Stroke prevention: Eat colourful foods
If you want to help prevent stroke and hardening of the arteries, eat colourful fruits and vegetables. Dr. David Spence, a specialist in stroke prevention and research, offers this colour coded diet advice.
By his definition, a healthy diet is not only low in harmful stuff such as cholesterol and saturated fat. It’s also high in good substances, such as vitamins and antioxidants, which protect the body.
“We’re just starting to understand some of the beneficial substances in fruit. In grapefruit juice, we discovered an effect on blood metabolism. We know that grapefruit triples the levels of a number of drugs. There’s a 15-fold increase in a couple of the cholesterol medications.”
“There are also potent anti-oxidants in grapefruit and orange juice that lower cholesterol levels. They have a stronger anti-cancer effect than soy, which has been mentioned as a reason why Asian women have less breast cancer, because they get protection from phylo-estrogen in soy.”
Antioxidants tend to be highly coloured and flavourful, hence the slogan about eating colourl food. Lycopene is the antioxidant in tomatoes, the source of their bright red colour. And hespertin is the bright coloured antioxidant in oranges and grapefruits, according to Dr. Spence.
He’s the director of Stroke Prevention and Artherosclerosis Research Centre in London, Ontario. He spoke at a recent forum on men’s health in Toronto, sponsored by Roche Vitamins.
Heart disease and stroke are ranked as the number one cause of death in Canada, according to the Heart & Stroke Foundation of Canada.
“Strokes in Ontario alone have been projected to go up 32 per cent between 1996 and 2006, and double again in the following 10 to 15 years. And vascular disease is a disease that is very dependent on nutrition,” says Dr. Spence.
It’s well known that a bad diet is a major contributor to cardiovascular disease risk. But he says the importance of fat in all this has been hugely underestimated.
“People have been focusing on the wrong thing. We’ve focused on the fats in cholesterol and not understood that what is affecting the artery lining most of the day are the fats in the blood after meals. These are called post-prandial fat,” he says.
He says this post-prandial fat is about five times as important as cholesterol. It causes the artery to balloon and spasm for about four hours after a meal. Eating fruits and vegetables that contain antioxidants such as vitamins E and C and lycopene can diminish the amount of spasm, he says.
“If you put ketchup on your french fries, you’re helping to protect your arteries from the damage from the free radicals in the fat,” he jokes. He is especially critical of high protein diets such as the Aitkins or Montignac, because they recommend foods which put fat into the blood stream the whole day. These fats damage artery walls.
He describes the lining of the arteries as being much more than just ‘saran wrap’. The lining, or endothelium, produces a substance called nitro oxide. It protects the artery from damage by:
- Dilating the arteries
- Inhibiting the growth of rigid or smooth muscle cell in the artery wall
- Inhibiting the clumping of platelets.
Meat contains an amino acid which can be converted into homocysteine, which consumes nitro oxide. It also releases free radicals which further damage arteries.
“Homocysteine was identified in the mid-80’s as a factor in the premature hardening of the arteries. It has a steep curve in relation to vascular risk. People who have high levels in their blood have almost a 10-fold increase in risk. So lowering the levels might be beneficial. But part of the reason this has been so neglected is that doctors are trained in medical school to have their eyes glaze over when they look at how homocysteine is metabolized and how that leads to treatment,” says Dr. Spence.
The good news, he says, is that homocysteine can be converted back to a harmless amino acid. That’s done with the help of two vitamins, B12 and B6 and also folic acid. The research centre in London is one of seven centres in Canada taking part in an international controlled trial evaluating vitamin therapy for stroke prevention.
“What I’m giving to my patients and what we’re using in the trial is 2.5 mg. of folic acid, 25 mg of vitamin B6 and 400 to 500 micrograms (one half mg.) of B12 a day,” says Dr. Spence.
“The doses available in multi-vitamin tablets are not high enough for most people-particularly B12,” says Dr. Spence. B12 is not well absorbed, particularly as people age. Recent recommendations say anyone over 50 should take a B12 supplement or fortified food such as soya or rice beverages.
Dr. Spence says most patients will absorb enough B12 if they take enough orally. Even for patients with pernicious anemia, the most severe form of mal-absorption, a mg. a day of B12 will usually provide enough that they wouldn’t need injections, he says.
Vitamin B12 is also a common deficiency for vegetarians, because it comes from meat. B6 is also a muscle meat vitamin. Bananas and potatoes are other sources for B6.
Dr. Spence advises his patients with heart disease to go vegetarian for every other day.
“For about 10 years I’ve been giving out vegetarian recipe books to my patients. The dietician prepared them for us years ago in our clinic. Some of my friends and colleagues have thought I was a bit extreme in that. But it’s finally been proven by a study done in France published in 1999.”
“They took 400 heart attack survivors and randomized them, half to the diet they called the prudent western diet. And the other half were randomized to a very low fat Mediterranean diet, mainly grains, fruits and vegetables, a bit of fish, very little cholesterol, low fat.”
“Within four years, the very low fat diet had reduced the occurrence of heart attacks and death by 60 per cent, twice the effect of the cholesterol medications. I feel like Inspector Clouseau saying ‘this is what I’ve been telling you all along, you fool.’ ” says Dr. Spence.