Welcome to our long read on seed oils. In certain quarters, seed oils - also known as vegetable or plant oils - are branded 'the enemy of health', the root of inflammation and obesity. They are "poison" and "toxic", canola oil especially. But scientific and dietary advice says that seed oils - affordable and neutral in taste - rich in monounsaturated (MUFA) and polyunsaturated fatty acids (PUFAs) - are healthy.
Are seed to be avoided at all costs? What effect do they have on chronic illness? What are the arguments, what does the evidence show us?
As ever, please talk to your doctor or medical practitioner most familiar with your medical history before implementing any changes in diet, exercise or lifestyle, especially if you are under treatment. Links to supporting studies and resources are found throughout the article and at the end of page, meta-analyses and reviews are in blue.
The Arguments against Seed Oils
There are several lines of argument to be found.
“Seed oils make us fat."
Irrespective of source, fat has 9 calories per gram. Without a doubt, seed oils can cause weight gain, just like any oil or fat, from plant or animal. Too much soybean oil causes weight gain, as does olive oil or lard. 1 Tbsp (0.5 oz) oil contains 120 calories.
Over the last decades seed oil consumption has massively increased as has the consumption of processed foods. But are seed oils uniquely fattening or is this an eating practice issue?
If you are eating processed or fried foods, you will ingest more oil, fats and calories, be they omega 6 or saturated fats. In the West, since the 1960s, consumption of oils and corn sweeteners has dramatically increased. As have waistlines. Processed foods (often ultra-processed grains, mixed with oil, loaded with salt) are both unhealthy and popular. If your aim is to manage your weight, you need to manage your caloric intake, be the calories from oils, processed foods, fatty animal products or even whole foods.
Making better food choices when eating out or eating at home can all have a positive effect on diet and caloric intake. Reducing processed foods and fried foods are two areas to be mindful of.
“Seed oils are toxic, they are chemically and heat processed.”
Many seed oils, for example, canola (from rapeseed) are heat processed and deodorised. Of particular concern is a chemical called hexane used during the processing. Like many chemicals, hexane (it's boiling point, for evaporation, is a modest 69 Celsius, 169 Fahrenheit) is only allowed to be present in foods in very low quantities. Is hexane poisoning us? Is oil, using high heat and industrial processes, damaged before being bottled and sent to the supermarket? These are valid questions, we need to investigate the evidence.
Many substances that we consume are toxic, dependent on how much is consumed. In high concentrations hexane is neurotoxic. Much of the evidence we have relating to hexane exposure comes from industrial exposure, rather than from food consumption. Allowable limits on hexane in food are stipulated by health authorities. There does not appear to be any evidence of toxicity at quantities that might be consumed in the diet, unless one was consuming gallons of seed oils.
Worth to mention, seed oils are often used in commercial kitchens, for deep fat frying. These oils might be reused, reheated time and time again. Breaking down the oil into toxic components. A good argument for not eating fast food or, in the home kitchen, reheating or burning any oil for that matter.
“We eat too many MUFAS and PUFAs - and not enough omega-3 fats - this causes inflammation and promotes chronic illness.”
There are concerns over the ratio of oils in the diet, too much omega-6 vs omega-3 creating chronic inflammation. Confusingly while early trials (including many in rodents) suggested this conversion to arachidonic acid in the body, later studies including randomised control trials in humans have shown this not to be the case.
Studies...
Wang Q, Zhang H, Jin Q, Wang X. Effects of Dietary Linoleic Acid on Blood Lipid Profiles: A Systematic Review and Meta-Analysis of 40 Randomized Controlled Trials. Foods. 2023 May 25;12(11):2129. doi: 10.3390/foods12112129. PMID: 37297374; PMCID: PMC10253160.
Li J, Guasch-Ferré M, Li Y, Hu FB. Dietary intake and biomarkers of linoleic acid and mortality: systematic review and meta-analysis of prospective cohort studies. Am J Clin Nutr. 2020 Jul 1;112(1):150-167. doi: 10.1093/ajcn/nqz349. PMID: 32020162; PMCID: PMC7326588.
Marangoni F, Agostoni C, Borghi C, Catapano AL, Cena H, Ghiselli A, La Vecchia C, Lercker G, Manzato E, Pirillo A, Riccardi G, Risé P, Visioli F, Poli A. Dietary linoleic acid and human health: Focus on cardiovascular and cardiometabolic effects. Atherosclerosis. 2020 Jan;292:90-98. doi: 10.1016/j.atherosclerosis.2019.11.018. Epub 2019 Nov 15. PMID: 31785494.
Innes JK, Calder PC. Omega-6 fatty acids and inflammation. Prostaglandins Leukot Essent Fatty Acids. 2018 May;132:41-48. doi: 10.1016/j.plefa.2018.03.004. Epub 2018 Mar 22. PMID: 29610056.
Su H, Liu R, Chang M, Huang J, Wang X. Dietary linoleic acid intake and blood inflammatory markers: a systematic review and meta-analysis of randomized controlled trials. Food Funct. 2017 Sep 20;8(9):3091-3103. doi: 10.1039/c7fo00433h. PMID: 28752873.
Farvid MS, Ding M, Pan A, Sun Q, Chiuve SE, Steffen LM, Willett WC, Hu FB. Dietary linoleic acid and risk of coronary heart disease: a systematic review and meta-analysis of prospective cohort studies. Circulation. 2014 Oct 28;130(18):1568-78. doi: 10.1161/CIRCULATIONAHA.114.010236. Epub 2014 Aug 26. PMID: 25161045; PMCID: PMC4334131.
A meta-analysis on randomised controlled trials of CLA showed mixed results, perhaps increasing inflammatory markers CRP and TNF-α but decreasing IL6.
