A large study on the effects of nutrition on the heart has just been published for The BMJ magazine . This is a study that is part of the Epic-Oxford survey, a study that evaluated the effects of diet on health on a sample of British people for about 18 years. They were recruited from 1993 to 2001 and observed until 201o. 48,000 people attended.

So despite being an observational study (with data collected from interviews and food diaries plus blood tests), the large sample and the length of time make it important. Specifically, the researchers looked at whether there were any correlations between animal protein in the diet and heart health.

The results were surprising, but in line with some previous studies, such as the one on the Japanese population.

People who eat a vegetarian diet (no meat or fish) and those who eat a vegan diet therefore a diet without animal proteins according to the study have a higher risk of heart attack, and a slightly lower risk of ischemia. The risk of heart attack would be 20% higher than those who eat meat and fish.
How can such a thing be explained?

DIET WITHOUT ANIMAL PROTEIN AND HEART: THE POSSIBLE LINK

First of all it must be said that the participants were divided into 3 groups, to have three large samples of the population.

One group ate a diet with meat included, one with fish but no meat (plus cheese and eggs), one mixed with vegetarians and vegans.
Scientists had to combine vegetarians and vegans into one group because there were too few vegans compared to those on an omnivorous diet.

The group of vegetarians and vegans reportedly consumed more fruit and vegetables, more legumes, soy products and fiber, while consuming less saturated fat than the other two groups.

While the lower risk of ischemia can be explained, according to the researchers, with less LDL cholesterol from blood tests, the higher risk of heart attack can be explained by particular deficiencies.
Vitamin B12, some amino acids, vitamin D and omega3 are the deficiencies found in the group of vegetarians and vegans.
Probably some of these deficiencies or the overall effect of these deficiencies explains the increased risk of heart attack, the researchers say.

However, another possible explanation may be that of lower saturated fat.

A 2007 meta-analysis (sample analyzed: 80,000 people) had already established that reducing saturated fat did not reduce the risk of death. 
A 2003 cohort study pointed out that saturated fat was not related to an increased risk of heart attack.
Meat, cheese, eggs contain not only saturated fat, but also vitamin D, B12 and complete amino acids.
Surely a diet without animal proteins can expose us to a greater risk of deficiencies: and it is not certain that reducing saturated fats to a minimum can save us from the risk of heart attack.