What’s the Hype About Plant Sterols?
You may have noticed that your favourite fruit juice, salad dressing, or yogurt now says it has added plant sterols, which are good for your heart. Health Canada recently approved the use of specific health claims on phytosterol-enriched foods that meet certain conditions.
Plant sterols (phytosterols) are cholesterol-like compounds found in plant foods. When consumed at sufficiently high levels, phytosterols can help lower bad (LDL) cholesterol levels while having no detrimental effect on good (HDL) cholesterol levels.1 This is a particular benefit for those who have high LDL-cholesterol levels, a well known risk factor for heart disease.
In Canadian diets, vegetable oils (e.g., soybean, canola, flax seed) are a major source of phytosterols. Other plant-derived foods also contain varying amounts, including cereals (e.g., rice bran, wheat germ, corn), vegetables (e.g., Brussels sprouts, beet root, onion), nuts (e.g., cashew, almond, pecan) and legumes (e.g., kidney beans, peas).
How safe are phytosterol-enriched foods?
In May 2010, following a safety assessment in response to numerous submissions from the food industry, Health Canada’s Food Directorate (FD) approved the addition of phytosterols to a limited range of foods, including certain spreads, mayonnaise, margarine, calorie-reduced margarine, salad dressing, yogurt, and vegetable/fruit juices.2 Other regulatory bodies in the US, EU, and Australia have also approved the use of added phytosterols in certain foods.
In Canada, the regulatory status of foods with added phytosterols has evolved significantly over the past decade. Phytosterols sold in isolated form have historically been sold as drugs and, later, when Canada’s Natural Health Product Regulations came into effect, as natural health products to treat high cholesterol (hypercholesterolemia). When manufacturers first proposed phytosterol-enriched foods, the resulting product was considered a drug rather than a food because it was manufactured for a therapeutic purpose. At that time, there was insufficient data to support the safety of foods containing phytosterols.
The numerous human trials recently analyzed by the FD showed a lack of adverse effects at doses as high as 8.8g of free phytosterols/day for 10 weeks. Taking into consideration the subset of the population who may hyper-absorb phytosterols from the diet, the FD has set safe intake levels at 3g per day for adults and 1g per day for children. They stated that there are no safety concerns for the general population, children, and pregnant women, who may unintentionally consume phytosterol-fortified food products.
How do they work?
Health Canada reviewed current research and concluded that sufficient evidence exists to support an association between the regular consumption of a variety of foods containing phytosterols as part of an individual’s daily diet and the lowering of cholesterol levels in the blood.3 Studies have shown that phytosterols mimic cholesterol in the small intestine and stop, or slow, the absorption of dietary cholesterol and cholesterol produced by the liver. Phytosterols themselves are minimally absorbed from the small intestine, so they do not enter the bloodstream.
The overall result of 84 randomized control trials showed an 8.8% reduction in LDL-cholesterol with an average intake of 2g/day of plant sterols. Because phytosterols are not nutrients, they cannot be included in the Nutrition Facts table, although manufacturers may state their content in grams per serving and percentage of recommended daily intake elsewhere on the label.
In order to include the claim, “Plant sterols reduce cholesterol” a food product must:
- contain a minimum level equivalent to 0.65g of free plant sterols or stanols per reference amount and per serving of stated size;
- contain at least 10% of the weighted recommended nutrient intake of a vitamin or mineral per reference amount and per serving of stated size;
- contain 100mg or less of cholesterol per 100g of food;
- contain 0.5% or less alcohol;
- contain 480mg or less of sodium per reference amount and per serving of stated size, and per 50g if the reference amount is 30g or 30mL or less; and
- meet the criterion “low in saturated fatty acids”.
In the future, the food industry may apply to add phytosterols to other products, such as baked goods, cereals, egg noodles, meats, frozen desserts, food flavourings, and coffee. For more information about phytosterols and their approved use in Canada, visit the Health Canada website: http://www.hc-sc.gc.ca/.