We’ve come to expect Dr Michael Mosley to be at the cutting edge of the latest health thinking, but with coconut oil, it seems the TV presenter has been ahead of the curve for literally decades — 30 years in fact.
‘As a medical student, I spent three months working in a hospital in Sri Lanka and I acquired a taste for it,’ he says. ‘I use it to make curries, but also put it in cakes and desserts — as it’s slightly sweet you don’t need to use as much sugar.
‘I like the taste and the fact that it is less oily than butter. Plus, it is more stable at high heat than many other oils, so if you’re frying it produces fewer potentially health-harming compounds than something like olive oil.’
Not just a fad: When it comes to coconut oil Dr Mosley has been ahead of the curve for literally decades, 30 years in fact
In recent years, all kinds of health claims have been made about this ‘superfood’ and UK sales have dramatically increased from £4.4 million in 2014 to an expected £24 million this year.
‘Enthusiasts claim it will cure everything from bad breath to digestive disorders — you can even use it as a moisturiser,’ says Dr Mosley. ‘But perhaps the most surprising claim is that eating this stuff can cut your risk of heart disease by reducing your cholesterol levels.’
Surprising because coconut oil is around 92 per cent saturated fat — higher than butter (63 per cent) and lard (39 per cent) — and studies have shown that saturated fats raise levels of ‘bad’ LDL cholesterol. The established thinking is that because coconut oil contains more saturated fat than butter, it must be bad for you.
Dr Mosley decided to investigate, conducting a groundbreaking experiment with researchers from the University of Cambridge to see exactly what coconut oil does to cholesterol levels.
In recent years, all kinds of health claims have been made about coconut oil and UK sales have dramatically increased from £4.4 million in 2014 to an expected £24 million this year
The results, which you can watch tomorrow on the BBC2 show Trust Me, I’m A Doctor and which will be published in full in the BMJ Online, took everyone by surprise.
‘I expected to find that the coconut oil would raise levels of [bad] LDL cholesterol and have no real effect on [good] HDL cholesterol,’ says Dr Mosley.
In fact, the oil didn’t raise bad LDL cholesterol at all; and it actually boosted levels of good HDL.
For the experiment, the team had recruited nearly 100 volunteers, all aged over 50. They were split into three groups and every day for four weeks each ate 50g of coconut oil (about two tablespoons), or 50g olive oil — an unsaturated fat already known to lower bad LDL cholesterol — or 50g butter.
This amount of coconut oil contains more than 40g of saturated fat, twice the maximum daily amount for women, according to Public Health England, but is the level previous research has revealed is necessary to show measurable changes in blood cholesterol over a four-week period.
Before the experiment, all the volunteers had their bad LDL and good HDL cholesterol levels measured, as well as their height, waist, blood pressure, weight and body fat percentage. Four weeks later, these tests were repeated.
The group who ate butter saw their bad LDL levels rise by about 10 per cent, as expected.
But the olive oil and coconut oil groups saw no rise in bad LDL — despite coconut oil having more saturated fat than butter.
Even more surprisingly, while butter and olive oil both raised good HDL cholesterol by 5 per cent, coconut oil raised it by a staggering 15 per cent, meaning that it seemed to have a more positive effect on cholesterol-related health than olive oil.
Dr Mosley (pictured) decided to investigate, conducting a groundbreaking experiment with researchers from the University of Cambridge to see exactly what coconut oil does to cholesterol levels
Interestingly, the participants’ weight and body fat remained unchanged, possibly because fat is quite filling so they ate less.
‘These results were not what we were expecting,’ says Kay-Tee Khaw, a professor of gerontology at the Cambridge School of Clinical Medicine, who oversaw the test.
‘And they’re not in keeping with the results of previous studies, which mostly show that coconut oil raises LDL less than butter but more than polyunsaturated oils. However, this is the largest study of its kind, and the first to be done in the UK.’ In other words, the results can’t be dismissed.
As for why coconut oil might have this effect, Professor Khaw suggests: ‘It could be that the extra virgin coconut oil we used behaves differently — not all the previous studies specified what type of coconut oil they used.
‘Or it could be because coconut oil is rich in a very specific saturated fatty acid, lauric acid, which may be processed differently by the body than other types of saturated fat.’
Lauric acid, which makes up around half the saturated fat in coconut oil, is often the reason why this oil is considered healthy. It has antimicrobial and anti-inflammatory properties and also occurs in breast milk.
However, Professor Khaw points out that one short-term study doesn’t give us all the answers.
‘We don’t know what would happen if you took coconut oil for a whole year,’ she says. ‘And we don’t have long-term studies on the impact of coconut oil on heart disease, stroke, etc.
‘But what this does seem to show is that it’s too simplistic to think that all saturated fats are bad — we need to look at their composition, how they’re manufactured and the context in which they’re eaten.’
Dr Mosley, who admits that in the past he has tried to minimise his use of coconut oil because of fears about saturated fats, is ‘delighted’ with the results.
‘I’m not going to be glugging it by the litre, but I’m also not going to worry about using it in cooking.’
While this experiment does seem to suggest coconut oil is a heart-friendly food, how do its other health benefits measure up?
A handful of studies have reported that coconut oil can increase satiety, meaning you eat less, and can encourage the body to burn more fat
A handful of studies have reported that coconut oil can increase satiety, meaning you eat less, and can encourage the body to burn more fat.
However, many of these findings are based on trials involving medium-chain triglycerides (found in coconut oil), not coconut oil itself.
‘There is no convincing evidence that coconut oil significantly helps weight loss,’ says Sally Norton, a consultant weight-loss surgeon at North Bristol NHS Trust.
ONE theory is that Alzheimer’s disease is caused by brain cells losing their ability to use glucose for energy, which ultimately leads to poorer brain function.
It’s thought compounds called ketones could provide an alternative energy source and ease, or reverse, symptoms.
When the fatty acids in coconut oil are digested, they create ketones, so the theory is coconut oil could provide an alternative energy source for the brain cells.
However, Dr Clare Walton, research manager at the Alzheimer’s Society, says: ‘There is limited evidence to show that this actually works.
‘Without high-quality research in people, we can’t be sure that coconut oil is safe, or of any benefit to people living with dementia.’
The antibacterial and anti-inflammatory properties of lauric acid might boost the health of your scalp, but there’s no evidence to suggest it has any effect on the yeast that causes dandruff, as is sometimes claimed
The antibacterial and anti-inflammatory properties of lauric acid might boost the health of your scalp, but there’s no evidence to suggest it has any effect on the yeast that causes dandruff, as is sometimes claimed.
One study found that coconut oil conditions hair by preventing protein loss, but trichologist Iain Sallis of the Hairmedic group says any oil ‘prevents moisture getting into hair which can be really important if your hair is very dry.
‘It also acts as a heat conductor if used before heated tools and so will cause more damage than it prevents.’
When it comes to treating dry skin, coconut oil has been statistically shown to be at least as effective, if not better than, mineral oils
Devotees advocate using coconut oil as everything from a daily moisturiser to a treatment for eczema, so what’s the truth?
‘Some studies have shown that it can be used to treat conditions such as bacterial skin colonisation [the presence of bacteria on the skin] and atopic dermatitis [inflammation of the skin],’ says Dr Shirin Lakhani, a GP and aesthetic physician.
‘When it comes to treating dry skin, it has been statistically shown to be at least as effective, if not better than, mineral oils.’
Trust Me, I’m A Doctor is on BBC2 tomorrow at 8.30pm.