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Bureau of Nutritional Sciences
Food Directorate, Health Products and Food Branch
In March 2012, Health Canada's Food Directorate received an application for a therapeutic claim about ground flaxseed and blood cholesterol lowering. The information below is a summary of Health Canada's review based on the Guidance Document for Preparing a Submission for Food Health Claims.
Health Canada has recently reconsidered the classification of food products with disease risk reduction claims or therapeutic claims in light of clarified principles for the classification of foods at the Food-Natural Health Product interface. Health Canada's position is that when food products are marketed for a disease risk reduction or therapeutic benefit, which comes as a result of the food's normal use as part of the diet, these products may be classified and regulated as foods. In other words, the use of a disease risk reduction claim or a therapeutic claim alone is not sufficient to classify the product as a natural health product.
The petitioner provided a literature review up to May 2011 to substantiate the proposed health claim. The petitioner's literature review was updated by Health Canada's Food Directorate to June 2013, bringing the total number of relevant studies to 8.
All relevant studies were clinical trials conducted in normo- and hypercholesterolemic males and females ranging from 8 to 75 years of age. Treatment duration ranged from 4 weeks to 12 months and the quantity of ground flaxseed consumed ranged from 30 g/day to 50 g/day. Ground flaxseed was used in all studies except one (Simbalista et al., 2010), which used partially defatted flaxseed meal at a dose equivalent to 25 g/day of whole seed. The smallest study included 10 subjects, while there were 179 subjects in the largest study. The main endpoints considered were total cholesterol and low-density lipoprotein (LDL) cholesterol. These are recognized as risk factors or biomarkers for heart disease.
The direction of effect was highly consistent towards a reduction in total cholesterol (100%) and LDL cholesterol (100%) levels when flaxseed was consumed. However, a very low proportion of studies showed a statistically significant reduction in total cholesterol (25%) and LDL cholesterol (0%) levels. These conclusions were similar when only higher quality studies were taken into account.
The petitioner conducted a meta-analysis which was reproduced and expanded by Heath Canada's Food Directorate. Pooled estimates of both meta-analyses were similar. The estimates from the Food Directorate meta-analysis are reported here. All 8 studies identified as part of the systematic review were included. Baseline and final values for the control and treatment groups were extracted from the studies to calculate the change for each group, except when change was already provided. The pooled effect was -0.21 mmol/L (p=0.0001) for total cholesterol levels and -0.22 mmol/L (p<0.0001) for LDL cholesterol levels.
The only study using partially defatted flaxseed meal was included in the meta-analysis, but it was deemed insufficient to demonstrate a cholesterol lowering effect of partially defatted flaxseed meal because of its high risk of bias (total and LDL cholesterol levels at baseline were statistically different between the control and test groups).
The daily intake of ground whole flaxseed in the studies of higher quality in adults ranged from 38 g (Arjmandi et al., 1998) to 40 g (Bloedon et al., 2008; Dodin et al., 2005; Lucas et al., 2002). This includes the study assigned the most weight (most subjects and least dispersion) in the meta-analysis which administered 40 g of ground whole flaxseed per day (Dodin et al., 2005).
The evidence consistently supports a direction of effect towards a reduction in total and LDL cholesterol levels when ground flaxseed is consumed. A low proportion of studies reached statistical significance, but this was addressed by a meta-analysis which showed a statistically significant reduction in total and LDL cholesterol levels with ground flaxseed consumption.
Health Canada's Food Directorate has concluded that scientific evidence exists to support a claim about ground whole flaxseed and blood cholesterol lowering. The claim is relevant and generally applicable to the Canadian population given that a high proportion of the population (39% of Canadians aged 6 to 79)Footnote 1 has unhealthy total cholesterol levels, putting them at an increased risk for heart disease.
The following statements may be made in the labelling and advertisingFootnote 2 of food products meeting the qualifying criteria.
