By Christopher Tack |
Clinical Specialist Physiotherapist
Cholesterol is a health buzzword. It is blamed, whether rightly or wrongly, for a large amount of the health issues we get as we age- particularly those involving the heart.
Statins (aka HMg-CoA reductase inhibitors) assist reduction in cholesterol by limiting the amounts of an enzyme which is essential for its production. Everyone is on a station. Ask your parents, your aging uncle, your work colleagues. Someone will be taking them. GPs notoriously give out statins to reduce cholesterol in attempts to reduce the impact and prevalence of heart disease.
This article aims to help you take back control and prevent you needing to take statins to manage your cholesterol. Instead we will discuss how you can be use your nutrition plan and effectively diet to minimise or reduce your cholesterol level.
Cholesterol & Hyperlipidaemia
Cholesterol is an organic molecule known as a sterol (modified steroid alcohol). It is also a lipid (fat) which is produced by animals. In fact cholesterol is the most commonly discussed and analysed form of animal sterol.
It’s function is as an essential part of animal cell membranes to prevent the need for a cell wall. Cell walls are present in plants and fungi cells to predominantly prevent cells exploding under the pressure of too much water. However, the inclusion of cholesterol in animal cells walls ensures structural integrity alongside the ability remain fluidity to the animals movements. Cell walls restrict movement of plants, which is not the case in animals.
Cholesterol is also a precursor to fat soluble vitamins (such as vitamins A, D, E and K) and the five major classes of steroid hormones (e.g. progestagens, glucocorticoids, mineralocorticoids, androgens, and estrogens).
Hyperlipidaemia is the abnormally elevated concentration of lipids (fats) or lipoproteins (fat + protein molecules) in the blood. These lipids predominantly include cholesterol and triglycerides (a type of dietary fat found in meats, dairy products and cooking oils).
Now whilst cholesterol is an essential component to our bodies cells, essentially if the levels of these molecules rise too high, hyperlipidaemia ensues and it becomes dangerous to our bodies. In fact hyperlipidaemia is a common risk factor for the development of cardiovascular disease (1).
When there is a build up of cholesterol in your circulatory system it will collect inside the walls of your blood vessels, which narrows the arteries and impedes flow of blood from the heart. This can lead to heart tissue ischaemia, cell death, pain and eventually heart failure. This narrowing is called atherosclerosis.
The main form of cholesterol which causes atherosclerosis is low density lipoprotein (LDL). It’s less harmful counterpart is HDL (or high density lipoprotein) which also travels around the blood system. A final form of lipid in our blood, which is unfortunately also a contributor to cardiovascular disease are triglycerides.
Nutrition & Cholesterol
Whilst statin medications are often prescribed, it is largely recommended that non-pharmacological treatment should be the go to therapy for those with hyperlipidaemia (3).
Based upon this premise, the National Cholesterol Education Program devised the Therapeutic Lifestyle Changes (TLC) approach (4), which highlights diet as an essential component of the health strategy required to balance levels of total cholesterol, LDL, HDL and triglycerides.
Their recommendations are as follows (4):
✓ Sustain 25-35% daily calories from fats
✓ Reduce saturated calories to <7%
✓ Reduce intake of cholesterol to
Beyond this work other reviews are available which comprehensively examine the influence diet has on blood fat levels and the association with cardiovascular disease (5-6).
Based upon these works further recommendations should be considered (3):
✓ Replace saturated and trans fats with polyunsaturated and monounsaturated fats (7)
✓ Reduce saturated fat levels to <7% of total calories – reduce LDL to 9-12% of total calories
✓ Reducing LDL to 12% and total cholesterol to 8% decreases risk of cardiocerebrovascular disease by 19% (8)
In essence dietary recommendations for lowering cholesterol can be summarised into two distinct ideas.
1) Reduction of saturated fat and LDL cholesterol by reducing specific foods of animal origin as this will reduce total levels of cholesterol and triglycerides. For example, a vegetarian diet which minimised saturated fat and cholesterol intake (due to minimal animal product consumption) reduce levels of LDL cholesterol by 17-40% (9-10). These steps could also assist to reduce triglyceride levels by 20% (11).
2) Substitution of saturated fats/ LDL/ Triglycerides with foods with high content of HDL. For example, various types of nuts (almonds, peanuts, pecans) demonstrate fat reducing benefits, which are ascribed to their content of fibre, plant sterols (as found in margarine) and unsaturated fats (12).3
3) Increased consumption of soluble fiber which allows cholesterol to be bound to bile acids and excreted in the gut (13). An 8g per day intake is suggested to lower both total cholesterol and balance levels of LDL vs HDL (14). Common forms of soluble fibre include fruits, vegetables, oats and barley. We will now examine some of the best foods to assist cholesterol lowering to help you plan a low-cholesterol diet with ease!
Cholesterol Lowering Foods | NUTS
On the whole, people are wary of eating too many nuts, simply because they are full of fats and dietary fats (as mentioned) have become synonymous with heart disease. However, a large base of scientific studies suggest that the most important factor to consider is the type of fat consumed, rather than the total amount of fat in the diet (15).
Nuts predominantly contain monosaturated and polyunsaturated fats which help reduce LDL cholesterol levels (rather than the bad saturated and trans fats). Additionally, nuts contain other positive biologically active compounds for heart health; including plant proteins high in arginine, fibre and magnesium (16); anti-oxidant tocopherols (17); and phytosterols (plant steroid compounds) (18).
