Flaxseed (Omega 3)

 

Flaxseed (Omega 3) Clinical Report Summary

Written Exclusively for MyNutritionStore.com by Sarah Dzida 

 

Flaxseed is an essential fatty acid that is beneficial for heart health and treats inflammatory bowel disease, arthritis and a variety of other conditions.  Due to its antioxidant and lipid-lowering properties, preliminary studies have reported that flaxseed may have an effect on atherosclerotic plaque formation, which can cause chronic inflammation of the artery walls, but experts believe there is a scarcity of human data that would make this evidence conclusive (1).  However, diets rich in alpha-linolenic acid (ALA), which is an omega-3 fatty acid highly present in flaxseed, are a source of promising evidence as people who follow the Mediterranean diet tend to have a higher level of "good" cholesterol or HDL (2, 3).  Consisting of a balance between omega-3 and omega-6 fatty acids, the Mediterranean diet emphasizes whole grains, roots, vegetables, fruit, fish, poultry and olive/canola oil, and excludes red meat, butter and cream.  As a laxative, studies have noted positive effects due to flaxseed and continue to build upon the need for more defined conclusions.  One trial observed that patients treated with 45 g of flaxseed had looser stools (4).  Another small trial concluded that flaxseed was a more effective treatment for constipation than the popular laxative psyllium (5, 6).  However, researchers note that if flaxseed is taken with an inadequate amount of water, then a patient may experience bowel obstruction.

 

Flaxseed (Omega 3) Overview

 

Flaxseed and its derivative oils: flaxseed and linseed, are rich sources of the fatty acid known as alpha-linolenic acid (ALA) (7, 8).  In fact, flaxseed products are approximately 35% oil, which means that 55% of the product is alpha-linolenic acid.  ALA belongs to the group known as the omega-3 fatty acids, but unlike EPA and DHA that are found primarily in fish, ALA is dominantly found in flaxseed and other vegetable oils.  The typical American diet tends to be lacking in omega-3 fatty acids, which reduces inflammation, but high in omega-6 fatty acids, which promotes inflammation (9).  Studies show that it is important to maintain a balance between the polyunsaturated fatty acids (omega-3 and omega-6) as the two substances work together and contribute toward health rather than toward illness.  As of yet, there is no standardization for flaxseed products due to lack of data, but flaxseed is available in the following forms: oil, capsule, powder, liquid, leaf, in foods and as a topical poultice.  Non-medicinally, flaxseed is used in oil paints and varnishes, as cooking oil, in animal feed, and for linen cloth.

 

Safe Use of Flaxseed (Omega 3)

 

Persons with a known allergy or hypersensitivity to flaxseed, flaxseed oil or any member of the Linaceae plant family or Linum genus plant family, as well as pregnant or breastfeeding women should avoid flaxseed.  Persons with hormone-sensitive conditions like breast, uterine or prostate cancer or endometriosis should also avoid flaxseed (10).  Because flaxseed may inhibit other oral medications, it is recommended that a dose of flaxseed be taken an hour or two before the other medication.  Additionally, experts recommend flaxseed only be used for under four months.  Flaxseed should be taken with an adequate amount of water to avoid bowel obstruction. 

 

Clinical Studies for Flaxseed (Omega 3)

 

1. Flaxseed (Omega 3) and Heart Health

 

Whole flaxseed consumption lowers serum LDL-cholesterol and lipoprotein (a) concentrations in postmenopausal women.  Arjmandi BH, Khan DA, Juma S, et al. (11)

We conducted a double-blind cross-over study to compare the effects of whole flaxseed and sunflower seed, as part of the daily diet, on the lipid profile of postmenopausal women. During two 6-wk periods, thirty-eight mild, moderate, or severely (5.85-9.05 mmol/L) hypercholesterolemic postmenopausal women were randomly assigned to one of the two regimens: flaxseed or sunflower seed. The subjects were provided with 38 g of either treatment in the forms of breads and muffins. The first treatment period lasted six weeks and was followed by a two-wk washout phase. After the washout phase, subjects switched regimens and treatments continued for another 6 weeks. Blood samples were collected at baseline, 6, 8, and 14th wk of the study periods. Significant (pless than 0.01) reductions in total cholesterol were observed for both treatments (6.9 and 5.5% for flaxseed and sunflower seed, respectively). However only flaxseed regimen was able to significantly (pless than 0.001) lower LDL-cholesterol (14.7%). Serum HDL-cholesterol and triglyceride concentrations were unaffected by either of the treatments. Most interestingly, lipoprotein(a) [Lp(a)], a strong predictor of cardiovascular disease, concentrations were significantly (pless than 0.05) lowered by the flaxseed treatment (7.4% compared to baseline values). Regression analyses showed the strongest association between age and both total and LDL-cholesterol concentrations. Among the dietary variables, total and soluble fiber intakes were negatively correlated with serum total and LDL-cholesterol concentrations. The cholesterol lowering effects of flaxseed and sunflower seed may be due to the activity of single or multiple components, including alpha-linolenic or linoleic acids, total and soluble fiber, and non-protein constituents present in these seeds.