Haghighatdoost F, Nobakht M Gh BF. Effect of conjugated linoleic acid on blood inflammatory markers: a systematic review and meta-analysis on randomized controlled trials. Eur J Clin Nutr. 2018 Aug;72(8):1071-1082. doi: 10.1038/s41430-017-0048-z. Epub 2017 Dec 29. PMID: 29288248.
Canola (rapeseed) oil (about 18% linoleic acid), heat and chemically processed, is often highlighted as a seed oil of particular concern. The study below - an analysis of 42 randomised controlled trials in humans - demonstrates its positive effect, certainly for metabolic health.
Amiri M, Raeisi-Dehkordi H, Sarrafzadegan N, Forbes SC, Salehi-Abargouei A. The effects of Canola oil on cardiovascular risk factors: A systematic review and meta-analysis with dose-response analysis of controlled clinical trials. Nutr Metab Cardiovasc Dis. 2020 Nov 27;30(12):2133-2145. doi: 10.1016/j.numecd.2020.06.007. Epub 2020 Jun 18. PMID: 33127255.
Soybean oil (about 50% linoleic acid) does not affect inflammatory biomarkers or increase oxidative stress....
Messina M, Shearer G, Petersen K. Soybean oil lowers circulating cholesterol levels and coronary heart disease risk, and has no effect on markers of inflammation and oxidation. Nutrition. 2021 Sep;89:111343. doi: 10.1016/j.nut.2021.111343. Epub 2021 May 16. PMID: 34171740.
TIME, 2014, "Eat Butter"
In 2014 TIME Magazine front paged a meta-analysis that reversed years of advice to avoid saturated fat. Unfortunately the meta-analysis by Siri-Tarino had some significant flaws in its design but by the time the article had been published, the damage was done.
Both the Siri-Tarino and in a similar vein Chowdhury meta-analyses have caused significant confusion about the role of saturated fat in heart disease. Their conclusions conflict with a wider body of research, including rigorous randomised controlled trials (RCTs), which show clear benefits to reducing saturated fat intake. Key Issues with both studies:
Replacement Nutrients: Both analyses ignored what replaced saturated fat in people's diets. If saturated fat is swapped for refined carbs (e.g. cookies or sugary foods), heart disease risk stays the same or worsens. However, replacing saturated fat with polyunsaturated fats, unrefined carbs, or plant protein (e.g., nuts, fish, whole grains) significantly lowers heart disease risk.
Over-Adjustment: About half the studies included controlled for blood cholesterol levels, which removes the very factor (higher LDL cholesterol from saturated fat) linked to heart disease. This "over-adjustment" invalidates their findings.
Specific to the Chowdhury study, when a flawed study (the Sydney Diet Heart Study, 1966) was removed from the meta-analysis, results showed a 19% reduction in heart disease risk when saturated fats were replaced with polyunsaturated fats.
Why was the Sydney study flawed? The intervention used a margarine that contained trans fats, which are now known to be harmful and significantly increase the risk of heart disease. This confounded the effects of replacing saturated fats with PUFAs, making it unclear whether the observed outcomes were due to the replacement itself or the presence of trans fats.
Despite this correction, misleading headlines like "Butter is Back" had already misinformed the public. Properly conducted research consistently supports replacing saturated fat with healthier alternatives for better heart health.
The Effect of Replacing Saturated Fat with Omega-6 PUFAs
What happens if you replace saturated fat in the diet? This 2021 meta-analysis concluded the following:
Conclusion: Although only limited data were available, replacement of saturated fats with other macronutrients, such as polyunsaturated fats, was associated with reduced cardiovascular disease occurrence. Supporting evidence from research in the general population increases confidence in these findings. Until more data are available to better comment on dietary fat intakes in cardiovascular disease risk of those with type 2 diabetes, it appears appropriate that saturated fats be replaced in the diet with other macronutrients, such as polyunsaturated fats." Schwab U, Reynolds AN, Sallinen T, Rivellese AA, Risérus U. Dietary fat intakes and cardiovascular disease risk in adults with type 2 diabetes: a systematic review and meta-analysis. Eur J Nutr. 2021 Sep;60(6):3355-3363. doi: 10.1007/s00394-021-02507-1. Epub 2021 Feb 21. PMID: 33611616.
"In this large prospective cohort, intakes of butter and margarine were associated with higher all-cause, cardiometabolic, and other major cause-specific mortality, whereas intakes of canola oil and olive oil were related to lower mortality. Substituting corn oil, canola oil, or olive oil for butter and margarine was associated with lower all-cause, cardiometabolic, cancer, respiratory disease, and Alzheimer's disease mortality." Zhang, Y., Zhuang, P., Wu, F. et al. Cooking oil/fat consumption and deaths from cardiometabolic diseases and other causes: prospective analysis of 521,120 individuals. BMC Med 19, 92 (2021). https://doi.org/10.1186/s12916-021-01961-2
"High saturated and trans fat intake (which elevates LDL like saturated fat) in the Nurses and Health Professional Follow-Up Studies combined is associated with an 8–13% higher mortality and replacement of saturated fat with any carbohydrate, PUFA and MUFA is associated with lower mortality with PUFA being more effective than MUFA (19% reduction versus 11%).
With CVD mortality only PUFA and fish oil replacement of saturated fat lowers risk with a 28% reduction in CVD mortality per 5% of energy. Replacing saturated fat with PUFA or MUFA is equally effective at reducing CHD events and replacement with whole grains will lower events while replacement with sugar and starch increases events.
Replacement of saturated fat with carbohydrate has no effect on CHD events or death. Only PUFA replacement of saturated fat lowers CHD events and CVD and total mortality. Replacing saturated fat with linoleic acid appears to be beneficial based on the Hooper Cochrane meta-analysis of interventions although other analyses with fewer studies have shown no effect." Clifton PM, Keogh JB. A systematic review of the effect of dietary saturated and polyunsaturated fat on heart disease. Nutr Metab Cardiovasc Dis. 2017 Dec;27(12):1060-1080. doi: 10.1016/j.numecd.2017.10.010. Epub 2017 Oct 18. PMID: 29174025.
