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Is oil healthy?
This is an ongoing debate in the world of plant-based nutrition!
There is a body of evidence to suggest that eating any amount of oil, from any source, can be harmful to health, specifically in the development of heart disease and type 2 diabetes. Conversely, there are a number of studies demonstrating ability of unsaturated fats to lower LDL cholesterol and HbA1c, and improve insulin resistance.
But as with many things nutrition-related, there isn’t really a straight forward yes or no answer.
Something is clear to me, and that is that not all oils are created equal. Although one thing they do share in common is that they are highly processed and have a high caloric density, due to their fat content.
Dietary fat is required to support the body in a range of functions, including the absorption of some vitamins, as well as the production of hormones. However, there are plenty of whole food plant-based sources of fat that can fulfil this role.
Firstly, I think we should distinguish between the different types of fats present in plant-based oils:
Trans Fatty Acids (TFA)
HydrogenatedTFA are made during the process of stabilising vegetable oils by adding hydrogen to them, so they become solid at room temperature, and are usually found in fried and ultra-processed foods, including margarines. However, trans fats have also been found in corn oil. The detrimental health implications of trans-fats are indisputable, and they have been banned in a number of countries.
Saturated Fatty Acids (SFA)
Equally, it is the recommendation of health authorities worldwide to reduce consumption of SFA which are found in coconut and palm oils (although the main source of SFA in our diets comes from animal products, we’re just talking here about oils..).
Unsaturated Fatty Acids (UFA) and Essential Fatty Acids (EFA)
Polyunsaturated Fatty Acids (PUFA) can be classified as either Omega-6 EFAs (sources are soybean and rapeseed oils) or Omega-3 EFAs (sources are walnut and flaxseed oils).
Monounsaturated Fatty Acids (MUFA) are found in sunflower, olive, avocado, peanut, and canola oils.
Many plant oils contain a combination of UFA, and some of these oils contain smaller amounts of SFA as well. Some UFA, like unrefined Extra Virgin Olive Oil (EVOO), also contain antioxidant polyphenols and vitamins.
The quality of the oil matters, as does the extraction technique used. The devil’s in the detail.
People who may benefit from completely excluding oils in their diet include those with a high risk of developing – or already established – heart disease, type 2 diabetes and metabolic syndrome.
In some of the Blue Zones, EVOO consumption is high; up to 6 Tbsp/day, suggesting that UFA oil can be included in a healthy, balanced diet. Adding fruits and vegetables to a meal partially restores arterial function and blood flow, which may provide a degree of protection, such is the convention of the Blue Zones who base their diets around whole plant-based foods.
Application should also be considered; deep frying food in corn oil is different from wiping a pan with a small amount of EVOO to prevent food from sticking.
Is oil healthy? – my conclusion
The balance of evidence certainly isn’t conclusive either way, so I think the best approach is a pragmatic one.
What it always boils down to for me (as always) is overall dietary pattern, rather than singling out individual foods, or even macronutrients (neither of which we eat in isolation).
My opinion is that unrefined virgin plant oils can be part of a healthy diet when consumed in small amounts in low risk individuals who eat a nutritious (plant-predominate) diet, and practice other health-promoting lifestyle choices.
Rather than promoting oil as a ‘health food’ though, a conservative view should be taken, and you should consider your personal health status and assess your individual risk before deciding whether to include oil in your diet.
From a gut health perspective, fats from plant-based sources, including vegetable oils, have shown positive alterations in gut microbiota diversity.
So given all of this, I am comfortable keeping some unsaturated oils in my diet.
Where do you stand?
- Analysis of Trans Fat in Edible Oils with Cooking Process
- Effects of Olive Oil on Markers of Inflammation and Endothelial Function—A Systematic Review and Meta-Analysis
- Influence of antioxidants in virgin olive oil on the formation of heterocyclic amines in fried beefburgers
- Plant-Based Fat, Dietary Patterns Rich in Vegetable Fat and Gut Microbiota Modulation