Intermittent fasting is merely going without food for a set period of time, for 12 hours, 16 hours, or more. It increases the process of autophagy, and this may very well protect against heart attacks.
The rise and fall of coronary heart disease
Myocardial infarction – heart attack – is an important cause of death and disability. While we know that the immediate cause is due to arterial blockage, the longer term causes are less decided. The idea that it may be caused by high cholesterol due to high fat diets can safely be consigned to the garbage bin of history.
Furthermore, the rise and decline of coronary heart disease cannot be fully explained. My own guess would be that a combination of smoking, trans fat consumption from hydrogenated oils (like Crisco and margarine), and perhaps sugar consumption played a role.
Autophagy declines with aging
Autophagy is the process of controlled degradation of cellular components which is crucial to normal function, and it declines with aging. Whether the decline is causative of aging is an open question, but lifespan extension through calorie restriction or fasting requires autophagy, so there’s obviously a close relationship between autophagy and aging. “[A]utophagy may act as a central regulatory mechanism of animal aging.”
Autophagy and myocardial infarction
A recent study took a look at the expression of autophagy genes in peripheral leukocytes of patients with myocardial infarction. This simply means that the researchers looked at white blood cells obtained with a simple blood test. Patients who had suffered a heart attack were much more likely to have decreased expression of autophagy genes. This of course doesn’t prove anything about causation. It could be simply a marker of increased aging, with which decreased autophagy is associated. We know that older people are much more likely to have heart attacks. Could this be due to decreased autophagy?
Intermittent fasting strongly increases autophagy
Autophagy increases in response to amino acid starvation. The body has very limited storage ability for dietary protein, which is composed of amino acids. What this means in practical terms is that, once protein in the diet has been digested, and the human or animal is no longer in the “fed” state, but is now fasting, muscle is broken down to provide the necessary amino acids in the bloodstream. Autophagy is the mechanism that does this. Normally, autophagy increases after a simple overnight fast. Longer periods of fasting strongly increase autophagy. “[A] growing body of literature suggests that fasting periods and intermittent fasting regimens can trigger similar biological pathways as caloric restriction (i.e., increased autophagy and mitochondrial respiratory efficiency), which can result in a host of beneficial biological effects including increased circulation and cardiovascular disease protection, and modulation of reactive oxygen species and inflammatory cytokines (Lee and Longo, 2011), periods have also been shown to have antimutagenic, antibacterial, and anticarcinogenic effects (Lee and Longo, 2011).” (Fasting or caloric restriction for Healthy Aging.)
Fasting may protect the heart
So, we know that both myocardial infarction and aging are associated with decreased autophagy, and that fasting retards aging and increases autophagy.
In animal studies, intermittent fasting protects the heart from ischemic injury, which is the type of injury heart attacks cause. (Beneficial effects of intermittent fasting and caloric restriction on the cardiovascular and cerebrovascular systems.) This shows a plausible mechanism by which autophagy protects against injury to the heart.
There’s little downside to regular periods of intermittent fasting, and a using an 8-hour feeding window followed by 16 hours of fasting is easily done and will increase autophagy, due to deprivation of amino acids. Will it protect against a heart attack? It just might.