"Authors' conclusions: The findings of this updated review are suggestive of a small but potentially important reduction in cardiovascular risk on reduction of saturated fat intake. Replacing the energy from saturated fat with polyunsaturated fat appears to be a useful strategy, and replacement with carbohydrate appears less useful, but effects of replacement with monounsaturated fat were unclear due to inclusion of only one small trial. This effect did not appear to alter by study duration, sex or baseline level of cardiovascular risk. Lifestyle advice to all those at risk of cardiovascular disease and to lower risk population groups should continue to include permanent reduction of dietary saturated fat and partial replacement by unsaturated fats. The ideal type of unsaturated fat is unclear." Hooper L, Martin N, Abdelhamid A, Davey Smith G. Reduction in saturated fat intake for cardiovascular disease. Cochrane Database Syst Rev. 2015 Jun 10;(6):CD011737. doi: 10.1002/14651858.CD011737. Update in: Cochrane Database Syst Rev. 2020 May 19;5:CD011737. doi: 10.1002/14651858.CD011737.pub2. PMID: 26068959.
The Role of Omega-3
Importantly, regarding omega-3 intake, we know that sub-optimal amounts of dietary omega-3 fatty acids leads to poor health outcomes. Many people are not consuming enough omega-3. Therefore, if the omega-6:omega-3 ratio is too high, it is possibly not that the total quantity of omega-6 is to blame but rather that many people have a deficit of essential omega-3 that drives poor health outcomes.
Once again the solution lies in the shopping basket or at the dining table. Consuming more omega-3s, primarily from oily fish like sardines, salmon and mackerel; or alternatively walnuts, flaxseed and chia seed. Another method, an omega-3 (DHA, EPA) supplement, from fish or algal sources. And at the same time reducing processed foods - will bring about health benefits.
Are seed oils inherently harmful to health, or, are they simply part of poor eating practices in modern times?
The Nutrition Transition: From Bolivia to the USA
As societies transition from ancient to modern or rural to urban lifestyle, eating practices change. Typically, fibre is lost from the diet, sugar consumption increases, processed foods and modern cooking techniques such as deep frying become more commonplace. We can compare two different societies and cultures, the Tsimane tribe from Amazonian Bolivia and the US public.
The Tsimane
Anthropologists from UC Santa Barbara studied this in depth as part of the Tsimane Health and Life History Project, studying the diet of a hunter-gatherer Amazonian tribe (the Tsimane) in transition, as they increasingly accessed processed foods and modern eating practices.
Over five years they saw the Tsimane’s total energy intake increase significantly, particularly the consumption of food additives:
Lard (animal fat)
Oils
Sugar
To quote from the study "Most dramatically, per-capita consumption of refined sugar and oil increased by 15.8 g/d and 4.9 mL/d over the 5.5-y study period." In caloric terms this equates to an additional 63.2 calories per day from sugar and 40.6 calories per day from oil.
Read an interview with one of the study's authors, Michael Gurven, here, and this is the study:
Kraft TS, Stieglitz J, Trumble BC, Martin M, Kaplan H, Gurven M. Nutrition transition in 2 lowland Bolivian subsistence populations. Am J Clin Nutr. 2018 Dec 1;108(6):1183-1195. doi: 10.1093/ajcn/nqy250. PMID: 30383188; PMCID: PMC6290367.
The US Public
Looking to a society that has transitioned, we can see greater shifts in eating patterns. In the US, while refined sugar consumption has gone down, both seed oil and sugar in other forms has increased. This includes corn sweeteners (also 'sugar') and 'corn products' - likely refined flour, which is effectively... sugar. Read more on the research from Pew Research here.
The average US citizen faces a triple whammy of highly calorific oils/fats, sugars/sweeteners and processed carbohydrates that lead to weight gain and ill health. While beef consumption may have declined by a third, chicken (by no means a health food given modern rearing practices) has doubled, as has cheese consumption.
Related to this topic, there is sometimes an argument that the US Dietary Recommendations have caused the obesity crisis although the data shows that US residents simply have not or not been able to follow them.
The CDC website states that "In 2019, 12.3% and 10.0% of surveyed adults met fruit and vegetable intake recommendations, respectively. Meeting fruit intake recommendations was highest among Hispanic adults (16.4%) and lowest among males (10.1%). Meeting vegetable intake recommendations was highest among adults aged ≥51 years (12.5%) and lowest among adults with low income (6.8%)." Source: link here
Are seed oils the root of America's obesity problem? Partially. Perhaps America's processed food eating practices are more to blame rather than the seed oils themselves.
Where Does the Evidence - in Humans - Lead Us?
When we look at the evidence below, across multiple trials and studies on human health outcomes (as opposed to short timeframe studies on mice or in vitro) there is little evidence to show that seed oils are harmful.
That is not to say that all studies are 100% consistent, studies can show different results so it is worthwhile to see what the totality of the evidence shows. We have focused on using systematic reviews and meta-analyses (studies that combine multiple studies) and where (but not always) possible, randomised control trials to reduce research bias.
As the science has evolved rapidly in this area, it is also worthwhile to focus on recent evidence.
Below we review key studies on the consumption of seed oils and various chronic illness outcomes. We quote directly from the studies and include more than one to provide a broader perspective. It's a bit of a read. Sources are provided immediately after each quote.
