Nutrition with Caution: WHO’s New Rules on Fortifying Oils for Public Health

The World Health Organization's 2025 guideline on fortification of edible oils and fats with vitamins A and D, developed in collaboration with leading research institutes such as the University of California Davis, Wageningen University, and the Swiss Federal Institute of Technology (ETH Zurich), sets a new global benchmark in nutrition policy. It comes as vitamin A deficiency continues to drive childhood blindness and infections, while vitamin D deficiency remains widespread due to limited dietary sources and sunlight exposure. The guideline positions oil fortification as a practical, scalable public-health intervention, while cautioning that it must complement, not compromise, healthy-diet goals.

A Dual-Deficiency Solution with Careful Boundaries

The document issues two central recommendations. Fortifying edible oils and fats with vitamin A is strongly recommended as a public-health measure where deficiency is a recognized problem, even though the evidence certainty is low. In contrast, fortifying with vitamin D receives a conditional recommendation; countries may consider it if deficiency is common and the food supply allows safe, equitable implementation. Both recommendations rest on clear prerequisites: deficiencies must affect multiple age groups, edible oils must be widely consumed, and there must be sufficient industrial consolidation to ensure population-level reach.

Evidence, Efficacy, and the Case for Context

The guideline relies on a global evidence review showing modest results but clear potential. Trials indicate that vitamin-A-fortified oils and fats have limited effects on serum retinol levels overall, though one study found increased vitamin A concentration in breast milk among women who consumed fortified oil. Vitamin D data are even sparser; one small trial found no meaningful change in blood vitamin D levels, while historical evidence from Europe's margarine fortification programs hints at benefits such as reduced rickets and fewer fractures. WHO acknowledges these gaps but argues that fortification remains justified where deficiencies are severe and alternatives, like supplementation, are not feasible.

To guide countries, WHO provides safe fortification ranges: 12–26 mg/kg of oil or fat for vitamin A (as retinyl palmitate or acetate) and 0.20–0.43 mg/kg for vitamin D (as cholecalciferol or ergocalciferol). The organization advises national authorities to model these levels carefully against dietary patterns, overlapping programmes, and the risk of excessive intake from multiple fortified foods.

Technology, Safety, and the Science of Stability

The guideline delves deeply into the chemistry of fortification. Vitamins are added to refined, bleached, and deodorized oils at 45–50°C, using premixes stabilized with antioxidants like tocopherol, BHA, or BHT. Uniform mixing is critical, achieved through either batch blending in tanks or continuous microdosing in production lines. Packaging matters: sealed, light-protected containers with inert gas can prevent oxidation and preserve nutrient stability. Oil quality, measured by peroxide and anisidine values, determines how well vitamins survive storage and cooking. Visual diagrams in the report illustrate how refining and dosing points interact, underscoring that poor-quality oil undermines the very goal of fortification.

Health First: Avoiding Nutrition Trade-Offs

The WHO warns that fortification must not increase total fat consumption or justify marketing unhealthy products. Edible oils and fats are calorie-dense foods, and fortifying them should encourage consumers to switch from non-fortified to fortified options, not to consume more. Countries are urged to align fortification policies with the WHO's dietary guidelines that call for limiting total, saturated, and trans fats while promoting healthier unsaturated vegetable oils. Regulators must also prevent misleading health claims that equate fortification with overall dietary improvement. The document makes clear: fortification is a complement to healthy diets, not a substitute.

Equity, Monitoring, and the Global Path Forward

Equity is woven through every chapter. Because the poorest households often buy unbranded or bulk oils that escape regulation, the WHO urges governments to design policies ensuring coverage across rural and low-income groups. Disaggregated monitoring using the PROGRESS-Plus framework, capturing data by gender, geography, and income, is key to identifying who benefits and who is left behind.

As of 2024, 35 countries have mandatory oil fortification policies, and 8 allow voluntary programs. About 39 countries fortify with vitamin A and 13 with vitamin D. Levels vary widely: vitamin A between 3.5–41 mg/kg, vitamin D between 0.01–0.75 mg/kg. WHO calls this diversity healthy, evidence that countries are adapting to their own dietary contexts and capacities.

Ultimately, the 2025 guideline is both pragmatic and visionary. It asks governments to fortify oils and fats where the need is clear, but to do so smartly: through modelling, regulation, and monitoring that protect public trust. In WHO's words, fortification should be a "nutrition safeguard for populations at risk, not a license for unhealthy diets." The message is simple but profound: fortify to nourish, not to sell.