In a recent paper a research project based at the University of Utah has shown that comparatively low levels of sugar added to the diet can have substantial negative effects on mouse survival, competitive ability, and reproduction. In particular it was found that when mice ate a diet of 25% extra sugar – the mouse equivalent of a healthy human diet plus three cans of soda daily – females died at twice the normal rate and males were a quarter less likely to hold territory and reproduce (1).

According to the lead author James Ruff the mice didn’t become obese and showed few metabolic symptoms. The researchers used a specially designed system of toxicity testing which demonstrated that the mortality of the females on the high sugar diet doubled while males produced 25% less offspring and their control of territories was reduced by 26% (2)

The additional sugar was a 50:50 mixture of glucose and fructose which is the same as ordinary table sugar and similar to High Fructose Corn Syrup (HFCS) which is widely used in the manufacture of processed foods.

The researchers concluded that:

Our results provide evidence that added sugar consumed at concentrations currently considered safe exerts dramatic adverse impacts on mammalian health.”

As a consequence of the findings one of the investigators has decided to alter his own personal diet by reducing his intake of refined sugar and is encouraging his family to do the same.

The significance of this work is that sensitive toxicity tests have enabled the researchers to detect deleterious effects at much lower intakes of sugar than could be achieved with the conventional approach.

These results add to the growing body of evidence which leads to the conclusion that it is the increase in the amount of sugar in the typical diet which the critical factor responsible for the huge increase in the incidence of diabetes and many related diseases/conditions including obesity, heart disease, hypertension and various cancers.

This information fits very well with the views of Dr Robert Lustig (Blog 35) who strongly advocates that the ill-health effects of sugar are so damaging (toxic) and well-established it should be subjected to legislative control in the same way as tobacco.


“Is sugar toxic?”

Peter Attia has discussed this question in detail (3). He points out toxicity can be categorized as acute, sub-chronic or chronic depending on how long it takes to progress from exposure to insult and the number of exposures necessary to cause an insult. Furthermore the dose is crucial…even water can be toxic if large amounts are consumed. So the question which we ought to posing is:

“What dose of sugar can I (or my child) safely tolerate to avoid chronic toxicity?”

This is where it gets difficult because the amount which individuals can consume without ever experiencing an adverse effect can vary quite considerably. Peter explains that his level of tolerance is relatively low and limits his intake to 5 grams per day but that his wife can safely consume much higher levels. Peter has described how an individual can determine their own personal tolerance level.

The big problem is that this is quite complicated and does involve having blood tests. In reality this is just not practical for the vast majority of people. For this to be feasible it would require the appropriate facilities to available through the NHS (in the UK) which would be dependent on a major policy initiative by the government. This is unlikely to happen in the near future, especially as the current emphasis is on cholesterol testing.

In view of the increase in sugar consumption which has occurred over the past 50 years or so, it is probable that a very high proportion of the population in many countries already has an intake of sugar which is toxic for them in the sense that it is probably responsible for many different aspects of poor health. Hence the only way that this can be addressed is by altering the composition of the national diet so that it contains very much less sugar than it does at the present time. It is certainly true that individuals can make personal changes to their habitual diet eg. taking less in tea and coffee.  More realistically it means reversing the major changes which have resulted in the growth of sugar consumption. Essentially there would have a big reduction in sugar-sweetened soft drinks. The other major contributor is the plethora of “low fat” products which are usually formulated by removing some of the fat and replacing it with sugar.

A good example is yoghurt. If you browse the shelves in the supermarkets you will a wide variety of different products, the majority of which are “low fat”. So most shoppers select these because they have been convinced their intake of fat should be kept reasonably low. Unfortunately this is wrong on 2 counts. First the case against the fats in milk just does not stand up to examination. Many of the individual fats in milk are present in human breast milk. In addition the fats are invariably replaced by sugar. A regular pot of yoghurt may contain as much as 12 grams of sugar which is much more than Peter Attia reckons he should consume only one a day. So the net effect is many people who believe they are improving the nutritional quality of their diets in reality are doing the exact opposite.


  1. J S Ruff et al (2013) Nature Communications 4 doi.10.1038/ncomms 3245