Condition - Chronic Illness
Cardiovascular Disease
“PUFAs are abundant in many fat-rich foods, especially vegetable oils and fish, and have attracted wide attention due to their important physiological functions in the human body. Our study found that dietary intake of PUFAs such as ODTA, ALA, DPA, and ODA were significantly associated with different CVDs. Higher level of dietary ALA intake was related to lower risks of all-cause mortality, CVD-specific mortality, and other cause-specific mortality. In addition, AA and DPA were also seemed to be benefit to cardiovascular health.
"Results: Twelve studies from 11 observational articles involving 47 836 individuals were included in the meta-analysis. We observed an inverse association between biomarkers of dietary LA and risk for total stroke (HR, 0.88; 95% CI, 0.83-0.94; P < 0.001). Meta-regression analysis suggested that ethnicity (P = 0.029) and study design (P = 0.049) contributed to between-study heterogeneity. Subgroup analysis showed that the association was statistically significant among studies conducted in white (P < 0.001) and Asian (P = 0.032) populations, and those with cohort (P = 0.001) and case-cohort design (P = 0.007). Moreover, we found that higher LA levels were associated with a reduced risk for ischemic stroke (HR, 0.87; 95% CI, 0.80-0.95; P = 0.001), although no statistically significant association was found between LA levels and the risk for hemorrhagic stroke.
Conclusions: The present study supported an inverse association of LA levels with the risk for stroke, particularly ischemic stroke. Racial disparity exists in the association between LA and the risk for stroke, which deserves further studies."
Zhang W, Zhou F, Huang H, Mao Y, Ye D. Biomarker of dietary linoleic acid and risk for stroke: A systematic review and meta-analysis. Nutrition. 2020 Nov-Dec;79-80:110953. doi: 10.1016/j.nut.2020.110953. Epub 2020 Jul 25. PMID: 32862121.
"In this harmonized, individual-level pooled analysis across 30 prospective studies from 13 countries, higher in vivo levels of the n-6 PUFA LA were associated with lower risk of CVD events, in particular, CVD mortality and stroke. AA levels were not associated with higher risk, and were associated with lower CVD risk in some analyses. To our knowledge, this is the largest pooled analysis of fatty acid levels and CVD end points, including ≈70 000 individuals and 10 000 total CVD events.
Our findings provide evidence to help inform currently inconsistent global dietary recommendations on n-6 PUFA consumption. LA, an essential fatty acid not synthesized by humans, is the main dietary PUFA, comprising ≈85% to 90% of the total. Although circulating and adipose tissue LA levels can be influenced by metabolism, they are established and useful markers of diet because they increase in a dose-response manner in response to dietary LA in controlled feeding trials and consistently correlate with self-reported dietary estimates in large cohort studies, including a considerable number of studies participating in the current analysis. Several lines of evidence support mechanisms by which dietary LA may reduce CVD. In randomized controlled feeding trials, dietary PUFA (primarily LA) as a replacement for either carbohydrates or saturated fat lowers low-density lipoprotein cholesterol, triglycerides, and apolipoprotein B levels, and raises high-density lipoprotein cholesterol, and also lowers hemoglobin A1c and insulin resistance and potentially augments insulin production. Other potential cardiometabolic benefits of dietary LA may include favorable effects on inflammation, blood pressure, and body composition, including prevention and reduction of visceral and liver fat. In a pooled analyses of prospective cohort studies, self-reported estimates of LA consumption are associated with lower CHD risk. Similarly, in meta-analyses of older, limited clinical trials, increased consumption of LA-rich vegetable oils, especially soybean oil, reduces the risk of CHD. Our findings evaluating in vivo levels of LA status across multiple global studies add strong support for the cardiovascular benefits of LA.
Although AA has long been considered an archetypical proinflammatory and prothrombotic fatty acid, growing evidence suggests that its effects may be more complex. In the present investigation, AA levels were not associated with higher risk of CVD, and indeed in some analyses were associated with lower risk. These results do not provide support for adverse cardiovascular effects of AA. Although AA is the precursor to potentially proinflammatory leukotrienes, it is also the main precursor to key anti-inflammatory metabolites, such as epoxyeicosatrienoic acids and prostaglandin E2, and other mediators that actively resolve inflammation, such as lipoxin A4, as well. It also gives rise to prostacyclin, a potent antiaggregatory and vasodilatory molecule. These complex biological effects preclude simplistic inference on the health effects of AA metabolites and further support the importance of the empirical assessment of relationships with clinical events, such as in our investigation." Marklund M, Wu JHY, Imamura F, Del Gobbo LC, Fretts A, de Goede J, Shi P, Tintle N, Wennberg M, Aslibekyan S, Chen TA, de Oliveira Otto MC, Hirakawa Y, Eriksen HH, Kröger J, Laguzzi F, Lankinen M, Murphy RA, Prem K, Samieri C, Virtanen J, Wood AC, Wong K, Yang WS, Zhou X, Baylin A, Boer JMA, Brouwer IA, Campos H, Chaves PHM, Chien KL, de Faire U, Djoussé L, Eiriksdottir G, El-Abbadi N, Forouhi NG, Michael Gaziano J, Geleijnse JM, Gigante B, Giles G, Guallar E, Gudnason V, Harris T, Harris WS, Helmer C, Hellenius ML, Hodge A, Hu FB, Jacques PF, Jansson JH, Kalsbeek A, Khaw KT, Koh WP, Laakso M, Leander K, Lin HJ, Lind L, Luben R, Luo J, McKnight B, Mursu J, Ninomiya T, Overvad K, Psaty BM, Rimm E, Schulze MB, Siscovick D, Skjelbo Nielsen M, Smith AV, Steffen BT, Steffen L, Sun Q, Sundström J, Tsai MY, Tunstall-Pedoe H, Uusitupa MIJ, van Dam RM, Veenstra J, Monique Verschuren WM, Wareham N, Willett W, Woodward M, Yuan JM, Micha R, Lemaitre RN, Mozaffarian D, Risérus U; Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Fatty Acids and Outcomes Research Consortium (FORCE). Biomarkers of Dietary Omega-6 Fatty Acids and Incident Cardiovascular Disease and Mortality. Circulation. 2019 May 21;139(21):2422-2436. doi: 10.1161/CIRCULATIONAHA.118.038908. PMID: 30971107; PMCID: PMC6582360.
