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Review
Benefits and hazards
of fat-free diets
Ivan
cica Dela
s*
University of Zagreb, School of Medicine, Department
of Chemistry and Biochemistry,
Salata 3, HR-10 000
Zagreb, Croatia (Tel.: D385 1 4566757; e-mail:
ivancica.delas@mef.hr)
Since excess adiposity is thought to be responsible for the
development of coronary heart disease, diabetes, cancers of
several types, and other disorders, recommendations for
reduced intake of dietary fats have generally been accepted.
On the other hand, low-fat and fat-free diets are poor in essen-
tial linoleic (18:2u-6) and linolenic (18:3u-3) fatty acids, and
other long chain polyunsaturated fatty acids necessary for
unhindered cell function, especially during foetal and early
neonatal brain development. Furthermore, decreased blood
concentrations of u-3 fatty acids have been associated with
several neuropsychiatric disorders, like Alzheimer’s disease,
schizophrenia and depression.
Nutritional fats obviously play a significant role in the
development of obesity, cardiovascular disease and other met-
abolic disorders, but they are also essential in the structure and
function of human body, and therefore cannot be considered
as intrinsically bad. Instead, total energy intake and the com-
position of fats, as well as other lifestyle risk factors should
be taken into consideration.
Introduction
Dietary fats continue to be a major subject of concern
and a research priority because of their association with
heart disease, cancer and other chronic diseases. There is
a strong tendency to overlook their nutritional importance,
and to focus on the negative health implications with an
increased abundance of misconceptions. Although lipids
are highly heterogeneous group of compounds, conclusions
about their health effects have been drawn generally,
regardless of the lipid class and specific metabolic role.
Widely accepted recommendations for a reduction of fat
intake resulted in the total fat rejection in a notable number
of individuals. However, there is still a vast majority of
population, especially in the developed, but also in the
developing countries, who consume fats in amounts that
are far beyond the requirements. It is therefore essential
for professionals and experts to continue with the efforts
to educate a wide population and to assure the availability
of accurate information for everyone. After all, we are the
only ones who must take the responsibility for our own
health.
Dietary fats
Human body contains certain amounts of fats in the ratio
which depends significantly on the gender and age, and
consists of essential fats involved in quite a number of
physiological functions, as well as stored fats, mainly tria-
cylglycerols, responsible for energy supply when necessary.
Generally perceived simply as triacylglycerols, fats com-
prise a heterogeneous group of compounds characterized
by their solubility in organic compounds, but insolubility
in water. Usually they are classified as: a) simple lipids
(fatty acids, neutral fats and waxes); b) complex lipids
(phospholipids, glycolipids and lipoproteins); and c) cho-
lesterol and isoprenoid derivatives (vitamins A, D, E and
K). All of them play significant physiological and meta-
bolic roles during our entire life.
Compared to carbohydrates and proteins, dietary fat is
a concentrated energy source. However, various fats also
contribute to the physical and functional properties of
most food products, affecting nutritional as well as sensory
aspects of foods, i. e. palatability, smoothness, crispness,
flakiness, plasticity and feeling of satiety. Furthermore,
fats serve in heat transport, aeration and fermentation, as
well as carriers for colours, flavours, spices and vitamins.
In the attempts to reduce the fat content, food manufac-
turers have been forced to search for fat substitutes and
quite a number of them have been developed but with dif-
ferent applicability. However, this topic goes beyond the
subject of this review.
Like other macronutrients, fat is never eaten separately
but in a combination with other nutrients and in a variety
of forms. The bulk of lipid digestion takes place in the
duodenum and small intestine by the action of pancreatic
enzymes: pancreatic lipase, phospholipase A2 and choles-
terol esterase. Since lipolytic enzymes act on the borderline
between water and lipid droplet, digestion is improved by
emulsifying effect of bile acids, secreted from the gallblad-
der. In infants lingual and gastric lipases play a significant
* Corresponding author.
0924-2244/$ - see front matter Ó2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tifs.2011.08.008
Trends in Food Science & Technology 22 (2011) 576e582
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role in digestion of already emulsified milk fats, thus pro-
viding more energy essential for the growing organism.
