By Yvonne V. Yuan, PhD, School of Nutrition, Toronto Metropolitan University
While the terms functional foods, nutraceuticals, and even superfoods have been a part of the food and agriculture industry, lay media, and everyday vernacular for many years now, the first two terms were defined in a 1998 policy paper from Therapeutic Products Programme and the Food Directorate of the Health Protection Branch of Health Canada. A functional food is “similar in appearance to, or may be, a conventional food, is consumed as part of a usual diet, and is demonstrated to have physiological benefits and/or reduce the risk of chronic disease beyond basic nutritional functions, while, a nutraceutical is “a product isolated or purified from foods that is generally sold in medicinal forms not usually associated with food. A nutraceutical is demonstrated to have a physiological benefit or provide protection against chronic disease.”
On the other hand, the terms “superfood” and “superfruit” began to appear around 2004 as marketing terms within the food and beverage industry to describe richly pigmented vegetables and fruits, particularly berries (e.g., goji, açai, cranberry, seabuckthorn, blueberry, blackberry and raspberry) with demonstrated in vitro antioxidant capacity and potential epidemiological links to healthful effects in reducing diet-related chronic disease risk factors.
The desire to include healthful foods, and functional foods in particular, in our diets to improve or maintain physical health, immunity, and even mental health has been consistent over the years in the face of an increasing body of knowledge about how foods can affect our bodies and even moods. Therefore, it is not surprising that since March 2020, with the onset of the SARS-CoV-2 (COVID-19) pandemic, consumers, self-isolating at home, have renewed their focus on self-care, health, immunity, and sustainability of the foods we choose to purchase.
Some estimates indicate that the functional foods market in Canada could potentially increase two-fold or greater from a value of approximately $9.67 billion in 2014 to $16.73 billion in 2022 and ultimately $20.80 billion in 2025. Further analyses of the functional food market by product class indicated that dairy products accounted for 39.4% of market share due to their ease of use as delivery systems of functional food ingredients, followed by bakery and confectionary, fish and eggs, soy products, and pulse-based, flax-based and canola-based products, including fats and oils among others. What is nice to see from this breakdown of market is the importance of Canadian agriculture in many of these commodities that make up functional foods.
Five functional foods to pay attention to:
Edible seaweeds or sea vegetables
More than just the Nori (Porphyra tenera, a red seaweed that when roasted, turns green due to the underlying chlorophyll) in your California or other sushi maki rolls, Kombu kelp (Laminaria digitata) in your miso soup, or Wakame kelp (Undaria pinnatifida) seaweed salad, edible seaweeds have a rich culture and history in coastal communities across the globe, including the west and east coasts of Canada.
Atlantic Canadians have long harvested Irish Moss (Chondrus crispus) and Dulse (Palmaria palmata)—both red seaweeds—for gelling properties (i.e., carrageenan soluble fibre in products such as Irish moss drink, seaweed pie) and protein content, respectively.
Indigenous peoples of the Pacific coast including Haida and Tlingit, Tshimshian, Wakashan, and Salish peoples harvest red seaweeds (Porphyra abbottiae) for nutrition and medicinal purposes as well as trade. As photosynthetic organisms, seaweeds are naturally rich in antioxidants such as tocopherols, carotenoids including beta-carotene and fucoxanthin, phlorotannins; contain small amounts of omega-6 and omega-3 polyunsaturated fatty acids (PUFAs) including arachidonic acid, linolenic acid and EPA, as well as protein, vitamins, minerals, and insoluble and soluble fibres.
Blue-green microalgae such as Spirulina, perhaps better known as part of macrobiotic diets, are regarded as rich sources of proteins, PUFAs, and carotenoids. As functional foods, there is a rich body of evidence from in vitro, animal, and clinical studies that seaweeds may help reduce the risk of diet-related chronic diseases including cardiovascular disease and breast and colon cancers.
Fermented foods including Kefir, Sauerkraut, Tempeh
Fermented foods have been part of many cultures for millennia, due to the capacity of naturally occurring or inoculated bacteria, yeasts, or moulds to extend the shelf life of the foodstuffs and reduce the risk of foodborne illnesses from pathogenic bacteria.
Other benefits of fermentation include reduction in levels of lactose in dairy products for the lactose intolerant; production of amino acids or biologically active peptides, organic acids, and flavour compounds; potential probiotic effects of lactic acid bacteria in colonizing the gastrointestinal tract; the conversion of constituents such as phenolic compounds (e.g., flavonoids) into biologically active metabolic products; and the potential production of prebiotic carbohydrate-based metabolites during fermentation.
