One facet of our modern lifestyle that wasn't mentioned in the main
article is the possibility that eating a 'healthy' diet may have played a
part in the huge increases seen in both diabetes and Alzheimer’s disease
since 'healthy eating' was introduced in the 1980s. That diabetes is a
direct result of eating a carbohydrate-rich diet is indisputable, but
there is a growing body of evidence that our starch-based, 'healthy' diet
is also the cause of many other chronic degenerative conditions, of which
Alzheimer's disease is but one.
The number of people with Alzheimer's has more than doubled since
1980. Although normally a disease of the elderly, over the last 30 years
Alzheimer's is increasingly being seen in younger people. There are also a
disproportionate number of cases of deteriorations of memory, cognition,
speech memory, working memory and visual-spatial skills among diabetics
compared with non-diabetics; diabetics also have a two- to three-times
increased risk of Alzheimer's compared with the general population.[1,2]
Population studies indicate that Alzheimer's disease is much more
prevalent in diabetics across the world. Stolk and colleagues at Erasmus
University Medical School, Rotterdam, say that: 'These findings are more
compatible with a direct effect of insulin on the brain than with an
effect through an increase in cardiovascular risk factors.' High-
carbohydrate diets could lead to Alzheimer's disease through chronic over-
exposure of cells to insulin signalling, which accelerates cellular damage
in cerebral neurons,[3] and can cause insulin resistance.[4]
For nine years a research team followed 824 Catholic priests and
nuns, 127 of whom had diabetes.[5] One hundred and fifty-one of them went
on to develop Alzheimer's. Two thirds of these were diagnosed diabetics.
Researcher Zoë Arvanitakis found that insulin in the blood stimulates a
protein called 'tau' which tangles brain cells into Alzheimer knots.
In a commentary in Lancet, Dr Mark Strachan reviewed research showing
that, while normal levels of insulin have a significant effect on
improving memory, high levels are associated with a significant decline in
memory function. This suggests that the malfunction associated with
insulin resistance leads to cognitive dysfunction because of insulin’s
inability to carry out its proper function.[6]
Adding weight to a diabetes link, recent studies have indicated an
association between Alzheimer's disease and central nervous system insulin
resistance. Northwestern University researchers suggested that Alzheimer's
disease may actually be a third form of diabetes.[7] This was confirmed in
2008. In a longitudinal study, impaired acute insulin response at midlife
was associated with an increased risk of Alzheimer's disease (AD) up to 35
years later suggesting a causal link between insulin metabolism and the
pathogenesis of Alzheimer's disease.[8]
Insulin and insulin receptors in the brain are crucial for learning
and memory, and it's known that these components are lower in people with
Alzheimer's disease. In the brain, insulin binds to an insulin receptor at
a synapse, which triggers a mechanism that allows nerve cells to survive
and memories to form. The research has shown that a toxic protein, amyloid
beta-derived diffusible ligand (ADDL), found in the brain of Alzheimer's
patients, removes insulin receptors from nerve cells, and renders those
neurons insulin resistant. It is this substance that causes the plaques
found in Alzheimer’s disease.
The brain also produces insulysin which protects the brain by
degrading ADDL. But insulysin is active on two competitors, ADDL and
insulin, with a much greater affinity to insulin than ADDL. The more
insulin circulating in the blood the less insulysin is available to clean
up the ADDL, which is then left to aggregate and produce the Alzheimer's
plaques in the brain. If we eat so much carbohydrate that insulin levels
skyrocket, we get no degradation of ADDL due to the high insulin levels.
Healthy diet and Alzheimer’s
Starchy foods may be as much the cause of Alzheimer's disease as they
are of diabetes. A report showed that a diet rich in saturated fats and
low in carbohydrates can actually reduce levels of a brain protein,
amyloid-beta, which is an indicator of Alzheimer's disease in mice with
the mouse model of Alzheimer's disease.[9] The authors believed that
insulin and a related hormone, insulin-related growth factor-1 (IGF-1),
are the key players. They said: 'Insulin is often considered a storage
hormone, since it promotes deposition of fat but insulin may also work to
encourage amyloid-beta production.'
