People in the ‘low carb high fat’ camp are bound to have a field day with the findings of a new study published in latest issue of the Open Heart journal. In essence, the study makes a strong case for the notion that the national dietary guidelines (advocating low fat) introduced in 1977 and 1983 by the US and UK governments respectively, amounted for the most part to a large scale blind experiment that involved some 276 million people at the time.
Both sets of guidelines advocated a reduced fat intake as a means of reducing the risk of coronary heart disease (CHD). In so doing they inadvertently promoted an increase in carbohydrate consumption. The study; lead by Zoe Harcombe from the Institute of Clinical Exercise and Health Science at the University of the West of Scotland, UK, examined the available scientific evidence to support low fat intake as a means of reducing CHD. Relying only on randomised controlled trials (RCTs) meant that Harcombe and her fellow researchers only had 6 studies on which to conduct their analysis. Collectively this amounted to a total of 2467 males.
Each of the studies examined in some way the relationship between dietary fat, serum cholesterol and mortality. What’s more, each study had a hypothesis relating to a reduction or modification of dietary fat or cholesterol.
Having conducted the appropriate statistical analyses on the available RCTs, the researchers found that there was no statistically significant difference in deaths from CHD when dietary intake of fat and/or cholesterol was reduced. Although the analysis did reveal there was a significant reduction in cholesterol levels, this did not have any subsequent effect on the risk of death from CHD.
While the national Australian Dietary Guidelines were not included as part of the study, they are very similar to that of the US and UK, despite being introduced several years later. As such, the study is likely to generate healthy debate among Australian healthcare professionals such and doctors, dietitians and nutritionists.
It’s interesting to consider that industries like sports supplements have a high rate of product development/turnover (on the back rapidly evolving nutrition research), but this is not reflected in any major changes at the level of national dietary guidelines. Despite being published over 30 years ago, both the UK and US national dietary guidelines have not fundamentally changed. This is an intriguing thought to consider given the wealth of sound nutritional research science that has been published in that time. With studies such as this seemingly becoming more common, it will be interesting to see what changes (if any) the current trends in nutrition research bring to national dietary guidelines for western countries like Australia, US and UK.
Harcombe Z, et al. Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis. Open Heart. 2015;2e000196.