Consumers, retailers, practitioners, and media people are hearing that flax oil can increase prostate cancer. So many have asked me for clarification on this issue that I have assembled here the information that I consider helpful. I have looked up the research studies, and have added to what I've found, my own experience of working with flax and other oils for the past 20 years.

The following report summarizes what I have discovered so far. As new information brings further clarity, I will update this article.

I'll strive to give you a balanced view. I want neither to over-emphasize the safety nor the potential toxicity of flax oil, and I hope that the information that follows provides you with much needed insight into this topic.

Promoters of flax oil have touted its benefits, but have not adequately addressed the down side of exclusive use of flax oil. Flax oil has benefits and shortcomings. Ignored, its shortcomings can lead to serious health problems.

A recent review article points out that prostate cancer is increasing, and is the second leading cause of cancer deaths in the Western world. The "etiology of prostate cancer remains unclear, course and progression are unpredictable, and definite treatment is not yet established". Lifestyle and diet could contribute to the progression from small, latent, non-metastatic tumors to clinically significant, invasive, metastatic lesions.1

Research on the involvement of fats and fatty acids in prostate cancer has led to inconsistent conclusions. Most of the available information comes from epidemiological (or population) studies. Direct data from animal and human studies are limited.1

Further confusion results from the fact that results from rat studies cannot be automatically generalized to humans, because rats and humans metabolize fats differently. Also, rats don't fry steaks, don't use salad dressings and mayonnaise made with oils that have been highly processed, and don't eat butter that has been exposed to light and air, sometimes for weeks. The reason I make this point will become clear a little later.

Studies done on cell cultures do not take into account the effects of fats on glands and organs, which can affect tumor development and tumor growth. In particular, some fatty acids up- or down-regulate the functions of genes, and it appears that some fatty acids also change the effectiveness of hormones even if they don't change hormone levels present in tissues.

Within this context, the suggestion has been made in published literature that flax oil should not be used because it can increase prostate cancer. The Prostate Forum2 lists six studies showing positive correlation between ALA (in serum, adipose tissue, and red blood cell membranes) and prostate cancer. Of the six studies, one showed no correlation3. One found a small (not statistically significant) positive correlation.4 Four studies found a strong positive correlation between ALA and prostate cancer5,6,7,8. At least two other studies have also shown a correlation of alpha-linolenic acid with increased prostate cancer.9,10

According to Prostate Forum, several labs have found that ALA is one of the most powerful growth stimulants for human prostate cancer cells in tissue culture.2 The Prostate Forum has recommended against the use of flax oil by men with prostate cancer because flax oil is the richest available food source of ALA. The reasoning is that this oil should cause the most prostate cancer because it contains the most ALA.

The 'ALA' in human population (epidemiologic) studies comes from two main sources: vegetable oil, and red meat animal products.  Both were shown to correlate with similar increases in prostate cancer. In cell studies, chemically 'pure' fatty acids are usually used. In the cited studies, the source of ALA-the omega-3 EFA that is 5 times more easily destroyed by light, oxygen, and heat than LA (the omega-6 EFA)-was foods that have been processed destructively and treated with great carelessness. Let me illustrate this point.

In one of the epidemiologic studies, five sources of ALA - butter, red meat, bacon, salad dressing, and mayonnaise-were listed.

The animal sources included butter, red meat and bacon. Butter is extensively exposed to light and air between the time the cow is milked and the time the butter is consumed. Butter also contains some trans- fatty acids which, research suggests, may also correlate with increased cancers.

All three animal sources of ALA usually contain traces of sex hormones, pesticides, and antibiotics. Sex hormones are known to increase the growth of certain cancers, especially those of prostate and breast. Many pesticides have cancer-causing properties. Antibiotics lower immune function. No one knows whether the synergy of these three can augment the detrimental effects of each of them individually, but chances are good that this is the case.

The vegetable sources included salad dressing and mayonnaise. These are made from soybean and/or canola oils that have been destructively processed by degumming, refining, bleaching, and deodorizing (so-called 'RBD oils'). While these oils are generally free of hormones and antibiotics, they can contain carcinogenic pesticides. Insecticides, herbicides (weed killers) and fungicides are used in agriculture. Of these, the fungicides have the most potential for increasing cancer.

Interestingly, a study done with flax grain has shown that flax inhibits the growth of prostate cancer.6 The study was short-term, and therefore does not predict what would happen if flax grain was used as the sole source of fat for a long time, measured in years.

