For about 30 years we’ve had our Governments, health agencies, doctors and dieticians urging us to eat less fat and more carbohydrate. Yet, we now know that many of the fats in the diet, including saturated fat, appear harmless as worst. Some, including the omega-3 fats found in oily fish, look positively beneficial. And on the other wide we also know that excesses of certain carbohydrates (those that are disruptive to blood sugar and insulin) in the diet have some capacity to induce all sorts of ills including weight gain, type 2 diabetes and cardiovascular disease. There is some suggestion that encouraging us to turn away from fat and towards carb is one major factor that is fuelling the burgeoning rates of chronic disease we have seen over the last 3 decades or so.
I was interested to read about a recent study which appears to show quite graphically the potential hazards of applying the low fat/high carb paradigm. In this study, post-menopausal women were asked to increase their carbohydrate intake over a 4 week period. As a result, they ended up eating more starch over the course of the study. The glycaemic index of the diet was increased as well, which essentially means the new diet was more disruptive to sugar and insulin levels. There was some evidence of increased fruit and vegetable consumption over the course of the study too.
First the good news: the subjects lost weight and a measure of antioxidant capacity of the blood was enhanced.
Now, the bad news: the subjects saw significant increases in the level of ‘unhealthy’ blood fats called triglycerides as well as significant decreases in the level of ‘healthy’ HDL cholesterol. The authors of the study conclude In postmenopausal women, following the UK dietary guidelines resulted in changes in the lipid profile that were more likely to favour an increased risk of CHD [coronary heart disease].
While the authors suggest that this may be balanced by the reduced BMI and increased antioxidant status in the body, I suggest that these benefits are also available to those adopting a lower-carb diet. Those adopting a lower-carb diet have the capacity to maintain a high antioxidant status by keeping up a good intake of, say, low-carb vegetables including green leafy ones.
And if a reduction in BMI is what’s required, then it’s perhaps useful to reflect that low-carb diets consistently outperform low-fat ones in the weight loss stakes.
This study, I think, demonstrates at least some of the potential hazards that come with taking conventional dietary advice. And it should serve to remind us of the fact that some carbohydrate sources are not the cosy, wholesome, healthy foods some maintain they are.
References:
Arefhosseini SR, et al. Effect of advice to increase carbohydrate and reduce fat intake on dietary profile and plasma lipid concentrations in healthy postmenopausal women. Ann Nutr Metab. 2009;54(2):138-44.
Dietary Carbohydrates and Dental-Systemic Diseases P. Hujoel This paper also shows that the lipid theory may not be correct and suggests that fermentable carbohydrates may not only be the cause of dental caries, periodontal disease, certain oral cancers, and leukoplakia and that poor oral health predicts the onset later of chronic non-communicable diseases such as Cardiovascular diseases, diabetes mellitus, certain cancers, and dementia late onset conditions arising from the same cause.
It is a thought and an unanswered question that I have lived with for a while now – might there be a ceiling to the degree of aggregate glycaemic load (GL) that can healthily be sustained over time? It is a bit like the acknowledgment of the protein ceiling as illuminated in the so called ethnographic atlas.
The idea might seem to fit with actuality but the dynamic may not be so simple. A diet of high GL may also be one that is low in plant fibre. A diet of high GL may also be one that is high sweetener. Sucrose is digested to glucose and fructose. Does the fructose component get handled differently to the manner in which glucose is metabolised? Is it possible that fructose places a load on the liver for which the human body is poorly prepared? It becomes difficult to be singular in explanation.
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There’s no mention of omega-6 oils here, John. As yet I am under read upon the oils but I pursue the topic with great suspicion of the overabundance of omega-6 oils. These ought not to be a problem in a diet high in natural components, but they creep into many of the value-added lines that dominate the supermarket shelves. They are favoured by industry because they are generally more stable than the healthier oils.
Omega-3 fats might be mitigating in a high GL diet but might too much omega-6 be acerbating? While it may sound whacko the longer I live with it the greater regard I have for the potential allegory in the biblical tale of bread and fish.
Am I alone in noticing how the Flora brands packaging got a face-lift coincident with the FSA anti-sat-fat launch? Might anyone be able to empirically support the fleeting and casual observation that just possibly the brands were also re-formulated to address n6:n3 balance around this time? Perhaps I am just of suspicious mind.
CHris. Good point but you need to distinguish between needed omega 6 as in seeds and nuts and processed omega 6 as in all oils except olive and all margerines. They are absolutely everywhere in processed foods even raisins! They go into the cell membranes and affect every aspect of our health. They affect diabetes as insulin cannot attach to cells where the receptors are not working proplerly.
Hilda, I’m grateful for your encouraging remarks, thanks.
“They affect diabetes as insulin cannot attach to cells where the receptors are not working proplerly.”
Can you suggest a reference for this – one I might be able to follow – it interests me.
Stephan’s Blog
http://wholehealthsource.blogspot.com/
is probably the best place to look for information on dietary fats, sucrose etc.