Kefir (produced from fermenting milk with kefir grains containing various yeasts, and lactic, and acetic acid, producing bacteria) has been reported to exhibit antimicrobial activity in vitro associated with fermentation products including organic acids, ethanol, carbon dioxide, etc.
Milk protein (casein-derived) peptides have demonstrated immune system stimulation in animal studies. Various strains of lactic acid bacteria demonstrated the potential to colonize the gastrointestinal tract and increase the population of Lactobacillus, Lactococcus and Bifidobacterium in animal studies. However, much less is known about non-dairy water kefir.
Sauerkraut is traditionally the result of a wild-fermentation of cabbage initiated by salt-tolerant Leuconostoc and Lactobacillus species, but can also result from commercially available starter cultures. Sauerkraut-derived Lactobacilli have demonstrated probiotic potential and antimicrobial activity in vitro. Sauerkraut fermentation products have been shown to increase antioxidant enzyme systems in animal models, as well as result in glucosinolate breakdown products with free radical scavenging activity.
Tempeh is produced by incubating boiled, dehulled soybeans with Rhizopus mould species to create a protein-rich patty or cake. Tempeh has been shown to contain lower phytic acid and protease inhibitors, which are naturally occurring antinutrients in raw soybeans. Tempeh constituents also demonstrate free-radical scavenging activity in vitro thought to be related to polyphenol molecules. Health effects of tempeh still require clinical investigations.
Chia (Salvia hispanica) seeds also have an ancient history of use as oilseeds by the Mayans of southeast Mexico, Guatemala, Belize, Honduras, and El Salvador, as well as the Aztecs of central Mexico (the name is a derivation of the Spanish “chian” or “chien” meaning “oily”). In fact, the Aztecs and Maya used whole and ground chia seeds in medicines and foods, as well as for oil extraction.
Chia seed constituents with potential biological activities include the omega-3 PUFA alpha-linolenic acid as a precursor of EPA and DHA; dietary fibres ranging between 34-40 g/100 g, including 5-10% soluble fibre or mucilage, with the remainder insoluble fibre; as well as antioxidants such as tocopherols, phenolic acids and flavonoids.
When diabetic patients consumed 37 grams of chia per day as chia flour bread and additional seeds to sprinkle on foods for 12 weeks, there was a small decrease in plasma glucose, decreased C-reactive protein, and decreased systolic blood pressure by approximately 6 mm Hg. The soluble fibre component of chia is noted to absorb up to 12-fold their mass of water as a gel, resulting in such uses as an addition to yogurt to form a pudding. Chia, soluble fibre can result in increased satiety and slowed carbohydrate digestion.
There are approximately 2000 varieties of edible mushrooms, including the common white button, brown crimini, portobello/portobella (all are of the genus Agaricus bisporus but differ in maturity), shitake (Lentinus edodes), oyster (Pleurotus ostreatus), and chanterelle (Cantharellus cibarius) mushrooms. Other wild-harvested highly valued varieties include the matsutake (Tricholoma matsutake), morel (Morchella esculenta), and porcini (Boletus edulis) mushrooms, among others.
Global mushroom production has been steadily increasing, with Canadian mushroom growers producing 132,589 metric tonnes of mushrooms in 2020, led by Ontario and British Columbia.
Mushrooms are generally regarded as low-fat sources of soluble (e.g., beta-glucan, chitosan) and insoluble (chitin) fibres (3 g/100 g fresh wt.), protein (3 g/100 g fresh wt.), minerals and ergosterol (provitamin D2), terpenes, terpenoids and phenolic acids, as well as having “umami” flavour, enhancing capacity from glutamate. The phenolic acids of mushrooms are thought to be responsible for the free-radical scavenging activities of oyster, white button, chanterelle mushrooms as well as others. As aromatic compounds, terpenes and their terpenoid derivatives such as those extracted from chaga mushrooms (Inonotus obliquus) have been reported to exert hypoglycemic antidiabetic effects; decreased serum cholesterol, triacylglycerols and lipid oxidation products; and increased antioxidant enzyme activity in animal studies.
A variety of mushrooms have been used in bakery (cakes, bread, biscuits) and meat-based or meatless formulations. When a water-soluble polysaccharide fraction was extracted and purified from matsutake mushrooms, the extract showed anti-tumor activity against implanted sarcoma (soft tissue tumours) cells in mice, potentially associated with a stimulated cell-mediated immune response.
These functional foods have in common ancient histories of use across the globe, protein, fat, vitamins, minerals, insoluble and soluble fibres to support basic nutrition and health, but also many potentially biologically active molecules that can influence chronic disease risk factors, immunity and gut health.