Are oils from plants and seeds “harmful”?!

If you find yourself browsing TikTok, engaging in health discussions online, or keeping track of the latest dietary fads, you’re likely to encounter strong viewpoints regarding plant oils. These oils—referred to as “seed oils”—have recently been described in various ways, from “toxic sludge” to “the largest unnoticed contributor to chronic illness.” But how much of this narrative is based on scientific evidence?

To simplify things, we’ll investigate what plant oils are, their processing methods, and what contemporary studies indicate about their effects on health. We’ll also look into which fats are most suitable for cooking, which ones to be cautious with, and how to incorporate oils into a balanced eating plan.

What Are Plant Oils, Exactly?

Plant oils are fats extracted mainly from the seeds of various plants. The most frequently used varieties include:

• Canola oil
• Corn oil
• Soybean oil
• Sunflower oil
• Safflower oil
• Sesame oil
• Grapeseed oil

These differ from oils such as olive, avocado, or coconut oil, which are derived from the fruit of the plant and typically aren’t classified within the same contentious “seed oil” category.

How Are These Oils Produced?

The oil content in seeds is quite low; thus, producers implement a complex, multi-stage process to extract the oil. This process includes:

• Crushing: Seeds are mechanically pressed to release oil.
• Solvent Extraction: A chemical like hexane may be utilized to obtain additional oil.
• Refining and Deodorizing: The oil is heated (often to around 400°F) to neutralize taste and eliminate impurities, during which antioxidants and nutrients can often be lost. Small quantities of trans fats may also form in this phase.

Due to such extensive processing, detractors claim these oils are “unnatural.” While that assertion may be overstated, it is accurate that many refined plant oils are devoid of beneficial nutrients and might contain minor levels of unhealthy substances.

What Does Research Indicate?

Instead of categorically viewing all plant oils as unhealthy, it’s beneficial to analyze their types, composition, and role within an individual’s overall diet.

Monounsaturated and Polyunsaturated Fats

Plant oils are abundant in unsaturated fats—especially polyunsaturated fats (PUFAs) and, in some varieties, monounsaturated fats (MUFAs). Research indicates that these fats can:

• Assist in lowering LDL (bad) cholesterol
• Enhance heart health
• Deliver essential fatty acids like omega-3 and omega-6

However, polyunsaturated fats are more susceptible to oxidation, particularly when subjected to heavy refining or repeatedly heated during cooking—potentially leading to the development of inflammatory substances.

The Omega Fatty Acid Discrepancy

Contemporary diets frequently have an excess of omega-6 fatty acids and insufficient omega-3s, a lopsided ratio that some researchers argue may lead to chronic inflammation. While omega-6s are indeed essential, it is the disparity—not the overall quantity—that may present health concerns.

Nevertheless, context is crucial: obtaining omega-6 fats from whole foods (such as seeds and nuts) is typically health-enhancing. In contrast, an overabundance of omega-6s from ultra-processed foods could be problematic, especially if they replace healthier choices.

Refined Oils vs. Cold-Pressed and Expeller-Pressed Oils

The extent of processing influences the quality of the oil:

• Cold-pressed and expeller-pressed oils are mechanically extracted without chemical solvents or intense heat.
• Refined oils are chemically treated and subjected to extensive heating, which diminishes their nutritional profile and stability.

For instance, expeller-pressed canola oil retains more advantageous compounds than its refined counterparts and is rich in heart-healthy MUFAs and plant-derived omega-3s.

Choosing Oils: What’s the Best Option?

Extra Virgin Olive Oil (EVOO)

Extra virgin olive oil is minimally refined, abundant in monounsaturated fats, and loaded with antioxidants known as polyphenols. Studies associate EVOO consumption with decreased risks of