***Flaxseeds: health benefits..
..The seeds of most plants are rich in nutrients and can provide us with health benefits. Yet flaxseeds are also nutritionally unique and offer us health benefits not found across the board within the seeds food group. The nutritional uniqueness of flaxseeds features three nutrient aspects, and all three play a key role in the outstanding health benefits of this food.
***Unique Nutrient Features of Flaxseeds
..The first unique feature of flax is its high omega-3 fatty acid content. Among all 127 World's Healthiest Foods, flaxseeds comes out number one as a source of omega-3s! The primary omega-3 fatty acid found in flaxseeds is alpha-linolenic acid, or ALA. The ALA in flaxseed has found to be stable for at least 3 hours of cooking at oven temperatures (approximately 300F/150C), which makes it available after ground flaxseeds have been added to baked goods like muffins or breads.
..The second unique feature of flaxseed is its lignans. Lignans are fiber-like compounds, but in addition to their fiber-like benefits, they also provide antioxidant protection due to their structure as polyphenols. The unique structure of lignans gives them a further health-supportive role to play, however, in the form of phytoestrogens.
..Along with isoflavones, lignans are one of the few naturally occurring compounds in food that function as weak or moderate estrogens when consumed by humans. Among all foods commonly eaten by humans, researchers rank flaxseeds as the number one source of lignans.
..Sesame seeds come in second, but contain only one-seventh of the total lignans as flaxseeds. To give a few further examples, sunflower seeds contain about 1/350th as many lignans, and cashews nuts contain about 1/475th as many lignans as flaxseeds.
..A third unique feature of flaxseeds is their mucilage (gum) content. "Mucilage" refers to water-soluble, gel-forming fiber that can provide special support to the intestinal tract. For example, gums can help prevent the too rapid emptying of the stomach contents into the small intestine, thereby improving absorption of certain nutrients in the small intestine. Arabinoxylans and galactoxylans are included within the mucilage gums found in flaxseeds.
..This combination of features—omega-3 fatty acids, high-lignan content, and mucilage gums—is a key factor in the unique health benefits of flaxseeds. The specific areas of health benefit described below all draw in some way from this unique combination of nutrients not found in other commonly eaten nuts or seeds.
***Cardiovascular Benefits
..The primary omega-3 fatty acid in flaxseeds—alpha-linolenic acid, or ALA—can be helpful to the cardiovascular system in and of itself. As the building block for other messaging molecules that help prevent excessive inflammation, ALA can help protect the blood vessels from inflammatory damage.
..Numerous studies have shown the ability of dietary flaxseeds to increase our blood levels of ALA, even when those flaxseeds have been ground and incorporated into baked goods like breads or muffins. When flaxseeds are consumed, two other omega-3 fatty acids have also been shown to increase in the bloodstream, namely, eicosapentaenoic acid (EPA) and docosapentaenoic acid (DPA). Increases in EPA and DPA also help provide inflammatory protection.
..Protection of our blood vessels from inflammatory damage is also provided by the lignans in flaxseeds. These lignans can inhibit formation of platelet activating factor (PAF), which increases risk of inflammation when produced in excessive amounts.
..The overall anti-inflammatory benefits of ALA and lignans in flaxseeds has been further corroborated by studies in which flaxseed-enriched baked goods (like muffins) lead to decreases of 10-15% in C-reactive protein (CRP) levels. CRP levels are a commonly used indicator of inflammatory status in the cardiovascular system.
..Risk of oxidative stress in the blood vessels can also be lowered by flaxseed intake. In addition to being a very good source of the mineral antioxidant manganese, polyphenols in flaxseed—including flaxseed lignans—provide measurable antioxidant benefits.
..The antioxidant benefits of one particular flaxseed lignan, secoisolariciresinol, have been especially well-documented. Decreased lipid peroxidation and decreased presence of reactive oxygen species (ROS) in the bloodsteam have both been associated with flaxseed intake in amounts of approximately 2 tablespoons per day.
..Intake of flaxseeds has also been shown to decrease the ratio of LDL-to-HDL cholesterol in several human studies and to increase the level of apolipoprotein A1, which is the major protein found in HDL cholesterol (the "good" cholesterol). This HDL-related benefit may be partly due to the simple fiber content of flaxseeds, since 2 tablespoons of ground flaxseed provide about 4 grams of dietary fiber.
..Although direct studies on flaxseed and blood pressure are limited (and mostly confined to flaxseed oil versus ground flaxseed), numerous studies have shown the ability of increased omega-3 fatty acid intake to help regulate blood pressure and to help reduce blood pressure in persons who have been diagnosed with hypertension.
..With its excellent content of the omega-3 fatty acid alpha-linolenic acid (ALA), flaxseed can definitely help us increase our overall omega-3 intake and, by doing so, decrease our risk of high blood pressure.
..There is one area of concern that we want to note involving flaxseeds and the cardiovascular system. We've seen one very small-scale study from Canada involving 30 children and teens (ages 8-18), all previously diagnosed with hypercholesterolemia (high cholesterol) and given added flaxseed in their diets over a period of 4 weeks.
..The flaxseed amount was 2 tablespoons, and the form was ground flaxseeds incorporated into breads and muffins. In this study, blood levels of total cholesterol and LDL cholesterol did not significantly change, but blood fat levels (in the form of triglycerides) increased and HDL cholesterol (the "good" cholesterol) decreased.