Absorption of lipolytic products, i.e. fatty acids,
2-monoacylglycerol, lysophospholipids and cholesterol,
occurs throughout the small intestine, but more than 95%
is absorbed at the beginning of jejunum. In enterocytes
the absorbed products are resynthesised into triacylglycer-
ols and phospholipids, and along with cholesterol and apo-
lipoproteins (synthesised by the enterocytes) packed into
chylomicrones and released through the lymph into the
blood. Fatty acids of medium chain length, i.e. 8 to 12 car-
bon atoms, are more soluble than higher homologues and
therefore do not need to be esterified into triacylglycerols
or phospholipids. From intestinal cells they are released
directly into blood circulation and taken to peripheral tis-
sues for utilisation, bypassing chylomicron formation and
metabolism. In this way, medium-chain fatty acids are
available for utilisation in quite a short time, which makes
them a desirable component of infusions for parenteral
nutrition. Still, a certain caution is necessary, because fast
metabolism may result in the synthesis of ketone bodies
and, if not controlled, in ketoacidosis.
Fatty acids
Dietary fatty acids are usually present as esters in a com-
plex either with glycerol or sphingosine, rarely as unesteri-
fied free fatty acids. They are classified as saturated and
unsaturated, and the latter are subdivided into mono- and
polyunsaturated fatty acids (MUFA and PUFA, respec-
tively). Saturated fatty acids (SFA) contain no double bonds,
hence all available carbon bonds are taken by hydrogen
atoms. They can be converted to MUFA by dehydrogenation,
and the commonest of them is oleic acid (C18:1u-9). The
term u-9 signifies that the first double bond exists as the
ninth carbonecarbon bond from the terminal eCH
3
end
(u) of the carbon chain. This series of fatty acids can be syn-
thesized by human body and therefore is not essential in the
diet. However, PUFA linoleic (18:2u-6) and linolenic
(18:3u-3) contain additional double bonds as the sixth
(u-6) and the third (u-3) carbonecarbon bond from the ter-
minal eCH
3
end (u) of the carbon chain, respectively.
Human body does not contain enzymes required for the
introduction of double bonds at these positions and therefore
they have to be ingested with the food. Discovered in 1923,
they were originally designated as vitamin F, but Burr, and
Burr (1929, 1930) have shown that they are better classified
with the lipids as essential fatty acids (EFA). From these par-
ent essential fatty acids, higher homologues are metaboli-
cally derived in a cascade of reactions catalysed alternately
by desaturases and elongases, resulting in the formation of
long chain polyunsaturated fatty acids (LC-PUFA) of u-6
and u-3 series, respectively (Fig. 1).
Polyunsaturated fatty acids in health and disease
Finding the association between food composition and
risk of certain illness is very complex. The same is with
the impact of dietary fatty acids on health and disease,
where the evidence is still accumulating (Table 1). Con-
vincing associations for reduced risk of coronary heart dis-
ease (CHD) include consumption of foods high in linoleic
acid, eicosapentaenoic acid (EPA, 20:5u-3) and docosahex-
aenoic acid (DHA, 22:6u-3) (fish and fish oil). In this view,
Mediterranean diet, rich in green vegetables, fish and olive
oil, has been recognized as the one to be recommended in
the prevention as well as in the treatment of CHD (Shai
et al., 2008).
Although the precise mechanisms by which unsaturated
fatty acids reduce CHD risk are still not fully understood,
those identified so far include effects on blood lipid concentra-
tions, blood pressure, inflammatory response, arrhythmia and
endothelial function (Anand, Alkadri, Lavie, & Milani, 2008).
As part of phospholipids and sphyngolipids, PUFAs are
indispensable for the construction, maintenance and func-
tion of cell membranes. Number and position of double
bonds in the chain of fatty acids greatly influence the fluid-
ity and thus the function of cell membranes. Through the
Fig. 1. Metabolic pathway of u-6 and u-3 essential fatty acids in
humans.
Table 1. Unsaturated fatty acids in health and disease.
Cardiovascular disease Blood lipid concentrations
Atherogenesis
Endothelial function
Thrombogenesis and fibrinolysis
Arrhythmia
CHD
Stroke
Diabetes
Cancer
Inflammatory conditions Asthma
Inflammatory bowel disease
Arthritis
Foetal and infant
development
Cognitive function
and behaviour
Cognitive function
Mood
Depression
Schizophrenia
Bipolar disorder
Dementia
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action of phospholipase A2, fatty acids at sn-2 position are
liberated and become part of the cell signalling system.
