Dietary Fats - The Facts
This is a subject that can be totally confusing, as there is so much conflicting information in the media, so let me summarise the facts based on the latest medical research…
Advice in the 1970/80’s was to eat a low-fat diet, as fat was ‘bad’ and contributed towards heart disease, not to mention weight gain. Soon supermarket shelves were full of ‘low-fat’ products, with very low nutrient content. What we didn’t know back then, is that many food manufacturers replaced the fat they took out of the foods with sugar, to improve the taste. Around the same time sugary cereals replaced eggs for breakfast, so more and more sugar, along with chemicals and hydrogenated (chemically altered) fats ended up on our plates. In a nut-shell, this is what we now believe to have been a major contributing factor in the rise in chronic diseases and obesity over the last 20/30 years, as recent medical research now reports that its sugar not fat, that has played a greater role in damaging our health1-3.
However, here’s another confusing bit… all fats are not equal and this is really important. Some types of fat are beneficial to our health and should be included in our everyday diets, but there are others that can be damaging and we should try to avoid/exclude.
So, why do we need fat? Well firstly, fat provides us with energy, 9kcal per gram to be exact, compared to 4kcal each for both proteins and carbohydrates. Healthy fats provide the body with essential fatty acids (EFA’s), which are critical to our health and as we are unable to produce them, they need to be obtained through our diet. Adequate intake of EFA’s is important as deficiencies can result in a variety of symptoms including depression, hair loss, behavioural and learning problems, dry flaky skin, malabsorption, water retention, PMS and joint pain. It’s not only important to include good sources of omega-3 and omega-6 (EFA’s) in your diet, but they also need to be consumed in the proper ratios. Fat is the transport mechanism for the fat-soluble vitamins (A, D, E, K), so without fat, our bodies cannot absorb them. Our cell membranes are made up of phospholipids (a fat that provides structure and protection to our cells), so a good intake is essential for proper function. If this isn’t enough, healthy fats also play an important role in brain health (60% of the dry weight of our brain is fat), supporting the nervous and immune systems, as well being needed for hormone production.
The main types of dietary fat are:
Saturated fat (solid at room temperature)
Animal based sources include meat, butter, cheese and cream. Plant based sources include coconut and palm oil. It was previously thought that saturated fats increased risk of heart disease, however, a large meta-analysis by Cambridge University recently stated that there isn’t any evidence to support this. So, based on these recent findings, new advice is that’s it’s okay to enjoy these things occasionally, but when choosing animal sources, always buy organic, grass-fed, locally reared options if possible.
Monounsaturated fat (liquid at room temperature)
Sources include olive oil, rapeseed oil, nuts and seeds, avocados and are generally classed as healthy fats. The Mediterranean diet includes lots of monounsaturated fats (as well as fish, fruit, vegetables and olive oils) and has been reported to support and promote good health.
Polyunsaturated fat (liquid at room temperature)
Sources include vegetable oils, meat, fish, dairy, eggs, nuts and seeds. The essential fatty acids (omega-3 and omega-6) are classed as ‘good’ polyunsaturated fats.
Trans fats
Largely artificial, made by heating unsaturated fats so they are chemically altered to turn them into solids in a process called hydrogenation. Trans fats are found in margarines, cakes, pastries, biscuits, processed foods, ready meals, low-fat/diet foods and hydrogenated oils. Trans fats extend the shelf life of these products, but they are very detrimental to our health. They are classed as ‘bad’ fats and should be avoided, as studies have implicated them in diabetes, heart disease, cancer and inflammation.
Here is a list of the good/healthy fats that I try to include in my diet daily…
Coconut Oil – best for cooking as it remains stable at high temperatures
Olive Oil – best for making dressings, drizzling over roasted vegetables
Avocado – omega-3, potassium, vitamins B & E, fibre
Nuts – omega-3, vitamin E, arginine
Seeds – omega-3, high in zinc
Eggs - Free range/organic from chickens fed a high omega-3 diet
Flax seed oil (vegetarians) – omega-3
And the following fats in moderation - 2-3 times per week with meat & oily fish, and small portions of organic dairy if consumed daily…
Oily fish (mackerel, sardines, wild salmon - 2-3 times a week) - omega-3
Pasture-fed red meat, poultry – omega-3
Organic dairy – B vitamins. Include butter, whole milk and yoghurts. Avoid processed cheese; always choose fresh such as goats and feta
Note on EFA’s - I mentioned earlier that EFA’s are essential to our health and it’s important to consume them in the correct ratios. This because omega-3 is considered to be anti-inflammatory and omega-6 is pro-inflammatory; therefore, if you don’t get the balance right it can lead to increased inflammation in the body. This subject is a blog post in itself, so I promise I’ll do this one soon…
References:
1. Mozaffarian D, Ludwig DS. The 2015 US Dietary Guidelines: lifting the ban on total dietary fat. JAMA. 2015;313(24):2421-2422.
2. Mansoor N, Vinknes KJ, Veierød MB, Retterstøl K. Effects of low-carbohydrate diets v. low-fat diets on body weight and cardiovascular risk factors: a meta-analysis of randomised controlled trials. Br J Nutr. 2016;115(3):466-479.
3. Mozaffarian D, Hao T, Rimm EB, Willett WC, Hu FB. Changes in diet and lifestyle and long-term weight gain in women and men. N Engl J Med. 2011;364(25):2392-2404.
