This week, we’re diving into how we can use nutrition to help support specific aspects of heart health (high cholesterol, high blood pressure, and diabetes (1)) to reduce our risk of developing heart disease. In fact, many studies suggest that nutrition may be the most preventive factor of cardiovascular disease-related death and could even reverse heart disease (2) This article will focus on cholesterol, and how our nutrition choices can impact our levels.
What Is Cholesterol, Anyway?
If we want to make lasting changes to our cholesterol levels, it’s important that we understand what cholesterol is. Dietary cholesterol is found in animal-based products. Despite it’s typical reputation, cholesterol is a vital component to our overall health – so important that 80% of the cholesterol found in our bloodstream is actually produced by the liver (3). It is a crucial building block in cell membranes, and is needed to make vitamin D, hormones (including reproductive hormones), and digestive enzymes (4, 5). Cholesterol is a fat and travels through our bloodstream. Since fat doesn’t travel well in blood, cholesterol is wrapped up in packaging known as lipoproteins. We most commonly hear about low-density lipoproteins (LDL) and high-density lipoproteins (HDL), both of which play important roles in our health.
LDL transports cholesterol from the liver to the cells, in order to carry out the tasks we described above. However, it is also the main ingredient in vessel plaque (6), which can lead to blockages in our arteries. It is particularly susceptible to oxidation, which can lead to oxidative stress (7). Oxidative stress, itself, has also been linked to heart disease (31). This has lead people to refer to LDL as the “bad” cholesterol. HDL, on the other hand, is known as the “good” cholesterol, because it scoops up excess cholesterol and transports it to the liver for disposal. When determining cholesterol levels, one of the things doctors look at is the ratio between LDL and HDL levels.
If you’ve been keeping an eye on your cholesterol levels, you should also be aware of your triglycerides. Triglycerides are how we store excess energy. Calories we consume that we don’t utilize right away can be turned into triglycerides and stored for later use. Then when our body needs it (say, between meals), these triglycerides are released into the bloodstream to use as energy. Consistently eating more calories than our bodies need can lead to elevated triglycerides (8).
Knowing Our Numbers
When we get bloodwork done, our total cholesterol, our LDL, HDL, and triglyceride levels are all measured. Knowing our starting point can help give us clues on how we can move forward with specific changes to improve our numbers. Depending on the values, your health history, and other health considerations or risk factors, your doctor will tell you how they want you to proceed.
According to the Medical Council of Canada, normal cholesterol values are as follows (9):
Total Cholesterol Levels
between 3.5 - 5.2 mmol/L
> 1.3 mmol/L (females) and > 1.0 mmol/L (males)
< 2.6 mmol/L
≤ 1.7 mmol/L
To improve our cholesterol levels, experts often suggest eating a "healthy diet", which can feel vague and overwhelming. Generally, we can define a "healthy diet" specific to lowering cholesterol levels as choosing whole grains, fruits and vegetables more often, consuming more low-fat dairy, lean meats, fish, and poultry (if choosing to consume animal products), limiting consumption of trans fats, and incorporating plant-based foods such as nuts, seeds, and legumes into our day. This type of eating pattern provides fibre, protein, heart healthy fats, important vitamins and minerals, and antioxidants - all of which have been shown to individually improve our cholesterol levels (33). We could also describe this type of eating as one that limits refined flours, added sugars, and trans fats, all of which have been linked to having a negative effect on cholesterol levels (34). To read more about how this way of eating improves our cholesterol levels, read through our drop down sections below:
Lowering LDL Levels
Some specific dietary changes that can positively effect LDL levels include: eating more poly- and mono-unsaturated fats, limiting trans fats, increasing soluble fibre intake, and consuming more plant sterols (10). Since LDL cholesterol is sensitive to oxidation, consuming a diet rich in antioxidants may also be beneficial. In addition to choosing foods that help to lower our cholesterol, consuming foods without dietary cholesterol (such as plant-based meals) would also be helpful. Poly- and mono-unsaturated fats (omega 3 and omega 6) have been shown to improve cholesterol levels, reduce inflammation, prevent clotting, and decrease our triglycerides (13). In addition to incorporating more omega 3s and omega 6s, limit trans fats as much as possible. These fats are used to increase the shelf life of a food. They have been shown to increase LDLs and lower HDL levels (23). Trans fats seem to compete with health fatty acids (such as the ones mentioned above), and can reduce blood vessel elasticity and function (24). Fibre (especially soluble fibre) has been shown to lower our LDL levels, as well as our triglyceride levels (20). Experts recommend more than 25g of fibre per day, which is almost double what the average person gets in their diets (21). In addition to consuming fruits and vegetables, this can be achieved by choosing a variety of whole grains and high fibre seeds, such as flax seeds, hemp seeds, and chia seeds (22). Plant sterols limit the body's ability to absorb cholesterol. Small amounts are found in nuts, fruits and vegetables, whole grains, and vegetable oils. Experts recommend consuming 2 grams per day (11). Given the low amounts found in our food, it would be very difficult to consume enough to reach the daily recommendation. To help make it easier for us to reach that recommendation, many foods have been fortified with plant sterols, including dairy products, cereals, margarines and more (12).