Arachidonic acid (AA, 20:4u-6), which is usually linked
to this position, serves as a precursor in the synthesis of
eicosanoides: prostaglandines, prostacyclines and leukotri-
enes, important mediators in intra- and intercellular
signalling.
Furthermore, dietary fatty acids affect a number of dif-
ferent metabolic pathways, including those involved in gly-
cemic control; hence the composition and the amounts of
dietary fats may have a role in the management of type 2
diabetes. Although the level of evidence is currently insuf-
ficient, there are indications that unsaturated fatty acids
may also be associated with a reduced risk of developing
certain cancers, including cancers of colon, breast and pros-
tate. Since PUFAs serve as precursors for eicosanoids, there
are a number of inflammatory conditions, such as asthma,
Crohn’s disease and arthritis, which could potentially be
alleviated by dietary modifications (Chapkin, McMurray,
& Lupton, 2007).
Brain cells are especially rich in certain long chain u-3
fatty acids and numerous researches have been undertaken
in order to clarify the relationship between dietary
consumption of these fatty acids and the behaviour and
cognitive function, observed in epidemiologic and cross-
sectional studies. Broadhurst, and Cunnane (1998) and
Cunnane (2007) even suggested that the availability of
food rich in u-3 fatty acids has had an influence on the
development of human brain and evolution.
Because of their importance in the foetal growth and
development, placental transport of EFA has been inten-
sively studied. Campbell, Gordon, and Dutta-Roy (1996)
have shown that placenta plays a significant role in prefer-
ential accumulation of LC-PUFA in foetal tissues. It was
found that membrane-binding sites are specific to fatty
acids, with a strong preference for LC-PUFA in the order
AA >> LA >ALA >> oleic acid. Haggarty, Page,
Abramovich, Ashton, and Brown (1997) also showed that
the human placenta can selectively transfer LC-PUFA and
EFA to the foetal circulation in preference to the nonessen-
tial FA. Specific plasma membrane-associated fatty acid-
binding proteins have been identified. Fatty acid translocase
and fatty acid transport protein (FATP), located on both
sides of the placental cells, allow bidirectional flow of all
FA (nonessential, essential, LC-PUFA), while p-FABPpm
on the maternal side may favour the unidirectional flow
of maternal PUFA to the fetus by preference for these fatty
acids (Dutta-Roy, 2000).
Cholesterol
Cholesterol belongs to the class of sterol lipids, with
cyclic structure and characteristic eOH group, thus being
an amphipathic molecule. This property makes cholesterol
the integral component of almost all cell membranes with
a corrective effect on membrane fluidity. Namely, by
increasing the content of cholesterol in membrane lipids,
the membrane fluidity increases. However, at higher ratios,
the effect is just the opposite.
Although naturally occurring in most membranes and as
a precursor for physiologically important compounds like
steroid hormones and bile acids, cholesterol was also put
on the “list of shame” because of its relationship with ath-
erosclerosis process. Because of its susceptibility to oxida-
tion, cholesterol is involved in lesions that are responsible
for atherosclerosis and thus in the pathogenesis of heart dis-
ease. There is no doubt that high level of blood cholesterol
is a risk factor for the development of CHD. However, the
question remains about the impact of dietary cholesterol on
total body content. Since virtually all tissues are capable of
cholesterol synthesis, it is not an essential component of
a diet. It has a vital role as a precursor for the synthesis
of bile acids, vitamin D and steroid hormones, including
those of adrenal cortex and gonads. Metabolized in the
liver, bile acids and cholesterol are excreted in the faeces,
and about 1 g of cholesterol is eliminated from the body
per day, while more than 98% of secreted bile acids is
absorbed in the ileum and returned to the liver via portal
circulation. This enterohepatic circulation, along with the
endogenous cholesterol synthesis, accounts for the majority
of total cholesterol content, with dietary intake having
much less impact on the final regulation than desired.
