So, we all know that dietary fats have had a long and infamous reporting of health claims made against them. Since the 1950s researchers and food scientists have been concerned with fats in your diet and how they may contribute to health problems, most notably heart disease. One such researcher – Ancel Keys – was very prominent in the 1950s and '60s in his belief that saturated fat can damage the arteries and along with cholesterol, cause heart disease.
These beliefs became widespread in the 1970s and '80s which lead to the evolution of dietary guidelines from governments first in the US then elsewhere. The main advice at the time was to avoid fat, and especially saturated fat in your diet and go for starchy foods – sounds familiar right?
It is worth noting that the studies that were used to support this argument were fairly weak, and even though most were peer reviewed at the time, looked upon with today’s scrutiny, studies like Key’s 1950s “7 countries study” were pretty fallible.
In the 1990s, a bunch of studies came out and the popular opinion moved from blaming all fats for being bad to the theory that there were two main types of fats – good and bad. Good, healthy fats were from mainly plant based sources and were unsaturated – examples include Olive oil, avocados, nuts, and oily fish and veg oils (vegetable, sunflower etc). The other types were saturated fats – examples include butter, beef, eggs & coconut oil. A third type called trans fats were brought to popular press and these so called ‘bad brothers’ of trans and saturated fats represented the bad fats that we should stay away from if we wanted to protect our hearts.
In the late '90s and early 2000s a growing body of scientists and researchers began to doubt the validity of the diet heart hypothesis as it is called – that excess dietary saturated fat and cholesterol damaged the arteries and led to heart disease. Studies such as Souza (2015) in the BMJ and Siri-Tarino (2010) in the AJCN to name but a few, do not show a link between saturated fat and heart disease. However many studies do show a link to the man-made trans fats and heart disease and a general increase in health problems.
So, which fats are actually healthy for me, I hear you cry?
It’s probable that all natural fats from any unprocessed sources have health benefits. More research needs to be done to weight up the pros and cons surrounding what fats might be the healthiest. The advice from most food agencies such as the FSA is still to limit saturated fats. Whilst all types of fats may carry undesirable health problems, they can also carry benefits – see polyunsaturated fats and their ability to become oxidised. So it is best to eat a wide variety of foods in moderation including fats from different sources but make sure it is natural fats and not man made trans fats. Avoid processed foods, especially those with higher levels of trans fats such as biscuits, cakes and pastries and margarine – instead choose fats like butter, goose fats and coconut oils.