Flaxseed is a popular item in the health food aisle, but it's not new -- evidence of flaxseed cultivation dates back to ancient times. Flax has long been considered a healthful seed, and preliminary research confirms some of its benefits. While flaxseed's full nutrition profile may not yet be understood, its touted benefits are often linked to omega-3 fatty acid, fiber and lignan content. In people with diabetes, adding flaxseed to the diet may impart helpful benefits, including blood sugar control, improvement of cholesterol and triglyceride levels, and a potential role in kidney health. However, larger studies are needed to fully understand the role of flaxseed in diabetes management.
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Blood Sugar Improvements
Flaxseed may help lower blood sugar levels. A study published in the September 2011 issue of “Journal of Dietary Supplements” showed that participants whose diets were supplemented with flaxseed powder experienced a 20 percent drop in average fasting blood sugar levels. Another study published in the July 2009 issue of "International Journal of Food Sciences and Nutrition" reported a 12 percent reduction in average fasting blood sugars in participants whose diets were supplemented with flax gum. Participants in both studies had type 2 diabetes. While the precise reason for the benefit is unknown, the fiber in flax may be responsible. Flax contains mucilage, or gum -- a gluey, gel-forming fiber that can slow digestion and allow the glucose from foods to be digested and released into the blood more slowly. These studies were small and short-term, so larger studies are needed to better understand the role of flax in blood sugar control.
Cholesterol and Triglyceride Lowering
In addition to blood sugar improvements, these studies linked flax to improved cholesterol and triglyceride levels. The research published in “Journal of Dietary Supplements” reported added flax powder decreased total cholesterol by about 14 percent and triglycerides by 18 percent. The study published in "International Journal of Food Sciences and Nutrition" reported the addition of flaxseed gum dropped total cholesterol by about 10 percent, but triglycerides were not improved in this study. While these benefits may be related to the mucilage action in flax, lignans may also play a role. Flax is the highest dietary source of lignans, a compound classified as a fiber that acts as a beneficial plant estrogen and also has anti-inflammatory and antioxidant effects. However, not all research shows a benefit. A small study published in the September 2002 issue of "Obstetrics and Gynecology" showed that flaxseed did not lower cholesterol levels in women. Larger studies are needed to determine how flax effects cholesterol and triglyceride levels in people with diabetes.
Flaxseeds contain alpha-linolenic acid (ALA), an omega-3 fat linked to cardiovascular benefits. A review article published November 2010 in the “Canadian Journal of Cardiology” linked ALA-rich diets to a reduced risk of heart attack and stroke. According to the American Heart Association, adults with diabetes are 2 to 4 times more likely to have heart disease or suffer a stroke compared to those without diabetes. Because research specific to flaxseed's ALA content and related cardiovascular benefits is not available, more quality research is needed to fully understand the role of flaxseed in diabetes management and its role in managing or reducing the risk of cardiovascular disease.
Diabetes increases the risk of developing kidney disease. Preliminary research published in the December 2003 issue of “Kidney International” suggests that consumption of flaxseed could reduce the likelihood of kidney damage, which can ultimately reduce the risk of kidney failure. In this study -- conducted on obese rats -- researchers found that substituting ground flaxseed for milk protein reduced the presence of abnormal amounts of protein in the urine, which signal kidney damage. This study was not able to determine which components of flaxseed meal were responsible for the noted benefits. Quality research on humans is necessary to determine if flax imparts a kidney-protective benefit to people with diabetes.
The Form of Flax Matters
Flaxseed is a nutrient-packed seed, with benefits linked to its ALA content and fiber -- including the mucilage and lignan content. However, the form of flax is an important consideration. Flaxseed oil, for example, is ALA-rich but lacks fiber, lignans and other beneficial compounds. Also, whole seeds provide fiber, but the full benefits of the ALA and mucilage content may not be realized unless the seeds are chewed. In addition, flax capsules and pills may not have the same plant compounds compared to ground flaxseed, or flax meal. To obtain the full benefits of flax, purchase flax meal or grind the whole seeds at home, and refrigerate to maintain freshness if not using right away.
Warnings and Precautions
Flaxseed consumption is generally considered safe, particularly in the amounts used in most research studies -- 1 to 4 tablespoons of ground seeds daily. However, some precautions are in order. Individuals with a history of gastrointestinal disorders or symptoms should discuss the use of flaxseed with a doctor, because large amounts, particularly from whole seeds or flaxseed oil, could worsen symptoms. Because flaxseed can lower blood sugar, anyone with diabetes needs to monitor blood sugar more closely -- medication requirements may decrease if flax improves blood sugars. As with any supplement or medication, consult a doctor prior to starting. Anyone with uncontrolled blood sugar levels needs to work with their doctor and diabetes care team for management advice, and flaxseed is not a replacement for insulin or diabetes medications.