O3I: your index of health

Decades of advice from so-called ‘health experts’ has led many people to believe that that dietary fat is something to be minimized or avoided, particularly in the context of dieting and weight loss. However, over the past 20 years or so, this myth is being gradually dismantled. The reality is that consuming the right kinds of dietary fat is essential – not just for health, but also for physical performance.

The right kinds of fats

What are the right kinds of fat, and which fats are not so desirable? Again, this is an evolving science. Forty years or so ago, the general consensus was that in order to ensure cardiovascular health, saturated animal fats should be avoided or minimized, and replaced instead with ‘healthier’ vegetable polyunsaturated fats⁽¹⁾.

However as more and more research was conducted in this area, it became clear that the relationship between health (particularly cardiovascular health) and dietary fat is far more nuanced. Indeed, the current thinking is that while excessive saturated fat might play a role in cardiovascular disease, there are more important dietary factors including high intakes of processed ‘trans fats’ (often from vegetable sources), high intakes of refined and sugary carbohydrates, low intakes of antioxidants from fresh fruits and vegetable and low intakes of the essential omega-3 and omega-6 fats (see box 1), but especially omega-3⁽²⁾. In short, it’s much less about the quantity of fat or it’s saturated/unsaturated nature, but far more about the quality of the fat, in particular, how unprocessed it is and how rich it is in essential omega-3.

Box 1: What are EPA and DHA?

There are two types of essential fats for human health: omega-3 oils and omega-6 oils. These two types of fats are essential, because as well as being absolutely vital to build healthy cell membranes in our bodies, their chemical  structure means that they can also be used to make hormone-like substances in the body called prostaglandins, which go on to regulate a host of other functions. Although omega-6 can be synthesized from omega-3, the reverse is not true. This makes ensuring an optimum intake of dietary omega-3 oils especially important, especially as omega-6 oils are relatively abundant in the diet. EPA and DHA are two particularly important omega-3 oils as they provide a number of health benefits when consumed in the diet (and they cannot be synthesized in the body). Their long chains containing lots of carbon-carbon double bonds gives them the necessary shape and chemical reactivity needed to facilitate key metabolic functions in the body required for health.