Food for Thought: Have We Been Giving the Wrong Dietary Advice?

doi:10.4236/fns.2013.43032

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Food and Nutrition Sciences, 2013, 4, 240-244

http://dx.doi.org/10.4236/fns.2013.43032 Published Online March 2013 (http://www.scirp.org/journal/fns)

Food for Thought: Have We Been Giving the Wrong

Dietary Advice?

Zoë Harcombe1, Julien S. Baker1, Bruce Davies2

1Institute of Clinical Exercise and Health Science, Faculty of Science and Technology, University of the West of Scotland, Hamilton,

UK; 2University of Glamorgan, Pontypridd, UK.

Email: [email protected]

Received January 16th, 2013; revised February 18th, 2013; accepted February 25th, 2013

ABSTRACT

Background: Since 1984 UK citizens have been advised to reduce total dietary fat intake to 30% of total energy and

saturated fat intake to 10%. The Nationa l Institute of Clinical Excellence [NICE] suggests a further benefit for Coronary

Heart Disease [CHD] prevention by reducing saturated fat [SFA] intake to 6% - 7% of total energy and th at 30,000 lives

could be saved by replacing SFAs with Polyunsaturated fats [PUFAs]. Methods: 20 volumes of the Seven Countries

Study, the seminal work behind the 1984 nutritional guidelines, were assessed. The evidence upon which the NICE

guidance was based was reviewed. Nutritional facts about fat and the UK intake of fat are presen ted and the impact of

macronutrient confusion on public health dietary advice is discussed. Findings: The Seven Countries study classified

processed foods, primarily carbohydrates, as saturated fats. The UK government and NICE do the same, listing biscuits,

cakes, pastries and savoury snacks as saturated fats. Processed foods should b e the target of public h ealth advice but no t

natural fats, in which the UK diet is deficient. With reference to the macro and micro nutrient composition of meat, fish,

eggs, and dairy foods the ar ticle demon strates th at dietary trials cannot ch ang e one typ e of fat for another in a contro lled

study. Interpretation: The evidence suggests that processed food is strongly associated with the increase in obesity,

diabetes, CHD, and other modern illness in our society. The macro and micro nutrients found in meat, fish, eggs and

dairy products, are vital for human health and consumption of these nutritious foods should be encouraged.

Keywords: Cardiovascular Disease; Obesity; Fatty Acids; Saturated Fatty Acids; Monounsaturated Fatty Acids;

Polyunsaturated Fatty Acids; Dietary Fats; Dietary Carbohydrates; Epidemiology

1. Introduction

History has presented us with a very confused and some-

times misinformed message with reference to healthy

eating. Following the completion of the Seven Countries

Study in 1970, the seminal work of Ancel Keys [1] had a

profound influence on the diets of the USA [2] and the

UK [3]. K e ys’ conclusions were:

1) The incidence rate of CHD [Coronary Heart Dis-

ease] tends to be directly related to the distributions of

serum cholesterol values.

2) The average serum cholesterol values of the cohorts

tended to be directly related to the average proportion of

calories provided by saturated fats in the diet.

3) The CHD incidence rates of the cohorts are as

closely related to the dietary saturated fatty acids as to

the serum cholesterol level.

2. Dietary Advice

In 1983 these findings prompted the National Advisory

Committee on Nutrition Education [NACNE], to rec-

ommend a reduction in total dietary fat intake to 30%

with saturated fatty acids being no greater than 10%. In

1984 this was followed by the Committee on Medical

Aspects of Food Policy [COMA] policy paper “Diet and

Cardiovascular Disease [4].” This report endorsed the

findings of Keys stating that the dietary energy derived

from saturated fatty acids tends to be related to mortality

from CHD and that this relationship is consistent be-

tween countries.

The 2010 public guidance document from the National

Institute of Clinical Excellence [NICE] [5] entitled “Pre-

vention of Cardiovascular Disease at a Population Level”

also emphasised that the reduction of dietary saturated fat

is crucial to the prevention of CHD. They recommended

that a halving of the average intake (from 14% to 7%)

might prevent 30,000 deaths annually. Personal corre-

spondence with NICE with reference to these recom-

mendations confirms that they were very much influ-

enced by the work of Harris et al., 2009 [6 ]. In retro spect

it would seem that the work of two research groups i.e.

