High cholesterol has traditionally been associated with total fat intake. Although some fats like polyunsaturated fats, such as omega-3 oils, have received positive messages, saturated fats and trans fats have been labeled as the bad guy of fats for decades. But recent research shows that the culprit behind elevated cholesterol and triglycerides may be sugar.
The main reason for this is the increased consumption of carbohydrates from sugary sweetened beverages. Learn how to protect your heart and control your cholesterol levels by reducing your added sugar intake.
How fat became the culprit
In 2016, the Journal of the American Medical Association, JAMA, released a special communication where they reviewed internal documents and historical reports from the Sugar Research Foundation and assembled a narrative case study. In 1965, the JAMA article noted that the Sugar Research Foundation singled out fat and cholesterol as the dietary causes of cardiovascular disease.
Further, the researchers reported that the foundation downplayed the risk that sugar also played for cardiovascular disease. One thing to keep in mind is that the research conducted is more than 50 years old and done at a time when researchers were not required to disclose funding sources, according to a New York Times article on this same research.
According to the American College of Cardiology (ACC), saturated fats, and trans fats should be reduced to <10% and <1% respectively of the calories consumed to reduce the risk of cardiovascular disease. Some of the main saturated fats studied that have led to increased risk of cardiovascular disease include butter, cow’s milk, red meat, egg yolks, chocolate, coconut, and palm kernel oils. Trans fats in the U.S. are due to the hydrogenation of vegetable oil in snack foods like chips, packaged baked goods, margarine, and frying fast food. Not all fat is bad, though.
Per the ACC, there has been good justification that supports the substitution of saturated and trans fats for mono and polyunsaturated fats and fatty acids, including high-quality carbohydrates from fruits, vegetables, and grains.
How sugar becomes fat
Your body runs on a sugar molecule called glucose. In your body, your liver helps control whether you use glucose, turn glucose into fat, or create glucose. When you fast, your liver is responsible for making glucose from stores like glycogen or fat. When you eat carbohydrates, which are broken down to glucose, insulin is released by the pancreas, which then signals the liver to turn extra energy into long-term energy storage: fat. There are many signaling molecules involved in this process, but ultimately, the more energy you consume, the more fat you will make.
Fat travels from the liver to other parts of the body through proteins called lipoproteins, like LDL and HDL, which along with triglycerides, are the molecules your doctor measures to see how well your cholesterol is under control.
Our consumption of added sugar has increased six-fold, particularly in the form of sweetened beverages. In a systematic review in the American Journal of Public Health, researchers found two studies showing increased energy intake when drinking soft drinks with added sugar.
The researchers found five other studies that identified an association between the consumption of soft drinks with added sugar and overall energy intake compared to those who consumed water with their meals. This indicates that when people consume soft drinks, they do not compensate for the added sugar in their energy intake, leading to excess caloric consumption and making more fat, and increasing cholesterol levels.
How sugar impacts your cholesterol
There is a positive association between added sugar and cardiovascular disease. Much of the intake of sugary sweetened drinks is now due to sodas, fruit-flavored drinks, sports drinks, and sweetened coffees and teas. One of the ways that researchers feel that consuming sugary sweetened beverages may contribute to cardiovascular health risk is due to dyslipidemia, or high concentration of triglycerides, increased LDL, bad cholesterol, and low HDL, the good cholesterol.
In a population-based cohort study of U.S. adults by the Journal of the American Heart Association, researchers found that greater consumption of sugary sweetened beverages was associated with higher rates of triglycerides, low levels of HDL, good cholesterol, and high levels of LDL, the bad cholesterol. Therefore, when you eat diets high in sugar, your liver then starts to make more bad cholesterol, known as LDL, and it lowers your good cholesterol, HDL. Because there is excess energy in the form of sugar, the liver is then forced to make that excess sugar into fat, and it does this by making more triglycerides.
Other studies have shown that diets high in sugar may also lead to other abnormalities associated with cardiovascular risks, including high levels of glucose and insulin, impaired glucose tolerance, insulin resistance, and non-alcoholic fatty liver disease. Most importantly, in the Journal of Progress of Cardiovascular Diseases, researchers pointed out that a diet high in added sugars has been found to cause a three-fold increased risk of death due to cardiovascular disease.
Is all sugar bad?
