VOLUME 10 NUMBER 1 • MARCH 2013
9
SA JOURNAL OF DIABETES & VASCULAR DISEASE
REVIEW
Correspondence to: Dr Wayne May
Endocrinologist, Kingsbury Hospital, Cape Town
e-mail:
S Afr J Diabetes Vasc Dis
2013;
10
: 9–11
T
he management of diabetes has evolved over the years and
has become more individualised with time. As we learn more
we have come to understand that we need better approaches
if we are to reduce the incidence of diabetes and its complications,
no more so than with regard to diet. Recently there has been much
controversy with regard to the ideal diet, and the aim of this article
is to look critically at the evidence to see if there is one ideal diet.
One diet that is receiving attention is the low-carbohydrate
diet (LCD). This diet has been around for centuries. One of the
first reports was by John Rollo and William Cruickshank, who
put two soldiers with diabetes onto a vegetable-free diet, low in
carbohydrates and high in protein and fat.
1
They were able to show
a reduction in body weight and glycosuria.
In 1825, a French lawyer and gourmand, Brillant-Savarin
published
The Physiology of Taste
, in which he said he had identified
the cure for obesity: ‘More or less rigid abstinence from everything
that is starchy or floury.’ A more well-known account is that of
William Banting,
2
who in 1863 was advised by William Harvey to
give up beer, potatoes and bread, which he did successfully. Since
then there have been numerous reports of the LCD being used to
treat type 1 diabetes before the advent of insulin.
Without doubt, the most popular version of the LCD is the Atkins
diet, first published in 1972.
3
He initially studied the LCD in patients
to control seizures, and then on himself. Since his initial book, there
have been multiple other LCD books published. There are various
classifications of what constitutes a LCD, but one common one is as
follows: low-carb ketogenic diet < 50 g daily, low-carb diet 50–130
g daily, moderately low-carb diet 130–225 g daily.
The traditional diet that has been advocated for the last couple
of decades has been the low-fat diet (LFD). The origin of this dates
back to 1951 when Ancel Keys, a professor at the University of
Minnesota, attended a conference in Rome on nutrition and disease
and learned that heart disease was rare in some Mediterranean
populations who consumed a low-fat diet. He noted, too, that
the Japanese had low-fat diets and low rates of heart disease. He
hypothesised from these observations that fat was the cause of
heart disease. In 1953 he published his Seven Country analysis,
suggesting an association between dietary fat and mortality from
heart disease.
4
Following on this, in 1956, the American Heart Association (AHA)
conducted a TV fundraiser on all three networks urging Americans
to reduce their intake of total fat, saturated fat and cholesterol. In
1961, Keys made the cover of
Time
magazine, and from then on
the media pushed the low-fat diet as the healthy option.
In 1961, the Framingham Heart study showed that men
under 50 years with elevated cholesterol and other risk factors
were at greater risk of heart disease.
5
These became the famous
Dietary management of type 2 diabetes
WAYNE MAY
Framingham ‘risk factors’, and elevated cholesterol was at the top
of the list. It is important to note that these were associations, not
cause and effect.
In 1977, after conducting six additional hearings, Senator
McGovern’s Senate Select Committee issued the final version of
the Dietary guidelines for Americans. For the first time, an agency
of the USA federal government told the American people to eat
less fat. In 1988, the National Institutes of Health and the American
Heart Association established the National Cholesterol Education
Program.
6
Guidelines were issued the following year, and blood
cholesterol levels over 5.147 mmol/l were treated as a disease.
Following on the above, a LFD has become entrenched in
all dietary guidelines, and so the question is ‘how strong is the
cholesterol evidence?’ Firstly, cholesterol is an essential molecule,
playing an important role in multiple physiological functions, and
life cannot exist without it. There certainly is, however, no lack of
association in studies such as the Seven Countries, Framingham
Heart and INTERHEART
8
studies showing a link between cholesterol
and heart disease, but when one looks for direct cause and effect
studies, these are not as strong.
There are some animal studies, and one of the first was by
Anitschkow in 1913, showing that rabbits fed cholesterol in
sunflower oil developed lesions resembling human atherosclerosis,
whereas the ones fed only sunflower oil developed no lesions.
Unfortunately other researchers were unable to replicate the
findings. Certainly, some of the best clinical evidence comes from
patients with familial hypercholesterolaemia,
7
as these patients are
at high risk of heart disease.
The next question is ‘does lowering cholesterol impact on
reducing the incidence of heart disease?’. There is no doubt that
statins reduce incidence of heart disease, as this has been replicated
in numerous studies, but the same cannot be said for dietary
interventions, i.e. can a low-fat diet and blood cholesterol lowering
reduce the incidence of heart disease.
The Finnish Mental Hospital study showed that by reducing
saturated fat intake in an in-patient population, the patients were
able to reduce cholesterol levels and death from coronary heart
disease by more than 50%.
9
In other studies, the results have not
always been the same as in the Women’s Health initiative.
10
We are
therefore left with those who believe that high cholesterol levels are
harmful and should be treated, and those who doubt the evidence
and are unconvinced.
The next aspect to focus on is how carbohydrates have become
so entrenched in the guidelines. To do this we need to look at
the evolution of the food pyramid.
11
It is important to note that
the main driving force behind the food pyramid is the American
Agriculture Department, and hence there is an in-built bias. The
forerunner of the eventual food pyramid and subsequent ‘My Plate’
started with ‘Food for young children’ published in the
Farmer’s
Weekly
in 1916, followed a year later by ‘How to select foods’.
This was followed by the ‘Basic seven’ in 1943 and then the ‘Basic
four‘ in 1956.
In 1980 in the Dietary Guidelines for Americans, sparsely named
Food
, the US Department of Agriculture addressed the link between
