Flaxseed Reduces Blood Pressure, Heart Disease
Adding flaxseed to our diet can significantly boost our heart health and reduce blood pressure according to multiple studies. What makes flax so healthy for our cardiovascular system?
Flaxseed and blood pressure
In a 2017 study from the University of Regina and the University of Saskatchewan,1 scientists studied 32 healthy adults who were between 60 and 80 years old. The researchers gave half the group a placebo. The other half were given a flaxseed supplement.
After six months of the supplement program, those taking the flax supplement saw their systolic blood pressure go down from an average of 155 mm Hg before the trial began, to an average of 140 mm Hg. The flaxseed supplement was the only change among the participants.
The supplement consisted of 600 milligrams of a flaxseed lignan-enriched supplement The researchers concluded:
“These data further support the safety and tolerability of long-term flaxseed lignan-enriched complex supplementation in older adults and identify an ability to favorably modulate SBP, an important risk factor in cardiovascular disease.”
Ground flax reduces blood pressure
Ground flaxseed can also significantly reduce blood pressure, according to another human study.
Peripheral artery disease is typically accompanied by hypertension or high blood pressure. Peripheral artery disease occurs when the walls of blood vessels throughout the body become thickened with a buildup of plaque. Often this is more pronounced among the blood vessels of the lower legs. This thickening of plaque drives up blood pressure.
In a 2013 study from the St Boniface Hospital Research Center in Winnipeg, Canada,4 researchers gave 110 peripheral artery disease patients a placebo or 30 grams of ground flaxseed every day for six months.
After the six months, the flaxseed group had significantly higher levels of omega-3s in the bloodstream and their blood’s lignan levels – associated with lower cholesterol and less artery damage – increased by between double and fifty times. The placebo group had no such increases.
Furthermore, the blood pressure of the flaxseed group was lowered significantly. Their systolic blood pressure (SBP) on average was 10 mm Hg lower than the beginning of the study, and their diastolic blood pressure (DBP) was lower by 7 mm Hg on average.
But those patients who had extremely high blood pressure at the beginning of the study (more than 140 mm Hg systolic) and were part of the flaxseed group saw even greater reductions. These patients had an average reduction of systolic blood pressure by 15 mm Hg.
The researchers were astounded by the results, and stated that flaxseed supplementation is one of the best strategies to reduce blood pressure with diet:
“In summary, flaxseed induced one of the most potent antihypertensive effects achieved by a dietary intervention.”
Dr. Grant Pierce, the study’s lead researcher, stated that the results have surprised many. “This is the largest decrease in blood pressure ever shown by any dietary intervention – including the Mediterranean Diet and low-sodium diets,” said Dr. Pierce.
Dr. Grant also indicated that these sort of reductions will reduce heart attack and stroke incidence by as much as 50%.
Flaxseed reduces bad cholesterol
Other research has found that flaxseed significantly reduces bad cholesterol, including low-density lipoprotein (LDL-cholesterol) and triglycerides. A 2016 review of research from the University of California2 analyzed research related to foods that reduce bad cholesterol and found that flax had the ability to reduce bad cholesterol by up to 10 percent.
These “bad” cholesterols can significantly damage our blood vessels, increasing the risk of heart disease.
Flax constituents work together
Flaxseed contains a number of constituents that work synergistically to reduce cholesterol and blood pressure. These include alpha-linolenic acid, linoleic acid, oligosaccharide-rich fiber, and various lignans.5
Other research has found that flaxseed reduces cholesterol and helps maintain healthy bowel movements. This may relate directly to the fact that flaxseeds also improve our gut bacteria.
Lignan reduces lipid peroxidation
The mechanisms at play with regard to flax and oxylipins relate to the fact that various lignans and sterols of flax reduce two problematic mechanisms linked to cardiovascular disease: lipid peroxidation and the formation of oxylipins.
Lipid peroxidation occurs when cholesterol vehicles such as low-density lipoproteins (LDL) and very low-density lipoproteins (VLDL) become oxidized.
Lipid peroxidation causes free radicals, and these oxidative free radicals damage blood vessel walls, producing the plaque that causes peripheral artery disease and other cardiovascular diseases.
The fact that the lignans in flaxseed lower lipid peroxidation were illustrated in a recent study from researchers at the University of California at Davis. For six weeks, 37 people (24 women and 13 men) were given either a bar with flaxseed with 0.41 grams of lignans or a bar with three grams of flaxseed with 0.15 grams of lignans. Both bars had the same amount of omega-3 fats (primarily alpha linolenic acid).
The researchers tested levels of cholesterol and lipoprotein carriers such as LDL and HDL.
The group that ate the high-lignan flax bars every day for six weeks had 12% lower cholesterol levels. They also had 15% lower LDL-c levels and more importantly, had 25% lower levels of oxidized LDL by 25% compared to the lower-lignan flax group.
The researchers concluded:
“High-lignan FLX has the unique property of decreasing Ox-LDL, which is an independent risk factor for cardiovascular disease.”
Ox-LDL or oxidized LDL is an independent risk factor for cardiovascular disease specifically because it damages blood vessel walls as discussed above.
Oxylipin levels reduced
Another study done by the researchers from the St Boniface Hospital Research Center found that flaxseed supplementation significantly reduces oxylipin levels.6 The researchers measured oxylipin levels in the placebo group and the flaxseed group following the supplementation period. The research found that oxylipin levels were significantly lowered in the flaxseed group.
