Can your diet improve your cholesterol levels?
Cholesterol plays a key role in the progression of heart disease, which has consistently been a leading cause of mortality in developed countries for more than 80 years.
There are several dietary components that can have a noticeable effect on cholesterol levels. However, increasingly the evidence is suggesting that the value of diet as a whole is greater than the sum of its individual parts, and as people don’t only consume single nutrients, there is a compelling argument for focusing on our overall diet quality.
What are the diets that work?
Diets low in; trans and saturated fat, refined carbohydrates and sugar sweetened beverages. And diets high in unsaturated fats, wholegrains, fruits and vegetables were shown to be associated with a reduced risk. Several protective diets have also emerged and subsequently been studied for their beneficial effects on heart disease risk.
The Mediterranean Diet
The Mediterranean diet is one of the most extensively studied diets, with evidence showing that its benefits/risk reduction properties are not exclusively limited to heart disease.
The Mediterranean diet typically consists of
- Olive oil
- Alcohol in moderation
Olive oil, vegetables, legumes and fruit are suggested to be the most cardio-protective elements of the Mediterranean Diet, however isolated components are less effective than the diet as a whole.
What does the research say?
The landmark PREDIMED study of the Mediterranean diet was conducted in Spain, and recruited 7,447 individuals with a high risk for CVD.
Participants were allocated into one of three groups;
- Implement the Mediterranean diet with a focus on extra-virgin olive oil
- Implement the Mediterranean diet with a focus on mixed nuts
- A control group who received advice only to reduce fat intake and limit consumption of olive oil and nuts
When compared to the control group, the two treatment groups demonstrated a reduced risk of CVD by approximately 30%.
Undoubtedly, the PREDIMED trial confirmed that diet can have significant and meaningful effects on our health, however it does also leave some questions answered. For example, whether introducing olive oil and nuts would have a similar effect on other diets, and what is the optimum amount to see beneficial effects but not incur weight gain.
The EVIDENT study developed a diet quality index that predicts adherence to the Mediterranean diet, which also showed a significant association with CVD markers.
Furthermore, the INTERMAP study, analysing nutrient intake and CVD risk in 17 populations from 4 countries including the UK, found those categorised as low risk had diets similar in composition to a Mediterranean diet.
While diet quality analysis in research often links to adherence to the Mediterranean diet, using the Mediterranean diet to reduce CVD risk is highly dependent on the length of time the diet is adhered to, and requires a lifelong commitment.
Why does the Mediterranean Diet work so well?
The association between the Mediterranean diet and heart disease is largely undisputed, with several hypotheses suggested to explain its beneficial effects.
Moderate alcohol consumption is associated with decreased cardiovascular risk in part by increasing HDL levels, and both red wine and some Mediterranean plant foods contain large amounts of flavonoids, which are natural antioxidant and antithrombotic (blood thinning) substances.
The Mediterranean diet also contains a-linolenic acid (omega 3), with increased intake being shown to promote platelet aggregation and oxidation of LDL cholesterol.
Undoubtedly, encouraging people to follow the principles of the Mediterranean diet could have extensive long-term health benefits. However, despite the convincing evidence backing the Mediterranean diet, its popularity is on the decline as people are shifting to more typical western diets.
HDL – High density lipoprotein, one of the main components in cholesterol
LDL – Low density lipoprotein, the other main component in cholesterol
Flavonoids – Are molecules, found in some fruit & vegetables
Antioxidant – Reverses the effect of damaged cells within the body
Antithrombotic – Reduces the formation of blood clots
Platelet aggregation – Clumping together of platelets within the blood
Oxidation – the process of a molecule gaining oxygen