From the first studies about the effect of dietary cholesterol
on blood cholesterol levels, performed by Keys, Anderson,
Mickelsen, Adelson, & Fidanza in 1956 up to the latest re-
search, the results are still contradictory. The studies have
mainly failed to show a correlation between the daily intake
of foods considered rich in cholesterol and the concentra-
tion of cholesterol in the serum (Kahn et al., 1969;
Morris, Marr, Heady, Mills, & Pilkington, 1963). There
are, however, publications reporting a relationship between
nutritional habits and increased blood cholesterol levels,
but it should be noticed that such results are generally
observed in food intervention trials with the already over-
weight and/or hypercholesterolaemic subjects (Gorder,
Bartsch, Tillotson, Grandits, & Stamler, 1997). Family phy-
sicians and specialists should therefore be aware of the fact
that hypercholesterolaemia is rarely improved by simple
reduction of cholesterol intake, and nowadays it is well
known that other dietary components have much more pro-
nounced influence on cholesterol synthesis. These include
trans-unsaturated fatty acids and some saturated fatty acids,
like myristic and palmitic. However, it should be kept in
mind that hereditary factors also play a significant role in
the onset of type II hiperlipidaemia, i.e. familiar
hypercholesterolaemia.
Despite the fact that dietary restriction rarely improves
the existing hypercholesterolaemia, there are still some
rigid nutritional recommendations. Since cholesterol is
present only in food of animal origin, i. e. meat and meat
products, restricted intake of such food was recommended.
Chizzolini, Zanardi, Dorigoni, and Ghidini (1999) have
shown in their review that total cholesterol intake from
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meat consumption varies between 100 and 150 mg/day.
Such values would imply that amounts ranging from one
third to one half of the daily recommended cholesterol
intake (300 mg/day) are provided by meat. On the other
hand, diets in which meat consumption is restricted or
even excluded, i. e. vegetarian diet, can be a significant
risk factor for iron and vitamin B
12
malnutrition.
Phospholipids
Phospholipids are minor and less investigated compo-
nents of food lipids. However, there is an increasing interest
in their role in cell signalling and regulation processes. The
results of some investigations have pointed out how ceram-
ide is involved in growth inhibition and differentiation, and
that it induces the apoptosis of tumour cells (Sugawara,
Kinoshita, Ohnishi, Nagita, & Saito, 2003). Gastrointestinal
hydrolysis of sphingolipids results in the formation of bio-
active metabolites (ceramide and sphyngoid bases), which
could therefore act as inhibitors of tumorigenesis (Merrill,
& Sandhoff, 2004).
Phospholipids form an integral structural base of all cell
membranes, as well as subcellular structures. They can also
play various specific roles, i.e. as a pulmonary surfactant,
participating in cell signalling, etc. Substituted mainly at
sn-2 position of glycerophospholipids, upon liberation by
phospholipase A2, arachidonic acid serves as a precursor
in biosynthesis of eicosanoids. These compounds with 20
carbon atoms and multiple double bonds comprise prosta-
glandins, leucotrienes and prostacyclines, important media-
tors in metabolic control.
Vitamins and antioxidants
A broad category of water-insoluble compounds, fats, act
as solvents in the absorption of fat-soluble vitamins A, D, E
and K, which are indispensable for our health. Vitamin A is
a specific component of the retina in the eye, and plays a role
in a variety of functions like skin health, bone metabolism,
gene transcription, immune response and reproduction.
Since growing evidence suggests that oxidative stress and
a proliferation of free radicals can induce severe damage
and set out inflammatory processes, there is an increasing
interest in food rich in compounds with antioxidant activity.
Vitamin E is considered the most abundant fat-soluble anti-
oxidant in the body and one of the most efficient chain-
breaking antioxidants available. Acting as a primary
defender against oxidation, vitamin E in food is accompa-
nied by other fat-soluble compounds with antioxidant capac-
ity. These include phenols with confirmed anti-inflammatory
effect, acting as inhibitors of lipoxygenase activity, and thus
reducing the synthesis of leucotrienes and other mediators. A
significant protective activity is attributed to phytosterols,
which competitively reduce cholesterol absorption in the
gut and consequently decrease its concentration in the blood.
Recently, the attention of researchers has been focused on
squalen, because of its assumed activity in cancer prevention
(Smith, 2000). Finally, having in mind the role of vitamin D
in the absorption and metabolism of calcium, the question re-
mains what the use of dairy products with 0.1% fat is.
