Partially hydrogenated oils

Partially hydrogenated oils (PHOs) are vegetable oils chemically processed to be more solid, creating artificial trans fats. For decades, PHOs were widely used in fast-food fry oils, shortenings, and baked goods to extend shelf life and improve texture – but these trans fats also raise “bad” LDL and lower “good” HDL cholesterol, a combination that increases the risk of heart disease. Due to these health risks, the U.S. FDA determined in 2015 that PHOs were not safe for use in food and mandated their removal from the food supply (with a final phase-out by 2018).

Aliases / Common Names: partially hydrogenated vegetable oil; hydrogenated fat; artificial trans fat Regulatory Status & Exposure: In the United States, the FDA’s 2015 ruling declared PHOs no longer GRAS (Generally Recognized as Safe), leading to a nationwide ban by 2018. Health Canada similarly prohibited PHOs as of 2018. The European Union adopted a 2% limit on industrial trans fat in foods (Regulation 2019/649, effective 2021). The World Health Organization has called for eliminating industrial trans fats globally by 2023. No acceptable daily intake is set – experts advise keeping artificial trans fat consumption as low as possible (ideally <1% of calories). Thanks to such regulations, current PHO exposure in U.S. fast food is essentially zero, though trace amounts of trans fat occur naturally in meat and dairy. Technical Evidence: PHOs increase the content of trans fatty acids in foods, which negatively impacts human health. Mechanistic studies show that trans fats from PHOs worsen cholesterol profiles (raising LDL and lowering HDL), which accelerates plaque build-up in arteries. Trans fats also trigger inflammation and may promote blood clot formation, compounding cardiovascular risk. Epidemiological research consistently links higher trans fat intake to elevated cardiovascular disease outcomes. A large meta-analysis found that people consuming the most trans fat had ~20–30% greater risk of coronary heart disease compared to those consuming the least. Some evidence suggests trans fat intake may also contribute to insulin resistance and type 2 diabetes, but findings are mixed (e.g. a non-significant ~10% increase in diabetes risk at high intakes). Notably, the U.S. Institute of Medicine (NAS) concluded that the only safe intake of industrial trans fat is “zero,” urging consumers to avoid PHOs altogether. Fast-Food Context: Before the ban, PHOs were common in fast-food cooking and frying because they provided a long-lasting oil for deep fryers and gave foods a desirable crispy texture. Many popular items – from french fries and fried chicken to pie crusts, doughnuts, and cookies – were traditionally made with partially hydrogenated oils. By the late 2000s, however, fast-food chains began switching to trans-fat-free oils in response to local regulations and health concerns. For example, some major restaurants eliminated PHOs years before the federal ban (Starbucks cut trans fats in 2007, and others followed suit). Today, U.S. fast food contains virtually no added PHOs, and alternative oils (like high-oleic vegetable oils or fully hydrogenated oils without trans fat) are used for frying. Sensitive Populations / Notes: Individuals with existing heart disease or high LDL cholesterol are especially vulnerable to trans fat’s effects and should avoid PHOs entirely. U.S. labeling laws allow products with <0.5 g trans fat per serving to be labeled “0 g,” so eating multiple small servings can unknowingly add trans fat. Also, naturally occurring trans fats in dairy and meats (which are not from PHOs) are not subject to the ban, but they generally appear in low amounts. Overall, virtually everyone – especially those at risk for cardiovascular disease – benefits from the removal of PHOs from food.

We assign the high tier using published research, regulatory guidance, and PRūF’s additive taxonomy. Restaurant usage is derived from public ingredient disclosures and mapped to menu items where this additive appears.