Another study showed that prostatic alpha-linolenic acid was lower in cancerous prostate glands that exhibited perineural invasion, seminal vesicle involvement, and stage T3 tumors.7

In a review article on omega-3 fatty acids and cancer, the author makes the observation that the effect of omega-3 polyunsaturated fatty acids (PUFAs) on cancer depends on "background levels of omega-6 PUFAs and antioxidants, and this could account for previously inconsistent results in experimental carcinogenesis." He also makes the observation that "omega-3 PUFAs appear to be excellent substrates for lipid peroxidation in situations where an oxidative stress is involved, such as in the action of several cytotoxic agents in the treatment of cancer."8

Yet other researchers suggests that among fatty acids, the omega-6 derivative arachidonic acid (AA), delivered in larger than normal quantities to prostate cancer cells in tissue culture by LDL cholesterol via over-expression of its receptor (LDLr), increases the activity of the cancer-related genes c-fos and cox-2.10

In 1994, one review suggested that for prostate cancer, fat consumption should be decreased to 15% of calories. The antioxidant mineral selenium and vitamin E should be supplemented, and a soy product should be used.11

Another study shows that the same omega-6 derivative AA, stimulates growth and division of prostate cancer cells (both hormone-sensitive and hormone-insensitive) by increasing lipoxygenase enzyme activity (increasing inflammation). The researchers show that if you block this enzyme, the prostate cancer cells self-destruct (apoptose) very rapidly.12 This could be achieved by inhibitor molecules, by decrease of AA in the medium (or diet), and by increase of omega-3 fatty acids that inhibit the production of AA. By the way, AA is found in meat, eggs, and dairy products.

One further study showed a positive association between prostate cancer and animal fat, as well as the omega-3 EFA (ALA). It also showed an inverse association between the antioxidant vitamin C and prostate cancer.13

A 1999 publication concludes that the combination of fatty acids makes a difference. In this study, GLA, ALA, and EPA increase the death of prostate cancer cells. A slight increase of cancer cell death was obtained when ALA was combined with AA, OA, or GLA. But ALA with LA or EPA had no effect or even decreased prostate cancer cell deaths.16

A study with another prostate cancer cell line reports that GLA and EPA, which inhibit an important enzyme in carcinogenesis (urokinase-type plasminogen activator [uPA]), suppress cell proliferation (growth and division). Low EPA and high uPA levels have been reported in cancer. ALA, LA, and AA also suppressed cell proliferation in this study.17

Another study found that rats grow faster when vitamin E is given along with linseed oil (which is refined, bleached, deodorized flax oil), grow slower if linseed oil was given without vitamin E, and grow even slower in the presence of pro-oxidant.18

A study in women found that only ALA, but not saturates, monounsaturates, or long chain polyunsaturates omega-3 or omega-6, had a protective effect on breast cancer.19

A 1999 study found that mutation of the androgen receptor (AR) gene as a cause of prostate cancer is rare, and that over-expression of the AR gene seems to be the most common alteration in hormone-refractory prostate cancer.20 A question left unanswered is what causes this over-expression.

Finally, a study found that DHA and EPA decreased expression of several genes that are up regulated by androgen in LNCaP prostate cancer cells. They thereby reduced androgen-mediated cell growth of this prostate cancer cell line. DHA increased the proto-oncoprotein c-jun.23

What can one conclude from all of these studies? Science has become so technical that we get lost in a sea of details that defies common sense; then we get confused. This confusion makes it easier for 'high-tech' industries to benefit, whose drug products suppress symptoms without effecting cures.

One major problem with these studies is the isolation in which they are carried out. In Nature, EFAs are found along with many other substances. In the lab, substances are isolated into chemically pure forms, which are easier to manage, but may be far out of line with what happens in a body fed by whole foods containing hundreds or even thousands of interacting (synergistic) ingredients.

I will attempt to address the contradictory findings of the studies by applying some common sense, and add some overlooked details that may help us practically.

EFAs are chemically very active molecules. The body cannot make them. They are required for vital functions in all cells and tissues. We cannot live without them. They must be provided by foods.

The big question that begs to be answered is why substances that are absolutely required for health can at the same time give you cancer and kill you. It doesn't make sense. Omega-3s, in particular, have a long history of anti-cancer benefits. If they have anti-cancer properties, why are they causing cancer? Essential nutrients, which the body must have for life and for health, cannot easily be both pro-cancer and anti-cancer at the same time.