Oxylipins arise from the oxidation of polyunsaturated fatty acids. Like lipid peroxides, oxylipins are heightened in cardiovascular disease.
Oxylipins are formed when polyunsaturated fatty acids (PUFAs) are oxidized. This can occur from lipids such as DHA and EPA, along with others. The types of PUFAs typically related to oxylipin production are free PUFAs.
Black sesame seeds also reduce blood pressure according to other research.
Does flax reduce our testosterone levels?
A number of websites have proposed, using anecdotal information, that because flax contains mildly estrogenic compounds (phytoestrogens), it will reduce a man’s testosterone levels.
The research does not show this. A 2008 study from the University of Texas tested 161 patients.7 Some were given a diet supplemented with 30 grams of flax per day for 21 days. The researchers found no difference in testosterone levels. They did, however, find that flax was “protective for prostate cancer.”
A 2004 study8 gave 15 men a diet supplemented with 30 grams per day of flaxseed. The researchers found “no statistically significant change was seen in total testosterone.” Thay also found a benefit for the prostate in this study. However, a 2001 study9 of 25 men did find that 30 grams per day of flax lowered total cholesterol among the men. But these men had prostate cancer and were heading into a prostatectomy (removal of the prostate). The flaxseed supplementation diet also included a severe reduction of fat in the diet – which can reduce testosterone depending upon their normal fat consumption. So there were other factors involved with respect to the conversion of testosterone in the prostate in this case.
When flax is part of a full-spectrum wholefood diet and supplementation plan, we find a different story. For example, in a study of 50 men and women10 with an average age of 31, researchers gave the volunteers a full spectrum green drink and other supplements that included flaxseed. After 21 days, the researchers found the volunteers on the supplement plan had an increase in testosterone of 111 ng/dl.
1. Di Y, Jones J, Mansell K, Whiting S, Fowler S, Thorpe L, Billinsky J, Viveky N, Cheng PC, Almousa A, Hadjistavropoulos T, Alcorn J. Influence of Flaxseed Lignan Supplementation to Older Adults on Biochemical and Functional Outcome Measures of Inflammation. J Am Coll Nutr. 2017 Nov-Dec;36(8):646-653. doi:10.1080/07315724.2017.1342213.
2. Surampudi P, Enkhmaa B, Anuurad E, Berglund L. Lipid Lowering with Soluble Dietary Fiber. Curr Atheroscler Rep. 2016 Dec;18(12):75.
3. Caligiuri SP, Aukema HM, Ravandi A, Guzman R, Dibrov E, Pierce GN. Flaxseed Consumption Reduces Blood Pressure in Patients With Hypertension by Altering Circulating Oxylipins via an α-Linolenic Acid-Induced Inhibition of Soluble Epoxide Hydrolase. Hypertension. 2014 Apr 28.
4. Rodriguez-Leyva D, Weighell W, Edel AL, LaVallee R, Dibrov E, Pinneker R, Maddaford TG, Ramjiawan B, Aliani M, Guzman R, Pierce GN. Potent antihypertensive action of flaxseed in hypertensive patients. Hypertension. 2013 Dec;62(6):1081-9. doi: 10.1161/HYPERTENSIONAHA.113.02094.
5. Almario RU, Karakas SE. Lignan content of the flaxseed influences its biological effects in healthy men and women. J Am Coll Nutr. 2013;32(3):194-9. doi: 10.1080/07315724.2013.791147.
6. Tourdot BE, Ahmed I, Holinstat M. The emerging role of oxylipins in thrombosis and diabetes. Front Pharmacol. 2014 Jan 7;4:176. eCollection 2014 Jan 7.
7. Demark-Wahnefried W, Polascik TJ, George SL, Switzer BR, Madden JF, Ruffin MT 4th, Snyder DC, Owzar K, Hars V, Albala DM, Walther PJ, Robertson CN, Moul JW, Dunn BK, Brenner D, Minasian L, Stella P, Vollmer RT. Flaxseed supplementation (not dietary fat restriction) reduces prostate cancer proliferation rates in men presurgery. Cancer Epidemiol Biomarkers Prev. 2008 Dec;17(12):3577-87. doi:
8. Demark-Wahnefried W, Robertson CN, Walther PJ, Polascik TJ, Paulson DF, Vollmer RT. Pilot study to explore effects of low-fat, flaxseed-supplemented diet on proliferation of benign prostatic epithelium and prostate-specific antigen. Urology. 2004 May;63(5):900-4.
9. Demark-Wahnefried W, Price DT, Polascik TJ, Robertson CN, Anderson EE, Paulson DF, Walther PJ, Gannon M, Vollmer RT. Pilot study of dietary fat restriction and flaxseed supplementation in men with prostate cancer before surgery: exploring the effects on hormonal levels, prostate-specific antigen, and histopathologic features. Urology. 2001 Jul;58(1):47-52.
10. Balliett M, Burke JR. Changes in anthropometric measurements, body composition, blood pressure, lipid profile, and testosterone in patients participating in a low-energy dietary intervention. J Chiropr Med. 2013 Mar;12(1):3-14. doi: 10.1016/j.jcm.2012.11.003.