Good fats, bad fats & the truth about Coconut oil

In the past couple of years, the fat debate has been very present in the media, and more recently sparked by the research findings of Dr David Unwin. A Diabetes doctor from the North of England, he was finding that putting his patients on low carbohydrate diets was proving beneficial in the fight against diabetes. In the place of high carbohydrate foods, patients were instructed to eat more vegetables, low GI fruits and more fat (1). Despite Public Health England sticking by their advice of limiting fat intake, the media and many food and fitness bloggers took the idea of a high fat diet and ran with it.

There is however, one key feature of the diet plans that Dr Unwin prescribed, that is often  overlooked…and that is the type of fats that he encourages people to eat. Alongside lean protein and lots of vegetables, the patients were encouraged to eat “Good fats” and I have written a brief overview below of what fat to eat and what to avoid…

Good fats

Your body needs some fat to carry out essential functions such as muscle movement, nerve protection and the absorption of some dietary vitamins.

Monounsaturated fat

Found in foods such as olive oil, nut & seed oils, and avocado

These are important for our heart health. They support levels of HDL (good) cholesterol, whilst reducing LDL (bad) cholesterol.

Polyunsaturated fats

These are essential fats, meaning that your body cannot create them so they must be included in the diet. Examples of polyunsaturated fats include Omega 3 & 6 fatty acids.

Good sources of these fats include: nuts, flax seed & flax oil, salmon, mackerel, sardines, and soy beans.

Also important for heart health, Polyunsaturated fats have proven to reduce the risk of heart disease as omega-3 fatty acids help to reduce blood pressure and improve blood vessel function (2).

Bad fats

Trans fat

Linked with heart disease, diabetes and stroke, trans fats are a by product of hydrogenation, which turns healthy oils into solids at room temperature (3). Although they were commonly used in margarine & processed high calorie foods, there are no known health benefits to this type of fat, therefore they are rapidly falling out of use in the food industry.

Saturated fat

Found in animal fats in meat, butter and whole dairy, processed meat (eg sausages & bacon), and coconut oil.

A study published in the British Medical Journal at the end of 2013 suggested that there isn’t enough evidence to support the statement that saturated fat increases risk of a heart attack. Despite this, the NHS, British Heart Foundation and American Heart Association stand by their recommendations to limit saturated fat in the diet (4). Whilst new research is being carried out, it has been proven that saturated fat does increase cholesterol, and  high cholesterol has in turn been associated with cardiovascular disease.

Coconut oil

Coconut oil is another trendy ingredient that is a favourite of many bloggers, however the evidence supporting the supposed health claims is limited. Coconut oil is rich in Medium chain fatty acids (MCFAs); and it has been suggested that this form of fat is metabolised differently to other fats. Consequently having a positive effect on the body’s metabolism and resulting in weight loss… However, coconut oil is around 90% saturated fat (compared with butter at 50%), and as mentioned above, this has consistently been linked with high cholesterol and heart disease.

A review of the scientific research about coconut oil was conducted in 2016, and it identified that from 21 research papers, no links were identified between coconut oil intake and blood lipid levels or participants weight. However, a link was identified between coconut oil intake and higher LDL & total cholesterol levels, more so than with plant oils (5).

It is therefore recommended that we use cold pressed rapeseed oil or olive oil. There is much more scientific evidence supporting the health benefits of these oils, which are lower in saturated fat and high in monounsaturated fat, omega 3 and omega 6.

References

(1) http://www.diabesityinpractice.co.uk/media/content/_master/4311/files/pdf/dip4-3-102-8.pdf

(2)https://www.hsph.harvard.edu/nutritionsource/omega-3-fats/

(3) http://www.drsarma.in/files/medicine/Lipids%20Metabolic%20syndrome/Trans%20fats.pdf

(4) https://www.bhf.org.uk/news-from-the-bhf/news-archive/2014/march/saturated-fats-explained

(5) https://academic.oup.com/nutritionreviews/article/74/4/267/1807413/Coconut-oil-consumption-and-cardiovascular-risk

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