There’s a new incentive to get your cholesterol levels under control: It may reduce the risk of dementia, according to new research presented at the Alzheimer’s Association International Conference in Philadelphia.
Growing evidence suggests that excess cholesterol, which clogs your arteries with fatty deposits, is now officially recognised as one of 14 modifiable dementia risk factors.
Of course, it is also a risk factor for heart attack and stroke.
Julie Ward, senior cardiac nurse at the British Heart Foundation, describes high cholesterol as a common “hidden risk factor” for the disease. “It can be present without anyone knowing until it’s too late,” she says. “That’s why it’s so important to get checked. You can ask your GP to check your cholesterol levels, which are measured using a simple blood test. Alternatively, finger-prick cholesterol tests are available at some pharmacies or as part of the free NHS Health Check in England.”
So what exactly is cholesterol, what role does it play in the body, and what can you do to lower it?
What is cholesterol?
Cholesterol is a waxy substance that comes in two main forms – LDL cholesterol and HDL cholesterol. Although it is often described in a negative context, our body actually needs cholesterol, which is naturally synthesized by the liver.
“It is important for human health because of its various roles in the body, including neural insulation, cell membrane structuring and hormone production,” says Matt Taylor, health and wellbeing physiologist at Nuffield Health.
Excessive intake of LDL cholesterol can lead to fatty deposits that form plaques in the arteries. This can block blood flow to the brain, which is one reason why cholesterol is linked to dementia. HDL cholesterol has long been considered the “good cholesterol” because, despite still being a type of fat in your blood, it doesn’t block your arteries. However, studies looking at drugs that increase HDL cholesterol have not yet found any reduction in heart problems. For this reason, the NHS still recommends looking at your total cholesterol score as an indicator of whether you are at high risk.
According to the NHS, around 220,000 people have familial hypercholesterolaemia, an inherited condition that causes high cholesterol levels from birth. Although it can be treated with statins, less than eight per cent of people are aware they have the condition.
“There may be visible symptoms, such as cholesterol bumps in the joints of your hands, knees, or Achilles tendon at the back of your ankle,” Ward says. “Other symptoms include small yellow cholesterol lumps near the inner corner of your eye or a faint white ring around your iris, the colored part of your eye.”
But for the vast majority of people, the primary cause of high cholesterol is diet. According to nutritionists, the following six foods tend to be the primary culprits.
The six worst foods that raise cholesterol
Sugary drinks
While Coca-Cola and other sodas are known to be not the best for our health, you may be surprised to know that they can also affect your cholesterol. This is because of how the body metabolizes and stores excess sugar, especially fructose, which is found in high amounts in sodas due to their low cost.
“When we drink calories, the body uses calories [different] “Pathways in the liver are used to store this excess energy by producing new cholesterol for later use,” says registered nutritional therapist Katherine Paton.
Drinking fructose is much worse than eating it because it is found in higher concentrations. The lack of solids to slow down metabolism means that it reaches the bloodstream much more quickly, meaning that it is easier to drink larger amounts. This leads to more cholesterol buildup.
Excessive consumption of alcohol, which is broken down in the liver and remanufactured as cholesterol, can also raise your total cholesterol levels.
Coconut oil and coconut milk
One of the problems with eating foods high in saturated fat is that, like fructose, the body converts it into cholesterol. Consultant dietitian Orla Walsh recommends we consume less than 30g of saturated fat a day, and a surprising contributor is coconut oil.
According to the British Heart Foundation, coconut oil is 86% saturated fat, a third more than butter. The same goes for coconut milk, says Walsh. “One tin of coconut milk has twice the recommended amount of saturated fat you should eat in a day,” he says. “It contains [around] “66g per box.”
James Vickers, nutritionist at Vitality, says that although coconut oil is generally considered healthy, it is best used in moderation. “Use only small amounts and look for alternative unsaturated fats [such as olive or sunflower oil] “Instead, on a day-to-day basis,” he says.
At the same time, the jury is still out on coconut oil. The Mayo Clinic strongly agrees with Walsh and Vickers, saying that coconut oil raises both LDL and HDL cholesterol more than olive oil or canola oil. But a clinical study published in 2018 British Medical Journal Coconut oil has been shown to have less of an impact on LDL cholesterol than butter and is closer to olive oil overall.
As always with nutrition, the evidence is ambiguous.
Fried foods
Perhaps less controversially, Vickers says fried foods of all kinds, such as French fries, battered onion rings, fried chicken, spring rolls, and doughnuts, tend to be particularly high in both saturated fat and so-called trans fats. The latter are created through an industrial process that adds hydrogen to vegetable oil, causing the oil to solidify at room temperature and be converted into LDL cholesterol.
