Green tea is made with the leaves of Camellia sinensis that have undergone minimal oxidation during processing. It has high levels of flavonoids, plant metabolites that are responsible for a number of plant-related functions, including pigmentation, UV filtration and chemical messaging. The mean content of flavonoids in a cup of green tea is higher than in food and drinks we traditionally associate with having a health-contributing nature, including fresh fruits, vegetable juices or wine.
The health benefits of green tea
Flavonoids – and specifically catechins – have antioxidant and vascular protective effects, and have been studied widely for their potential health benefits, including anti-cancer activity and improvement of cardiovascular health and neurological function. Epigallocatechin gallate (EGCG), the most abundant catechin in green tea (and not present in black tea), has also been studied for potential use in the treatment of AIDS-related dementia, Chronic Fatigue Syndrome, autoimmune diseases and endometriosis.
Some of the latest research on the effect of catechins in humans looks at the link to body composition, particularly body fat distribution. Catechins and caffeine (also contained in green tea) have been proposed as being able to affect how energy and fat are used in the body. The link is thought to relate to the EGCG and caffeine content of green tea’s induction of thermogenesis – the process of heat production in organisms – and stimulation of fat oxidation, which boosts metabolic rate.
Other possible health benefits of green tea include: reducing or delaying the onset of Parkinson’s disease, treating low blood pressure, treating high blood pressure, reducing abnormal cell development caused by human papilloma virus infection, and the prevention of stroke, osteoporosis and diabetes.
And this is just a drop in the bucket – there is a lot of research looking at the health benefits of green tea. However, the food and beverage industry does not yet appear to be getting the advantages of health-benefit labelling of green tea or green tea products.
Permitted label claims in Canada
In Canada, green tea has been approved by the Natural Health Products Directorate (NHPD) as a non-medicinal ingredient in vitamin and mineral supplements (recommended for the maintenance of good health), as an antioxidant (for the maintenance of good health), and in a body wash recommended for the treatment of acne.
In addition, Health Canada has approved function claims that can be used on the labelling of green tea products. Function claims relate to the specific beneficial effects that the consumption of a food at levels consistent with normal dietary patterns has on the normal functions or biological activities of the body. Such claims portray a positive contribution to health and the maintenance of a physiological function, or to physical or mental performance.
Approved function claims for green tea link its consumption in specified amounts – one cup or 250 mL – to the protection of blood lipids from oxidation, an antioxidant effect in blood, and increased antioxidant capacity in the blood. This list of acceptable function claims can be updated as new claims for green tea are presented to, and found to be acceptable by, Health Canada.
In addition to the above, there is an approved Natural Health Product (NHP) Monograph for green tea extract which provides it is a source of antioxidants for the maintenance of good health, and can be used with a program of reduced dietary intake of calories and increased physical activity to help in weight management. This means that applicants for products containing green tea extracts for the uses specified in the Monograph can reference the Monograph and speed up the approval process. The NHPD will not evaluate the safety and efficacy of NHP ingredients that are already known to be safe and efficacious when used under the conditions specified in the Monograph.
Permitted label claims in the U.S.
In the U.S., the FDA has not yet approved any health claims for use on the labels of green tea foods or dietary supplements. Health claims in the U.S. describe a relationship between a food, food component, or dietary supplement, and a reduced risk of a disease or health-related condition. Health claims must be pre-approved by the FDA following review of scientific evidence.
In the case of green tea, the FDA has allowed the use of qualified health claims. Qualified health claims are permitted when there is emerging evidence of a relationship between a food, food component, or dietary supplement and reduced risk of a disease or health-related condition. In this case, the evidence is not well enough established to meet the significant scientific standard for a bona fide health claim, and qualifying language is included as part of the claim to indicate that the evidence supporting the claim is limited.
The qualified health claim for green tea was approved in February 2011 and provides: “Drinking green tea may reduce the risk of breast or prostate cancer. FDA does not agree that green tea may reduce that risk because there is very little scientific evidence for the claim.” This claim is eligible for inclusion on green tea and conventional foods and dietary supplements that contain green tea.
The FDA’s decision to permit the qualified health claim was based on a review of 92 observational studies that evaluated the general category of tea, and 39 observational studies that specifically evaluated the relationship between green tea and one or more cancers. These studies consisted of seven prospective cohort studies, one nested case-control study, and 31 case-control studies. The types of cancer included breast, prostate, gastric, lung, colon/rectal, esophageal, pancreatic, ovarian, liver, bladder and skin.
In addition to the qualified health claim, in the U.S. green tea can be labelled with structure/function claims. These claims describe the role of a nutrient or dietary ingredient intended to affect normal structure or function in humans, may characterize the means by which a nutrient or dietary ingredient acts to maintain such structure or function, or may describe general well-being from consumption of a nutrient or dietary ingredient. Structure/function claims must be truthful and not misleading, but do not require pre-approval by the FDA.
The future for green tea?
While there may not be enough evidence to satisfy regulators that consumption of green tea can prevent or cure cancer, improve cardiovascular or neurological health, or help us to lose weight, the food industry is certainly abuzz with the promise of green tea. A simple Google search turns up literally hundreds of hits espousing the multitude of beneficial effects of green tea. In addition, green tea is often used in “alternative medicine” practices to promote well-being.
Perhaps the best news is that green tea is readily available, is relatively affordable and is generally safe, which means that informed consumers can access it to make their own decisions about the role of green tea in their diets. Hopefully, regulator-approved science will soon catch up, and industry can label green tea products to promote their health benefits.
Sara Zborovski is a partner at Gilbert’s LLP in Toronto, practicing food, beverage and drug law. She also hosts her own blog at www.thefoodlawyer.ca