So the question that must be answered is what other issues are being overlooked when medical professionals (untrained in nutrition-in this case, ALA and flax oil), issue edicts against the use of essential nutrients.

Authors of published studies have been clear that the correlation of ALA with increased prostate cancer is not proof that ALA causes prostate cancer, and point out that that the mechanisms involved in this finding remain unknown. These researchers have suggested that several possibilities need to be explored. These include:

1. Oxidation products of ALA formed during cooking of meat;
2. Damage done to ALA molecules during processing;
3. Lack of balancing molecules such as phytosterols and antioxidants, which are found in seeds, but are removed or damaged during processing and cooking practices;
4. Free radical formation from fatty acid oxidation;
5. ALA-based free radicals (products of processing) that can damage genetic material (DNA) and lead to tumor formation;
6. Decrease in the level of antioxidants, because they are used up to deal with ALA-based free radicals produced in the body;
7. Too low a ratio of LA: ALA (or too high a ratio of ALA: LA);
8. Alterations in eicosanoid synthesis;
9. Changes in cell membrane composition, affecting permeability and receptor activity;
10. Interference with 5-alpha-reductase activity; and
11. EFAs may increase steroid hormone production that is important in androgen sensitive growth. (Actually, EFAs appear to decrease steroid hormone levels. Apparently they make hormones-insulin, thyroid, androgens, and others-work better, and therefore smaller amounts of them are needed to get hormones' normal job done).

I learned about the highly sensitive omega-3 ALA in 1981. I have emphasized since that time that ALA should never be subjected to the destructive influences of light, oxygen, and high temperatures. One or more of these destructive influences is involved during:

1. Commercial and home frying, deep frying, and sautéing
2. Processing (deodorization) involved in the production of the cooking (RBD) oils that line the shelves of grocery, convenience, and health food stores
3. Hydrogenation, a process used to make margarine and shortening
4. Partial hydrogenation of oils used in making shelf-stable convenience foods.
   
   Damage done to ALA molecules by light, air, and heat can produce highly toxic unnatural molecules.24 ALA forms more toxic breakdown products due to processing damage than does the omega-6 EFA.24 Destructive processing is likely the cause of some of the changes that lead to increased prostate cancer. A more comprehensive story of how EFAs are damaged is found in the book Fats That Heal Fats That Kill.

Born in 1942, I'm in the age group of men that should pay attention to the condition of their prostate gland. I cannot give you medical advice or make decisions for you, but I can tell you what I do.

• I do not use, and recommend against the use of flax oil by itself, but do recommend this omega-3-rich oil in combination with omega-6 richer oils to get the omega-3/omega-6 ratio right. Flax is a great source of essential omega-3 but is deficient in the equally essential omega-6.
• The prostate gland appears to be quite sensitive to environmental toxins. Among these may be plasticisers and contaminants present in plastics. Because of environmental concerns and our very limited knowledge of the effects of these molecules on health, I recommend against using plastics for packaging, especially liquids (water, oil, milk, juices, vinegar, alcohol, tinctures, etc.). Liquids move, continually washing the inside of their container. Any molecules present in plastic containers (fillers, plasticisers, stabilizers, mould releasers, slip agents, sheen agents, contaminating metals such as lead (Pb) or aluminum (Al)), which might dissolve in the liquid contained, may drift from the plastic into the food. Drift of molecules from plastic into liquid is the reason why water in plastic bottles can acquire a 'plastic' taste.
• One is less likely to taste plastic in oils than in water. However, due to the chemical similarity of oil molecules and plastic molecules, oils swell plastics, opening pores in this non-natural synthetic material that make the drift of such molecules into oils even more likely than the drift of molecules from plastic into water.
• I do use and recommend an oil blend containing flax with sunflower and sesame oils from organically grown seeds, made with health in mind, and in the right omega-3: omega-6 ratio to prevent omega-6 deficiency. In fact, I created the formula for such a blend, and I use it daily with my food.
• I do insist that my oil blend is packed in brown glass, further protected by a box to keep out all light, and further protected by refrigeration in factory, store, and home to extend freshness.
• I also use and recommend zinc, selenium, antioxidants, phytosterols, saw palmetto, broccoli and other cruciferous vegetables, anti-inflammatory herbs, and maitake extracts or mushrooms as part of a prostate nourishing nutritional program.
• I use and recommend optimum intake of all components of health: 20 minerals; 14 vitamins; 8-11 essential amino acids; 2 essential fatty acids; detoxifying fiber; digestive enzymes; friendly bowel microorganisms; antioxidants; herbs (phytonutrients); filtered water; clean air; sunlight; and fuel.
• I engage in and recommend physical activity (work or exercise) to stay fit. I indulge myself in and recommend rest; sufficient sleep; recreation; the passionate pursuit of worthwhile goals; time spent with friends; a sense of humor; good balance between work and play; heart-felt gratitude; and faith in the grand scheme of things.
• I use ALA on a daily basis, combined with LA in my oil blend, as part of my program for health, along with lots of fresh organic green foods, proteins, support for digestion, and carbohydrate intake limited to the amount I burn. I take supplements of minerals, vitamins, antioxidants, and herbs.
• I do not worry about ALA from oils made with health in mind causing me prostate cancer. After all, common sense insists and research confirms that ALA (undamaged and accompanied by sufficient undamaged LA and natural antioxidants), is essential for life and for health.

