Technical Talk: March 2012

Scientific evidence is continuously shedding light on the preventive effects certain diets have on various chronic diseases.

Scientific evidence is continuously shedding light on the preventive effects certain diets have on various chronic diseases. Consumers are also more aware of the relationship between diet and health, which has food manufacturers actively developing new functional food products. In order to develop goods that will deliver benefits beyond normal nutrition, we need to use ingredients that contain bio-actives. These bio-actives must withstand processing conditions and remain active all the way to the end of the product’s shelf life. Many functional ingredients are available and most are categorized as antioxidants. Antioxidants normally prevent the formation of radicals that are responsible for the onset of different chronic diseases.

One important group of functional ingredients is phytosterols, which have proven beneficial in preventing cardiovascular disease. Phytosterols is a collective term for two major groups of compounds: plant sterols and plant stanols. Both of these groups of compounds are present in many fruits, vegetables, nuts, seeds, legumes, cereals and vegetable oils. Stanols are basically the saturated version of sterols. Beta-sitosterol is the most abundant phytosterol. Other phytosterols include avenasterol, campesterol and sigmasterol. Phytosterols are available naturally or in forms modified by esterification with fatty acids. Such modification makes the sterols and stanols easier to incorporate into fatty foods, such as margarines and spreads. 

Cereal grains are a rich source of phytosterols, which are normally found in the outer layers of the grain. Rye and wheat bran contain substantial quantities of these beneficial compounds. How effective ingredients are in delivering phytosterols to the body depends on how they are processed.

Phytosterols are interwoven into the bran matrix, which is difficult to digest. The finer the particle size of the bran, the better the availability of phytosterols to the small intestine during digestion. Mechanical and enzymatic treatments of fibrous plant materials may also increase the bioavailability of their phytosterols. Another important source of phytosterols is soybean oil; however, the refining process substantially reduces the amount of phytosterol in the oil. This reduction is even more drastic when the oil is hydrogenated. Phytosterols are commercially available as ingredients sourced mainly from food grade vegetable oils. Some major ingredient companies supply the industry with purified forms of phytosterol compounds for use as supplements or as functional ingredients in food formulations.

Because phytosterols are unique to each plant species, they can be used to identify the source of an oil and thus to detect adulteration of these ingredients.

In 2010, Health Canada’s Food Directorate (HC-FD) approved the addition of phytosterols to a limited number of products, including spreads, mayonnaise, margarine, salad dressings, yogurt and yogurt drinks, and vegetable and fruit juices. After an extended review, the HC-FD sets the reference for safe intakes for phytosterols incorporated into food at three grams per day for adults and one gram per day for children. In addition, they concluded that there are no safety concerns for the general population, including children and pregnant women, unintentionally consuming foods that have been fortified with plant sterols. Regulatory agencies in the United States, European Union and Australia have also approved phytosterols in certain foods. Although some research indicates phytosterols can potentially reduce serum beta-carotene, also known as provitamin A, HC-FD concluded that this does not pose any nutritional concerns. Beta-carotene is important in our diets for two reasons; it functions as an antioxidant and is the precursor for the formation of vitamin A. HC-FD also states that phytosterols are not nutrients; under nutrition labelling regulations, the amount of phytosterols in a food may not be included in the Nutrition Facts table (NFT). The total phyto-sterol content may be declared as grams per serving, rounded to the nearest multiple of 0.1 grams, elsewhere on the label. More information about health claim rules is available on Health Canada’s website. 

 The main health benefit associated with phytosterols is their ability to reduce the risk of coronary heart disease. This is due to their ability to lower the levels of low-density lipoprotein (LDL), which is considered bad cholesterol, without affecting the levels of high-density lipoprotein (HDL) or good cholesterol. Phytosterols have a similar chemical structure to human cholesterol. It seems they are able to block the absorption of human cholesterol by the small intestine, thereby theoretically reducing the levels of LDL in the blood.

 Successfully incorporating phytosterols into food means the phytosterols will be bioavailable to the consumer as they eat the product. Factors that affect the bioavailability of phytosterols in a product include the type of food, the processing conditions and the stability of the phytosterols themselves. Some research has shown that phytosterols may be resistant to oxidation even at somewhat higher temperatures. This makes it possible to incorporate them into various heat-treated products. Realizing a successful product development with phytosterols requires dedication and food expertise, but the benefits can be great for you and your customers.

For more information or fee-for-service help with food technical and processing issues and needs, please contact Dr. John Michaelides at John Michaelides & Associates, 519-743-8956 or at Bioenterprise,  519-821-2960 ext. 226, or by e-mail at j.jmichaelides@gmail.com  Bioenterprise is a company of experienced professionals that coach and mentor emerging agri-technology companies from planning to startup to profitability and beyond.