This study runs counter to others which purported to show that high-
fat diets had a negative effect on Alzheimer's. However, in an
accompanying editorial, Dr Richard Feinman, editor of the journal
Nutrition and Metabolism, explained that: 'Most studies of the deleterious
effects of fat have been done in the presence of high carbohydrate.' In
which case, isn't it conceivable that it is dietary carbohydrates and not
fats that are the causal factor?
In the last decade or so, there has been an increasing volume of
evidence that our 'healthy' diet isn't healthy at all. With its emphasis
on carbohydrates - starchy foods and fruit and vegetables - this
intervention inevitably leads to the hyperinsulinaemia and insulin
resistance that have been shown to be the root cause of many of the
conditions it was introduced to prevent, specifically diabetes. Any
prevention programme to reduce incidence of dementia (or diabetes) which
fails to recognise that our so-called 'healthy' diet has inadvertently
caused these problems is doomed to failure.
References
1. Leibson CL, et al. Risk of dementia among persons with diabetes
mellitus: a population-based cohort study. Am J Epidemiol 1997; 145: 301-
308.
2. Stolk RP, et al. Insulin and cognitive function in an elderly
population. The Rotterdam Study. Diabetes Care 1997; 20, 792-795.
3. Henderson ST. High carbohydrate diets and Alzheimer's disease. Med
Hyp 2004; 62: 689-700.
4. Rosedale R. Insulin and Its Metabolic Effects, Presented at
Designs for Health Institute’s BoulderFest, August 1999 Seminar. http://www.mercola.com/2001/ jul/14/insulin2.htm.
5. Arvanitakis Z, et al. Diabetes mellitus and risk of Alzheimer
disease and decline in cognitive function. Arch Neurol 2004; 61: 661-666.
Rapid Response:
'Healthy eating', insulin and Alzheimer’s disease
One facet of our modern lifestyle that wasn't mentioned in the main
article is the possibility that eating a 'healthy' diet may have played a
part in the huge increases seen in both diabetes and Alzheimer’s disease
since 'healthy eating' was introduced in the 1980s. That diabetes is a
direct result of eating a carbohydrate-rich diet is indisputable, but
there is a growing body of evidence that our starch-based, 'healthy' diet
is also the cause of many other chronic degenerative conditions, of which
Alzheimer's disease is but one.
The number of people with Alzheimer's has more than doubled since
1980. Although normally a disease of the elderly, over the last 30 years
Alzheimer's is increasingly being seen in younger people. There are also a
disproportionate number of cases of deteriorations of memory, cognition,
speech memory, working memory and visual-spatial skills among diabetics
compared with non-diabetics; diabetics also have a two- to three-times
increased risk of Alzheimer's compared with the general population.[1,2]
Population studies indicate that Alzheimer's disease is much more
prevalent in diabetics across the world. Stolk and colleagues at Erasmus
University Medical School, Rotterdam, say that: 'These findings are more
compatible with a direct effect of insulin on the brain than with an
effect through an increase in cardiovascular risk factors.' High-
carbohydrate diets could lead to Alzheimer's disease through chronic over-
exposure of cells to insulin signalling, which accelerates cellular damage
in cerebral neurons,[3] and can cause insulin resistance.[4]
For nine years a research team followed 824 Catholic priests and
nuns, 127 of whom had diabetes.[5] One hundred and fifty-one of them went
on to develop Alzheimer's. Two thirds of these were diagnosed diabetics.
Researcher Zoë Arvanitakis found that insulin in the blood stimulates a
protein called 'tau' which tangles brain cells into Alzheimer knots.
