Yes, diet does impact on your cholesterol level... here's what to eat to lower it
Arming yourself with information is the first step towards managing cholesterol, but there are so many competing facts out there - so what do you really need to know? Dietitian Orla Walsh has all the answers.
It's important to note that cholesterol isn't something completely awful. We don't want zero cholesterol floating about in our body. It is merely a chemical building block that is found naturally in cells of the body.
So just what is cholesterol and its job?
Its job in the body is to produce steroid hormones and vitamin D. It also makes bile acid which works like washing up liquid in the gut, emulsifying the fat we eat so that it can be absorbed into the body. Once it's in our blood cholesterol is carried around on the back of specialised proteins.
These proteins may sound familiar from blood results provided by your GP which include high density lipoproteins (HDL), aka 'good cholesterol', and low density lipoproteins (LDL), aka 'bad cholesterol'. Lowering your total cholesterol levels, or improving the balance of cholesterol, is less about removing foods from your diet and more about adding foods into your daily diet.
As a dietitian, one of the more infuriating things I hear is that diet has no impact on cholesterol levels. It does. In fact, it has a significant impact on your cholesterol levels. In studies a cholesterol-lowering diet lowered cholesterol on average by up to 25%. Those sticking to the diet more rigidly lowered their cholesterol the most.
When you get advice from a dietitian, and you incorporate even more cholesterol-lowering advice than the standard titbits (stanols, nuts, soluble fibre and soy), expect even greater results again. Not only will foods actively lower cholesterol, but they will also be nourishing the body and provide other health benefits. I'll discuss some of the changes you can make below.
Plant Stanols and/or Sterols: 2g daily
Plant sterols and stanols work by blocking the absorption of cholesterol that is naturally found in the food we eat. If it isn't absorbed into our body from the gut, it ends up vacating our body through our stool. Stanols and sterols also block the absorption of bile into the body. Bile is released by our bile duct into our gut to emulsify fats so that fats can be absorbed into our body. As bile is made from cholesterol, the blocking of its passage back into the body means that it is excreted into the toilet. The body is then forced to make more bile from cholesterol in our blood in order to replenish its stock. This further reduces cholesterol.
Although plant stanols or sterols are plant extracts that occur naturally in foods like wholegrains, fruits, vegetables and nuts, the amount needed to reduce cholesterol levels can only be achieved by eating foods specially fortified with extra plant stanols and sterols. Therefore these foods should be taken at mealtimes or as part of a main meal. If taken in the right amounts they can lower LDL cholesterol by 10% to 15%.
They are expensive, so the pros need to be weighed up against the cost. For some people they are an easy solution as it's a matter of simply knocking back a drink every morning.
Eat almonds: 30g (about 23 almonds) daily
All nuts are a good source of vegetable protein, fibre, heart healthy monounsaturated fats and vitamin E. Other nuts have been trialled in research with the same benefit. Therefore it's probably more accurate to encourage people to eat 30g of nuts each day and to mix up the sources. For example, Brazil nuts, almonds, pistachios, walnuts, pecans, cashews and peanuts. This should be easily done by adding some to your porridge in the morning, eating them as snacks, throwing cashews into a stir-fry or, if you're anything like me, eating peanut butter directly out of the jar.
Soluble fibre: 20g daily
Fibre is found in all plant foods in varying degrees. Fibre can be categorised into two types - soluble and insoluble fibre. Most plants have a mixture of these two types. When water is added to certain foods, the soluble fibre thickens and becomes a gel - this is why when chia seeds are mixed with water they look a little like frog spawn. This in turn soaks up cholesterol and bile like a sponge and carries it out of the body. Aim for at least 10 grams of soluble fibre every day, but preferably 20 grams each day.
Soya protein: Aim for 25 grams daily
Soy is a great source of healthy fats, protein and fibre. The fat from soyfoods is predominately polyunsaturated (approximately 60pc) and monounsaturated (approximately 30pc). Therefore part of its positive effect may be through its ability to naturally improve your diet's fatty acid profile. After all, soybeans are among a handful of plant foods that provide both the essential omega-6 and omega-3 fats.
The protein within soy may be cholesterol-lowering too. A meta-analyses of clinical trials reported that soy protein lowers 'bad' LDL cholesterol by 4% to 6%. This is enough to produce meaningful protection from heart disease.
Each 1% reduction in cholesterol is estimated to lower risk of heart disease by 1% to 2%. It also lowers triglyceride levels by approximately 5% to 10%, possibly increasing 'good' HDL cholesterol by 1% to 3%.
