Cholesterol: Down With the Bad, Up With the Good

Looking for ways to make unsaturated fats more user friendly, scientists found that hydrogenating unsaturated fats yielded products that were solid at room temperature, exhibited improved resistance to oxidative rancidity and possessed higher melt temperatures. Hydrogen atoms could be positioned around the carbon chains in either of two configurations: cis or trans. The former is more common in nature. The latter is the most often seen result of hydrogenation, although, there are some naturally occurring forms of trans fatty acids, such as conjugated linoleic acid (CLA).

Prior to the 1990s, trans fats were touted as a healthy alternative to saturated fats. Research has, however, revealed that trans fats actually increase LDL and decrease HDL. These revelations have resulted in mandatory labeling of any measurable level of trans fats (greater than 0.5g/serving), and AHA’s recommendation to limit trans fats to less than 1% of daily calorie intake. Contrary to the usual behavior of trans fats, CLA demonstrated potent anti-artheroslerotic properties in a study published in the Aug. 2007 edition of the British Journal of Nutrition (98(2):264-275).

Fatty fish such as salmon, trout, herring and mackerel, as well as some types of algae such as Crypthecodinium cohnii or Schizochytrium, deliver a special group of polyunsaturates, long-chain omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are available in ingredient form. Another omega 3, alpha-linolenic acid (ALA) can be obtained from flaxseeds and walnuts. Once consumed, ALA is converted to EPA and DHA.

While all three of these fatty acids provide healthful benefits, the allowable claims are different. Products containing EPA and DHA are eligible for FDA-approved qualified heart-health claims: “Supportive but not conclusive research shows that consumption of EPA and DHA omega-3 fatty acids may reduce the risk of coronary heart disease. One serving of [name of food] provides [x] grams of EPA and DHA omega-3 fatty acids. (See nutrition information for total fat, saturated fat and cholesterol content.)”

Phyt-ing the good fight

Plants possess specialized compounds called phytosterols. Similar in structure and function to mammalian cholesterol, plant phytosterols are separated into two groups based on the presence or absence of a double bond. Stanols are saturated (no double bonds) sterols. Despite the structural difference, both compounds are effective cholesterol-reducing agents.

Dietary cholesterol is absorbed through the intestinal walls as part of a combination of bile salts, fats and sterols called mixed micelles. Phytosterols displace cholesterol in the mixed micelles, reducing the amount of cholesterol that is absorbed. Consumption of 1.5 to 1.8 grams per day has been shown to reduce cholesterol absorption by 30% to 40%. Increasing levels to 2.2 grams per day resulted in a 60% reduction. Reduced absorption triggers increased clearance of LDL from the blood stream. And, while reduced absorption can increase the body’s own cholesterol production, net blood cholesterol levels are reduced. Studies show that daily intakes of 0.8 to 2.0 grams per day can provide serum cholesterol reductions ranging from 8% to 15%.

Phytosterols are lipids. Free sterols have a high melting point, around 140 C, and a waxy nature that hinders dispersion and solubility. Grinding to very small particle size can help, but dusting and lumping can still occur, especially in aqueous systems. Esterification, joining the phytosterols with fatty acids, provides processors with product forms that can be incorporated into high-fat products like spreads and dressings, as well as low-fat items like breads, cereals and yogurts.

Beverages have been a difficult application to address. Laura Troha, marketing manager for plant sterols and sterol esters, Cognis Nutrition and Health, LaGrange, IL, points out that while adding free sterols to beverages often results in high amounts of sediment, specialized new processing can combine free sterols with sodium caseinate or gum acacia to yield a free flowing powder. “These products have excellent water-dispersibility, making it perfect for beverage applications,” she says. “With 90% free sterols, you’re getting the highest amount of free sterol possible in a water-dispersible form.”