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Foods fortified with phytosterols—naturally occurring compounds found in plant cells—are a relatively new weapon in the struggle to lower high low-density lipoprotein cholesterol levels.

Orange juice, granola bars, oatmeal, cheese, and chocolates. With the flurry of new phytosterol-containing products on the market, we have one more tool to help our patients reach the strict low-density lipoprotein (LDL) cholesterol goals recommended in the 2004 update to the National Cholesterol Education Program (NCEP).1

Nicole Brown, a Virginia-based RD, often recommends phytosterol-fortified foods to her patients. They frequently eat cheeses, orange juice, and granola bars anyway, she says. Switching brands is “a simple way to attack the LDL levels.”

As their name suggests, plant sterols are cousins of cholesterol. Cholesterol helps form the structure of mammalian cell membranes, whereas plant sterols are important to the structure of the plant’s cell membranes.2 Various plants synthesize more than 40 sterols, with the most common being sitosterol, campesterol, and stigmasterol.3

The typical diet varies from approximately 167 to 437 milligrams per day of naturally occurring plant sterols.4 One tablespoon of corn oil contains 132 milligrams and 1 ounce of almonds provides 34 milligrams of plant sterols.5 Saturated plant sterols, or phytostanols, are naturally present in the diet in even smaller amounts.3 At these levels, they have no effect on serum cholesterol. However, in quantities of 800 milligrams to 2 grams per day, plant sterols and stanols interfere with the absorption of both exogenous and endogenous cholesterol, thus shunting cholesterol into the stool and effectively lowering serum levels.6 Typically, LDL cholesterol levels drop 10% to 14%.7 Plant sterols and stanols are themselves absorbed in only minute amounts. They are collectively called phytosterols. The cholesterol-lowering effects of phytosterols are additive to drug and other dietary treatments.

Pumped-up Margarinelike Spreads
Fifty-five years ago, researchers showed that beta-sitosterol decreased serum cholesterol in chickens during a cholesterol load.8 That finding started a series of studies in both animals and humans. Initial attention was focused on beta-sitosterol in doses of 10 to 15 grams per day, resulting in as much as a 20% reduction in total serum cholesterol. Study participants tolerated the various doses well; however, there was no additional cholesterol-lowering benefit above 3 grams daily.9 Further studies demonstrated the efficacy of stanols.9 Today, both stanols and sterols are added to foods in both their esterified and unesterified forms.

Perhaps the most commonly recognized phytosterol-enriched foods are the Benecol spreads (McNeil Nutritionals) and Take Control spreads (Unilever Bestfoods). Benecol spreads contain plant stanol esters made from the oils of pine trees and soy and Take Control products contain plant sterol esters from soybeans. Both have been shown to reduce total and LDL cholesterol when eaten in the recommended quantities. A study sponsored by Unilever and published in the European Journal of Clinical Nutrition in 1998 found that plasma total and LDL cholesterol concentrations were reduced by 8% to 13% for margarines enriched in soybean oil sterol-esters or sitostanol-ester compared with a control margarine. There was no effect on high-density lipoprotein (HDL) cholesterol levels. The authors concluded that the margarine products were equally effective.10

One of Many Tools
Phytosterols have an additive or synergistic effect when combined with other positive dietary changes, says David Jenkins, MD, PhD, DSc, research chair in nutrition and metabolism at the University of Toronto. Dietary restriction of cholesterol, saturated fats, and trans fats likely provides a 10% decrease in LDL cholesterol. Add phytosterols to the mix for an additional drop of 10%. Study volunteers consuming an NCEP Step II diet with a reduced-fat stanol ester-containing margarine lowered their total and LDL cholesterol as much as 18.3% and 23.6%, respectively. Control subjects following the Step II diet with no added phytosterols saw only a 7.7% reduction in their total cholesterol and a 9.9% drop in LDL cholesterol. Again, there were no significant changes in HDL cholesterol levels from baseline in any of the study groups.11

For Some, an Easy Fix
For Kathe Jefferson, one of Brown’s clients, adding phytosterols gave her LDL cholesterol the push she had been trying to get with other dietary strategies. Prior to adding the phytosterols to her diet, Jefferson had worked with Brown to improve her food choices. She kept a food record, followed an exchange-based meal plan, exercised daily, and began trying new foods. All combined, these efforts rewarded her with an 85-pound weight loss. With great disappointment, however, she saw that her LDL cholesterol barely moved. It fell from 143 milligrams per deciliter in December 2004 to 140 milligrams per deciliter in April 2005.

It wasn’t until Jefferson added plant sterols to her diet that she saw a dramatic reduction in her LDL cholesterol. She’s had a glass of phytosterol-containing orange juice daily since November 2005 and watched her LDL cholesterol fall from 140 to 127 milligrams per deciliter in only a few weeks after beginning the orange juice regimen.

In some patients, drug therapy may be avoided or continued at a lower dose. Thus far, Jefferson has avoided cholesterol-lowering medications, which is an important goal for her. “Why risk damaging my liver if I could do it [lower cholesterol] on my own?” she says. The fortified foods are readily accessible, they taste good, and it’s easy to do, she adds.

