Which oil?
Confused about which oil is best to eat?  No wonder – the latest research shows it's no longer a simple case of 'saturated fat = bad, polyunsaturated fat = good'.  We've summarised the latest scientific thinking...

Fat types
Saturated – no double bonds between carbon atoms.  Historically thought of as unhealthy, but recent research shows they tend to be healthier when cooking at high temperatures.  Found in coconut oil and butter.

Monounsaturated – one carbon-carbon double bond.  Found in avocados, olives, olive oil, almonds and hazelnuts, and also in lard and goose fat.

Polyunsaturated – two or more carbon-carbon double bonds.  Includes Omega-3 and Omega-6 fatty acids.  When eaten in as food such nuts, seeds, fish and leafy greens, they have clear health benefits.  However when cooked at high temperatures they can be damaging.

Cooking with oils
When frying or cooking at a high temperature, the molecular structures of the fats and oils change.  They undergo oxidation – they react with oxygen in the air to form aldehydes and lipid peroxides.  At room temperature something similar happens, although more slowly.

Consuming or inhaling aldehydes, even in small amounts, has been linked to increased risk of heart disease and cancer.  Oils that are rich in polyunsaturated fats generate more aldehydes than other oils when cooked.  Oils that are richer in monounsaturated and saturated fatty acids are much more stable when heated.  In fact, saturated fats hardly undergo oxidation at all.
Oils analysis
OilFat contentHow healthy is it?
Olive oil~75% monounsaturated fats
  • Raises HDL (the good) cholesterol and lowers the amount of oxidized LDL (the bad) cholesterol circulating in your bloodstream
  • Can be used for cooking – reasonably resistant to heat
Rapeseed oil28% polyunsaturated,
63% monounsaturated
  • Rich in Omega-6 and Omega-3 fatty acids (polyunsaturated) – can be used to cook with at high temperatures or eaten cold
Flax oil~70% polyunsaturated
  • Rich in the plant form of Omega-3, Alpha Linolenic Acid (ALA) (polyunsaturated) – not healthy when cooked, good when eaten cold
Hemp oil~75% polyunsaturated
  • Rich in Omega-3 and 6 fatty acids (polyunsaturated) – not healthy when cooked, good when eaten cold
Sunflower oil65% polyunsaturated,
20% monounsaturated
  • Rich in Omega-6 fatty acids (polyunsaturated) – not healthy when cooked
  • Can also be high in trans fats, which are toxic
Coconut oil~90% saturated fats
  • Best oil for cooking – very resistant to heat
  • Rich in a fatty acid called Lauric Acid, which can improve cholesterol and help kill bacteria and other pathogens
  • Fats in coconut oil can also boost metabolism slightly and increase feelings of fullness compared to other fats

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