Like fat, many different types of sugar include compounds like fructose and sucrose, which are made up of fructose and glucose. In many of the studies investigating the intake of sugary sweetened beverages, researchers looked at drinks containing fructose corn syrup or sucrose. It appears that fructose-containing sugars cause a greater imbalance in insulin levels, reduced insulin sensitivity, and increased glucose levels when fasting.
Interestingly, added fructose in the forms of sucrose and high-fructose corn syrup in processed foods and beverages appears to be especially potent for preventing your satiety signaling molecules from suppressing hunger, thus leading to increased energy consumption.
Excess consumption of fructose also increases the risk for non-alcoholic fatty liver disease, a type of liver disease that was previously seen in patients who suffered from excess alcohol intake but is now seen in obese patients who do not consume alcohol, hence the name.
Therefore, when it comes to sugar, remember it is about the quality of the sugar in the food you eat, not the quantity. Fruits are packed with sugars like fructose, but they also contain fiber, nutrients, and minerals.
When you consume fruit juices, you devoid yourself of these excellent nutrients found in the fruit itself and consume only the fructose, which may have the negative effects of making you eat more calories. Therefore, focus on consuming foods with a low glycemic index, like fruits, vegetables, oats, and whole grains, which can help stabilize your blood sugar, and control your appetite. Concerning your cholesterol, low glycemic index foods may help lower total and LDL cholesterol, therefore protecting your heart.
What about artificial sweetener
Artificial sweeteners are used in many soft drinks labeled as “Diet,” “Sugar-Free,” or “Low Calorie”..” Like sugar, there are many types of artificial sweeteners like sucralose (Splenda), aspartame (Equal), saccharin (Sweet’N Low), and steviol (Stevia). Some sweeteners may be made artificially, while others are found in nature, like in the stevia plant. In a study conducted by researchers at the New York Institute of Technology College of Osteopathic Medicine, researchers conducted animal trials to see the effect of artificial sweeteners on cardiovascular health.
They found no significant differences in the blood triglycerides, HDL, or non-HDL levels in the rats given Equal or Splenda in water compared to the control rats who just drank water. The researchers did see that artificial sweeteners cause some conduction abnormalities in the heart, which put them at increased risk of abnormal rhythms like atrial fibrillation. Although artificial sweeteners have been considered safe by the Food and Drug Administration (FDA), a recent study in 2021 showed that increased consumption of artificially sweetened beverages may increase the risk of cardiovascular disease.
Other concerns with artificially sweetened beverages include the risk of consuming more calories as you may feel the urge to reward yourself for drinking a “Calorie Free” drink and eating something high in calories or carbs, thus promoting your liver to store excess energy into fat. Additionally, when you drink beverages with artificial sweeteners, your body gets a signal that it is time to release insulin in response to sugar. Still, since insulin does not respond to artificial sweeteners, it will signal to your brain that you are not full and lead you to consume other forms of energy, usually in the form of carbohydrates.
Remember, water will be the best option when drinking a beverage with your meal. If you like the carbonated feel, you can opt for sparkling water or mineral water. Read the nutritional labels on foods, avoid excess added sugars and try to keep your sugar consumption to the American Heart Association recommendation of no more than 36 grams per day for men and 25 grams per day for women.
Gabriel Espinoza, MD has experience in caring for patients in both primary care and emergency settings. Some of the topics he has focused on during his medical career include various areas in public health, pediatrics, and wellness. He has co-authored a chapter on the utility of point of care ultrasound in the diagnoses of various eye conditions. The content written by Dr. Espinoza is for informative and educational purposes only. It is not intended as a substitute for professional medical advice, diagnosis, or treatment.
References:
- https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2548255
- https://www.nytimes.com/2016/09/13/well/eat/how-the-sugar-industry-shifted-blame-to-fat.html
- https://www.acc.org/latest-in-cardiology/ten-points-to-remember/2015/08/28/11/14/intake-of-saturated-and-trans-unsaturated-fatty-acids-and-risk
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3096021/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1829363/
- https://www.ahajournals.org/doi/10.1161/JAHA.119.014083
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4856550/
- https://www.nhs.uk/common-health-questions/food-and-diet/what-is-the-glycaemic-index-gi/
- https://academic.oup.com/fampra/article/30/5/485/683184?login=false
- https://peerj.com/articles/13071/
- https://www.ahajournals.org/doi/10.1161/STROKEAHA.118.023100
- https://www.heart.org/en/healthy-living/healthy-eating/eat-smart/sugar/how-much-sugar-is-too-much
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