Fat-free diets
Diet as a treatment is difficult to randomise in an effec-
tive way, especially through long periods of time required
to investigate the effects on a disease. Instead, high quality
epidemiological studies performed on large cohorts of
healthy individuals over a long period of time provide quite
a strong evidence of any interaction.
Since the obesity is just the first link in the chain of
developing causal metabolic disorders, for which a relation-
ship has been established, including diabetes, metabolic
syndrome and CHD, the permanent concern of public
health authorities comes as no surprise. Even more con-
cerning is the fact that there is a high rate of overweight
and obese children and adolescents, and it is well known
that obesity in childhood predicts obesity in adulthood. Fur-
thermore, insulin resistance and diabetes type 2, diseases
that occurred predominantly in overweight, middle-aged
adults, can nowadays be found in children as young as 7
or 8.
In attempts to reduce the risk of CHD, numerous diets
have been developed, some more than 400 can be found
on web pages. Focused on the body mass loss in the already
overweight and obese persons, they offer a “magic wand”
but with short-term effects. As a matter of fact, in some
cases, incompletely defined or partially applied nutritional
advice resulted in even worse obesity.
One of such examples is a fat-free diet, introduced in the
1990s as a general recommendation for different types of
hyperlipidaemia. Increased accumulation of body fats and
elevated values of blood lipids were taken as the only indi-
cator in risk assessment, resulting in unique recommenda-
tion to “reduce fat intake”. However, a significant
reduction in fat intake did not result in the expected body
mass reduction in general population. On the contrary, the
obesity epidemic continued to grow, accompanied by
increased prevalence of insulin resistance and diabetes. It
was omitted that the reduction of fats in a diet has to be
compensated with the increased intake of carbohydrates
in order to reach the same energy requirements. Elevated
blood glucose concentration induces insulin secretion and,
if prolonged, insulin resistance is developed, with diabetes
as the most probable consequence.
In order to evaluate the utility of low-fat diets in the
treatment of obesity, Pirozzo, Summerbell, Cameron, and
Glasziou (2003) performed a meta-analysis starting from
some 3000 references. However, after excluding unsuitable
studies, only six trials were left, and these six failed to con-
firm any significant advantage of low-fat diets compared to
other body mass-reducing diets in terms of sustained mass
loss. The reason for excluding so many studies was hetero-
geneity in their design, short time of intervention, more
than one parameter changed and similar failures, so the
obtained results were uncomparable. The main problem is
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the lack of compatibility of the terms used to describe the
applied diets. The term “low-fat” is often used for diets
containing 40% of energy intake from fats, and are com-
pared with so-called “control” diets supplying 60% of
energy from fats.
It has become apparent that nutritional fats are not an
exclusive contributor to the development of obesity and
consequent disorders, hence other risk factors had to be
taken into consideration. In 2003, WHO recognised differ-
ent risk factors and categorised them according to the level
of evidence of their contribution (Table 2). Among the fac-
tors with convincing evidence of increased risk for develop-
ment of CHD there are no fats per se. Nowadays, it is
generally accepted that some saturated fatty acids, i.e. myr-
istic and palmitic, as well as trans fatty acids have negative
impact on lipid metabolism, cholesterol synthesis and
health in general. On the other hand, for diets rich in
PUFA, positive effects on human health have been con-
firmed. Generally accepted recommendations for nutrient
intake goals (Table 3) published by WHO (2003) were
based on these data from epidemiologic, cross-sectional
and research studies.
However, in the meantime the damage had already been
done. The belief about “bad” fats was generally accepted,
and those faithful to this belief excluded all kinds of fats
from their nutrition. Following these trends, the food
industry has developed a wide assortment of “fat-free”
and “low-fat” products. Nowadays, everything is declared
and advertised as “fat-free” or “cholesterol-free”, regard-
less of the fact that the product naturally does not contain
any fats. And to be honest, they are doing it because we
accepted this oversimplified approach to sustainable weight
control and healthy eating.