Increasing HDL Levels
Increasing HDL levels is a little more complex. Since our cholesterol levels are calculated on the concentration of cholesterol in our blood, we can improve HDL concentration by lowering our LDL levels (14). (This may be why experts tend to suggest a more holistic approach to improving cholesterol levels, rather than isolating one or two specific things). Limiting trans fats is also important here, as we've already learned that trans fats have been shown to elevate LDLs and lower HDL levels (25). Vitamin B3 (niacin) has been shown to help increase our HDL levels (16), while also lowering LDL and total cholesterol levels (17). Studies have shown varies degrees of success with niacin, and so outside of choosing foods that are naturally high in B3, any supplementation should be done only on the advice of your doctor.
High carbohydrate consumption can impact our triglyceride levels, particularly simple carbohydrates such as sugar and refined flours (18). Conversely, complex carbohydrates seem to lower our triglyceride levels. This may be due to higher levels of fibre in complex carbohydrates such as whole grains and legumes.
Omega 3 fatty acids have also been linked to a reduction of triglyceride levels. One study showed that 3.4g per day of omega 3s resulted in a 25-50% reduction in triglyceride levels after only one month (19). As is the case with vitamin B3, it is important to consult your doctor and/or your pharmacist if you're considering taking a supplement.
Remember that my suggestions are meant to compliment, and not replace, advice given to you by your health care team (including doctors, specialists, and registered dieticians). If you’re looking to improve your cholesterol levels through diet, here are a few of my suggestions:
Incorporate more orange, red, and dark green fruits and veggies into your day to lower LDL levels. Broccoli, brussels spouts, carrots, sweet potatoes, tomatoes, swiss chard and apples are what I would describe as "heavy hitters". They offer so many cholesterol improving components including being excellent sources of vitamin C, fibre (particularly soluble fibre), antioxidants and plant sterols. Bonus: sweet potatoes are also a good source of niacin! Of course, fruits and vegetables are such nutritional powerhouses to begin with, just increasing your intake of any fruits and veggies will offer nutritional benefit (26). Since fruits and vegetables tend to be a good source of fibre, they will take a little longer for the body to digest, which will keep our blood sugar more controlled. If controlling your blood sugar is a health goal of yours, I recommend eating more vegetables than fruit throughout your day (try a 2:1 ratio) or try to pair your fruits with a protein or a poly- or mono-unsaturated fat.
Limit man-made trans fats as much as possible. Trans fats are one of the only things I ever suggest restricting in a person’s diet. They are a by-product of processing foods and help to improve a food’s shelf life (27). They increase our LDL levels and decrease our HDL levels, and even small amounts can effect our blood vessel elasticity. Trans fats will be indicated on nutritional information labels, which is the best way to monitor your overall intake.
Prioritize mono- and poly-unsaturated fats. My favourite sources include avocados, nuts, flax, chia, hemp seeds, and cold-water fish such as salmon, rainbow trout, and mackerel. Avocados are also a great source of soluble fibre and niacin, while the nuts and seeds contain fibre, plant sterols, and protein. In addition to protein and heart healthy fats, salmon is also a great source of niacin.
Eat more complex carbohydrates, such as whole grains. As we learned earlier, whole grains can help to lower our triglycerides (28). Additionally, they are typically better sources of fibre than a refined grain (such as white flour) (29). Since I’m all about nutritional multi-taskers, I like brown rice (a whole grain containing fibre and niacin), oats and oat bran (both great sources of soluble fibre and antioxidants), apples, strawberries and citrus fruits (excellent sources of soluble fibre in addition to being high in antioxidants, vitamin C, and plant sterols), and quinoa (which contains fibre, protein, antioxidants, and plant sterols).
Eat your beans. Since cholesterol is only found in animal-based foods, regularly consuming plant-based meals can have a significant impact on cholesterol levels (30). This reason is two-fold: 1, when we eat plant-based meals, we are not consuming cholesterol, and 2, whole grains and legumes found in many plant-based meals have cholesterol lowering properties. Legumes, especially, are excellent sources of fibre and protein, and as complex carbohydrates they help stabilize blood sugar levels. Peanuts (technically a legume) are a great source of protein, fibre, mono- and poly-unsaturated fats, and niacin. Soybeans are also excellent sources of protein, fibre, and antioxidants.
There are so many other heart healthy foods out there that didn’t make this list, simply because it would just take too long to go through them all. These foods are ones that specifically support improving cholesterol levels, but there are other components of nutrition that can influence other aspects of heart disease, such as blood sugar and high blood pressure. We’ll be looking at these two topics in the future.
If improving your cholesterol levels through diet is one of your health goals, let your doctor know first. Then, choose something that feels doable for you. Remember that our actions are cumulative, and every little bit helps. Just like with cardio and stress management techniques, the best nutrition techniques for heart health are the ones that you’re most likely to stick with.
Cheering You On,
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