Getting to the Heart of Sterol Fortification

One of the concerns of a demographic that has come to grips with its mortality is keeping cholesterol at a medically recommended level. Although certain drugs can achieve this goal, some feel more comfortable with “natural” remedies, others look for lesscostly options, and still others want to augment a drug-induced decrease in cholesterol. All of these result in an increased market demand for food products containing phytosterols, plant-based compounds that decrease cholesterol levels significantly.

Sterol stuff 

Plant sterols and stanols and their esters are generally recognized as safe (GRAS), with structures that mimic cholesterol. Stanols and sterols can be modified to ester forms, allowing easier addition into foods while maintaining the cholesterol-lowering ability. They occur in low concentrations in many plant foods, such as fruits, vegetables, nuts, seeds, grains, legumes, oils and other sources. A typical American diet contains approximately 0.25 grams of plant sterol per day, a level too low for significant cholesterol-lowering effects.

Research shows consuming 1 gram daily of stanol or sterol esters provides a statistically significant cholesterol reduction; however, maximum benefits come with 2 to 3 grams of sterols/stanols per day. Studies confirm cholesterol reduction by phytosterols in many different foods and, while a range of variables affect the degree, most clinical studies demonstrate an 8% to 15% reduction in LDL cholesterol.

“There have been dozens of clinical trials conducted on phytosterols,” says Melanie Goulson, applications manager, Cargill Health & Food Technologies, Minneapolis. “The range of food products they’re being consumed in include things like spreads, yogurt and orange juice, and even chocolate products. This large body of scientific evidence has provided support for the FDA health claim” that was authorized for sterol and stanol esters in 2000. FDA later issued a letter of enforcement discretion that included free sterol/stanols in the claim and gave wider latitude to the types of foods that could contain them. The claim states: Daily consumption of a total of at least 0.8 grams of plant sterols in two meals (0.4 grams per serving) may reduce risk of heart disease when part of a diet low in fat and cholesterol.

To tap into a market of the 101 million Americans with borderline-high or higher blood cholesterol concentrations identified by The American Heart Association, product designers must know what ingredients to work with and the products to add them to.

Delivering the good 

“For FDA health claim purposes, a product manufacturer needs only to meet the specified requirements of either claim, which includes having to use more than twice the amount of stanols as compared to sterols. Examples from the scientific research suggest that the nature of the ingredient and finished product should be considered,” says Brent Flickinger, Ph.D., research, nutritional science, ADM, Decatur, IL.

First, product designers must consider how to deliver phytosterol benefits to the consumer. For instance, the actual sterol content in ester forms is lower, so they must be added at a higher level to qualify for the health claim.

“The primary aim is having sterols in a form that achieves a high degree of molecular dispersion in the small intestine,” notes Flickenger. “The form of a sterol ingredient is a factor, but how the ingredient is incorporated into and the type of finished product can be just as, if not more, important.”

It turns out that, “The efficacy of sterols depends on the particle size,” says Franz Timmermann, Ph.D., global product line manager, Vegapure®, Cognis Nutrition & Health, LaGrange, IL. “Most effective are sterol esters, which are split in the gut into free sterols and which are distributed in the gut in molecular form. Due to the high melting point, free sterols have to be ground, but their particle size will always be higher than those of sterols derived from the esterified form.”

Timmermann calls sterols “very stable molecules” that generally remain unaffected by processing and normal storage conditions. However, he cautions, “Care has only to be taken in baked goods, where very high temperatures can be applied.”

Stocking up on sterols 

The next step is to consider the matrix and the type of ingredient that works best in that matrix. The first products on the market were spreads, but many other products have been commercialized, including breakfast cereal, nutritional bars, juice beverages, blended juice-and-milk smoothies, cooking oils, salad dressing and yogurt. “Recently, the FDA said that phytosterols may be considered GRAS for even more foods and beverages, so the demand continues to grow for new uses of phytosterols,” says Timmermann.

Phytosterols are lipids, so “they are hydrophobic,” says Goulson. “However, beyond that fact, sterols and stanols and their esters have very different physio-chemical properties.” For example, she notes “sterols have a very high melting point—they’re waxy, with low solubility in oil.” To overcome the processing challenges, the industry developed ester forms by adding a fatty-acid chain. These have a melting point just above room temperature, and “behave much more like an oil,” she says.

Other modifications broaden the use categories. A water-dispersible version is available for juice fortification, and if the product needs to be all-natural “we offer natural versions of the ingredient and also water-dispersible versions,” says Goulson. “In some applications we might need a very fine particle size with no mouthfeel implications, in others we might manipulate the particle size to optimize flow-ability.”

“Plant sterols are largely inert and thus typically do not affect the finished food.” “In specific cases, like for fat-containing products, we recommend the use of sterol esters which can be easily distributed in the fat phase to protect the integrity of the end product.”

It’s satisfying to develop phytosterol-fortified products that help consumers stay healthy. And best of all, from a formulation standpoint, “Today, there are a lot more ingredient technologies and systems to make them even more versatile for use in food products,” says Goulson.