Most people with a basic knowledge of nutrition have heard about trans fat.
For decades, trans fat has been added to processed food products to replace saturated fat, decrease cost and improve shelf life.
However, the consumption of trans fat has consistently been associated with an increased risk of heart disease. As a result, the FDA has determined that trans fat is not safe.
As a replacement, many food producers have started using interesterified fat. Below is a summary of a recent review on interesterified fat and its potential health effects.
This article reviewed the available evidence regarding the health effects of interesterified fat.
What are Interesterified Lipids?
Food producers have always sought to improve their profits.
Most of the time, this involves using chemicals to enhance the sensual qualities of foods — flavor, texture or color — and lengthen their shelf life. Unfortunately, consumer health is not necessarily high on the agenda.
The long-term health effects of many additives and modified ingredients are largely unknown.
For example, trans fat (hydrogenated oils) was once believed to be safe. Today, most scientists agree that eating high amounts of trans fat may impair heart health over time.
In 2015, the FDA gave food manufacturers 3 years to stop using trans fat completely, although they can apply for an exemption if necessary.
To replace trans fat, food producers are increasingly turning to interesterified fat, which has similar properties.
Interesterified fat is synthetic and has been used in the edible oils industry for decades. Understanding how it’s produced requires some understanding of fat structure.
Fat is normally in the form of triglycerides. Each triglyceride molecule is composed of a glycerol backbone with three fatty acids attached to it.
The types of fatty acids in a triglyceride molecule determine its physical properties, as well as its health effects.
When fat is interesterified, the configuration and composition of triglycerides on the glycerol backbone is changed.
Interesterification is a chemical reaction that basically leads to fatty acid exchange within or between triglycerides.
This results in the formation of new triglycerides with unique properties, such as a more desirable texture, mouthfeel or different melting point.
There are two different kinds of interesterification:
- Chemical interesterification: This type of interesterification is random. Specifically, there is a random exchange of fatty acids within and between triglycerides.
- Enzymatic interesterification: This type of interesterification is specific. Certain fatty acids are exchanged, depending on the type of enzyme used.
As opposed to trans fat production (hydrogenation), interesterification does not involve changing the structure of fatty acids.
However, interesterification may lead to unusual fatty acid configurations on the glycerol backbone.
Bottom Line: Interesterified fat is made by exchanging fatty acids within or between triglycerides. This changes the triglycerides’ physical properties.
How Does Interesterified Fat Affect Health?
The health effects of fat (triglycerides) depends on at least three factors:
- The amount consumed.
- The types of fatty acids it contains.
- The position of the fatty acids on the glycerol backbone.
Interesterification is usually carried out between a liquid oil and a fat that is solid at room temperature (with a high melting point).
Liquid oil is usually interesterified with stearic acid — the second most common saturated fatty acid in the US diet.
Bottom Line: The health effects of interesterified fat depend on which fatty acids it contains, but the position of fatty acids on the glycerol backbone may also be relevant.
What Are the Health Effects of Interesterified Fats?
A few studies have investigated the health effects of interesterified fats. Below is a summary of their main findings.
- Blood sugar control: Three studies comparing interesterified fat with normal fat found no significant differences in insulin or glucose levels (1, 2, 3).
- Blood lipid profile: Studies comparing interesterified fat with normal fat found it had similar effects on the blood lipid profile.
- Blood coagulation: One trial in 17 healthy men compared the effects of interesterified cocoa butter (ICB), with normal cocoa butter. It showed that the ICB decreased the levels of factor VII, reducing blood coagulation.
Taken together, the available evidence suggests that interesterified fat does not adversely affect the blood lipid profile, blood sugar control or coagulation.
Bottom Line: No evidence suggests that interesterified fat adversely affects health, but further studies are needed.
Summary and Real-Life Application
In short, this review concluded that eating interesterified fat does not impair health when compared to non-interesterified fat with a similar fatty acid composition.
Therefore, they may be a healthy replacement for trans fats in processed food products.
However, many aspects of interesterified fat still warrant further investigation. More studies are needed to fully reveal its long-term effects.