Is LCHF associated with CVD? – Zoë Harcombe

Executive summary

* A study was published in March 2024, which claimed that “After 11.8 years, 9.8% of LCHF [low carb high fat] vs 4.3% of SD [standard diet] participants experienced a cardiac event.”

* The study was first presented at a conference in March 2023. This was the peer-reviewed paper (one year on).

* The study used UK Biobank, which has data for over 500,000 participants. From these, the researchers identified just 305 people who completed one “what did you eat yesterday?” dietary questionnaire at the start of the study, who weren’t on statins and were consuming <25% carbohydrate and >45% fat (i.e., lowER carb highER fat). Just 305!

* These 305 people were matched for sex and age only with 1,220 people who self-reported eating a standard diet.

* The 305 people averaged fewer than 1,500 calories compared to the SD group intake of almost 2,000. The entire study was founded on unreliable recall and thus no claims are robust. When only those who completed two dietary questionnaires were reviewed, there were no findings.

* Having matched for sex and age only, many characteristics differed between the LCHF and SD groups. The LCHF people were more likely to have non-white ethnic origin, three times more likely to have diabetes, far more likely to be obese and to have a higher BMI. The paper did not present any model that adjusted for all baseline differences. The claim that cardiac incidents were double was based purely on incidents in each group, not incidents in each group having adjusted for all differences between the two groups.

* At the end, I summarise the rebuttal to this paper if anyone tries to use it to claim keto or LCHF diets are even associated with cardiac events (let alone cause).