In a growing fear from heart attack, brain insult and
other events related to overweight and obesity,
accompanied by atherosclerosis and high blood pressure,
we have forgotten how important roles the lipids play in
our organism. Because of their high energy density with
around 37.7 kJ/g, they are used by the organism as
a long-term fuel reserve. Although this particular property
is the subject of our concern, it is our own responsibility
to put the entire food and energy intake under control and
not to exceed the needs.
Having in mind the fact that fat-free diets are insufficient
in essential fatty acids, as well as their importance for cell
structure and function, Dela
s, Popovi
c, and Dela
s (1999)
were interested in mechanisms by which cells compensate
for the lack of these acids. In the experiments with labora-
tory animals it was shown that fat-free diet results in the
activation of compensatory mechanisms and endogenous
synthesis of similar fatty acids (Dela
s, Popovi
c, Petrovi
c,
Dela
s, & Ivankovi
c, 2008). However, distribution of double
bonds in these fatty acids differs significantly from that in
EFA, since in higher organisms there are no enzymes capa-
ble of introducing double bonds beyond C9.
Although the importance of EFA was recognized early,
at the beginning of the last century, it seems necessary to
recall on the knowledge. Insufficient dietary intake results
in “essential fatty acid deficiency syndrome”, characterized
by skin lesions, scaliness, hair loss, and, in animals, fertility
problems were recorded. As already mentioned, besides
traditionally known linoleic and linolenic fatty acids, u-3
polyunsaturated fatty acids EPA and DHA are considered
to be of fundamental importance for the central nervous
system and brain development, as well as for better cogni-
tive properties, not only during foetal and early neonatal
period, but throughout the whole life (Plourde, &
Cunnane, 2007).
While research undertaken so far seems to confirm that
dietary cholesterol has only minor effect on total serum and
Table 2. Summary of strength of evidence on lifestyle factors and risk of developing cardiovascular diseases (WHO, 2003).
Evidence Decreased risk No relationship Increased risk
Convincing Regular physical activity Vitamine E supplements Myristic and palmitic acids
Linoleic acid trans-Fatty acids
Fish and fish oil (EPA and DHA High sodium intake
Vegetables and fruits (including berries) Overweight
Potassium High alcohol intake
Low to moderate alcohol intake
(for coronary heart disease)
Probable a-Linolenic acid Stearic acid Dietary cholesterol
Unfiltered boiled coffeeOleic acid
NSP
Wholegrain cereals
Nuts (unsalted)
Plant sterols/stanols
Folate
Possible Flavonoids Fats rich in lauric acid
Soy products Impared foetal nutrition
Beta-carotene supplements
Insufficient Calcium Carbohydrates
Magnesium Iron
Vitamin C
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LDL cholesterol levels (Hu et al., 1997; Nelson, Schmidt,
& Kelley, 1995), there are studies which connected
low-cholesterol diets with the onset of depression and the
increase of overall mortality due to increased suicide,
homicide and accidents (Fowkes et al., 1992; Endelberg,
1992; Muldoon, Manuck, & Matthews, 1990). On the other
hand, a meta-analysis performed by Booth-Kewley and
Friedman (1987) found a strong positive correlation
between depression and CHD and myocardial infarction.
Fielding (1991) also found that premorbid depression pre-
dicts coronary artery disease, with poor survival outcome.
This correlation is in contrast with the proposed association
of low cholesterol with depression, from which a protective
effect of depression on CHD might be predicted.
Further epidemiologic and interventional studies suggested
that symptoms of psychiatric disorders are actually induced by
the diet depleted of essential u-3 fatty acids. Namely, low-fat
diets recommended in the treatment of CHD were desirably
low in cholesterol, but consequently low amounts of u-3 fatty
acids resulted in undesirable effects. Furthermore, although
the brain and central nervous system accounts for only 2%
of the body mass, it contains 25% of the free cholesterol in
the whole body (Dietschy, & Turlay, 2001). It seems therefore
reasonable to presume certain relationship between the choles-
terol content of the brain and the brain function. In the studies
with non-human primates as well as in in vitro experiments it
was shown that low cholesterol content leads to lower seroto-
ninergic activity (Troisi, 2009). Since it is known that a high
serotoninergic activity is associated with less impulsivity
and aggression it was hypothesised that low cholesterol diets
could increase the risk from external-cause mortality
(Boscarino, Erlich, & Hoffman, 2009). As a support to this
hypothesis, Lalovic et al. (2007) have recently demonstrated
in a post-mortem study of suicide completers that certain
regions of the brain of violent suicide completers had a lower
cholesterol level than in non-violent suicide completers. Taken
all together there is an increasing concern about possible del-
eterious effects of low cholesterol diets (Stanley, 2010) and the
widely prescribed blood cholesterol lowering drugs (While, &
Keen, 2010).