Keys et al., 1970 [1] and Harris et al., 2009 [6] have con-

Food for Thought: Have We Been Giving the Wrong Dietary Advice? 241

siderably influenced the conclusions and recommenda-

tions of two of the most important and influential health

reports that have been published in the last quarter of a

century.

When we examine the work of these two research

groups it is surprising how their results and conclusions

were accepted with such conviction and more impor-

tantly superimposed on society to such an extent that

they determine UK eating habits.

3. Classification Errors

Volume XVII of Keys’ study is called “The Diet” [7] and

yet there is very little mentioned about the diet of any of

the countries studied. Each country is discussed in a

separate volume and there is no scientific quantification

of the foods consumed by any of the countries involved

in the study. The dietary references that were mentioned

used unquantifiable descriptions such as “loaded with

saturated fatty acids” and “cholesterol from butter, cream,

meats and eggs”.

More importantly the study classified cake and ice

cream as saturated fats, as opposed to refined carbohy-

drates, an error which is repeated by contemporary food

scientists. Meat and eggs are described as saturated fat

when their fat content is primarily unsaturated. Butter

and cream are one third unsaturated fat, which was not

noted in their analysis. So here we have a profoundly

influential research project introducing imprecise evalua-

tions of macronutrients which have continued to the pre-

sent day.

The Seven Countries Study was not a scientifically

robust study. The dietary references are vague, sporadic

or absent. There were no comments on causation and no

attempt was made to consider association until 25 years

post study completio n [8] and 10 - 15 years after UK and

USA dietary advice had already been changed based on

the recommendations of Keys’ work. The study clearly

demonstrated that the science surrounding macronutri-

ents and nutrition was not as accurate as it is today. Yet

contemporary knowledge is not being applied when con-

sidering nutritional adv ice for the population.

4. Saturated Fats and Polyunsaturated Fats

Harris and his colleagues [6], using a meta analysis re-

view, were of the opinion that consumption of at least

5% to 10% energy from omega-6 polyunsaturated fats

[PUFAs] reduces the risk of CHD relative to lower in-

takes. They were confident about the safety of higher

intakes of these fats. The conclusion s to date are equivo-

cal with reports from robust research concluding that

diets high in PUFAs can increase the susceptibility to

LDL [low density lipoprotein] oxidation and vascular

inflammation [9].

In addition, Mozaffarian et al. [10], u sing angiography,

reported a direct association between PUFA intakes and

luminal narrowing in wo men with CHD. To date there is

no population study that has consumed large quantities of

polyunsaturated fatty acids for extended periods of time.

Therefore the benefits from the consumption of high in-

takes of PUFAs have not been proven to be safe [11].

Because of the important impact that PUFAs are claimed

to have on cardiov ascular h ealth it is critica l that research

disclosures are appraised with care to identify any con-

flict of interest with the sponsors of such projects.

Harris et al. excluded two studies, Rose [12] and

Frantz [13], which were unfavourable claiming no sig-

nificant effect was seen. Selecting six studies [14-19] for

their analysis as opposed to eight studies does present a

confounding variabl e when considering thei r conclusions.

5. Nutrient Classification

It would seem that two influential nutritional recom-

mendations written during the period from 1980-2010

were the COMA [3] and NICE [5] reports and that the

writing of these reports was in turn considerably influ-

enced by the research of Keys [1] and Harris [6]. To da te

we have been guilty of imprecision in the identification

and classification of foods. This leads to dietary recom-

mendations, based on incorrect information and in many

instances poor science.

There is a need to accurately define the macro and mi-

cronutrient conten t of food. Biscuits, savoury snacks and

processed food should not be defined as saturated fats

because they are substantially carbohydrates. Red meat is

not a saturated fat but a combination of various fatty ac-

ids. Sirloin steak for example is approxima tely 71% wat e r,

21% protein, 3% unsaturated fat and 2% saturated fat

[20,21]. Natural food such as meat, fish, eggs and nuts

contain saturated, monounsaturated and polyunsaturated

fats, only the proportions vary. Few people appreciate

that it is impossible to eat saturated or polyunsaturated

fat alone. Dairy products are the only food group with

more saturated than unsaturated fat. Many of the foods

demonised by past research groups, even lard, contain

more unsaturated than saturated fat. Dietary fat consump-

tion is a key provider of essential fats and fat soluble vi-

tamins.