“Increasing polyunsaturated fatty acid (PUFA) intake probably makes little or no difference (neither benefit nor harm) to all‐cause mortality and probably slightly reduces the risk of coronary heart disease events and cardiovascular disease events (all moderate‐quality evidence). Increased PUFA intake may slightly reduce risk of coronary heart disease mortality and stroke (although for stroke the confidence intervals include important harm), but may have little or no effect on cardiovascular disease mortality (all low‐quality evidence). Increasing PUFA does reduce total cholesterol, probably reduces triglyceride, probably has little or no effect on high‐density lipoprotein (HDL) or low‐density lipoprotein (LDL) and probably increases body weight.
This suggests that increasing PUFA intake may have beneficial effects on risk of cardiovascular disease events, coronary heart disease mortality, coronary heart disease events and stroke. The mechanism may be via reduction of total cholesterol and triglyceride. However increasing PUFA will probably lead to slight body weight increase.” Source: Abdelhamid AS, Martin N, Bridges C, Brainard JS, Wang X, Brown TJ, Hanson S, Jimoh OF, Ajabnoor SM, Deane KH, Song F, Hooper L. Polyunsaturated fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane Database Syst Rev. 2018 Jul 18;7(7):CD012345. doi: 10.1002/14651858.CD012345.pub2. Update in: Cochrane Database Syst Rev. 2018 Nov 27;11:CD012345. PMID: 30019767; PMCID: PMC6513571.
Cognitive Health
Prostate Cancer
Type 2 Diabetes
Body Weight
In Summary
So, where does this leave us? Are seed oils “toxic” or "poisonous"? While some small scale and mechanistic studies (often in rodents) have shown negative results, a large body of research in human health outcomes shows the opposite. Multiple studies demonstrate that seed oils containing MUFAs and PUFAs lower cholesterol, improve cardiovascular heart health, contribute to better blood sugar control and even lead to better weight control than diets high in saturated fats. Please see below for additional studies to those already cited.
We can also see that overconsumption of fats, oils - from whatever the source, seed oil or not - is inherently fattening and harmful.
So what can we do when it comes to oils, from plant or animal?
Removing processed and fried foods leads to better weight and health outcomes. Minimise consumption of processed and fast foods; chips, crisps, buns, cakes and starchy delights. Save these for an occasional treat!
Focus on a whole food (or 'minimally processed' food) diet.
For general health and weight management, don’t consume any oil or fat in quantity. Using a seed oil to fry or a small knob of butter to flavour your vegetables is not going to harm you.
When frying at home, choose an oil with a high smoke point. Consider avocado, peanut, canola, sunflower or sesame oil. Avoid burning (smoking) or reusing oil when you cook.
Include nuts, seeds in your diet. These sources of oils are rich in health promoting polyphenols, antioxidant compounds, micronutrients and fibre.
Include omega 3 rich fatty fish into your diet; consider using an omega 3 supplement.
If you prefer to avoid seed soils, by all means do so. For home cooking use olive oil, rich in polyphenols, or avocado oil.
Ultimately it would appear to be wrong to demonise seed oils and more appropriate to focus on our broader eating patterns. To be more aware of 'hidden' fats and oils, to remove or minimise processed (and especially ultra processed) foods and concentrate on enjoying whole foods in our daily eating choices.
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, 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 me, or scroll down to contact us and learn more about our services:
Achieve your Dietary and Health Goals
Your 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 and arrange an introductory call. Contact us, by phone or WhatsApp, 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.
Related Studies
2024
Tillander V, Holmer M, Hagström H, Petersson S, Brismar TB, Stål P, Lindqvist C. Associations between dietary fatty acid and plasma fatty acid composition in non-alcoholic fatty liver disease: secondary analysis from a randomised trial with a hypoenergetic low-carbohydrate high-fat and intermittent fasting diet. Br J Nutr. 2024 Sep 18;132(4):1-13. doi: 10.1017/S0007114524001673. Epub ahead of print. PMID: 39290088; PMCID: PMC11499086.
Maleki Sedgi F, Mohammad Hosseiniazar M, Alizadeh M. The effects of replacing ghee with rapeseed oil on liver steatosis and enzymes, lipid profile, insulin resistance and anthropometric measurements in patients with non-alcoholic fatty liver disease: a randomised controlled clinical trial. Br J Nutr. 2024 Jun 28;131(12):1985-1996. doi: 10.1017/S0007114524000564. Epub 2024 Mar 19. PMID: 38501177.
O'Keefe EL, O'Keefe JH, Tintle NL, Westra J, Albuisson L, Harris WS. Circulating Docosahexaenoic Acid and Risk of All-Cause and Cause-Specific Mortality. Mayo Clin Proc. 2024 Apr;99(4):534-541. doi: 10.1016/j.mayocp.2023.11.026. Epub 2024 Mar 20. PMID: 38506781.
Akhgarjand C, Tavakoli A, Samavat S, Bagheri A, Anoushirvani A, Mirzababaei A, Amini MR, Ghorbi MD, Valisoltani N, Mansour A, Sajjadi-Jazi SM, Ansar H, Rezvani H. The effect of conjugated linoleic acid supplementation in comparison with omega-6 and omega-9 on lipid profile: a graded, dose-response systematic review and meta-analysis of randomized controlled trials. Front Nutr. 2024 Mar 19;11:1336889. doi: 10.3389/fnut.2024.1336889. PMID: 38567248; PMCID: PMC10985181.
