Symposiums 2005

Septembre - Functional Foods - Celebrating Canada's Achievement

Dr. Lilian Thompson, Université de Toronto, Toronto, ON

Flaxseed lignans: A multifunctional food component.

Since the discovery of the mammalian lignans enterolactone (EL) and enterodiol (ED) about 25 years ago, much work has been done on their potential health benefits. Mammalian lignans are produced from plant lignans by microflora in the colon of humans and animals. Flaxseed is the richest source of mammalian lignan precursors, particularly secoisolariciresinol diglucoside (SDG), with levels 75-800 times higher than other plant foods in the vegetarian diet. Studies with flaxseed suggest that it may reduce the risk of breast, prostate or colon cancer when given at either the preinitiation, promotion or progression stages of carcinogenesis. Similar anticancer effects were observed with SDG, ED or EL, suggesting that the effect of flaxseed is in part due to its lignans. Studies also suggest the potential role of flaxseed in reducing cardiovascular disease risk and menopause symptoms, also in part due to its lignans. The lignans are thought to exert their effects either by interfering with the binding of estrogen to the estrogen receptor, inhibiting the production of estrogen, influencing estrogen or androgen metabolism, or through antioxidant effects. The potential health benefits of flaxseed and its lignans have led to the production of many flaxseed-containing products and of SDG concentrates prepared from the flaxseed hull or extracts for use as food ingredient or supplement. Canada is a major producer of flaxseed and is likely to benefit from these developments.

Jacques Goulet, agr. Ph.D. and Édouard Brochu agr. M.Sc. Ph.D., Université Laval, Québec et Institut Rosell, Montréal, QC

Probiotics in North America: from Metchnikoff to nutraceuticals and functional foods.

The use of lactic acid bacteria (LAB) for their health benefits is a concept that was first presented to the scientific community by Élie Metchnikoff, professor at the Pasteur Institute of Paris in 1907. He then postulated that the regular consumption of fermented dairy products containing LAB such as Yogurt, Kefir, Koumiss,... helped prevent undesirable intestinal putrefactive fermentations with the net result of helping to prolong human life.

This concept was introduced in North-America by the publication of the English version of his book in 1908 and, among others, by Dr Jose-Maria Rosell, a co-founder of Institut Rosell in the early 1930's. The introduction and production of Yogurt cultures in Canada by Dr Rosell and collaborators occurred at about the same time as the launching of commercial Yogurt by J. Delisle in Montréal.

At that time, mixed cultures of bacteria were seen as preferable to single strain cultures, a concept that was further extensively used in the production of cheese starters. Since fresh cultures could not be kept for a long period of time and be shipped over long distances, drying techniques at atmospheric pressure and under vacuum and frozen states were successfully developed. This allowed a new marketing approach of active cultures for dairy processing as well as for health supplements (capsules, sachets, tablets). New technologies such as enteric coating and microencapsulation have also contributed to improve the stability of LAB in various commercial nutraceuticals and functional foods.

Although the mode of action of probiotics in humans and animals is not fully understood, there are much more evidences than at Metchnikoff's time, showing their numerous beneficial impacts on human and animal health on their own and through their interaction with foods.

Dr. Letty Rao, Hôpital St. Michael's & Université de Toronto, Toronto, ON

Lycopene and Bone Health.

Osteoporosis is a major metabolic bone disease that occurs primarily among women over the age of 50 because of the loss of estrogen at menopause. Several lifestyle factors including diet have been implicated in the development of osteoporosis. The risk factor for osteoporosis that has been of wide interest in recent years is oxidative stress. Oxidative stress, caused by reactive oxygen species (ROS), is involved in the activity and function of osteoblasts and osteoclasts, the two major bone cells involved in the pathogenesis of this disease. However, the cellular and molecular mechanisms involved in the action of ROS and the role played by dietary antioxidant phytonutrients such as lycopene are not clear and are the subject of our studies. Lycopene is a potent antioxidant present primarily in tomatoes and tomato products, but is also present in small amounts in other fruits and vegetables. Epidemiological data, clinical studies and in vitro cell culture studies have provided support for a role for lycopene in preventing major human chronic diseases. My presentation will review recent literature relating to the role of oxidative stress and antioxidants in the development and prevention of osteoporosis. We will discuss the results of our studies on the effects of lycopene on osteoblasts and osteoclasts as well as our ongoing clinical study evaluating the role of lycopene in preventing the risk of osteoporosis in postmenopausal women.

Dr. Bruce McDonald, Université de Manitoba, Winnipeg, MB

Canola: Canada's First Function Food.

Rapeseed, the progenitor of canola, is an ancient vegetable oil crop; Sanskrit records indicate it was used as a cooking and lamp oil as early as 2000 BC. Rapeseed was introduced to Canada in response to the blockade that cut off its supply to the Allied navies during World War II; with the development of steam power, a mixture of rapeseed oil and mineral oil was found to produce a superior lubricant for steam and water washed metal surfaces. Following WW II, interest developed in the use of rapeseed oil for edible purposes and by 1956 food use in Canada and Europe had surpassed industrial usage. Reports by scientists at the University of Western Ontario, that erucic acid (viz., 22:1n-9), the major fatty acid in rapeseed oil, was responsible for reduced weight gainand increased adrenal weight in rats, prompted Canadian plant breeders to develop canola; a low-erucic acid, high-oleic acid variety. However, it was reports in the early 70's by Dutch, French and Canadian scientists, that erucic acid caused myocardial lipidosis in young rats and myocardial necrosis when the oil was fed for an extended period of time, that prompted Canada to convert the entire crop to canola. Canola oil is characterized by a low level of saturated fatty acids (< 7%), a high level of oleic acid (approx. 60% - 2nd only to olive oil among vegetable oils) and an intermediate level of PUFA (> 30%) with an 18:2n-6/18:3n-3 ratio of 2.5/1. It also contains a relatively high level of phytosterols. Research in Canada, later confirmed by studies in the US and Finland, found canola oil not only resulted in lower serum total and LDL cholesterol levels in human subjects but lower thrombotic risk. It also has been found to inhibit cardiac arrhythmia in animal models. Canola oil, which accounts for over 60% of the vegetable oil consumed in Canada, also is a major Canadian agricultural export commodity. Growth of rapeseed from a small wartime industrial oil to canola, a healthy edible oil, in less than 40 years is a remarkable success story of cooperation among producers, processors, food manufacturers, government and researchers.