Since statin drugs and phytosterols lower cholesterol levels with different mechanisms, they can be used together. A phytosterol-containing spread reduced LDL cholesterol by 10% to 15% in both hypercholesterolemic patients taking a statin drug and those not taking cholesterol-lowering medication, according to a 2001 study published in Atherosclerosis.12

Is There a Downside?
“Plant sterols are nonabsorbable, so there are minimal side effects,” says Robert Nicolosi, PhD, CSN, professor and director of the Center for Health and Disease Research at the University of Massachusetts, Lowell. Compare that with statin drugs, the most widely prescribed cholesterol-lowering medications, which may cause muscle aching and intestinal discomfort. Occasionally, statins cause muscle cells to break down or liver enzymes to increase. The downside to phytosterols, says Nicolosi, is that “because they prevent the absorption of cholesterol, they can have an effect on the fat-soluble vitamins.” Researchers have observed decreased plasma levels of alpha-carotene, beta-carotene, alpha-tocopherol, and lycopene.2

As dietetic professionals, we need to assess our clients’ intakes of fat-soluble vitamins and phytonutrients when making recommendations about phytosterols. Increasing the usual intake of fruits and vegetables may be enough to offset the negative effects of the phytosterols. Consider a 2002 study published in the American Journal of Clinical Nutrition. Investigators measured the plasma beta-carotene concentrations of volunteers eating a spread either with or without added phytosterols. The subjects in each group were advised to eat at least five servings of fruits and vegetables daily, of which one or more was to be broccoli, carrots, spinach, tomatoes, sweet potatoes, pumpkins, or apricots. The researchers concluded that an average of one extra daily serving of carotenoid-rich fruits and vegetables maintains plasma carotenoid concentrations.13

Putting It Into Practice
Dietetic professionals have many practical considerations when advising clients on the use of these functional foods. Some products are costlier than their unfortified counterparts. However, compared with taking medication, the overall cost and safety of phytosterol-containing foods is favorable, says Kathryn Kolasa, PhD, RD, LDN, of the Brody School of Medicine at East Carolina University.

Adding calories and fat to the diet can also present problems. Substituting a fortified food for a nonfortified food avoids extra calories and may increase compliance. One CocoaVia chocolate bar (22 grams) provides 100 calories and 3.5 grams of saturated fat. Added to the diet, it would eventually cause weight gain and possibly affect blood lipids. But to replace a larger, more calorie- and fat-laden dessert with one CocoaVia bar may have the desired effects.

Ease of use and availability are other considerations. Kathy Dwyer, also one of Brown’s clients, watched her LDL cholesterol plummet from 178 to 140 milligrams per deciliter in approximately four months by following a reduced-calorie Therapeutic Lifestyles Changes diet incorporating phytosterol-containing orange juice and yogurt and walking for exercise. She found it easy to incorporate the new products into her diet, though some clients may wish for a wider selection of foods.

After several months of enjoying the yogurt daily, Dwyer could no longer find it in any grocery store. Changing the diet once is hard enough, but after successfully following a new, healthier plan, it can be frustrating to some clients to have to change again. Weeks passed before Dwyer found the time and made an effort to include another serving of phytosterol-fortified product. She settled on Nature Valley Healthy Heart granola bars.

Although still under debate, current recommendations suggest that the total daily dose be divided into two smaller doses.3,6 For many, this will mean having to find more than just one or two products they like. It’s a good idea to consume the phytosterols in two doses, says Jenkins. “Most things do better when spread out over the day.” He also says that phytosterols are more effective when consumed with fat because of increased bile excretion into the small intestine.

Some of your clients may ask whether it is safe and advisable for family members to use these products, too. Studies have been conducted in normocholesterolemic adults and hypercholesterolemic children. Phytosterol-containing foods appear to be safe in both populations.10,14 However, the decreased absorption of fat-soluble vitamins and phytochemicals may be of greater importance in children and others with increased nutrient needs.

Although the vast majority of the population absorbs only tiny amounts of phytosterols, a small number of people are homozygous for hyperphytosterolemia. In these individuals, large amounts of circulating phytosterols may contribute to premature atherosclerosis.2 Thus, they should avoid products with added phytosterols. Because they tend to develop multiple xanthomas, their condition is recognized early in life, so this should not be a concern to our typical clients or the public at large. These functional foods are very important, says Jenkins. We wouldn’t take bread off the grocery shelves because some people have celiac disease or remove peanut butter because many children have allergies, he adds. However, some researchers prefer the use of plant stanol esters over plant sterol esters because the latter may increase serum plant sterol levels and possibly the risk of coronary heart disease.15

The increasing variety of phytosterol-containing foods provides our clients a fairly inexpensive adjunct to other lifestyle and pharmaceutical therapies. To assist them in using this tool, we can offer taste testings, a list of products and their availabilities, an interpretation of their laboratory results, and our continued support.

