Seed oils been the center of much controversy in recent years, especially across social media platforms and wellness forums. Influencers, self-proclaimed nutrition experts, and various online communities have painted seed oils—such as soybean, canola, sunflower, and safflower oil—as dietary villains. The three most common negative claims circulating online are: (1) Seed oils are highly inflammatory and contribute to chronic disease; (2) They are “unnatural” due to industrial processing and thus unfit for human consumption; (3) Their high omega-6 polyunsaturated fat content disrupts the omega-6 to omega-3 ratio, thereby increasing cardiovascular and metabolic disease risk. These arguments have gained traction, but do they reflect the scientific consensus?

What Are Seed Oils?

Seed oils are extracted from the seeds of various plants and are primarily composed of mono- and polyunsaturated fatty acids (PUFAs), with only small amounts of saturated fat. They are rich in essential fatty acids—most notably linoleic acid (an omega-6 PUFA)—and often contain micronutrients such as vitamin E and plant-derived phytochemicals (e.g., phytosterols, tocopherols). These compounds play critical roles in cell membrane structure, inflammation modulation, and cholesterol metabolism.

What Does the Evidence Say?

Contrary to online narratives, a robust body of evidence supports the inclusion of seed oils in a healthy dietary pattern. Multiple large meta-analyses and systematic reviews have shown that replacing saturated fats with PUFAs from seed oils reduces the risk of cardiovascular disease (CVD) and all-cause mortality. For example, a comprehensive meta-analysis by Hooper et al. (2020) found that reducing saturated fat and replacing it with PUFAs lowered CVD events by 17%. Similarly, the American Heart Association’s scientific advisory (Sacks et al., 2017) concluded that PUFAs from seed oils lower LDL cholesterol and reduce heart disease risk. This is particularly useful given that LDL is one of the most commonly taken biomarkers, and correlates with cardiovascular disease risk. A meta-analysis by Schwingshackl et al. (2014) also found that higher PUFA intake was associated with reduced risk of coronary heart disease.

Beyond cardiovascular health, evidence suggests seed oils may benefit other outcomes. A systematic review by Wu et al. (2015) found that PUFA consumption was associated with lower risk of type 2 diabetes. Additionally, a meta-analysis by Imamura et al. (2016) reported that higher linoleic acid intake was linked to lower incidence of diabetes and CVD. A recent review by Abdelhamid et al. (2018) further confirmed that omega-6 PUFAs do not increase inflammation in humans, directly refuting a central argument of seed oil critics.

The negative commentaries on seed oils—namely, that they are inflammatory, “unnatural,” or disrupt fatty acid balance—are not supported by high-quality evidence. In fact, the best available data indicate the opposite: seed oils are neutral or beneficial for most health outcomes when used to replace saturated fats. The inflammatory claim is particularly unsupported, as multiple RCTs and systematic reviews (e.g., Johnson et al., 2022) demonstrate no pro-inflammatory effect from typical dietary intakes of seed oils. The idea that processing makes seed oils harmful also lacks evidence, as discussed in my previous blog post on food processing.

Seed Oils Are Not the Enemy

Seed oils are not inherently harmful. When used in moderation and sourced from reputable producers, they can be a heart-healthy component of your diet. As with any food or supplement, it is wise to consider processing and sourcing—but the level of processing alone does not determine healthfulness. Similarly, as with any food or supplement, the calorie content should be considered when determining an adequate portion size, or how it fits into your overall diet. The overwhelming consensus from this body of literature is that seed oils are safe, and may even be protective against chronic disease when included as part of a balanced dietary pattern.

All the best,

Kevin Rogers, RDN, LD

Founder | Redesign Nutrition

References:

1. Hooper L, et al. (2020). "Reduction in saturated fat intake for cardiovascular disease." Cochrane Database Syst Rev, 5:CD011737.
2. Sacks FM, et al. (2017). "Dietary Fats and Cardiovascular Disease: A Presidential Advisory From the American Heart Association." Circulation, 136(3):e1–e23.
3. Schwingshackl L, et al. (2014). "Dietary fatty acids in the secondary prevention of coronary heart disease: a systematic review, meta-analysis and meta-regression." BMJ Open, 4:e004487.
4. Wu JH, et al. (2015). "Omega-6 fatty acid biomarkers and incident type 2 diabetes: pooled analysis of individual-level data for 39,740 adults from 20 prospective cohort studies." Lancet Diabetes Endocrinol, 5(12):965–974.
5. Imamura F, et al. (2016). "Dietary intake of saturated, monounsaturated, and polyunsaturated fatty acids and risk of stroke and cardiovascular disease: systematic review and meta-analysis of prospective cohort studies." BMJ, 353:i1246.
6. Abdelhamid AS, et al. (2018). "Omega-6 fatty acids for the primary and secondary prevention of cardiovascular disease." Cochrane Database Syst Rev, 11:CD011094.
7. Johnson GH, et al. (2022). "Dietary linoleic acid and risk of chronic disease: a systematic review and meta-analysis of randomized controlled trials." Adv Nutr, 13(2):346–362.