Lifestyle and nutrition – Essential companions
With more and more people settling down to
sedentary jobs, the ‘burning’ or consumption of physical energy being minimal
and changes in lifestyles reflecting strongly in the etiology of chronic
diseases such as obesity, diabetes, heart disease, and even some cancers, the
services of dieticians or specialists in human nutrition are often sought after.
In this context, Specialist in Human Nutrition and Lifestyle Management, Dr.
Damayanthi Perera spoke to The Nation on healthy food habits which will ensure
By Randima Attygalle
The dictum ‘one man’s food is another man’s poison’ is the cardinal principle in
determining the best set of dietary guidelines for each individual, Dr. Perera
pointed out, stressing that a ‘blanket policy’ in this regard is not possible as
dietary requirements are highly individualised.
“The majority of the people who seek the services of a nutritionist believe in
the deep-rooted habit of relying on a general prescription or what is commonly
called a ‘diet sheet,’ which is ineffective,” explained Dr. Perera, adding that
systematic counseling of the client is vital in this aspect.
According to Dr. Perera, current diet, physical activities, socio-economic
background of the client, ethnicity, religious beliefs, job profile and most
importantly family health history are of importance in determining the ideal
diet of an individual for healthy living.
“Until about a one and a half decade ago, we did not know much about the effect
of stress on physical health until researchers like Dr. Dean Ornish, a renowned
cardiologist, published findings on stress, heart disease and unconventional
methods for treating heart patients. Today we know that stress has a direct
bearing on a person’s health and well-being. For instance, it can adversely
affect the blood sugar level. However, not many are still aware that stress can
also lead to an increase in cholesterol levels – bad news for many. Thus, it is
important to do a background study of all this prior to recommending a diet,”
explained Dr. Perera.
Taking into consideration new scientific evidence, particularly the influence of
stress on health (which was not available two decades ago), Dr. Perera
highlights that the old dictum ‘you are what you eat’ should now be broadened to
‘you are what you eat, drink and think.’
Eras of human nutrition
Elaborating on various ‘eras’ of human nutrition, Dr. Perera said, “We often
hear of terms such as ‘healthy diet’ or ‘balanced diet’ and guidelines for such
diets have been shaped by schools of thinking of each era. For example, the
global focus in 1920s and 1930s was on under-nutrition, and more particularly on
protein-deficiency. Therefore the initial basic guidelines for a healthy diet
were based on protein-energy requirements.”
Lack of sunlight as well as calcium deficiency which aggravated the situation
even in European countries (including the UK) further drove research scientists
in the field of human nutrition in the UK to recommend calcium-fortified wheat
Shedding light upon the Sri Lankan situation in the global context, Dr. Perera
said, “Nutritional information is subject to change with the improving status of
a particular country. At a time when protein-deficiency was a much discussed
subject, Sri Lanka introduced supplements like thriposha. Although we still have
pockets of under-nutrition in the island, it is very much on the decline today,
given the progress in the public health sphere and economic development. At
present we do not have a severe protein-energy deficiency. What Sri Lanka has
largely is marginal under-nutrition or non clinical growth retardation.”
According to Dr. Perera’s research, the diet of poor preschool children hailing
from poor socio-economic backgrounds was not deficient in total protein.
However, what the diets lacked was protein of ‘high biological value.’
Her research highlighted that out of the study nutrients (protein, energy
calcium and zinc) there was only a marginal deficiency in energy and zinc but
calcium was the most limited nutrient in the diet of the children studied.
Reduced physical activities
Vitamin and mineral deficiency which followed the controversial protein-energy
crisis resulted in a fresh set of guidelines evolving with more focus on vitamin
A and iron and more recently, iodine deficiency. This soon gave way to the novel
dilemma of ‘over- nutrition’ encountered by the US and Europe after World War II
and later the industrial growth (in the 1940s).
“This was an era during which communities worldwide were settling down to more
sedentary jobs. Physical activities were reduced and energy requirements came
down but ironically in the UK and North America, the emphasis was on high fat
animal products such as meat and milk,” explained Dr. Perera, adding that
dietary excesses and reduced physical activity in turn resulted in
“Heart diseases and cholesterol started soaring and then came a set of food
guidelines which required people to cut down, and especially cut down on
saturated fat,” explained Dr. Perera.
Lack of local research
According to Dr. Perera, different theories about food and healthy living
evolved based on people’s lifestyles. These theories are debated and challenged
from time to time. In addition, ‘blindly importing’ Western concepts of dietary
guidelines would be detrimental to the local community.
“One of the best illustrations is the US food pyramid drawn by the US Department
of Agriculture which has been criticised strongly by some eminent US scientists.
We often see locals blindly following this chart, grossly ignorant of the fact
that such information is arrived upon according to US data and not on locally
researched information. To adapt to local situations, we must have
well-researched local data. However, there is a dearth of long-term, good
quality nutrition research data in Sri Lanka,” emphasised Dr. Perera, adding
that any national guidelines or individual dietary advice offered therefore
should be formulated after extensive reviews, based on good quality,
international, experimental, dietary and nutritional epidemiological data when
developing dietary guidelines.
“Many people believe that skipping meals and going on a diet are synonymous. It
has been recently documented that if you are skipping meals or drastically
cutting down carbohydrates, you are meddling with the metabolism of the body in
the wrong way,” explained Dr. Perera. She further said that the important thing
was to strike a healthy balance between the ‘good carbs’ (carbohydrates) and
‘bad carbs’ based on the scientific information on the Glycaemic Index (GI)
“Ideally, a person should consume about two litres of water but this depends on
climate, physical activity, energy intake, etc. Especially in hot climatic
conditions like ours, where one perspires a lot, water is essential to maintain
the fluid balance in the body,” explained Dr. Perera.
