Mono- and Diglycerides vs Avobenzone: which is worse?

What is Mono- and Diglycerides?

Mono- and diglycerides are emulsifiers derived from glycerol and fatty acids, most commonly sourced from soybean, palm, or sunflower oil. They are partial glycerides that exist between monoglycerides (one fatty acid chain) and diglycerides (two chains). They are chemically similar to fats but are not classified as trans fats even when made from partially hydrogenated sources.

What is Avobenzone?

Avobenzone (INCI: Butyl Methoxydibenzoylmethane) is a chemical UV filter that is the only FDA-approved broad-spectrum UVA-absorbing active sunscreen ingredient in the US that covers the full UVA spectrum (320–400 nm). It is inherently photounstable and must be combined with photostabilizers.

Documented risks

Mono- and Diglycerides: Generally recognized as safe at typical food levels. However, mono- and diglycerides can be derived from partially hydrogenated oils, meaning they may carry trace trans fats that do not appear on the trans fat label because they are classified as emulsifiers, not fats. Some researchers have noted this labeling gap. A 2019 study published in Lipids in Health and Disease noted potential concerns with industrial trans fatty acids in these additives. For most consumers, exposure is low, and regulatory agencies including FDA and EFSA consider them safe at permitted levels.

Avobenzone: Avobenzone is effective and considered safe at approved concentrations (up to 3% in US OTC sunscreens). A 2019 FDA study found that several sunscreen actives including avobenzone were systemically absorbed above the 0.5 ng/mL threshold after repeated use, triggering a call for additional safety data. This does not indicate harm, but the FDA requested more studies under its proposed sunscreen monograph. Current evidence supports its continued safe use. No clear endocrine disruption or carcinogenicity at human exposure levels is established.