Primary statementFootnote 3:
[serving size from Nutrition Facts table in metric and common household measures] of (brand name) [name of food] supplies/provides X% of the daily amount [of ground (whole) flaxseed]* shown to help reduce/lower cholesterol.
For exampleFootnote 4:
16 g (2 tablespoons) of ground flaxseed supplies 40% of the daily amount shown to help lower cholesterol.
The "daily amount" referred to in the primary statement is 40 g of ground whole flaxseed. This amount is based on the evidence available concerning the amount of ground whole flaxseed shown to help reduce cholesterol. In this statement, the percentage of the daily amount of ground whole flaxseed provided in one serving should be rounded to the nearest multiple of 5%.
The following additional statements could be placed adjacent to the primary statement, in letters up to twice the size and prominence of those in the primary statement:
The following qualifying criteria apply to all food products carrying the above-mentioned health claim.
Arjmandi BH, Khan DA, Shanil Juma, Drum ML, Sreevidya Venkatesh, Sohn E, et al. Whole flaxseed consumption lowers serum LDL-cholesterol and lipoprotein(a) concentrations in postmenopausal women. Nutr Res. 1998;18(7):1203-14.
Bloedon LT, Balikai S, Chittams J, Cunnane SC, Berlin JA, Rader DJ, et al. Flaxseed and cardiovascular risk factors: Results from a double blind, randomized, controlled clinical trial. J Am Coll Nutr. 2008;27(1):65-74.
Cunnane SC, Hamadeh MJ, Liede AC, Thompson LU, Wolever TM, Jenkins DJ. Nutritional attributes of traditional flaxseed in healthy young adults. Am J Clin Nutr. 1995;61(1):62-8.
Dodin S, Lemay A, Jacques H, Legare F, Forest JC, Masse B. The effects of flaxseed dietary supplement on lipid profile, bone mineral density, and symptoms in menopausal women: A randomized, double-blind, wheat germ placebo-controlled clinical trial. J Clin Endocrinol Metab. 2005;90(3):1390-7.
Lucas EA, Wild RD, Hammond LJ, Khalil DA, Juma S, Daggy BP, et al. Flaxseed improves lipid profile without altering biomarkers of bone metabolism in postmenopausal women. J Clin Endocrinol Metab. 2002;87(4):1527-32.
Patade A, Devareddy L, Lucas EA, Korlagunta K, Daggy BP, Arjmandi BH. Flaxseed reduces total and LDL cholesterol concentrations in native American postmenopausal women. J Womens Health (Larchmt). 2008;17(3):355-66.
Simbalista RL, Sauerbronn AV, Aldrighi JM, Areas JA. Consumption of a flaxseed-rich food is not more effective than a placebo in alleviating the climacteric symptoms of postmenopausal women. J Nutr. 2010;140(2):293-7.
Wong HRD, Chahal NMN, N.P., Manlhiot CBS, Niedra EBS, McCrindle BW. Flaxseed in pediatric hyperlipidemia: A placebo-controlled, blinded, randomized clinical trial of dietary flaxseed supplementation for children and adolescents with hypercholesterolemia. JAMA Pediatr. 2013;167(8):708-13.
Statistics Canada. 2012. Cholesterol levels of Canadians, 2009 to 2011. http://www.statcan.gc.ca/pub/82-625-x/2012001/article/11732-eng.htm [last accessed on November 15, 2013].
The information in this document complements the labelling information published by the Canadian Food Inspection Agency. It is the responsibility of all manufacturers and importers to ensure that their products comply with all relevant Canadian legislation and regulations.
[ ] = mandatory; [ ]* = mandatory unless the [name of food] is "ground (whole) flaxseed"; ( ) = optional; / = acceptable alternate wording.
Examples are for illustration purposes only. They do not necessarily reflect acceptable health claims.
Packaged whole flaxseed would be eligible to carry the claim if the label clearly specifies that flaxseeds must be ground before consumption.