2023
Garg PK, Guan W, Nomura S, Weir NL, Tintle N, Virtanen JK, Hirakawa Y, Qian F, Sun Q, Rimm E, Lemaitre RN, Jensen PN, Heckbert SR, Imamura F, Steur M, Leander K, Laguzzi F, Voortman T, Ninomiya T, Mozaffarian D, Harris WS, Siscovick DS, Tsai MY; Fatty Acids and Outcomes Research Consortium (FORCE). n-6 fatty acid biomarkers and incident atrial fibrillation: an individual participant-level pooled analysis of 11 international prospective studies. Am J Clin Nutr. 2023 Nov;118(5):921-929. doi: 10.1016/j.ajcnut.2023.09.008. Epub 2023 Sep 26. PMID: 37769813.
Delgado-Alarcón JM, Hernández Morante JJ, Morillas-Ruiz JM. Modification of Breakfast Fat Composition Can Modulate Cytokine and Other Inflammatory Mediators in Women: A Randomized Crossover Trial. Nutrients. 2023 Aug 24;15(17):3711. doi: 10.3390/nu15173711. PMID: 37686743; PMCID: PMC10489665.
Lee SH, Zhao L, Park S, Moore LV, Hamner HC, Galuska DA, Blanck HM. High Added Sugars Intake among US Adults: Characteristics, Eating Occasions, and Top Sources, 2015-2018. Nutrients. 2023 Jan 4;15(2):265. doi: 10.3390/nu15020265. PMID: 36678136; PMCID: PMC9867287.
Wang Q, Zhang H, Jin Q, Wang X. Effects of Dietary Linoleic Acid on Blood Lipid Profiles: A Systematic Review and Meta-Analysis of 40 Randomized Controlled Trials. Foods. 2023 May 25;12(11):2129. doi: 10.3390/foods12112129. PMID: 37297374; PMCID: PMC10253160.
Bjornevik K, Cortese M, Furtado JD, Paganoni S, Schwarzschild MA, Cudkowicz ME, Ascherio A. Association of Polyunsaturated Fatty Acids and Clinical Progression in Patients With ALS: Post Hoc Analysis of the EMPOWER Trial. Neurology. 2023 Aug 15;101(7):e690-e698. doi: 10.1212/WNL.0000000000207485. Epub 2023 Jun 21. PMID: 37344230; PMCID: PMC10437021.
2022
Pigsborg K, Gürdeniz G, Rangel-Huerta OD, Holven KB, Dragsted LO, Ulven SM. Effects of changing from a diet with saturated fat to a diet with n-6 polyunsaturated fat on the serum metabolome in relation to cardiovascular disease risk factors. Eur J Nutr. 2022 Jun;61(4):2079-2089. doi: 10.1007/s00394-021-02796-6. Epub 2022 Jan 9. PMID: 34999928; PMCID: PMC9106625.
2021
Chen LH, Hu Q, Li G, Zhang L, Qin LQ, Zuo H, Xu G. Dietary Intake and Biomarkers of α-Linolenic Acid and Mortality: A Meta-Analysis of Prospective Cohort Studies. Front Nutr. 2021 Nov 3;8:743852. doi: 10.3389/fnut.2021.743852. PMID: 34805241; PMCID: PMC8595337.
Kapoor B, Kapoor D, Gautam S, Singh R, Bhardwaj S. Dietary Polyunsaturated Fatty Acids (PUFAs): Uses and Potential Health Benefits. Curr Nutr Rep. 2021 Sep;10(3):232-242. doi: 10.1007/s13668-021-00363-3. Epub 2021 Jul 13. PMID: 34255301.
Zhang Y, Zhuang P, Wu F, He W, Mao L, Jia W, Zhang Y, Chen X, Jiao J. Cooking oil/fat consumption and deaths from cardiometabolic diseases and other causes: prospective analysis of 521,120 individuals. BMC Med. 2021 Apr 15;19(1):92. doi: 10.1186/s12916-021-01961-2. PMID: 33853582; PMCID: PMC8048052.
Naghshi S, Aune D, Beyene J, Mobarak S, Asadi M, Sadeghi O. Dietary intake and biomarkers of alpha linolenic acid and risk of all cause, cardiovascular, and cancer mortality: systematic review and dose-response meta-analysis of cohort studies. BMJ. 2021 Oct 13;375:n2213. doi: 10.1136/bmj.n2213. PMID: 34645650; PMCID: PMC8513503.
2020
Amiri M, Raeisi-Dehkordi H, Sarrafzadegan N, Forbes SC, Salehi-Abargouei A. The effects of Canola oil on cardiovascular risk factors: A systematic review and meta-analysis with dose-response analysis of controlled clinical trials. Nutr Metab Cardiovasc Dis. 2020 Nov 27;30(12):2133-2145. doi: 10.1016/j.numecd.2020.06.007. Epub 2020 Jun 18. PMID: 33127255.
Li J, Guasch-Ferré M, Li Y, Hu FB. Dietary intake and biomarkers of linoleic acid and mortality: systematic review and meta-analysis of prospective cohort studies. Am J Clin Nutr. 2020 Jul 1;112(1):150-167. doi: 10.1093/ajcn/nqz349. PMID: 32020162; PMCID: PMC7326588.
Wu F, Mao L, Zhuang P, Chen X, Jiao J, Zhang Y. Plant-sourced cooking oil consumption is associated with lower total mortality in a longitudinal nationwide cohort study. Clin Nutr. 2020 Dec;39(12):3703-3710. doi: 10.1016/j.clnu.2020.03.031. Epub 2020 Apr 2. PMID: 32359931.