However, certain diseases and medical conditions make it
difficult for the body to tolerate fat, so a low-fat diet may be
required. (i) Gallbladder disease: bile secreted from the gall-
bladder contains bile acids that act as emulsifiers and help the
body to break down and absorb fats. In case of gallstones or
other gallbladder disease, a low-fat diet may be of certain
help. (ii) Delayed stomach emptying: low-fat diet may be
recommended in order to prevent further deterioration. In
case of long-term diarrhoea accompanied by malabsorption
of nutrients, a low-fat diet may help to control the symptoms.
Furthermore, there are some inherited metabolic diseases
characterised by the lack of certain enzymes responsible
for utilisation of lipids, like long chain fatty acid deficiency
(LCFAD) syndrome. Affected individuals are at risk of
insufficient energy supplementation and, especially in child-
hood, should be continuously monitored. In such cases, oils
containing medium-chain triglycerides (MCT) are usually
supplemented in order to prevent energy crisis.
Summarized in Table 4, predicted benefits and possible
hazards of fat-free diets indicate that there is no unequivo-
cal solution for all health problems. Taken all together there
is no doubt that nutrition has a great impact on human
health and the appropriate diet is a powerful tool in health
maintenance and disease prevention, as well as in the treat-
ment of the already developed illness, but each person
requires an individual approach.
Conclusions
Dietary fats are not just energy-rich triacylglycerols, but
also essential lipid components. Therefore, it seems reason-
able to review the current recommendations on fats in
nutrition. Fat-free diets are unacceptable as a long-term ther-
apy for obesity and other disorders, instead it is important to
preserve the appropriate ratio of saturated, monounsaturated
and polyunsaturated fatty acids. The time has come to accept
recommendations for 30% of nutritional fats as “standard” or
“control” diet, and those with higher amounts as “high fat”
Table 4. Predicted benefits and possible hazards of fat-free diets.
Predicted benefits Possible hazards
Lower energy intake Essential fatty acids syndrome
Body mass reduction Disturbances in cell membrane
structure and permeability
Reduced risk for
coronary diseases
Impaired intra- and intercellular
signalling
Reduced intake of
trans and SFA
Impaired cognitive properties
Improved concentrations
of serum lipids
Increased risk for neuropsychiatric
disorders
Reduced risk for gallbladder
disease
Fat-soluble vitamins deficiency
Improved status in hereditary
metabolic diseases
Hormone misbalance
Reduced risk for some
cancers
Chronic fatigue syndrome
Table 3. Nutrient intake goals (WHO, 2003).
Dietary factor Goal (% of total
energy or g/day)
Total fat 15e30%
Saturated fatty acids <10%
Polyunsaturated fatty acids (PUFAs) 6e10%
u-6 PUFAs 5e8%
u-3 PUFAs 1e2%
trans fatty acids <1%
Monounsaturated fatty acids (MUFAs) By difference
Total carbohydrate 55e75%
Free sugars <10%
Protein 10e15%
Cholesterol <0.300 g/day
Sodium chloride (sodium) <5 g/day (<2 g/day)
Fruits and vegetables 400 g/day
Total dietary fibre From foods
Non-starch polysaccharides (NSP) From foods
581I. Dela
s / Trends in Food Science & Technology 22 (2011) 576e582
Author's personal copy
diets. Subsequently, diets containing less than 25% of energy
from fat might be considered as “low fat”. In compliance
with health professionals and nutritionists the lowest limit
for nutritional fats is taken at 15% of energy intake, so fat-
free diets with less fat should be considered as health haz-
ards. Finally, it is a mistake to focus only on short-term
body mass loss. We should rather focus on sustainable
body mass control through healthy lifestyle practices.
Acknowledgements
The author thanks Mrs. Zrinka Pongrac Habdija for her
careful reading of manuscript.
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