To put this in real terms, each 1mg increase in HDL cholesterol is said to lower heart disease risk by 2% to 3%. A pint of soy milk provides about 20 grams of protein, so that's an easy trade. Other ideas include eating soy yoghurt, eating edamame beans, and incorporating soy mince or textured vegetable protein (TVP) to your meals.
Artichoke leaf extract
Artichoke leaf extract has been touted to be cholesterol lowering. A Cochrane study was completed which included only good quality randomised controlled trials (RCT). There were only three of these trials involving 262 participants.
Of the three trials, one trial was at low quality of risk, one at medium and one of unclear risk of bias. In the first trial, the total cholesterol level decreased by 4.2pc from 7.16 mmol/L to 6.86 mmol/L after 12 weeks. In the second trial, total cholesterol levels reduced from 7.74 mmol/L to 6.31 mmol/L after about six weeks. In the third trial, there was very limited data made available, but it did state that blood cholesterol significantly reduced. Since this review, an RCT aimed to evaluate the effects of artichoke leaf extract on lipid profile. There were 92 overweight subjects in total, with 46 taking this supplement for eight weeks. Supplementation was associated with a significant increase in 'good' HDL cholesterol. A significantly decrease also occurred with regard to total cholesterol and 'bad' LDL cholesterol. Therefore this may be considered in therapies going forward.
There is a growing body of evidence indicating that added sugars may have a significant impact on heart health. A study in 2014 reported that people who consume more added sugars have a much higher risk of death from heart disease.
People who consumed 10% to 25% of their calories from added sugars were 30% more likely to die from heart disease than those who consumed less than 10% of their calories from sugar. That equates to up to 31.5 teaspoons of sugar each day, versus less than 12.5 teaspoons per day. It also includes the added sugars in our food - not just the sugar you add to your food.
The average Joe consumes too much added sugar each day. Therefore most people could benefit from reducing their intake. In 2014, the World Health Organisation lowered its recommended intake from 10% to 5% of calories, or less than six teaspoons of added sugar each day, if eating 2,000 calories a day. 'Added sugars' refers to any calorie containing sweetener added to a food during processing, cooking or at the table. What the term 'added sugar' doesn't include is sugar naturally found in fruit or milk, as this is provided to the body with fibre and protein as well as lots of nutrients and water, so doesn't have the same negative effects on our body.
A 2014 review in the American Journal of Clinical Nutrition concluded that the more added sugars people consumed, the higher their triglyceride levels, total and LDL cholesterol was. They also reported that it raised blood pressure and all of these negative impacts were independent of the sugars' effect on body weight.
The impact on our cholesterol levels appears to occur quickly, as reported by a study in 2011. They found that 'bad' LDL cholesterol levels in healthy young people increased by 20% after just two weeks of consuming added sugars at the high level of 25% of daily calories. There are plenty of people here consuming this amount of sugar each day, and more! It has been noted in reviews that sugar causes the generation of reactive oxygen species, which is when there is a lot knocking around in our blood which may result in oxidative stress, which is involved in all stages of heart disease development.
To reduce your sugar intake, try to eat less foods that are processed and come in packets. If eating foods from packages, do look on the back of the pack to see how much sugar has been added. They can appear 'hidden' to the majority of consumers as they may be called different names such as beet sugar, raw sugar, sugar cane juice, nectar, caramel, juice, honey, molasses, syrup, treacle or any ingredient containing a word ending in '-ose', including sucrose, dextrose, glucose, fructose, maltose, lactose, galactose, saccharose, and mannose.
Exercise: the under-utilised prescription
Ah exercise ... the thing that makes us physically and mentally healthier, yet most people don't hold enough value to it.
The cool thing about exercise is that different types produce different results. For example, aerobic exercise training with different intensities such as moderate and high, as well as the type of exercise - aerobic, resistance or a combination of the two. A systematic review assessed this with regards to cholesterol levels. When they compared high versus moderate intensity aerobic exercise, results favoured high intensity. Moderate intensity is when you're out of breath and can't sing but can talk. High intensity exercise is even more out of breath, so that you can neither sing nor talk.
The most frequently observed change within this review was an increase in the protective HDL cholesterol. Interestingly, resistance exercise showed a positive trend with regards to 'bad' LDL cholesterol. A result that will surely please the gym-bros as well as yogis and Pilates enthusiasts. Combined exercise showed improvements in both the 'good' HDL and 'bad' cholesterol. More research is needed to be more confident in the results, but regardless it's safe to say 'Up ya get'.