Flaxseed & Cancer Risk
In the quest for more dietary fiber, flax has gained popularity. You have likely come across flaxseeds in some form or another. Flaxseeds (also known as linseed) are small gold, tan, or brown colored seeds that come from the common flax plant. Compared to other herbs/grains we’ve talked about, flaxseed has gained a lot of notoriety as a health food. Its packaging label will likely highlight health claims such as “high omega-3” and “high fiber.” Some say that Flaxseed increases the risk for prostate cancer. But do these claims hold weight?
Ground flaxseeds are a source of alpha-linolenic acid (ALA), a type of omega-3 fatty acid. The human body needs long-chain omega-3s (EPA and DHA), which are found in salmon and other oily, cold water fish. It can make them from ALA, but the conversion is not very efficient and is inhibited further if the diet is rich in the omega-6 fatty acids, which are found in most oils (mostly safflower, sunflower, grapeseed and corn oil) and processed food.
Omega-3 fatty acids are associated with reduced risks of heart attacks and stroke and also may decrease the risk of macular degeneration (a leading cause of age-related blindness). They are also known to reduce the risks of breast, prostate and colon cancers. If you don’t like fish (and don’t eat the recommended three servings of cold water fish per week), ground flaxseeds can help fill the gap. Ground flaxseeds are the easiest way to incorporate them into your diet. You can then sprinkle a tablespoon or two over salads, cereals, or potatoes or add them to baked goods such as breads and muffins.
In addition to providing some omega-3 fatty acids, flaxseeds are indeed an excellent source of fiber, which helps prevent constipation.
Prostate Cancer
Flaxseeds are rich in lignans, which are commonly referred to as “phytoestrogens.” Other foods, such as soy, care also rich in phytoestrogens. A few health advocates suggest that because phytoestrogens resemble our own estrogens, having them in the diet may affect our risk of hormone-related cancers, including prostate cancer. But like soy, clinical research has shown that the estrogen-like effects of lignans are compounds that actually offer protection against both breast and prostate cancer.
Research has demonstrated that eating flaxseeds can affect prostate tumor growth in men who have the disease, and blood levels of prostate specific antigen (PSA) in men who eat this food. One study published in 2013 followed 147 men who added flaxseeds into the diet. This study found that the men who had the highest levels of flaxseed nutrients had the lowest levels of tumor proliferation in the their prostate cancer. Proliferation refers to how quickly tumor cells are growing and reproducing. Less proliferation is better.
Caution with flaxseed oil
Some studies suggest that the alpha-linolenic acid found in flaxseeds may make prostate tumors more aggressive. In October 2004, Nutrition Journal published an analysis of nutrition and cancer. One meta-analysis included in that publication reviewed nine studies that revealed a possible association between flaxseed oil intake or high blood levels of alpha-linolenic acid and increased risk of prostate cancer. This seems confusing doesn't it: how can the seeds provide benefit, but the fat from these seeds cause harm?
Flaxseed oil does not contain lignans - the nutrients that are thought to potentially reduce prostate tumor aggressiveness. It only contains pure fat, and it’s a type of fat that may cause more harm than good. Also, some health experts suspect that genetic differences in how men metabolize alpha linolenic acid may contribute to whether or not this fat is harmful in terms of prostate tumor growth.
The important take away from all of this research is that if you are interested in adding flaxseeds to your diet, stick with ground flaxseeds, not flax oil.