Ultra-processed ice cream
One difference between many ultra-processed ice cream cups and fresh versions made by independent vendors is that they often contain combinations of added dairy fat, high-fructose corn syrup, multiple sources of liquid sugar, and coconut oil. All of these additives make it tastier but ultimately increase your cholesterol.
“These UPF ice creams are easy to spot if you read the ingredients label,” says nutritionist Rhian Stephenson, founder of supplement brand ARTAH. “Some will have baked goods added to them, such as cookie dough and brownie bites, and these will contribute as well.”
Filterless coffee
Overall, coffee is pretty good for your health as long as you don’t regularly add extra sugar, milk, and cream, as is the case with many common barista coffees like frappuccino.
However, when it comes to black coffee, it seems that filter or instant coffee is best. Increasing evidence suggests that coffee made using a coffee maker, Turkish coffee machine or espresso machine may raise your LDL cholesterol.
“The effect appears to be due to a compound called cafestol, found in unfiltered coffee, which interacts with genes that maintain cholesterol balance in the body,” says Federica Amati, chief nutritionist at Zoe. “In particular, cafestol reduces the production of bile acids, which normally help the body to remove cholesterol. So when their production is disrupted, it can upset the balance and lead to increases in LDL cholesterol.”
At the same time, experts have noted that this only seems to be the case if you drink excessive amounts of coffee, such as six or more cups a day. “If you’re only drinking one or two cups a day, it doesn’t really matter what type of coffee you drink,” says Tom Sanders, professor emeritus of nutrition and dietetics at King’s College London.
Processed meat
Like fried foods, many processed meats are often high in saturated fat, and Vickers recommends keeping bacon, in particular, to a minimum. “You should limit how much you eat,” he says. “Eat it only occasionally, in small amounts, and grilled, not fried. But if you already have high cholesterol, high blood pressure, or are at risk for cardiovascular disease, you should avoid it altogether.”
So what should you consume with caution?
Who doesn’t love a morning croissant? But the problem is that these treats tend to be high in trans fat, according to Jess Willow, a registered dietitian at Willow Nutrition. Artificial trans fats are thought to be even worse than saturated fat at raising cholesterol levels, with studies showing they increase the risk of heart disease.
“We often find trans fats in pastries and baked goods, so it’s a good idea to limit things like croissants and other pastry-type foods, cakes and biscuits,” she says.
Other foods high in saturated fat that can have a strong impact on cholesterol include red meats and butter, so experts recommend eating these in moderation.
High cholesterol foods that are actually good for you
There are many foods that are naturally high in cholesterol, but instead of avoiding them, they’re actually good for us. This may sound counterintuitive, and as dietitian Duane Mellor explains, it once led to some questionable nutrition advice.
But we now know that it’s not the cholesterol in our diet that’s causing us problems, but the excess fructose, saturated and artificial fats that our bodies use to produce LDL cholesterol, which then ends up in our blood vessels.
“Eggs, which contain cholesterol, were previously not recommended for people at high risk of heart disease,” says Mellor. “But they are a great source of protein and not as high in saturated fat, so cholesterol is not an issue.
“Shellfish are generally low in fat, unless they are battered and fried, and the cholesterol they contain is chemically different and has little effect on our own cholesterol levels.”
Since then, research has found that foods like full-fat yogurt and milk, while they do contain their own cholesterol, may actually reduce the risk of cardiovascular disease because they contain different fats called single-chain fatty acids and conjugated linoleic acid, which are thought to be protective. “Many studies have shown that people who eat more plain yogurt have a reduced risk of these diseases,” Mellor says.
How can you improve your cholesterol levels with diet?
Stephenson notes that overall dietary quality, and fiber intake in particular, is important in lowering and maintaining healthy cholesterol levels.
“An overall diet that is lacking in fiber, high in regular or heavy alcohol consumption, red and processed meats, and added sugar is likely to be problematic if cholesterol is a concern,” he says.
Mellor suggests trying to incorporate elements of what’s called the Portfolio Diet, which was developed at the University of Toronto as a way to improve cholesterol levels. The four main recommendations of the Portfolio Diet are:
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Add soy: Plant chemicals in soy, known as phytoestrogens, may help lower cholesterol levels. Soy sources include tofu, tempeh, or soy milk.
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Consume nuts and seeds every day: Mellor recommends adding them to salads, cereal, yogurt, or eating them as a snack.
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Eat more fiber: In general, it’s good to increase the amount of fiber in your diet through a variety of vegetables and fruits, as well as the glutinous fibers found in oats, lentils, beans, okra and eggplant.
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Consume plant sterols and stanols: These are natural compounds with a similar chemical structure to cholesterol and are found in nuts, beans, and peas, as well as some supplements and fortified foods. They reduce the absorption of cholesterol in the gut, allowing more of it to be excreted in your stool rather than being reabsorbed into your bloodstream.