In today’s note I open with the three major findings from the first paper published as part of my PhD, because these set the scene. The paper looked at the dietary fat trials available at the time that the US and UK dietary committees were making up dietary guidelines. It asked the simple question: did the evidence available at the time support the restrictions on total and saturated fat that were introduced?
The simple answer was “No”! The important additional finding to this one was that – even if the evidence had been overwhelming, the findings could not have been applied to the general population. Only about 2,500 sick men had been studied – no healthy men and no women – and therefore any results could only have applied to sick men. This ended up not mattering because there were no results...
There was another finding that was quite unexpected. There were six trials available to be reviewed. Each trial had a diet group (the intervention) and a do-nothing group (the control). Cholesterol levels fell in both the diet and control groups and by quite a lot. The falls were greater in the diet groups. Because there were no differences in deaths in the diet vs. control groups, we were able to conclude that lowering cholesterol had no impact on deaths. This immediately attacked the core of the diet heart hypothesis.
I needed to understand why cholesterol fell at all and why it fell more in the diet/intervention groups. This would have been too obvious a question in the viva to not have an answer ready. This turned out to be a really interesting and informative investigation.
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