— Jill Weisenberger, MS, RD, CDE, is a research dietitian and certified diabetes educator for Hampton Roads Center for Clinical Research in Norfolk, Va., and a freelance writer.

Health Claim6,16
The FDA permits a health claim for phytosterols and coronary heart disease.6,16 The regulations require that the health claim specify that the daily intake of phytosterols should be consumed in two servings at different times of the day and with other foods. The total daily dose must be at least 800 milligrams free sterols or stanols. There is no restriction in the types of foods that may contain the phytosterols and bear the health claim. However, there are qualifying criteria. A serving must do the following:
• contain at least 0.4 grams plant sterols or stanols;

• meet the criteria for a low-saturated fat and low-cholesterol food;

• not provide more than 13 grams of total fat and 480 milligrams of sodium per serving or per 50 grams (Exceptions for the fat restriction are made for margarine-type spreads, salad dressings, and vegetable oils.); and

• contain at least 10% of the Daily Value for one or more of the following nutrients: calcium, iron, protein, dietary fiber, vitamin A, and vitamin C. (Salad dressings are exempt from this requirement.)

Stock Your Pantry
Below is a list of phytosterol-containing foods. The FDA recently granted approval for the addition of plant sterols to a variety of other foods, including coffee, baked goods, cereals, vegetarian meat analogues, pasta, salty snacks, and soups.17 So watch your grocer’s shelves.

References
1. National Institutes of Health. Update on Cholesterol Guidelines: More Intensive Treatment Options for Higher Risk Patients. Available at: http://www.nhlbi.nih.gov/new/press/04-07-12.htm. Accessed April 28, 2006.

2. Lichtenstein AH, Deckelbaum RJ. AHA Science Advisory: Stanol/sterol ester-containing foods and blood cholesterol levels. Circulation. 2001;103(8):1177-1179.

3. Katan MB, Grundy SM, Jones P et al. Efficacy and safety of plant stanols and sterols in the management of blood cholesterol levels. Mayo Clin Proc. 2003;78(8):965-978.

4. Ostlund RE Jr. Phytosterols in human nutrition. Annu Rev Nutr. 2002;22:533-549.

5. Almond Board of California. The Portfolio Eating Plan. Available at: http://www.portfolioeatingplan.com/About/content.cfm?ItemNumber=4364. Accessed April 30, 2006.

6. U.S. Food and Drug Administration. Personal e-mail communication with Michael Herndon. Available upon request. Occurred November, 4, 2005.

7. Robert Nicolosi, director of the Center for Health and Disease Research, University of Massachusetts. Personal communication. Occurred October 14, 2005.

8. Normen L, Dutta P, Lia A, et al. Soy sterol esters and beta-sitostanol ester as inhibitors of cholesterol absorption in human small bowel. Am J Clin Nutr. 2000; 71(4):908-913.

9. Jenkins DJ, Kendall CW. Plant sterols, health claims and strategies to reduce cardiovascular disease risk. J Am Coll Nutr. 1999;18(6):559-562.

10. Westrate JA, Meijer GW. Plant sterol-enriched margarines and reduction of plasma total- and LDL-cholesterol concentrations in normocholesterolaemic and mildly hypercholesterolaemic subjects. Eur J Clin Nutr. 1998;52(5):334-343.

11. Hallikainen MA, Uusitupa MI. Effects of 2 low-fat stanol ester-containing margarines on serum cholesterol concentrations as part of a low-fat diet in hypercholesterolemic subjects. Am J Clin Nutr. 1999;69(3):403-410.

12. Neil HAW, Meijer GW, Roe LS. Randomised controlled trial of use by hypercholesterolaemic patients of a vegetable oil sterol-enriched fat spread. Atherosclerosis. 2001;156(2):329-337.

13. Noakes M, Clifton P, Ntanios F, et al. An increase in dietary carotenoids when consuming plant sterols or stanols is effective in maintaining plasma carotenoid concentrations. Am J Clin Nutr. 2002;75(1):79-86.

14. Amundsen AL, Ntanios F, van der Put N, et al. Long-term compliance and changes in plasma lipids, plant sterols and carotenoids in children and parents with FH concuming plant sterol ester-enriched spread. Eur J Clin Nutr. 2004;58(12):1612-1620.

15. Gylling H, Miettinen TA. The effect of plant stanol- and sterol-enriched foods on lipid metabolism, serum lipids and coronary heart disease. Ann Clin Biochem. 2005;42(Pt 4):254-263.

16. U. S. Food and Drug Administration. Title 21—Food and Drugs, Chapter I—Food and Drug Administration, Department of Health and Human Services, Part 101—Food Labeling Subpart E—Specific Requirements for Health Claims, Sec. 101.83 Health Claims: Plant sterol/stanol esters and risk of coronary heart disease (CHD). Available at: http://www.cfsan.fda.gov/~lrd/cf101-83.html. Accessed April 30, 2006.

17. U.S. Food and Drug Administration. GRAS Notices Received in 2005. Available at: http://www.cfsan.fda.gov/~rdb/opa-gn05.html. Accessed May 1, 2006.