Following on from the previous blog (1) based on the epidemiological evidence in John Yudkins’ book “Pure, White and Deadly: How Sugar Is Killing Us and What We Can Do to Stop It” this will focus on results from the experiments conducted with sugar. Here is a selection:
• One way of assessing the capability of the liver to produce fat is to measure the activity of some of the enzymes which are involved in the synthesis of fat. Using young rats it was found that those given sugar had 5 times the activity of one of these enzymes when compared with those not given any sugar. In another study, when sugar replaced starch in the diet of the rats. The activity another enzyme was doubled. With starch it is only glucose that is produced but sucrose is broken down to release both glucose and fructose. This particular result is consistent with other studies which confirm that the role of fructose is different from that of glucose and may possibly be even more damaging. It was also found that the sugar-fed rats show an increase in blood pressure, a deterioration in the ability to cope with high levels of blood glucose, an alteration in the properties of blood platelets and a change in the level of insulin in the blood. These are all observed in people with heart disease. When sugar was included in the diet of pigs, there was an increase in the level of triglycerides, which gives a much better indication of risk of heart disease than total blood cholesterol or LDL cholesterol. There was also an increase in the level of insulin in the blood.
• Studies with young men by Professor Ian MacDonald at Guy’s Hospital in London that consuming sugar for a few days caused a rise in blood triglycerides. With women it was observed in those after the menopause but not before. In Yudkins’ research team, it was found that in a group of 19 young men, they all had raised triglyceride levels after 2 weeks on a high sugar diet. In addition, 6 of them also gained about 2 kgs in body weight, there was an increase in insulin in the blood and the stickiness of the blood platelets increased. All of these changes reverted to the original values when they resumed their usual diet. These results raised a number of interesting issues:
1. The possibility that some individuals are susceptible to a heart attack specifically because of sugar.
2. The increased level of insulin in these men was in agreement with other researchers who had suggested insulin could be a critical factor in the development of atherosclerosis.
3. The rapid gain in weight which provided a clue about the relationship between excess weight and the risks of developing heart disease.
• Further studies with those who showed an increase in insulin concentration, confirmed that after a period on a high sugar diet, the platelets behaved like those of people with atherosclerosis, which returned to normal after cessation of the experimental diet.
• When Dr Robert Ahrens from the USA spent a period with Yudkins in London he studied the effect of sugar in the diet on blood pressure in young men. He observed a rise blood pressure, which was proportional to the amount of sugar added to the diet. In a review on sugar and heart disease he wrote that coronary heart disease:
“continues to increase on a world-wide scale in rough proportion to the increase in sugar consumption but not in proportion with saturated-fat intake”.
• In another experiment with those who produced high insulin levels it was found that a 40% rise in insulin after 2 weeks on the high-sugar diet was accompanied by a rise of 300 to 400% in the level of the adrenal hormone. A further study in which volunteers reduced their intake of sugar from150 gms to 55 gms per day showed that this was associated with a reduction of about 30% in the oestrogen level. These findings confirm that the sugar is causing a disturbance in the hormone balance.
• Discussing the significance of these results, Yudkin emphasises that because of the effects of sugar on the liver. kidney and the hormone balance, sugar is a food which does have a considerable impact on the body and the way in which it functions. In particular the disturbance of hormones would explain why sugar may be responsible for a number of different forms of ill-health as well as the differences between individuals. It is known that many people who have definite atherosclerosis have a high level of insulin in the blood. The risk of coronary disease is increased by other factors including cigarette smoking, being overweight , peripheral vascular disease and Type 2 Diabetes (T2D) and all of these are associated with increased insulin in the blood. Similarly, a reduction in excess weight and/or increased physical activity both reduce the risk of heart disease, result in a fall in insulin levels.
However the most compelling reason for believing that insulin, or possibly some other hormone, plays a central role in the development of heart disease is multiplicity of changes that accompany the disease. It is difficult to see how these could occur unless there has been some disturbance of the hormone levels. He considers that insulin is the most likely hormone to be involved. Yudkin suggests that a continuing high-sugar diet means that there is a persistent high demand for the pancreas to produce insulin. Because insulin has many different functions the excess may well be deleterious in other ways, such as upsetting the established hormone balance. It might be expected that the insulin would increase the deposition of fat resulting in obesity. It could also increase the accumulation of fatty material inside the arteries and alter the properties of the platelets thereby leading to atherosclerosis.
All of these comments are extremely perceptive. There is now little doubt about the role of insulin not only in heart disease but in a range of other diseases and conditions. There can no question that even if all his ideas do not prove to be absolutely accurate, he has been totally vindicated by the subsequent events. In fact, the incidence of obesity and T2D continued to increase enormously since the second edition of his book. This would have been entirely predictable on the basis of his work.
Furthermore, it is self-evident that current policies are failing and failing badly.
It is a great pity that there was no-one in a position to influence policy who recognised the significance of the work of Yudkin and those who had taken a similar stance. The time has come when his ideas must be applied. Unfortunately there is still powerful opposition as politicians and their acolytes continue to defend the indefensible.