Should You Stop Eating Vegetable Oils?

Chapter summary

“Oils ain’t oils.” Vegetable oil is a contentious area that polarises nutritionists, doctors and industry.
Many diets recommend avoiding seed oils: soybean, cottonseed, safflower, sunflower, peanut, sesame, rapeseed (canola) and rice bran.
Avoid margarine and fake butters. Use butter, olive oil or coconut oil.
Oils are calorie-dense and can undo a good diet, so do not overconsume them.

Seed oils were unavailable before the 20th century because extraction technology did not exist. Processing may involve bleaching, deodorising and the solvent hexane.
The ratio: Through evolution omega-3 to omega-6 intake was about 1:1 to 1:3. Today it is about 1:16, with omega-6 in most processed food.
Body fat: Stephan Guyenet reviewed seven papers and found omega-6 (linoleic acid) in US body fat rose by about 300% in 40 years. These oils are chemically unstable, and are built into cells.
Inflammation: Some polyunsaturated oils may drive inflammation and metabolic syndrome.
Research gaps: Few epidemiological studies looked at oil type. Many were short, but disease takes decades. Industry dismisses animal studies.
Gillespie’s Toxic Oil makes the strong case that vegetable oil is harmful.

The Australian Heart Foundation and many medical associations still treat seed oils as healthy and recommend replacing saturated fat with polyunsaturated fat.
A 2012 systematic review of randomised trials (Johnson and Fritsche) found no evidence in healthy people that adding linoleic acid increases inflammation markers.
Cherry picking: The author admits research is ambivalent and each side picks its studies.

Avoid (high omega-6): canola, corn, cottonseed, peanut, safflower, soybean, sesame, sunflower, rapeseed, rice bran.
Fine: coconut oil and olive oil are excellent. Ratio examples: flaxseed 1:0.24, canola 1:2, walnut 1:5, corn 1:46, sesame 1:138.

Eliminate margarine and use butter sparingly.
Cook with olive oil, coconut oil or lard, not canola or rice bran.
Avoid foods cooked in or loaded with polyunsaturated oil.
Limit omega-3 and omega-6 supplements.
Eat leafy greens and one to two oily fish meals a week.
Do not become a food zealot. Avoiding seed oils entirely makes eating out almost impossible.
Omega-3 has some cancer concerns, but cardiovascular disease kills more people than cancer, and omega-3 protects against it.

Gillespie, D. (2012) Toxic Oil: Why Vegetable Oil Will Kill You. Pan Macmillan.
Simopoulos, A. (2006) Evolutionary aspects of diet, the omega-6/omega-3 ratio and genetic variation. Biomed Pharmacother 60(9):502-507.
Guyenet, S. (2011) Seed oils and body fatness: a problematic revisit. Whole Health Source.
Johnson, G. and Fritsche, K. (2012) Effect of dietary linoleic acid on markers of inflammation in healthy persons: a systematic review of randomized controlled trials. J Acad Nutr Diet.
Gunnars, K. (2013) Are vegetable and seed oils bad for your health? Authority Nutrition.
Jaminet, P. (2013) Omega-3 fats and cancer. Perfect Health Diet.
Heart Foundation Australia (2009) Dietary fats and dietary sterols for cardiovascular health: position statement.