldwide to industrially produced trans fat. FSSAI's 2021 statement quoted 2017 estimates that about 71,000 of India's 1.5 million yearly coronary deaths, nearly 5 per cent, were due to trans fat. Both are estimates; the Indian one predates the 2 per cent limit.

A worked example: one day of snacks in Lucknow

This is an illustration, not a real person. Take a 38-year-old shopkeeper in Lucknow who eats about 2,000 kcal a day, so his WHO ceiling is 2.2 g of trans fat. Suppose his bought food for the day, two samosas, a packet of namkeen and four cream biscuits, carries 30 g of fat in all. If every item sits exactly at FSSAI's ceiling of 2 per cent, the industrial trans fat is 30 x 0.02 = 0.6 g, well under 2.2 g.

Now suppose the same 30 g came from old-style partially hydrogenated fat at WHO's lower figure of 25 per cent. That is 30 x 0.25 = 7.5 g, more than three times the ceiling from snacks alone. The regulation removed most of the trans fat. It did not remove the 30 g of fat or the salt and refined flour that came with it.

Common mistakes about trans fat

A second mistake is to treat vanaspati as a cheaper ghee. ICMR-NIN's advice is to avoid partially hydrogenated fat as a cooking medium because it may carry both trans fat and saturated fat, and to keep ghee or butter itself to one or two teaspoons a day; the comparison of ghee and sunflower oil sets out the fatty acids. A third is to assume home food is exempt: a week-old kadhai of oil is a home habit. Hard fats in general are covered in the entry on saturated fat.

People most at risk, and when to see a doctor

The people most exposed are those who eat bought fried and bakery food daily, which in the 2015 study meant 84.3 per cent of slum households against 31 per cent of village households. ICMR-NIN singles out pregnancy and breastfeeding as times when trans fat should be avoided altogether. Nothing on a plate tells you what trans fat has done to your arteries. If you have a family history of early heart disease, diabetes, high blood pressure, or an abnormal lipid profile, your doctor should decide which tests you need and what the results mean. Do not change a prescribed medicine on the strength of a diet change.

Learning this properly

Label reading is an everyday skill for anyone who advises on food. NNWA is a private skill academy based in Kolkata, and its teaching is online, in English and in Hindi. Its courses prepare people to coach healthy clients and to pass medical cases to a doctor, and no NNWA course is a degree or a dietitian qualification. Fats and food labelling are introduced in the Certification in Nutrition and taken further in the Diploma in Nutrition, Dietetics and Public Health.