A new clinical study notes that soy protein significantly reduces levels of LDL cholesterol (or “bad” cholesterol), helping the body to remove the potentially damaging fat.
In recent years, researchers have cautioned against eating too much animal protein, recommending more fruits and veggies instead. A part of the problem that comes with eating animal products is cholesterol.
Cholesterol is a type of fat that’s essential for body functioning. But get too much of it and you start having health problems. There are two types of cholesterol: High-density lipoprotein (HDL) cholesterol is the first one; it is often referred to as “good” cholesterol, which helps the body absorb the “bad cholesterol” and flush it out of the system. Low-density lipoprotein (LDL) cholesterol is the bad one, as it accumulates and forms plaques in the arteries, increasing the risk of heart disease and stroke.
Most of the cholesterol in the body is produced in the liver, and only around 20-25% comes from the foods we eat, but if we eat too much cholesterol, it can put us at risk.
Animal-based foods such as meat and dairy are high in cholesterol, while plant-based foods don’t contain cholesterol. So right off the bat, consuming plant-based foods could be a good way to lower your cholesterol intake. But soy could have a double effect.
Soy is a very versatile and nutritious food. It’s found in everything from sauces and milk replacements to things like tofu and meat replacements. The reason why soy is such a good alternative to meat is that it’s one of the few plants that contain more protein than meat (50 grams of protein per 100 grams of soy serving versus 23 grams for strip steak)
Previous studies have shown that the consumption of soybean protein might reduce cholesterol, and LDL in particular. However, there are several varieties of soy, and in the new study, researchers investigated the composition and effects of multiple soybean varieties digested under simulated gastrointestinal conditions on hepatic cholesterol metabolism and LDL oxidation in vitro.
The team defatted and ground soybean into flour, and using a simulation of the human digestive process (that was demonstrated in other studies), the team analyzed what kind of effect soy has on LDL. They found two proteins that are significant: glycinin and B-conglycinin. The proportion of glycinin in these varieties ranged from 22-60% while the B-conglycinin ratio ranged from 22-52%.
The inhibitory properties of the different types of soy varied greatly from 2 to 7 times less potent than simvastatin, a popular drug used to treat high LDL cholesterol. That may not seem like much, but look at it this way: a type of food has results comparable to a specialized medicine.
That wasn’t the only benefit. The digested soybeans were able to reduce lipid accumulation by 50-70%, comparable to the statin (which reduced it by 60%).
“This study found that the soybean variety affects the protein composition and peptide release under simulated gastrointestinal conditions. In turn, protein composition influenced the hypocholesterolemic properties of soybean varieties digested under gastrointestinal conditions,” the researchers write in the study. The study’s corresponding author is Elvira de Mejia, a professor of food science and human nutrition at the University of Illinois Urbana-Champaign.
“Soybean intake may help to regulate cholesterol homeostasis in the liver and LDL oxidation, improving the potential for cardiovascular health. Soybean ingredients made from soybeans with greater proportions of β-conglycinin may be useful to inspire foods and meals containing synergistic components that together can improve the potential for healthful outcomes,” they add.
The findings suggest that soy (and especially the varieties that produce the biggest LDL reduction) could be used to make food products with a protective effect against atherosclerosis and fatty liver disease.
However, this shouldn’t be interpreted as “soy is a medicine” — healthy food is an essential part of a healthy lifestyle, but you shouldn’t give up on prescribed medicine just because you’re eating healthy. This being said, if you have cholesterol issues or are concerned about cardiovascular health, or just want to have a healthier lifestyle, more soy protein could be worth checking out.
The study “Selected Soybean Varieties Regulate Hepatic LDL-Cholesterol Homeostasis Depending on Their Glycinin:β-Conglycinin Ratio” was published in the journal Antioxidants.