 

Effects of dietary oleic, linoleic and alpha-linolenic acids on blood pressure, serum lipids, lipoproteins and the formation of eicosanoid precursors in patients with mild essential hypertension.  Singer P, Jaeger W, Berger I, et al. (12)

Forty-four male in-patients with mild essential hypertension were randomly allocated to three groups and put on diets supplemented with 60 ml/day of olive (n = 15), sunflowerseed (n = 15) or linseed oils (n = 14), respectively, for two weeks within a blind study. In the group receiving sunflowerseed oil an increase of linoleic acid in serum lipids could be observed, whereas arachidonic and eicosapentaenoic acids appeared unchanged in serum triglycerides and even significantly lower in cholesterol esters. The subjects ingesting the linseed oil-rich diet showed an increase of alpha-linolenic acid in serum lipids, whereas arachidonic and eicosapentaenoic acids remained unchanged in serum triglycerides. In cholesterol esters, however, arachidonic acid was significantly decreased and eicosapentaenoic acid appeared increased only to a low level of significance. In the group put on the olive oil-rich regimen only a significant fall of linoleic acid was obvious in serum triglycerides. The results might indicate a defective desaturation and elongation of linoleic and alpha-linolenic acids and, consequently, a slow formation of arachidonic and eicosapentaenoic acids in patients with mild essential hypertension, which should be considered in dietary studies. After the sunflowerseed oil-rich diet a significant decrease of total cholesterol, low density lipoprotein (LDL) cholesterol and the LDL/high density lipoprotein (HDL) cholesterol ratio was found. Systolic blood pressure during a psychophysiological stress test and urinary sodium excretion appeared significantly lower after the linoleic acid-rich diet. After the linseed oil-rich diet, in addition to total cholesterol, LDL cholesterol and the LDL/HDL cholesterol ratio, serum triglycerides and lecithin cholesterol acyl transferase (LCAT) activity were significantly depressed.

 

2. Flaxseed (Omega 3) as Alpha-Linolenic Acid in the Mediterranean Diet

 

Mediterranean alpha-linolenic acid-rich diet in secondary prevention of coronary heart disease.  de Lorgeril M, Renaud S, Mamelle N, et al.

In a prospective, randomised single-blinded secondary prevention trial we compared the effect of a Mediterranean alpha-linolenic acid-rich diet to the usual post-infarct prudent diet. After a first myocardial infarction, patients were randomly assigned to the experimental (n = 302) or control group (n = 303). Patients were seen again 8 weeks after randomisation, and each year for 5 years. The experimental group consumed significantly less lipids, saturated fat, cholesterol, and linoleic acid but more oleic and alpha-linolenic acids confirmed by measurements in plasma. Serum lipids, blood pressure, and body mass index remained similar in the 2 groups. In the experimental group, plasma levels of albumin, vitamin E, and vitamin C were increased, and granulocyte count decreased. After a mean follow up of 27 months, there were 16 cardiac deaths in the control and 3 in the experimental group; 17 non-fatal myocardial infarction in the control and 5 in the experimental groups: a risk ratio for these two main endpoints combined of 0.27 (95% CI 0.12-0.59, p = 0.001) after adjustment for prognostic variables. Overall mortality was 20 in the control, 8 in the experimental group, an adjusted risk ratio of 0.30 (95% CI 0.11-0.82, p = 0.02). An alpha-linolenic acid-rich Mediterranean diet seems to be more efficient than presently used diets in the secondary prevention of coronary events and death.

 

Mediterranean diet, traditional risk factors, and the rate of cardiovascular complications after myocardial infarction: final report of the Lyon Diet Heart Study.  de Logeril M, Salen P, Martin JL, Monjaud I, Delaye J, Mamelle N.