Shedding light on consumption of tea and coffee, she further said, “This is a
much debated issue. Some argue that it can lead to water being excreted from the
human body. Although several negative connotations are attached to coffee, the
West has now identified favourable nutritional elements in coffee which are
comparable with tea. Green tea and even dark tea is regarded as a healthy
beverage today because of antioxidants. However, going back to the good old
dictum, one man’s food is another man’s poison. For those whose iron intake and
animal protein consumption are minimal, it is advised they refrain from drinking
plain tea after main meals as it prevents the absorption of iron from vegetable
sources. Milk is often encouraged as a healthy supplement.”
Fish and red meat
“Fish is healthier than meat and oily fish are best for your health. Local fish
such as salaya, kumbalawa, hurulla, para and thalapath contain the healthy omega
3 fish oil,” explained Dr. Perera, further adding that at least three fish
portions per week should be consumed.
“Unlike in the West where the majority are meat-eaters, in Sri Lanka, red meat
consumption is minimal and even in such cases, we advice people to keep away
from oily and fatty cuts as long-term consumption is associated with heart
diseases and certain cancers including bowel cancer,” explained Dr. Perera.
“Any fruit is good for anyone as long as one pays attention to the portion.
There was a time that diabetics dreaded fruits such as grapes but thanks to the
research information on the GI, we can now liberalise the dietary advice offered
to people with diabetes as well as other individuals based on scientific
evidence. If one does not exceed the portion required, no harm will be done,”
explained Dr. Perera, who added that as opposed to general guidelines which were
laid down for diabetic patients some time back, today the international policy
is very individualised.
“Even in the case of cholesterol, dietary cholesterol per se is not the only
factor which influences the cholesterol level in blood. It is now known that
blood cholesterol is affected more by the type of dietary fat that is used.
However, the frequency, the food portion size, etc., are also important and this
does not mean that you can feast on cholesterol rich foods. It is also known
that some people are more prone to develop high cholesterol due to genetic
reasons and there are individuals known as hyper responders,” stressed Dr.
More than a mere term, junk food is a sub-culture which has invaded even
developing countries like Sri Lanka with an array of international brand names,
very often causing numerous problems for parents whose young children are
addicted to such food.
“Children who eat burgers, chips and other fast food regularly are more prone to
have heart diseases and be obese as they grow older. To burn the calories of one
big burger, a two-hour walk is required,” explained Dr. Perera, adding that
principles of healthy eating commence from the time an infant is introduced to
“There have been many ‘fad diets’ in the past,” said Dr. Perera. “Although one
can lose weight by going on a fad diet, skipping meals and eating the wrong food
is not the way to do it. Some diets can make you experience bad consequences
such as arteries thickening, leading to heart disease, kidney problems,
osteoporosis, etc., in the long run. Thus, if you need to lose weight, it is
important to follow sound dietary advice,” explained Dr. Perera.
When not to go on a reduced diet
• During pregnancy
• When lactating
Speaking about the importance of fusing a healthy diet with regular exercise,
Dr. Perera said, “To lead a healthy life, the prevention of non-communicable
diseases is paramount and in achieving this, your healthy diet should be
complemented with regular physical activities or exercise and techniques to
Low birth weight is the culprit of diseases in
The fetal origins hypothesis proposes that
coronary heart disease, type 2 diabetes, stroke and hypertension originate in
developmental plasticity, in response to under nutrition during fetal life and
Why should fetal responses to under nutrition lead to disease in later life? It
seems that people who were small at birth are vulnerable to later disease
through three kinds of processes. First, they have fewer cells in key organs,
such as the kidney.
One theory holds that hypertension is initiated by the reduced number of
nephrons found in people who were small at birth. A reduced number necessarily
leads to increased blood flow through each glomerulus. Over time this hyper
filtration is thought to lead to the development of glomerulo-sclerosis which,
combined with the loss of glomeruli that accompanies normal ageing, leads to
accelerated age-related loss of glomeruli, and a self-perpetuating cycle of
rising blood pressure and glomerular loss. Direct evidence in support of this
hypothesis has come from a study of the kidneys of people killed in road
accidents. Those being treated for hypertension had fewer but larger glomeruli.
Another process by which slow fetal growth may be linked to later disease is in
the setting of hormones and metabolism. An undernourished baby may establish a
‘thrifty’ way of handling food. Insulin resistance, which is associated with low
birth weight, may be viewed as persistence of a fetal response by which blood
glucose concentrations are maintained for the benefit of the brain, but at the
expense of glucose transport into the muscles and muscle growth.
A third link between low birth weight and later disease is that people who were
small at birth are more vulnerable to adverse environmental influences in later
life. In a recent study of 3,676 men in Helsinki, those who had a low taxable
income had higher rates of coronary heart disease, as would be expected. There
is no agreed explanation for this, but the association between poverty and
coronary heart disease is a major component of the social inequalities in health
in many Western countries.
Among the men in Helsinki, however, the association was confined to men who had
had slow fetal growth and were thin at birth, defined by a ponderal index (birth
weight/length of less than 26 kilogrammes) Men who were not thin at birth were
resilient to the effects of low income on coronary heart disease.
One explanation of these findings emphasises the psychosocial consequences of a
low position in the social hierarchy, as indicated by low income and social
class, and suggests that perceptions of low social status and lack of success
lead to changes in neuroendocrine pathways and hence to disease. The findings in
Helsinki seem consistent with this.
People who are small at birth are known to have persisting alterations in
responses to stress, including raised serum cortisol concentrations. It is
suggested that persisting small elevations of cortisol concentrations over many
years may have effects similar to those seen when tumors lead to more sudden,
large increases in glucocorticoid concentrations. People with Cushings Syndrome
are insulin resistant and have raised blood pressure, both of which predispose
coronary heart disease.