About two weeks ago, Dr. Aseem Malhotra (@DrAseemMalhotra), a cardiologist at Croydon University Hospital, stated that it is time to, “bust the myth of the role of saturated fat in heart disease” and hence started the fierce debate over whether saturated fat really is a contributing factor to cardiovascular disease. In light of this, you are all likely to have reached saturation point with said story (no pun intended). However, having done extensive reading around the subject, I thought it would do no harm, and perhaps clarify things in my mind, if I put in my tuppence worth.
Throughout my dietetic training, we were taught that a diet high in saturated fat raised cholesterol levels, which in turn promoted atherogenesis (the formation of fatty masses in the artery lining) and hence cardiovascular disease. In fact, the majority of the advice I gave to the patients in my out-patient clinics, who suffered with hypercholesterolemia, was based around this knowledge. I also, carried out a cardiac-rehabilitation clinic where patients who had suffered a heart attack came to learn how they could prevent a second heart attack from occurring. Again, my advice to these patients was largely based on the above theory. So, have I really been giving out the wrong advice to all those individuals who I saw? I really do hope not. Alas, after several hours of reading , this is what I have come to understand from the debate.
In a BBC interview, Dr Aseem Malhotra stated that the basis of the current advice surrounding saturated fat and heart disease came from Ancel Keys’, 7 Countries Study, where a correlation was found between saturated fat, cholesterol levels and heart disease. For Dr Aseem Malhotra, herein lies the problem; correlation does not mean causation. Indeed, more recently, researchers at Harvard, who reviewed 21 studies involving around 350,000 people over 20 years, concluded that there is no convincing evidence that links saturated fat with heart disease.
It is important here to clarify that what is being called to question is the link between saturated fat and heart disease, NOT saturated fat and cholesterol levels. This is an important distinction if the rest of the story is to make any sense at all. What is not in question is that high intakes of saturated fat will raise the level of ‘bad’ or LDL cholesterol in our blood. What we are being told however, is that saturated fat in fact raises the large sub-particles of LDL cholesterol and these sub-particles are thought not to be atherogenic. More dangerous, argues Dr Malhotra, are the small sub-particles of LDL which are thought to be responsible for furring up our arteries. What raises these small sub-particles of LDL I hear you ask? The answer I’m afraid is sugar!
So sugar is now in the spotlight as ‘Mr. Baddie’ and rather problematic this is too. Unfortunately we are a nation addicted to sugar. It is everywhere, including places you wouldn’t expect, including low-fat, ‘healthy’ products. You see, in their attempt to help tackle obesity, food manufacturers replaced their fat content with sugar (it turns out things without fat really aren’t all that appetising!). And unfortunately, avoiding sugar takes a lot more time and consideration then avoiding saturated fat does. For example, cakes, biscuits, clotted cream, buttered bread, pastries are all fairly obvious contenders for the ‘not so good for you badge’ but low-fat yogurts, ready meals and zero-fat frozen yogurts are less conspicuous. Plus the lure of the low-fat signage is a hard one to ignore.
What does this all mean then? Well, for me, this debate highlights that we need to promote the eating of proper food but with emphasis on moderation. By this I mean, avoid low-fat, heavily manufactured products in favour of fruits, vegetables and wholegrains. Try and replace saturated fat with unsaturated fats such as olive oil, avocados, nuts and seeds and but, if you do fancy having a slice of thick cut bread with lovingly churned butter then do, just ensure it is kept as a treat. Let us not forget however, that regardless of its role in heart disease formation, high saturated fat products will still lead to significant weight gain if eaten too readily and obesity is an independent risk factor for heart disease as well as being responsible for a raft of other problems such as type 2 diabetes.
My conclusion is that no research is absolute, life produces far too many co-founding variables for that, but I say go with the obvious evidence. For example, individuals who live by a Mediterranean style diet have been shown to live longer than those who don’t. Why? Because they follow a diet similar to that outlined above, and this type of diet contains many elements which have been shown to have a positive effect on our heart disease risk.