These extra components in nuts help reduce LDL cholesterol and attenuate heart disease risk. General studies examining the association between consumption of nuts and coronary heart disease show that in those eating nuts >5 times per week risk of heart disease is reduced by 35% (15). These results are supported by other studies examining this relationship (19-20).
In studies generically examining tree nuts (such as cashews, almonds, pecans and walnuts) data indicates that increasing consumption can reduce levels of LDL cholesterol by 2-19% compared to “low fat” diets (21-22).
Of course because of the high calorie density of nuts, it is considered that they should be isocalorically substituted for other foods. Recommendations suggest approximately 1-3g per day at least 5 days per week (22-23).
With this in mind, it is worth examining which nuts are the best pick to include in your diet.
Studies demonstrate that a diet high in walnuts causes a 12-16% reduction in both total and LDL cholesterol levels, compared to a control diet (24). This was alongside a decrease in the LDL: HDL ratio by 12% (15).
The positive benefits of diets high in whole almonds to reduce risk of coronary heart disease and cholesterol levels has been established (25-26).
A more recent study aimed to identify how whole almond consumption can decrease heart disease risk by examining the fatty acid composition of these nuts and the effect of intake in individuals with diagnosed hyperlipidaemia (27).
This study examined 27 people with hyperlipidaemia who were given a 3 month diet with 1 month phases of either full, half or zero dosages of almonds. Their results showed an inverse association between almond intake and risk score for heart disease (as more almonds were consumed, risk scores reduced).
They also showed increases during the full and half almond phases of oleic acid, monounsaturated fatty acids, triacylglycerol and non-essential fatty acids which were positively associated with changes in HDL-cholesterol concentrations. Thus showing the rise in healthy cholesterol and lowering of heart disease risk.
One particular study (22) examined the effect of a high cashew nut diet on 64 individuals with metabolic syndrome over 8 weeks. This study is highlighted as one which contradicts the benefits of nut consumption for serum levels of cholesterol, as in these groups there was no significant change in total cholesterol or LSL: HDL ratio.
However, a couple of points need to be made to clarify these findings. Firstly, by the authors’ admission the group given a cashew diet started with a low baseline LDL-cholesterol level, which may have hidden any benefit which could have been caused.
Secondly, when dealing with subjects who have obesity and metabolic syndrome, the cholesterol-lowering response is likely to be lessened (compared to lean individuals) as in obesity production of cholesterol is increased due to insulin resistance (28).
These factors, when placed alongside evidence indicating that cashews are part of the group of nuts which contain positive, health enhancing compounds such as oleic acid, linoleic acid, tocopherols and squalenes (29); highlight that the current evidence may underestimate the positive effect of cashew nuts on cholesterol risk.
A cholesterol lowering association was also found with diets supplemented with macadamia nuts (30), pecans (31) and pistachios (32).
A similar effect was seen with peanuts which in fact are not a nut, but rather are a legume (33).
When studies examine the content, fatty composition and oxidative stability of nuts (such as Brazil nuts, pecans, pine nuts and pistachios) they find that these foods are excellent sources of cholesterol lowering agents.
Namely, these nuts have high levels of oleic acid and linoleic acid; tocopherols and squalenes (a biosynthetic precursor to animal and plant steroids), which have positive benefits on reducing serum levels of cholesterol (17, 34).
More Cholesterol Lowering Foods
Now, do not despair if nuts are not your favourite snack as they are not the only cholesterol-lowering food stuff you can choose.
For example, barley is a cereal grain which is a member of the grass family (think “garden” rather than “Snoop Dogg”). The sprout and extract of this cereal contains 4.9% fat, 52.6% carbohydrate (polysaccharide) and 34.1% protein (35).
However, it also contains a variety of additional goodies include polyphenols and various antioxidants (36-37). One such compound is hexacosanol which is a saturated primary fatty alcohol, which is thought to improve cholesterol metabolism by reducing its production and comprises 62-80% of barley extract. This lipid alcohol combines with a water soluble fiber and polysaccharide to form a policosanol, which has also shown to reduce cholesterol levels (38-41).
Another option to reduce cholesterol are oats. Due to their content of β-glucans, oats are considered to assist the management of cholesterol levels in those with hyperlipidaemia.
β-glucans are a group of polysaccharides which naturally occur in cereals, and studies have examined the form of β-glucan in oats which are used to make bread.
One study took 38 overweight males with mild to moderate hyperlipidaemia, who were given a diet containing bread which was made from 6g of β-glucan oats for 8 weeks (42).
Their results indicated a 27.8% increase in levels of good HDL-cholesterol, as well as a significant reduction in total cholesterol and LDL-cholesterol levels. The reduction in non-HDL cholesterol levels was 8.4% greater in the oats group, compared to the control diet. This was alongside a 24.9% greater reduction in total cholesterol: HDL ratio, and a 28.8% greater reduction in LDL: HDL ratio.
This study powerfully demonstrates the benefits of an oat diet which contains β-glucans to modify various aspects of cholesterol metabolism, even in overweight subjects.
Take Home Message
With statin medications being one of the most commonly prescribed in the UK (45), the prevalence of high cholesterol seems to be sufficient to make it a significant health issue for our population.
This article outlines some of the benefits of modifying your diet to include various cholesterol-lowering foods (e.g. nuts, oats and barley) so that you can make positive changes to your nutrition plan and reduce both your current levels of cholesterol AND reduce your future risk of heart disease.
Make the changes, take control and improve your health.