30 October 2008

Eating fruit may increase heart attack risk

Supports Chapters 8: Why 'five portions', and Chapter 21: Diseases of the heart and blood vessels

Dr Hans Selye first proposed that stress may be a cause of heart attacks back in 1950. There is now a considerable body of evidence to support this hypothesis, but the mechanism has been obscure.

There is also a hypothesis that a low pH in the blood (denoting acidity) increases cardiac risk. So we are told to avoid eating 'acid forming' foods such as meat, fats and dairy, and eat more 'alkaline foods' such as fruit and vegetables.

A recent hypothesis by Dr Carlos Monteiro in Brazil may have the answer - and it turns current acid/alkaline foods hypothesis advice on its head.

We have lived by eating meat and its 'saturated' fat for the whole of our existence as a species; ischaemic heart disease, against which 'healthy eating' is targeted, only 'took off' in the 20th century. The idea that our traditional diet should suddenly become the cause of this modern disease is a fraud and a delusion. Yet it is the sole basis for the current paradigm. It is also the basis for the 'acid/alkaline' theory.

But there is an acid that can lower pH in the blood and cause harm, and that is lactic acid. It’s not ingested lactic acid but produced by the body in response to stress. We live now in stressful times, where our 'fight-or-flight' reflex must be working overtime. A principal result of such stresses is increased levels of lactic acid in the blood.

A 'healthy' diet of glucose, fructose and other sugars from carbohydrates also raises blood lactic acid as a by-product of the metabolism of glucose for energy from dietary carbohydrates. The worst of these is the fruit sugar, fructose, which increases blood pressure and other heart attack risk factors.

If a low-carb, high-fat diet is adopted, that naturally reduces lactic acid production from anaerobic metabolism of glucose by increasing aerobic metabolism of fats for energy.

Carlos ETB Monteiro. Acidic environment evoked by chronic stress: A novel mechanism to explain atherogenesis. Available from Infarct Combat Project at http://www.infarctcombat.org/AcidityTheory.pdf


GaryB said...

Interesting theory - but I'm not sure I agree that we have always eaten meat... Surely the appendix was there to digest plant matter? It's only in relatively modern times that it has fallen into disuse - but it indicates to me that we are designed to live on plants originally.

Barry Groves said...

Hi Gary

I'm sure you are right - if we go far enough back. But the last 2.5 million years saw a series of Ice Ages. During that period, with long, cold winters and short, cool summers. There would have been very little in the way of plant foods to eat. No, our ancestors ate animals or they starved.

This period is quite a long enough for us to have adapted to a fundamental change in our diet. And as the birth of agriculture is so recent in our history - in some cultures it still hasn't occurred - it is the time of the Ice Ages which must have the major influence on what we are adapted to eat today.

Dana Seilhan said...

I think that in the end we are probably carnivorous-but-opportunistic-omnivorous like dogs are. They can eat some plant food without mishap, and so can we, but we can also live without it.

I read someplace that what is commonly believed about the Inuit diet isn't even true--that they let white explorers think they ate plant matter from caribou guts because it made for a great joke.

Also that glucose and vitamin C compete for the same receptors in cells and that if you're eating less glucose, you don't need as much vitamin C, explaining why people on carnivorous diets don't get scurvy. Go figure.

Barry Groves said...

Hi Dana

You are quite right.

I'm also sure that we did eat plant foods when they were available in the summer. And I think that, just a bears and other animals stock up body fat by eating carbs during this time, that is what signalled our bodies to store fat. There would be a survival advantage in carrying an energy store for times when food was difficult to find.

That ability is what is causing the problems now that we live in a permanent supermarket summer. If we went back to a more traditional way of eating, based on animals, only eating a relatively small amount of plant foods for a few weeks of the year, I am sure we would be much healthier now.

Anonymous said...

Several of the articles refer to 'lactic acid'. Is this the same acid produced during exercise and can one then assume that the by-product of exercise is not good for you? I am probably way off the mark.


Barry Groves said...

Hi Stuart

Yes, the lactic acid in foods such as cheese is the same compound as the lactic acid produced when metabolising glucose anaerobically. But the consequences of having it in food is quite different from having it building up in muscles and the bloodstream.

Just as potato in the gut isn't dangerous, but you wouldn't want potato in your bloodstream.

Anonymous said...

Thanks Barry. Fantastic book by the way, we've bought several copies for friends after they skimmed through out copy.