Seed Oils, Industrial Processing, Hexane and AGEs: Should You Be Worried?
- Alastair Hunt
- 19 hours ago
- 4 min read
Updated: 2 hours ago
Part 4 of the Seed Oils Series
One of the major concerns raised about seed oils relates to how they are processed. Unlike cold-pressed olive oil, many commercial seed oils are refined using industrial methods involving heat, chemical extraction, and deodorisation. Critics argue that these processes introduce toxins such as residual solvents (like hexane) and damage the oil’s structure, creating harmful byproducts that could promote disease.
First, the chemical extraction process often uses hexane, a petroleum-derived solvent. After extraction, the hexane is evaporated during refining, leaving behind minimal residues. Regulatory agencies such as the European Food Safety Authority (EFSA) and the United States Food and Drug Administration (FDA) have established strict limits on allowable hexane residues in food-grade oils. Analyses consistently show that residual hexane levels in bottled seed oils are extremely low, typically well below safety thresholds.
Human studies do not show any link between dietary intake of refined seed oils and hexane toxicity - there is no evidence of neurological damage from food sources which is what one would expect to see. Most toxicity concerns around hexane come from industrial exposure, where workers inhale high concentrations over long periods - a completely different scenario from trace dietary exposure.
Processing can, however, alter oils chemically. High heat, oxygen exposure, and extended storage can promote the formation of lipid peroxidation products, such as aldehydes and hydroperoxides. Some aldehydes, like 4-hydroxynonenal, have been associated with oxidative damage in laboratory settings when present at high concentrations.
In addition to lipid peroxidation, high-heat cooking methods - particularly deep frying - can lead to the formation of Advanced Glycation End Products (AGEs). AGEs form when fats or proteins react with sugars under high temperatures. They are naturally present in many cooked foods, but excessive intake of dietary AGEs has been linked to oxidative stress, inflammation, insulin resistance, and an increased risk of cardiovascular disease in observational studies.
The concern with reheated seed oils in fast-food environments is twofold:
The accumulation of lipid oxidation products over time.
The production of additional AGEs due to repeated high-temperature exposure.
However, home cooking practices are unlikely to produce the same risks. Using oils with an appropriate smoke point, cooking at moderate temperatures, avoiding visible burning or charring, and not reusing oil multiple times can significantly reduce the formation of harmful byproducts.
Practical strategies to minimise exposure include:
Choose fresh, cold-pressed oils (olive oil) when possible for low-heat cooking.
Use high-smoke-point oils such as peanut, sunflower, or canola oil for frying if necessary.
Avoid smoking oils or visibly burnt foods.
Prioritise gentler cooking methods such as baking, steaming, poaching, or sautéing.
While laboratory studies show that aldehydes and AGEs can cause cellular damage at high concentrations, real-world dietary exposure is much lower, and the body's natural detoxification systems handle these compounds effectively in moderate amounts. Concern should focus on overall dietary patterns, not occasional cooking practices. If you are particularly sensitive to oxidative stress (e.g., living with diabetes, cardiovascular disease or inflammatory conditions), discussing cooking strategies with your healthcare provider may be wise.
At the population level, it is clear that an ultra-processed, fried-food-heavy diet poses greater risk than moderate, thoughtful use of seed oils at home.
Next... Part 5: Seed Oils vs Saturated Fats: Clearing the Confusion
Final Thoughts
While seed oils can be a divisive issue online, we are relatively agnostic when it come to diet and eating patterns. If you enjoy cooking with olive oil or avocado oil - rather than a seed oil - we do too. But we are not concerned about a splash of canola in our stir fry and we try to avoid ultra-processed foods as part of our daily eating.
Changing health for the better is about progress, not perfection, and even small changes can make a meaningful difference over time. For most people, improving health is about finding motivation and prioritising self-care - with an ultimate goal of taking action. If you want to take effective and targeted steps that fit into your unique lifestyle and circumstances, The Whole Health Practice is here to help.
Whether your interest is healthspan and longevity, to beat chronic illness or to enhance your mental health and well-being, our consultations and programs deliver results that are tailored to your needs.
Our foundational Whole Health Consult identifies and prioritises the key factors - known and unknown - that affect health and wellbeing. It provides targeted recommendations tailored to you, the individual, and your unique lifestyle.
Stay Healthy,
Alastair
Join us, or scroll down to contact us and learn more about our services:
Achieve your Health Goals
Our health, physical – mental – social - is complex and affected by multiple factors within and outside of your control. Our consults and programmes address the whole person, the root causes of ill health and maximising your health, performance & vitality.
Take the first step. Contact us to arrange an introductory call, to discuss how we can support your journey to health. We are based in Singapore and work with clients globally.
Book a Whole Health Consult to assess, identify and prioritise key factors (known and unknown) that affect your health. And receive personalised recommendations on how to address them.
Want to put recommendations into action? Learn more about our programmes for individuals or teams.
Comments