Background: The Lyon Diet Heart Study is a randomized secondary prevention trial aimed at testing whether a Mediterranean-type diet may reduce the rate of recurrence after a first myocardial infarction. An intermediate analysis showed a striking protective effect after 27 months of follow-up. This report presents results of an extended follow-up (with a mean of 46 months per patient) and deals with the relationships of dietary patterns and traditional risk factors with recurrence. Methods and Results: Three composite outcomes (COs) combining either cardiac death and nonfatal myocardial infarction (CO 1), or the preceding plus major secondary end points (unstable angina, stroke, heart failure, pulmonary or peripheral embolism) (CO 2), or the preceding plus minor events requiring hospital admission (CO 3) were studied. In the Mediterranean diet group, CO 1 was reduced (14 events versus 44 in the prudent Western-type diet group, P=0.0001), as were CO 2 (27 events versus 90, P=0.0001) and CO 3 (95 events versus 180, P=0. 0002). Adjusted risk ratios ranged from 0.28 to 0.53. Among the traditional risk factors, total cholesterol (1 mmol/L being associated with an increased risk of 18% to 28%), systolic blood pressure (1 mm Hg being associated with an increased risk of 1% to 2%), leukocyte count (adjusted risk ratios ranging from 1.64 to 2.86 with count >9x10(9)/L), female sex (adjusted risk ratios, 0.27 to 0. 46), and aspirin use (adjusted risk ratios, 0.59 to 0.82) were each significantly and independently associated with recurrence. Conclusions: The protective effect of the Mediterranean dietary pattern was maintained up to 4 years after the first infarction, confirming previous intermediate analyses. Major traditional risk factors, such as high blood cholesterol and blood pressure, were shown to be independent and joint predictors of recurrence, indicating that the Mediterranean dietary pattern did not alter, at least qualitatively, the usual relationships between major risk factors and recurrence. Thus, a comprehensive strategy to decrease cardiovascular morbidity and mortality should include primarily a cardioprotective diet. It should be associated with other (pharmacological?) means aimed at reducing modifiable risk factors. Further trials combining the 2 approaches are warranted.

  

3. Flaxseed (Omega 3) as a Laxative

 

Efficacy of ground flaxseed on constipation in patients with irritable bowel syndrome.  Tarpila S, Tarpila A, Silvennoinen T, Lindberg L, et al.

We studied in an investigator-blinded trial the efficacy of roughly ground partly defatted flaxseed on constipation in 55 patients suffering from constipation predominant irritable bowel syndrome. Fifty-five patients were randomised to receive 6-24 g/d either flaxseed or psyllium for 3 months. During the blinded treatment period 26 patients received flaxseed and 29 received psyllium. In flaxseed group, constipation and abdominal symptoms were decreased significantly (p=0.002) whereas in psyllium group the reduction was not statistically significant. After the blinded treatment period, the difference between groups was statistically significant in constipation (p=0.05) and in bloating and pain (p=0.001). Forty patients continued to the open period with flaxseed treatment only, 18 from flaxseed group and 22 from psyllium group. After the open period of 3 months, constipation and abdominal symptoms were further significantly reduced (p=0.001). Safety laboratory values were unchanged with exception of serum thiocyanate that increased from 40.9 to 153.7 mmol/l in flaxseed group. After additional 3 months treatment with flaxseed this value was decreased to 104 mmol/l. Blood cadmium was normal (3.4 nmol/l) after six months flaxseed treatment.

 

Flaxseed (Omega 3) References

 

1. Prasad K. Dietary flax seed in prevention of hypercholesterolemic atherosclerosis. Atherosclerosis 1997;132(1):69-76.
2. de Lorgeril M, Renaud S, Mamelle N, et al. Mediterranean alpha-linolenic acid-rich diet in secondary prevention of coronary heart disease. Lancet 1994;343(8911):1454-1459.
3. de Logeril M, Salen P, Martin JL, Monjaud I, Delaye J, Mamelle N. Mediterranean diet, traditional risk factors, and the rate of cardiovascular complications after myocardial infarction: final report of the Lyon Diet Heart Study. Circulation. 1999; 99(6):779-785.
4. Clark WF, Parbtani A, Huff MW, et al. Flaxseed: a potential treatment for lupus nephritis. Kidney Int 1995;48(2):475-480.
5. Tarpila S, Kivinen A. Ground flaxseed is an effective hypolipidemic bulk laxative [published abstract]. Gastroenterology 1997;112: A 836.
6. Tarpila S, Tarpila A, Silvennoinen T, Lindberg L, et al. Efficacy of ground flaxseed on constipation in patients with irritable bowel syndrome.  Nutraceutical Research 2004; Vol. 2 No. 2: 119-125.
7. Carter J. Flax seed as a source of alpha linolenic acid. J Am Coll Nutr 1993;12(5):551.
8. Cunnane SC, Ganguli S, Menard C, et al. High alpha-linolenic acid flaxseed (Linum usitatissimum): some nutritional properties in humans. Br J Nutr 1993;69(2):443-453.
9. Belluzzi A, Boschi S, Brignola C, Munarini A, Cariani C, Miglio F. Polyunsaturated fatty acids and inflammatory bowel disease. Am J Clin Nutr . 2000;71(suppl):339S-342S.
10. Adlercreutz H. Epidemiology of phytoestrogens. Baillieres Clin Endocrinol Metab 1998;12(4):605-623.
11. Arjmandi BH, Khan DA, Juma S, et al. Whole flaxseed consumption lowers serum LDL-cholesterol and lipoprotein (a) concentrations in postmenopausal women. Nutrit Res 1998;18(7):1203-1214.
12. Singer P, Jaeger W, Berger I, et al. Effects of dietary oleic, linoleic and alpha-linolenic acids on blood pressure, serum lipids, lipoproteins and the formation of eicosanoid precursors in patients with mild essential hypertension. J Hum Hypertens 1990;4(3):227-233.