..Since we would consider these changes in blood lipids to be unwanted, we believe this study raises some preliminary questions about the role of daily flaxseeds in amounts of 2 tablespoons or above in the diet of children and teenagers who are already known to have high cholesterol.
..Much more research is needed in this area, but if you are the parent of a child or teen who is already diagnosed with high cholesterol, we recommend that you consult with your healthcare provider about the pros and cons of incorporating flaxseeds into your child's meal plan on a daily basis in any substantial amount.
***Antioxidant and Anti-Inflammatory Benefits
..It is important to realize that the antioxidant and anti-inflammatory benefits of flaxseed do not apply only to the cardiovascular system. Oxidative stress (which is often related to deficient intake of antioxidant nutrients) and excessive inflammation (which can also be related to deficient intake of anti-inflammatory nutrients) are common risk factors for a wide variety of health problems. These problems include development of insulin resistance, type 2 diabetes, asthma, obesity, and metabolic syndrome. There is preliminary evidence that flaxseed intake can decrease risk of all the problems above by increasing our anti-inflammatory and antioxidant protection.
***Cancer Prevention
..The antioxidant and anti-inflammatory benefits of flaxseeds also make them a logical candidate for cancer prevention. That's because chronic inflammation (even low level inflammation) and chronic oxidative stress are risk factors for cancer development. In the case of flaxseeds, evidence of risk reduction is strongest for breast cancer, prostate cancer, and colon cancer.
..Breast cancer and prostate cancer are included in the list of cancers know as "hormone-related" cancers. Their risk reduction may be more closely related to flaxseed than risk reduction for other cancers due to the high lignan content of flaxseed.
..Three of the lignans found in flaxseeds—secoisolariciresinol, matairecinol, and pinoresinol—can be converted by intestinal bacteria into enterolactone (ENL) and enterodiol (END). ENL and END have direct affects on our hormonal balance and in this way may play an especially important role in hormone-related cancer.
..In addition to decreased risk of breast and prostate cancer following flaxseed intake, there is also some preliminary evidence that ENL and END may be able to alter the course of hormone-dependent tumors once they are formed. The relationship between flaxseed intake and cancer prevention is complicated, however, due to the important role of gut bacteria in converting secoisolariciresinol and other lignans in flax into enterolactone and enterodiol.
..This conversion process involves many different enzyme-related steps provided by a complicated mix of gut bacteria including Bacteriodes, Bifidobacterium, Butyribacterium, Eubacterium and others.
..The lignans provided by flaxseed have also been shown to spark increased activity by certain Phase II detoxification enzymes that are responsible for deactivating toxins in the body. This support of the detox process may help prevent accumulation of toxins that might otherwise act as carcinogens and increase cancer risk.
***Digestive Health
..Benefits of flaxseed for the digestive tract—although mentioned earlier throughout this food profile—are worth repeating here. The strong fiber content of flaxseeds—including their mucilaginous fiber—help to delay gastric emptying and can improve intestinal absorption of nutrients. Flaxseed fibers also help to steady the passage of food through our intestines. Finally, the lignans in flaxseed have been shown to reduce risk of colon cancer. This impressive group of digestive tract benefits is likely to receive more attention in future research studies.
***Flaxseeds and Post-Menopausal Symptoms
..We've seen mixed findings in the area of post-menopausal benefits (such as reduction of hot flashes) and flaxseed intake, with some studies showing significant benefits and other studies showing a lack of significant benefits. However, there continues to be strong interest in flaxseeds and their components (including enterolactone and secoisolariciresinol diglucoside) as potential aids during management of perimenopausal and postmenopausal symptoms as well as during hormone replacement therapy (HRT).
..This area of flaxseed research is admittedly complex. For example, enterolactone made from flaxseed lignans has been shown to be an estrogen agonist (promoting estrogen production, through increased formation of transcription factors like ER-alpha and ER-beta), as well as an estrogen antagonist (working against estrogen production, through inhibition of enzymes like estrogen synthetase).
..It's also known to lower the activity of 5-alpha-reductase (an enzyme that converts testosterone into dihydrotestosterone) and 17-beta hydroxysteroid dehydrogenase (an enzyme that converts estrone into estradiol). Given this complicated set of circumstances that may vary from one woman to another, it may turn out that flaxseed intake is simply better at lessening menopausal symptoms in some women, and not as good at lessening symptoms in others.
***Other Health Benefits
..Although we've already mentioned decreased risk of insulin resistance in relationship to flaxseed intake, we're definitely expected to see more research studies in this area. The strong fiber content, antioxidant content, and anti-inflammatory content of flaxseeds make them a natural here.
..One final note about the health benefits of flaxseeds involves their feeding to animals. We've seen repeated studies on the content of beef, chicken, and eggs that reflect significantly increased omega-3 content in these foods when flaxseed meal and/or flaxseed oil are added to the diets of cows and chickens.
..For persons who enjoy these foods in their meal plan on a regular basis, this increased omega-3 content can really add up. Some manufacturers of beef, chicken, and eggs provide omega-3 information on their product packaging. Consumption of certified organic animal foods in which flaxseed was added to the animals' feed can be an effective way of increasing your omega-3 intake.