In a commentary in Lancet, Dr Mark Strachan reviewed research showing
that, while normal levels of insulin have a significant effect on
improving memory, high levels are associated with a significant decline in
memory function. This suggests that the malfunction associated with
insulin resistance leads to cognitive dysfunction because of insulin’s
inability to carry out its proper function.[6]
Adding weight to a diabetes link, recent studies have indicated an
association between Alzheimer's disease and central nervous system insulin
resistance. Northwestern University researchers suggested that Alzheimer's
disease may actually be a third form of diabetes.[7] This was confirmed in
2008. In a longitudinal study, impaired acute insulin response at midlife
was associated with an increased risk of Alzheimer's disease (AD) up to 35
years later suggesting a causal link between insulin metabolism and the
pathogenesis of Alzheimer's disease.[8]
Insulin and insulin receptors in the brain are crucial for learning
and memory, and it's known that these components are lower in people with
Alzheimer's disease. In the brain, insulin binds to an insulin receptor at
a synapse, which triggers a mechanism that allows nerve cells to survive
and memories to form. The research has shown that a toxic protein, amyloid
beta-derived diffusible ligand (ADDL), found in the brain of Alzheimer's
patients, removes insulin receptors from nerve cells, and renders those
neurons insulin resistant. It is this substance that causes the plaques
found in Alzheimer’s disease.
The brain also produces insulysin which protects the brain by
degrading ADDL. But insulysin is active on two competitors, ADDL and
insulin, with a much greater affinity to insulin than ADDL. The more
insulin circulating in the blood the less insulysin is available to clean
up the ADDL, which is then left to aggregate and produce the Alzheimer's
plaques in the brain. If we eat so much carbohydrate that insulin levels
skyrocket, we get no degradation of ADDL due to the high insulin levels.
Healthy diet and Alzheimer’s
Starchy foods may be as much the cause of Alzheimer's disease as they
are of diabetes. A report showed that a diet rich in saturated fats and
low in carbohydrates can actually reduce levels of a brain protein,
amyloid-beta, which is an indicator of Alzheimer's disease in mice with
the mouse model of Alzheimer's disease.[9] The authors believed that
insulin and a related hormone, insulin-related growth factor-1 (IGF-1),
are the key players. They said: 'Insulin is often considered a storage
hormone, since it promotes deposition of fat but insulin may also work to
encourage amyloid-beta production.'
This study runs counter to others which purported to show that high-
fat diets had a negative effect on Alzheimer's. However, in an
accompanying editorial, Dr Richard Feinman, editor of the journal
Nutrition and Metabolism, explained that: 'Most studies of the deleterious
effects of fat have been done in the presence of high carbohydrate.' In
which case, isn't it conceivable that it is dietary carbohydrates and not
fats that are the causal factor?
In the last decade or so, there has been an increasing volume of
evidence that our 'healthy' diet isn't healthy at all. With its emphasis
on carbohydrates - starchy foods and fruit and vegetables - this
intervention inevitably leads to the hyperinsulinaemia and insulin
resistance that have been shown to be the root cause of many of the
conditions it was introduced to prevent, specifically diabetes. Any
prevention programme to reduce incidence of dementia (or diabetes) which
fails to recognise that our so-called 'healthy' diet has inadvertently
caused these problems is doomed to failure.
References
1. Leibson CL, et al. Risk of dementia among persons with diabetes
mellitus: a population-based cohort study. Am J Epidemiol 1997; 145: 301-
308.
2. Stolk RP, et al. Insulin and cognitive function in an elderly
population. The Rotterdam Study. Diabetes Care 1997; 20, 792-795.
3. Henderson ST. High carbohydrate diets and Alzheimer's disease. Med
Hyp 2004; 62: 689-700.
4. Rosedale R. Insulin and Its Metabolic Effects, Presented at
Designs for Health Institute’s BoulderFest, August 1999 Seminar.
http://www.mercola.com/2001/ jul/14/insulin2.htm.
5. Arvanitakis Z, et al. Diabetes mellitus and risk of Alzheimer
disease and decline in cognitive function. Arch Neurol 2004; 61: 661-666.
6. Strachan, MWJ. Insulin and cognitive function. Lancet 2003; 362:
1253.
7. Zhao WQ, et al. Amyloid beta oligomers induce impairment of
neuronal insulin receptors. FASEB J 2008; 22: 246-260.
8. Rönnemaa E, et al. Impaired insulin secretion increases the risk
of Alzheimer disease. Neurology 2008, Apr 9. [Epub ahead of print]
9. Van der Auwera I, et al. A ketogenic diet reduces amyloid beta 40
and 42 in a mouse model of Alzheimer's disease. Nutr Metab 2005; 2: 28.
Competing interests:
Author of Trick and Treat: How 'healthy eating' is making us ill.
Competing interests: No competing interests