Updated: November 9, 2002

(Essential) omega-3 = omega-3 fatty acids include:

1. ALA (alpha-linolenic acid; abundant in flax, and present in small quantities in hemp, walnut, soybean, and canola); given enough ALA to start with, the body converts ALA into SDA, EPA, and DHA in various tissues, according to need; conversion varies, depending on several factors, and ranges from less than 5% to 36% per day of the amount of ALA consumed;
2. SDA (stearidonic acid; present in a few exotic seeds);
3. EPA (eicosapentaenoic acid; parent of Series 1 eicosanoid hormones; found in fish oils);
4. DPA (docosapentaenoic acid);
5. DHA (docosahexaenoic acid; the major brain omega-3; also found in eyeball (retina), red-brown algae, and fish oils).

ALA = Alpha-Linolenic Acid is the omega 3 (omega-3) EFA. It is sometimes shortened to LNA.
ALA is very fragile to destruction by light, oxygen (air), and heat, and must therefore be protected from these influences. If this is not done, ALA molecules change from natural and beneficial to unnatural and toxic. ALA is destroyed about 5 times faster than LA, the omega-6 EFA.

ALA is deficient in the diets of most people in affluent societies. Due to processing damage, shelf life considerations, and changes in food choices, average intake of omega-3 has decreased to less than 20% of what was present in common diets 150 years ago. Even back then, omega-3 intake was less than optimal because only a few foods are rich in omega-3.

About 90-95% of the population gets less omega-3 than required for good health (making omega-3 the essential nutrient most often lacking in people's foods) and omega-3 is therefore the most therapeutic of all of the essential nutrients (20 minerals, 14 vitamins, 8-11 amino acids, 2 fatty acids).

LA = Linoleic Acid = the omega-6 (omega-6) EFA.

LA is abundant in the diets of most people in affluent societies, its intake having doubled during the past 100 years due to increased use of corn and safflower oils.

Diets too high in LA (and too low in omega-3) are associated with increased cancer. Damaged omega-6 molecules due to processing, removal of antioxidants and phytosterols, and concomitant lack of omega-3 are likely responsible for this problem.

LA is essential to life and to health, and must be present in the diet.

LA is sensitive to destruction by light, oxygen (air), and heat (but 5 times less sensitive than omega-3), and should be protected from these destructive influences. If this is not done, LA molecules can change from natural and beneficial, to unnatural and toxic.

People on low fat or no fat diets are likely to get insufficient omega-3 and omega-6.

Omega-3: omega-6 Ratio: Both omega-3 and omega-6 are essential to health and must come from the diet because the body cannot make them. However, too much omega-3 can crowd out the omega-6 (as can happen with flax and flax oil used exclusively as the source of EFAs in the diet), and lead to omega-6 deficiency. Too much omega-6 can crowd out omega-3 (as is the case in 'normal' Western diets), and lead to omega-3 deficiency.

The ratio of omega-3 to omega-6 is important and must be carefully considered. I have seen the best results for health using an omega-3: omega-6 ratio of 2: 1. (Non-essential) N-9 = omega-9 = OA (oleic acid)

The body can itself make this monounsaturated fatty acid, and OA is therefore not essential. Essential means that the body cannot make it, cannot live without it, and must therefore obtain it from an outside source, i.e. food or supplement.

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