The only foods that contain no carbohydrate or protein

are oils [22,23]. Sucrose contains only carbohydrate, no

fat or protein. Every other food contains protein with fat,

carbohydrate or both. The only food th at can be modified

to assess the dietary implications of fat consumption

without changing the macronutrient composition is oil.

This explains why the COMA [3] report stated “There

has been no controlled clinical trial of the effect of de-

creasing dietary intake of saturated fatty acids on the

Food for Thought: Have We Been Giving the Wrong Dietary Advice?

242

incidence of coronary heart disease nor is it likely that

such a trial will be undertaken”.

6. Dietary Fat and Coronary Heart Disease

The Heart of Mersey Paper [THoMP] [24], which con-

sidered dietary fats and the prevention of coronary heart

disease, concluded that saturated fats are a clear agonist

for the development of CHD with the unsaturated fats

assuming an antagonist and beneficial influence. Using a

100 g steak, as an example, with 5.4 g of fat, it is difficult

to accept that the 39% of the fat which is saturated is

damaging to the cardiovascular system while the 61% of

the fat which is unsaturated is protective. Keeping in

mind that the to tal fat conten t o f the steak will prov ide all

but 3 of the 13 vitamins and 16 minerals that are a pre-

requisite for the maintenance of good health.

The verification for the saturated versus unsaturated

fat theory is equivocal. Mozaffarian et al. [10] reported

that postmenopausal women with relatively low total fat

intake and a greater saturated fat intake were associated

with less progression of coronary atherosclerosis. A re-

cent meta-analysis [25] reviewing 347,747 people re-

ported that there was no significant evidence for con-

cluding that saturated fat is associated with an increased

risk of CHD. The authors were of the opinion that more

evidence should be gathered on the nutrients that would

replace saturated fat. A prime candidate for this is sugar,

which has tripled in consumption worldwide over the last

50 years and is implicated in the rapid rise in obesity. It

is recommended that government intervention should be

directed towards “added sugar”. This is defined as any

sweetener containing the molecule fructose that is added

in food processing [26].

THoMP [24] refers to the COMA report [3], which

recommends a ratio of polyunsaturated fats to saturated

fat that is a P/S ratio of 0.45. The egg is the only natural

food with this ratio. Of the 10 g of fat per 100 g of egg,

37% is saturated, 46% is monounsaturated, and 17% is

polyunsaturated [27]. Precise daily dietary recommenda-

tions are required to demonstrate how total fat, saturated

fat and the P/S ratio can be met in parallel with micronu-

trient recommended daily allowances [RDAs].

7. Swapping Dietary Fats—The Limitations

and the Consequences

The THoMP [24] report also recommended that the pop u-

lation goals should be to replace dietary saturated fats

with small amounts of unsaturated fats. There are two

ways in which this can be done; one has no impact on

macronutrients but both methods will influence micronu-

trients. Sunflower oil, for example could replace olive oil

and slightly reduce saturated fat while increasing poly-

unsaturated fat at the expense of monounsaturated fat

(Table 1). Very little saturated fat (4 g/100g) would be

replaced by unsaturated fat. Vitamin E would increase

from 14 mg to 41 mg while Vitamin K would fall from

60 mcg to 5 mcg [22,23]; these are the only two nutrients

of small value in olive oil and sunflower oil. Oils gener-

ally, are deficient in vitamins and devoid of minerals.

Substituting foods other than oils, changes the relative

amounts of saturated and unsaturated fat, calorie intake

and the macro and micronutrients. Replacing 100 g of

cheese with 100 g of olive oil will reduce saturated fats

[SFAs] by 7 g and increase monounsaturated fats [MU-

FAs] eight fold (64 g) and PUFAs twelvefold. Calorie

intake doubles while losing: 25 g of protein; 33% of vi-

tamin A and B12 RDAs; 70% of the calcium and phos-

phorus RDAs and all zinc [28]. If whole milk is replaced

with the same oil, all protein and minerals are lost, calo-

ries increase 15 fold and all three fats increase substan-

tially SFAs seven fold, MUFAs 91 fold and PUFAs 55

fold [29].

Despite a vast amount of nutritional research over

many decades we are still surrounded by confusion, rap-

idly changing advice and substantial mythology. Many of

the contemporary eating habits are harmless but some,

particularly in the young, can be a threat to good health.

