Heart Health

Updated 16 September 2013

Diets that protect the heart

Heart disease is one of the most serious threats to our nation's health. Here's how you can protect your heart.

September is National Heart Awareness Month in South Africa. Heart disease is one of the most serious threats to the health of our nation. One in three men and one in four women in South Africa, will develop a heart condition. This translates to eight million men and six million women with ailing hearts.

In terms of population groups, heart attacks (including hypertension and strokes) are the primary cause of death in Whites (27,7%), Asians and Indians (29,1%) and Coloureds (18,6%) and the third most common cause of mortality in South African Blacks (10,8%) (HeartPlus, 2013).

Causes of ailing hearts

Most people are aware of the fact that lifestyle plays an important role in heart health. Factors including lack of regular exercise, stress, smoking and atherogenic, unhealthy diets rich in fats, refined carbohydrates and salt, lead to hypertension (high blood pressure) and heart disease.

A recent review of the hundreds of studies that have investigated the role of fat in the human diet which was published by Professor Sanders of the Diabetes and Nutritional Sciences Division at the School of Medicine, King’s College London, has confirmed the basic advice that can help to prevent heart disease (Sanders, 2013).

Historical background

Initially studies with animals and primates identified the fact that diets high in animal fats and added cholesterol led to the development of atherosclerosis.

In 1968, the International Atherosclerosis Project found that the incidence of atherosclerosis varied greatly between different countries - in countries where fat intake was higher, more people developed heart disease.

Studies with service men killed in combat and young people who had died of accidents, pinpointed the fact the even in young, otherwise healthy and fit individuals, the low-density lipoprotein cholesterol (LDL-C) levels in the blood (also known as the "bad" cholesterol levels) were positively related to atherosclerosis, while high-density lipoprotein cholesterol (HDL-C) levels in the blood (the "good"cholesterol levels) had the opposite effect and were protective against heart disease.

One by one, the other significant factors that contribute to heart disease such as ageing, male gender, smoking, obesity with increased BMI values and diabetes were identified by researchers (Sanders, 2013).

By the beginning of this century, the evidence was regarded as conclusive that high LDL-C-levels cause atherosclerosis and that measures which can lower LDL-C (and increase HDL-C) such as weight loss, strict control of diabetes, regular exercise, stopping smoking and a heart-friendly diet, are capable of halting the progression of this dread process and protecting us against heart disease.

Current dietary recommendations

We live in the era of meta-analyses where the results of vast numbers of experimental subjects treated with every kind of dietary intervention to prevent heart disease are combined and analysed to determine if a specific dietary adjustment has a significant effect on the incidence of heart disease or not.

Some of the dietary changes that have been evaluated in this way included reduction of the saturated fatty acid (SFA) content of the diet (SFA are regarded as particularly atherogenic), reduction of SFA plus substitution of fat with monounsaturated fatty acids (MUFA) and/or carbohydrates, reduction of dietary cholesterol intake, diets to induce weight loss to reduce BMI-values, and diets to control insulin resistance.

In general, these dietary changes did reduce LDL-C levels to a varying degree, but not as much as statins (medications to lower blood cholesterol levels)(Sanders, 2013).

After reviewing the above mentioned findings, the WHO/FAO did however conclude that there is sufficient convincing evidence that it is prudent to reduce SFA and replace these saturated fatty acids with MUFA rather than refined carbohydrates.

A general guideline that no more than 10% of energy should come from SFA was decided upon by both the WHO/FAO and the Dietary Guidelines for Americans compiled by the Institute of Medicine in the USA.

The current situation

According to Prof Sanders (2013), dietary intake of SFA has fallen signficantly in many countries around the wold including in the UK.

The SFA intake in the UK has been reduced from 17% of energy intake in 1987/87 down to 13% in 2001, where it has apparently remained with no further reductions. Total fat intake also fell from 42% to about 35% in the UK, with a marked increase in the intake of polyunsaturated fatty acids (PUFA). 

Prof Sanders (2013) attributes these changes to the introduction of low-fat or fat-free milk and dairy products (e.g. yoghurt, cottage cheese), the fact that chicken and pork are cheaper meat cuts than beef or lamb which encourages consumption of the former meats and that the intake of yellow fat spread (butter, margarine) dropped because less bread is being eaten in the UK nowadays.

It is interesting to note that in South Africa researchers have found that in comparison to the 1950s when our red meat contained 32% fat, nowadays the meat is trimmed before consumption to reduce the fat content down to 10% and if only muscle meat is eaten then the fat content of our red meat is currently as low as 5% (Simela, 2012).

The view of reason

Prof Sanders (2013) finally points out that “the more important issue is the overall balance of the diet in relation to cardiovascular risk”.

He warns against discouraging the intake of all foods that contain some SFA (e.g. fatty fish, nuts, dairy products, etc), because these foods are known to actually reduce the risk of heart disease.

In addition it has been found that foods derived from animals such as mutton and lamb that are trimmed of visible fat and prepared without adding SFA-rich fats, can be eaten as part of a balanced diet without boosting the fat content of the diet (Simela, 2012).

So at the end of the day, eating a balanced diet which contains a minimum of visible fat, which does not contain an excess of any one food or nutrient and which does not promote weight gain or the development of insulin resistance, metabolic syndrome, or type 2 diabetes, will also protect your heart against atherosclerosis.

Moderation and sensible food intake, plenty of exercise, not smoking, taking statins if they are indicated and keeping an eye on total fat and salt intake (see the example of the Dash Diet), will help to prevent ailing hearts.

References: (Health24.com (2012). What is heart health? www/health24.com/ Medical/Heart/; HeartPlus (2013). The “Heart” Facts. http://www.heartplus.co.za/heart-facts.html ; Sanders T A B (2013). Conference on ‘Dietary strategies for the management of cardiovascular risk’. Reappraisal of SFA and cardiovascular risk. Proc Nutr Soc, 4:1-9; Simela L (2012). Chapter 7: Red meat & Fat. In: Red Meat in Nutrition & Health. Schönfeldt HC, Hall N - Eds. Institute of Food, Nutrition & Well-being, UP, Pretoria, SA)


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