Azodicarbonamide vs Partially Hydrogenated Oils: which is worse?

What is Azodicarbonamide?

Azodicarbonamide (ADA) is a synthetic chemical used in the food industry as a flour bleaching agent and dough conditioner, and industrially as a blowing agent in foam rubber and plastic production. Its chemical formula is C2H4N4O2. When it reacts with water or heat, it breaks down into biurea (primary product) and semicarbazide (SEM).

What is Partially Hydrogenated Oils?

Partially hydrogenated oils (PHOs) are vegetable oils that have been treated with hydrogen gas in the presence of a catalyst to make them semi-solid at room temperature. This process creates artificial trans fatty acids (trans fats) as a byproduct. They were developed in the early 20th century as a cheaper, longer-lasting alternative to lard and butter.

Documented risks

Azodicarbonamide: ADA's primary food safety concern is its breakdown to semicarbazide (SEM) during baking. In a 2002 study, SEM was found to increase the incidence of vascular tumors in female mice at high doses. This single animal finding was sufficient under the EU's precautionary principle to ban ADA in food use in 2005. The FDA conducted a comprehensive SEM exposure assessment in 2016, concluding that US population exposure to SEM from ADA-treated bread is many orders of magnitude below doses showing tumor effects in rodents and does not warrant regulatory change. This reflects the FDA's risk-based approach. Urethane (ethyl carbamate) is another potentially harmful breakdown product of ADA. Urethane is classified as an IARC Group 2A probable human carcinogen. Small amounts of urethane can form from SEM in fermented or alcohol-containing environments. The 2014 'yoga mat chemical' controversy highlighted ADA's dual use: it is the same chemical used as a blowing agent in foam rubber and plastic manufacturing — including yoga mats. Consumer advocacy blogger Vani Hari's 'Food Babe' campaign led over 50,000 people to petition Subway, which voluntarily removed ADA from its bread in 2014. The dual industrial-food use raised public concern even though ADA's behavior in each context is chemically different. From occupational health: workers exposed to ADA powder in bakery or plastic manufacturing settings can develop occupational asthma. WHO recognizes ADA as a respiratory sensitizer in occupational settings, though dietary exposure through bread is fundamentally different from inhalation exposure.

Partially Hydrogenated Oils: Artificial trans fats (from PHOs) have the most well-established cardiovascular harm of any food ingredient ever banned. Multiple large meta-analyses have confirmed that trans fat consumption increases LDL ('bad') cholesterol, decreases HDL ('good') cholesterol, increases inflammatory markers, and significantly raises cardiovascular disease risk. The Harvard Nurses' Health Study and other landmark prospective studies in the 1990s identified trans fat as uniquely harmful — worse than saturated fat in its cardiovascular effects. A 2006 NEJM meta-analysis by Mozaffarian et al. estimated that eliminating artificial trans fats from the US diet could prevent 72,000 to 228,000 heart attacks per year and 30,000 to 100,000 coronary heart disease deaths annually. The WHO estimates that industrially produced trans fats cause over 500,000 cardiovascular deaths per year globally. The FDA revoked PHOs' GRAS status in 2015 based on this evidence, with compliance by 2018. Denmark banned artificial trans fats in 2003, the first country to do so, and observed a dramatic reduction in cardiovascular mortality in subsequent years.