The myth of cholesterol and low-fat diets - Food for the Brain

The myth of cholesterol and low-fat diets

A major study of thousands of older people found two blood test markers that predict increased dementia risk: 1. having a high homocysteine level (a consequence of low levels of B vitamins) and 2. having a low cholesterol level. This makes sense because cholesterol is vital for brain function. In an earlier email you will have seen that cholesterol is part of the structure of brain cells, so it makes sense that if you have too little, your ability to think optimally will be affected. (Memory loss is a very common symptom of statin medication).

In this study, having a cholesterol level of around 4mmol/l, and an LDL cholesterol around 2mmol/l, was strongly associated with an increased risk of dementia.

The problem is that too many people with raised cholesterol, which is anything above 6 mmol/L, are put on statins which block cholesterol production. But to sell more statins the ‘normal’ cholesterol level got pushed down from 6 to 5 mmol/l. The problem with this is a well-known adverse effect of statins: memory loss, as well as another effect: loss of sex drive as cholesterol is vital for making sex hormones.

People have been misled into thinking the following 3 statements are true:

  1. Eating fat and cholesterol rich foods raises cholesterol
  2. Raised blood cholesterol leads to arterial blockage
  3. Blocking cholesterol production with statins reduces heart disease

Every one of these statements are wrong. There is no reason to avoid eggs or shellfish, high in cholesterol. Cholesterol is a good guy, not a bad guy and your body will make more if needed. There’s no need to avoid fat unless you are one of the one in 500 people with heart disease who have familial hypercholesterolemia, a genetic disorder, in which case cholesterol-lowering statins are a must.

Excessive total and ‘LDL’ cholesterol (the so-called bad guy) can occur from eating too many carbs, not fat. The more important marker for cholesterol here is triglycerides – blood fats made from sugar (and alcohol). We talk about this in the LOW GL domain.

Walnuts help, too. An analysis of 13 studies, published in the American Journal of Clinical Nutrition finds that walnuts, given for 4 to 24 weeks on a daily basis, lowers ‘LDL’ cholesterol, which is the one you don’t want too much of.


Most importantly, you want your triglycerides low, your HDL cholesterol high and making up one third of your TOTAL cholesterol. If you’re not sure what yours is and want to find out, in the UK there’s an Essential Health Check home test kit you can buy from YorkTest, which is extremely good value. It also tests your B12, folate and vitamin D. Your doctor can also test these for you.