Chen CG , Wang P , Zhang ZQ , Ye YB , Zhuo SY , Zhou Q , Chen YM , Su YX , Zhang B . Effects of plant oils with different fatty acid composition on cardiovascular risk factors in moderately hypercholesteremic Chinese adults: a randomized, double-blinded, parallel-designed trial. Food Funct. 2020 Aug 1;11(8):7164-7174. doi: 10.1039/d0fo00875c. Epub 2020 Aug 5. PMID: 32756661.
Hooper L, Martin N, Jimoh OF, Kirk C, Foster E, Abdelhamid AS. Reduction in saturated fat intake for cardiovascular disease. Cochrane Database Syst Rev. 2020 Aug 21;8(8):CD011737. doi: 10.1002/14651858.CD011737.pub3. PMID: 32827219; PMCID: PMC8092457.
2019
Marklund M, Wu JHY, Imamura F, Del Gobbo LC, Fretts A, de Goede J, Shi P, Tintle N, Wennberg M, Aslibekyan S, Chen TA, de Oliveira Otto MC, Hirakawa Y, Eriksen HH, Kröger J, Laguzzi F, Lankinen M, Murphy RA, Prem K, Samieri C, Virtanen J, Wood AC, Wong K, Yang WS, Zhou X, Baylin A, Boer JMA, Brouwer IA, Campos H, Chaves PHM, Chien KL, de Faire U, Djoussé L, Eiriksdottir G, El-Abbadi N, Forouhi NG, Michael Gaziano J, Geleijnse JM, Gigante B, Giles G, Guallar E, Gudnason V, Harris T, Harris WS, Helmer C, Hellenius ML, Hodge A, Hu FB, Jacques PF, Jansson JH, Kalsbeek A, Khaw KT, Koh WP, Laakso M, Leander K, Lin HJ, Lind L, Luben R, Luo J, McKnight B, Mursu J, Ninomiya T, Overvad K, Psaty BM, Rimm E, Schulze MB, Siscovick D, Skjelbo Nielsen M, Smith AV, Steffen BT, Steffen L, Sun Q, Sundström J, Tsai MY, Tunstall-Pedoe H, Uusitupa MIJ, van Dam RM, Veenstra J, Monique Verschuren WM, Wareham N, Willett W, Woodward M, Yuan JM, Micha R, Lemaitre RN, Mozaffarian D, Risérus U; Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Fatty Acids and Outcomes Research Consortium (FORCE). Biomarkers of Dietary Omega-6 Fatty Acids and Incident Cardiovascular Disease and Mortality. Circulation. 2019 May 21;139(21):2422-2436. doi: 10.1161/CIRCULATIONAHA.118.038908. PMID: 30971107; PMCID: PMC6582360.
Zhao JV, Schooling CM. Effect of linoleic acid on ischemic heart disease and its risk factors: a Mendelian randomization study. BMC Med. 2019 Mar 14;17(1):61. doi: 10.1186/s12916-019-1293-x. PMID: 30866921; PMCID: PMC6417131.
2018
Virtanen JK, Wu JHY, Voutilainen S, Mursu J, Tuomainen TP. Serum n-6 polyunsaturated fatty acids and risk of death: the Kuopio Ischaemic Heart Disease Risk Factor Study. Am J Clin Nutr. 2018 Mar 1;107(3):427-435. doi: 10.1093/ajcn/nqx063. PMID: 29566193.
Innes JK, Calder PC. Omega-6 fatty acids and inflammation. Prostaglandins Leukot Essent Fatty Acids. 2018 May;132:41-48. doi: 10.1016/j.plefa.2018.03.004. Epub 2018 Mar 22. PMID: 29610056.
2017
Su H, Liu R, Chang M, Huang J, Wang X. Dietary linoleic acid intake and blood inflammatory markers: a systematic review and meta-analysis of randomized controlled trials. Food Funct. 2017 Sep 20;8(9):3091-3103. doi: 10.1039/c7fo00433h. PMID: 28752873.
Wu JHY, Marklund M, Imamura F, Tintle N, Ardisson Korat AV, de Goede J, Zhou X, Yang WS, de Oliveira Otto MC, Kröger J, Qureshi W, Virtanen JK, Bassett JK, Frazier-Wood AC, Lankinen M, Murphy RA, Rajaobelina K, Del Gobbo LC, Forouhi NG, Luben R, Khaw KT, Wareham N, Kalsbeek A, Veenstra J, Luo J, Hu FB, Lin HJ, Siscovick DS, Boeing H, Chen TA, Steffen B, Steffen LM, Hodge A, Eriksdottir G, Smith AV, Gudnason V, Harris TB, Brouwer IA, Berr C, Helmer C, Samieri C, Laakso M, Tsai MY, Giles GG, Nurmi T, Wagenknecht L, Schulze MB, Lemaitre RN, Chien KL, Soedamah-Muthu SS, Geleijnse JM, Sun Q, Harris WS, Lind L, Ärnlöv J, Riserus U, Micha R, Mozaffarian D; Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Fatty Acids and Outcomes Research Consortium (FORCE). Omega-6 fatty acid biomarkers and incident type 2 diabetes: pooled analysis of individual-level data for 39 740 adults from 20 pros Lancet Diabetes Endocrinol. 2017 Dec;5(12):965-974. doi: 10.1016/S2213-8587(17)30307-8. Epub 2017 Oct 12. PMID: 29032079; PMCID: PMC6029721.
Su H, Liu R, Chang M, Huang J, Wang X. Dietary linoleic acid intake and blood inflammatory markers: a systematic review and meta-analysis of randomized controlled trials. Food Funct. 2017 Sep 20;8(9):3091-3103. doi: 10.1039/c7fo00433h. PMID: 28752873.