For instance a reduction in the consumption of dairy

foods would seriously challenge the daily prerequisite

levels of vitamin A and D and the key minerals calcium

and phosphorus. There is evidence of a re-emergence of

rickets and osteoporosis is rising [30]. The most recent

Family Food survey has reported that the present UK diet

is deficient in retinol and vitamin D, providing less than

one third of the UK Reference Nutrient Intake and barely

a fifth of the recently revised American RDA for vitamin

D [31].

The consumption of oily fish is now considered a must

and caution is given over red meat. However if 100 g of

pork is replaced with the same quantity of mackerel we

double the intak e of calories and saturated fat. The intak e

of MUFAs would triple and PUFAs increase almost

seven fold [32,33] with the protein remaining the same.

Vitamins are gained and some minerals are gained and

others lost.

8. Conclusion

Nutritional science despite many years of enquiry is in a

state of equivocation, resulting in many false promises

being given with reference to a diet which will keep the

majority of the population fit lean and healthy. Despite

the influence of epigenetics we remain hunter gatherers

surrounded by a preponderance of food and automation.

This presents us with many problems of adjustment but it

is not as complicated to solve as some would have us

believe, albeit with ulterior motives mostly financial.

Food for Thought: Have We Been Giving the Wrong Dietary Advice?

243

Table 1. Nutritional content of foods in article.

(All per 100 g) Sirloin steak Eggs Sunflower oilOlive oilCheese Milk (whole) Pork Mackerel

Water (g) 71 76 0 0 37 88 75 64

Carbohydrate ( g) 0 1 0 0 1 5 0 0

Protein (g) 21 13 0 0 25 3 21 19

Fat (g) 5.4 8.3 100 100 31 2.9 3.8 12.1

SFA/MUFA/PUFA (g) 2.1/3/0.3 3.1/3.8/1.4 10/45/40 14/73/1121/9/0.91.9/0.8/0.2 1.5/1.8/0.5 3.3/5.5/3.3

Calories 154 143

884 884 403 60 123 205

Vitamins USA RDA

A (3000 IU) 0 487 0 0 1002 102 0 167

B1 (1.2 mg) 0.1 0.1 0 0 0 0 0.5 0.2

B2 (1.3 mg) 0.1 0.5 0 0 0.4 0.2 0.2 0.3

B3 (16 mg) 7.2 0.1 0 0 0.1 0.1 8.6 9.1

B5 (5 mg) 0.6 1.4 0 0 0.4 0.4 0.7 0.9

B6 (1.7 mg) 0.6 0.1 0 0 0.1 0 0.7 0.4

Folic Acid (400 mcg) 13 47 0 0 18 5 0 1

B12 (2.4 mcg) 1.2 1.3 0 0 0.8 0.4 0.5 8.7

C (90 mg) 0 0 0 0 0 0 0 0.4

D (600 IU) 0 35 0 0 12 40 0 360

E (15 mg) 0.3 1 41 14 0.3 0.1 0.1 1.5

K (120 mcg) 1.2 0.3 5.4 60 2.8 0.2 0.1 5

Minerals (Macro)

Calcium (1000 - 1200 mg) 27 53 0 0 721 113 5 12

Magnesium (420 mg) 22 12 0 0 28 10 23 76

Phosphorus (700 mg) 193 191 0 0 512 91 290 217

Potassium (4700 mg) 323 134 0 0 98 143 479 314

Sodium (1500 mg) 54 140 0 0 621 40 226 90

Minerals (Trace)

Copper (0.9 mg) 0.1 0.1 0 0 0 0 0.1 0.1

Iron (18 mg) 1.5 1.8 0 0 0.7 0 0.4 1.6

Selenium (55 mcg) 24.1 31.7 0 0 14 3.7 39.6 44

Zinc (11 mg) 3.9 1.1 0 0 3.1 0.4 1.4 0.6

The highest value is highlighted for each macro and micro nutrient for prima facie observation.

There is a need to return to eating natural foods such as

meat, eggs and dairy from grazing animals, fish, vegeta-

bles, nuts, seeds and local seasonal fruits. These were a

feature of the British diet prior to a myriad of dietary

advice based on questionable research, resulting in two

thirds of the population becoming overweight/obese and

sick within three decades.

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