The story of atherosclerosis and iodine deficiency is an interesting one. It begins with how the cholesterol hypothesis came about.
The idea that atherosclerosis is caused by too much cholesterol in the diet began with a study of rabbits. In 1911, two Russian scientists fed rabbits a high cholesterol diet and reported that upon examining the rabbits’ arteries, they found severe arterial plaque had developed.
The problem with extrapolating these results to human subjects is that rabbits are plant eaters and have not evolved the physiology to digest and metabolize cholesterol which comes from animal flesh; it is not surprising that the foreign cholesterol in the rabbit bodies built up in the blood; there would be no physical mechanisms to absorb it. This is supported by the results of studies of the same type done on dogs and other carnivores; these studies did not produce the same results.
But here’s an interesting twist on this subject. In 1933, researchers repeated these rabbit cholesterol experiments but decided to add different substances to see if they could prevent atherosclerosis. They divided the rabbits into several groups:
- All of the rabbits were fed a high cholesterol diet which resulted in the high blood levels of cholesterol.
- The control group of rabbits was only given a high cholesterol diet.
- Experimental group 1: the diet plus desiccated whole thyroid gland.
- Experimental group 2: the diet plus thyroxin or T4 (Synthroid).
- Experimental group 3: the diet plus potassium iodide.
- Experimental groups 4 and 5: the diet plus potassium bromide and potassium chloride.
The results from each group were intriguing:
- Control rabbits fed cholesterol developed marked aortic atherosclerosis.
- Rabbits fed the cholesterol-rich diet and thyroxine (T4) showed slight to moderate aortic atherosclerosis.
- Rabbits fed the cholesterol-rich diet and either desiccated thyroid or iodine had NO atherosclerotic lesions.
- In the group of rabbits given the potassium bromide or potassium chloride and the cholesterol, all of the rabbits exhibited marked atherosclerosis. In other words, the effectiveness of potassium iodide was not shared by potassium bromide or potassium chloride, so potassium was not the mitigating factor.
The study showed that the presence of whole thyroid or iodine resulted in a marked decline in the development of atherosclerosis.
Currently, coronary heart disease is the number one cause of death in the United States. The evidence from the study above may point to a lack of iodine in the American diet as a contributing factor in that mortality rate.
Today, in the United States and around the world, iodine deficiency is a growing problem. In 1970, only 2.6% of the US population was iodine deficient. By 2005, that number had jumped to 16.5%.
This is in part due to the Federal government and medical personnel’s advice to the American public to reduce salt consumption. Since iodized salt is one of the main sources of iodine in the Western diet, the effect has been to induce iodine deficiency issues as well.
Other causes of iodine deficiency are related to the reduction or removal of iodine in commercial bakery and dairy products in the late 60s and 70s.
In addition, bromine, which is toxic to humans, will interfere with iodine and replace it in the thyroid gland. The levels of bromide ingestion and exposure in the US have increased significantly in the past 30 years.
For example, bromine can be found in antibacterial agents, pesticides, and fumigants, and these substances are found in 70% of our food supply. The EPA says that the amount of bromine in human breast milk has increased 10 fold in the last decade.
And other diseases may also be rooted in a lack of displacement of iodine. As dietary iodine levels have fallen 50% over the last 30 years, thyroid and breast cancers have also significantly increased.
What Do the Japanese Have That We Don’t?
And here’s an interesting fact: the Japanese eat, on average, about 13 mg of iodine on a daily basis, and their rates of heart disease, cancer, adult and infant mortality are among the lowest in the industrialized world. Our mortality rates for all of these health factors are much higher.
How much higher? Well, in 2006, the US adult mortality rate (AMR), which is defined as the probability of dying between the ages of 15 – 60 years, was 109/1000. This means that 109 Americans out of every 1000 died before the age of 61 because of a health issue. In Japan, the AMR is a low 67.
Could iodine intake be a factor in this astonishing difference? I don’t know, but here’s more information about how the intake of iodine and health factors differ between Japanese and US citizens. At the least, studies looking at these differences should be done. But since iodine is a natural substance and can’t be patented by the pharmaceutical companies, it may be a while before we see any studies on this subject.
Resources for Further Reading on Iodine Deficiency
- Hypothesis: Dietary Iodine Intake in the Etiology of Cardiovascular Disease a paper by Stephen A. Hoption Cann, Ph.D.
- Studies On The Prevention Of Cholesterol Atherosclerosis In Rabbits study by Kenneth B. Turner MD, 1933.
- Dr. David Brownstein’s website. Dr. Brownstein is an authority on hypothyroidism and iodine.
- Iodine Research Collection