Richter CK, Bowen KJ, Mozaffarian D, Kris-Etherton PM, Skulas-Ray AC. Total Long-Chain n-3 Fatty Acid Intake and Food Sources in the United States Compared to Recommended Intakes: NHANES 2003-2008. Lipids. 2017 Nov;52(11):917-927. doi: 10.1007/s11745-017-4297-3. Epub 2017 Sep 27. PMID: 28956299.
2014
Nigam P, Bhatt S, Misra A, Chadha DS, Vaidya M, Dasgupta J, Pasha QM. Effect of a 6-month intervention with cooking oils containing a high concentration of monounsaturated fatty acids (olive and canola oils) compared with control oil in male Asian Indians with nonalcoholic fatty liver disease. Diabetes Technol Ther. 2014 Apr;16(4):255-61. doi: 10.1089/dia.2013.0178. PMID: 24625239.
Wu JH, Lemaitre RN, King IB, Song X, Psaty BM, Siscovick DS, Mozaffarian D. Circulating omega-6 polyunsaturated fatty acids and total and cause-specific mortality: the Cardiovascular Health Study. Circulation. 2014 Oct 7;130(15):1245-53. doi: 10.1161/CIRCULATIONAHA.114.011590. Epub 2014 Aug 14. PMID: 25124495; PMCID: PMC4189990.
Krishnan S, Cooper JA. Effect of dietary fatty acid composition on substrate utilization and body weight maintenance in humans. Eur J Nutr. 2014 Apr;53(3):691-710. doi: 10.1007/s00394-013-0638-z. Epub 2013 Dec 22. PMID: 24363161.
Farvid MS, Ding M, Pan A, Sun Q, Chiuve SE, Steffen LM, Willett WC, Hu FB. Dietary linoleic acid and risk of coronary heart disease: a systematic review and meta-analysis of prospective cohort studies. Circulation. 2014 Oct 28;130(18):1568-78. doi: 10.1161/CIRCULATIONAHA.114.010236. Epub 2014 Aug 26. PMID: 25161045; PMCID: PMC4334131.
2012
Bjermo H, Iggman D, Kullberg J, Dahlman I, Johansson L, Persson L, Berglund J, Pulkki K, Basu S, Uusitupa M, Rudling M, Arner P, Cederholm T, Ahlström H, Risérus U. Effects of n-6 PUFAs compared with SFAs on liver fat, lipoproteins, and inflammation in abdominal obesity: a randomized controlled trial. Am J Clin Nutr. 2012 May;95(5):1003-12. doi: 10.3945/ajcn.111.030114. Epub 2012 Apr 4. PMID: 22492369.
Perez-Herrera A, Delgado-Lista J, Torres-Sanchez LA, Rangel-Zuñiga OA, Camargo A, Moreno-Navarrete JM, Garcia-Olid B, Quintana-Navarro GM, Alcala-Diaz JF, Muñoz-Lopez C, Lopez-Segura F, Fernandez-Real JM, Luque de Castro MD, Lopez-Miranda J, Perez-Jimenez F. The postprandial inflammatory response after ingestion of heated oils in obese persons is reduced by the presence of phenol compounds. Mol Nutr Food Res. 2012 Mar;56(3):510-4. doi: 10.1002/mnfr.201100533. Epub 2011 Dec 9. PMID: 22162245.
2011
Rett BS, Whelan J. Increasing dietary linoleic acid does not increase tissue arachidonic acid content in adults consuming Western-type diets: a systematic review. Nutr Metab (Lond). 2011 Jun 10;8:36. doi: 10.1186/1743-7075-8-36. PMID: 21663641; PMCID: PMC3132704.
Pfeuffer M, Fielitz K, Laue C, Winkler P, Rubin D, Helwig U, Giller K, Kammann J, Schwedhelm E, Böger RH, Bub A, Bell D, Schrezenmeir J. CLA does not impair endothelial function and decreases body weight as compared with safflower oil in overweight and obese male subjects. J Am Coll Nutr. 2011 Feb;30(1):19-28. doi: 10.1080/07315724.2011.10719940. PMID: 21697535.
Perez-Herrera A, Delgado-Lista J, Torres-Sanchez LA, Rangel-Zuñiga OA, Camargo A, Moreno-Navarrete JM, Garcia-Olid B, Quintana-Navarro GM, Alcala-Diaz JF, Muñoz-Lopez C, Lopez-Segura F, Fernandez-Real JM, Luque de Castro MD, Lopez-Miranda J, Perez-Jimenez F. The postprandial inflammatory response after ingestion of heated oils in obese persons is reduced by the presence of phenol compounds. Mol Nutr Food Res. 2012 Mar;56(3):510-4. doi: 10.1002/mnfr.201100533. Epub 2011 Dec 9. PMID: 22162245.
2010
Mozaffarian D, Micha R, Wallace S. Effects on coronary heart disease of increasing polyunsaturated fat in place of saturated fat: a systematic review and meta-analysis of randomized controlled trials. PLoS Med. 2010 Mar 23;7(3):e1000252. doi: 10.1371/journal.pmed.1000252. PMID: 20351774; PMCID: PMC2843598.
Griffin BA. How relevant is the ratio of dietary n-6 to n-3 polyunsaturated fatty acids to cardiovascular disease risk? Evidence from the OPTILIP study. Curr Opin Lipidol. 2008 Feb;19(1):57-62. doi: 10.1097/MOL.0b013e3282f2e2a8. PMID: 18196988.
Goyens PL, Spilker ME, Zock PL, Katan MB, Mensink RP. Conversion of alpha-linolenic acid in humans is influenced by the absolute amounts of alpha-linolenic acid and linoleic acid in the diet and not by their ratio. Am J Clin Nutr. 2006 Jul;84(1):44-53. doi: 10.1093/ajcn/84.1.44. PMID: 16825680.
Comentarios