1 March 2009

Busting Food Myths with Nicole Senior

Myth: Flaxseed oil is just as good as fish oil

Nicole Senior

Fact: A client once told me she poured flaxseed oil over her breakfast cereal. My initial (private) thought was ‘yuck, that can’t taste good’, but I was also intrigued. A web-search on flaxseed oil advertisements yielded claims bordering on the miraculous. I felt relieved she wasn’t swigging it straight from the bottle! There’s a lot to the omega-3 story, but here’s a taste.

There are two types of omega-3 fatty acids: the long chain marine types (EPA, DHA, DPA), and the short chain plant type (ALA). Both the plant and marine type of omega-3 fatty acids are necessary for good health, and especially important for a healthy heart. It is recommended we consume around 2 g of short chain ALA (Alpha-Linolenic Acid) daily to reduce heart disease risk. Flaxseed oil (also called linseed oil) is one of the richest sources of ALA. One gram of flaxseed oil yields around 0.6 g of ALA. Some quick maths shows 3-4 g of flaxseed oil (less than a teaspoon) will give an optimal amount of ALA. Pouring it over cereal is a bit over the top.


If you prefer ALA in a tastier form, try a small handful of walnuts (30 g), it provides 3 g ALA – your entire day’s optimal amount, plus some change. Canola oil, mustard-seed oil, soybean oil, breads and cereals containing linseeds, and high-omega eggs also contain good amounts of ALA, while small amounts are present in a range of other foods such as soy beans, green leafy vegetables, oats and wheatgerm. The practical advantage of canola and soybean oils is you don’t need to keep them in the fridge. Flaxseed oil is very unstable and will go rancid (oxidise) quickly just left in the cupboard. For the same reason, don’t even think of cooking with flaxseed oil.

Both short chain and long chain omega-3 are needed, but when it comes to protection against dying from cardiovascular disease, it is the long chain omega-3s that have shown the most convincing benefit because of their potent anti-inflammatory and anti-arrhythmic effects (among others). Both the American Heart Association and the Heart Foundation (Australia) recommend people who have already had a heart attack, or currently have angina, need 1000 mg (1 g) of long chain omega-3s a day from food and/or supplements for further prevention. The rest of us should consume on average 500 mg (1/2 a gram) daily. You can get this from 2–3 small serves of oily fish per week, such as swordfish, salmon, sardines, herring and tuna (check your local recommendations on fish and mercury content). These long chain omega-3s are not found in flaxseed oil.

In the past it was believed the body could convert short chain ALA to the long chain forms, and the more ALA you consumed the more EPA and DHA your body would make (thus the flaxseed on the breakfast cereal I guess). Studies have since shown this elongation process is limited, inadequate, and varies widely between individuals. Conversion estimates vary from 0.1%–10%, and one third of the population are unable to convert any at all. We need to get the pre-formed long chain omega-3s as well as the short chain ALA. So, the long and the short of it is, I’m off to shallow fry some Atlantic salmon in canola oil, and I’ll be pouring low fat milk on my cereal tomorrow for breakfast. Bon appetit!

For more information about omega-3s, food sources, and high omega-3 recipes, grab a copy of Eat to Beat Cholesterol by Nicole Senior and Veronica Cuskelly from Great Ideas in Nutrition and check out www.eattobeatcholesterol.com.au



Anonymous said...

Thanks for the article re: flaxseed oil. Those of us with high cholesterol AND high PSA readings (pre-prostate-cancer blood marker) have to do a precarious balancing act, since some things that benefit one situation agrivate the other. Both conditions are helped by the intake of Omega-3's, but apparently Omega-6's do just the opposite. And I've read strong warnings that Flaxseed oil can be detrimental to prostate health in men who are thus inclined. Sometimes, trying to keep balance between several medical conditions can be really discouraging.

Hank M.
Mocksville, N.C.

Anonymous said...

Pouring flax see oil on one's cereal is not "over the top"!! The person in question would have poured his/her 1 teaspoon daily allowance of the oil on the cereal THEN used milk in the normal way!!! The writing of this article suggested the person used the oil in place of the milk!! That would be over the top...

Anonymous said...

Regarding the title and description of the book *Eat to Beat Cholesterol*, doesn't fish oil increase LDL?

Or is there a subtle meaning in the word "beat"?

Anonymous said...

I include flax seeds rather than the oil in my muesli - how much would I need in each serve to get the required 3g?
Susan M

GI Group said...

Dear Hank,
It is discouraging to balance seemingly divergent advice, however I have some good news for you. The evidence for any harm from consuming omega-6 fatty acids or flaxseed oil (rich in omega-3 ALA) for men with high PSA levels is flimsy. There are two studies showing associations between men who developed prostate cancer and high intakes of ALA in their diet or in their blood, however this association does not prove one causes the other. It may be a coincidence, the cancer itself may increase ALA in the blood, or it may be the ALA is a marker for another risky behaviour. The American men in the two studies I mentioned consumed the majority of their ALA from animals foods (meat and dairy), not the heart-friendly plant foods I talked about. Studies published since have been inconsistent, with some even showing a protective effect of unsaturated fatty acids. Even the Prostate Cancer Foundation says you can’t eliminate ALA – it is essential (check out more info at http://www.prostatecancerfoundation.org/site/c.itIWK2OSG/b.47431/k.8A27/Nutrition_and_Lifestyle.htm). There is simply not enough evidence to change the healthy eating advice to eat mostly unsaturated fatty acids omega-3 and omega-6 for men at risk of prostate cancer. While dietary variety and moderation is always prudent advice, don’t be too concerned about omega-6 and omega-3 ALA – you have bigger fish to fry: eating more long chain omega-3s from marine sources such as oily fish is good for the heart and the prostate! There are many more dietary recommendations that work both ways too, such as eating more vegetables, fruits, wholegrains, pulses and legumes. You can eat to beat cholesterol as well as care for your prostate.
Nicole Senior

GI Group said...

More answers to your questions from Nicole:

Re LDL cholesterol: "Eating fish as part of a healthy diet low in saturated fat does not increase LDL cholesterol. Taking fish oil capsules may increase LDL slightly however the good HDL cholesterol goes up too, meaning the net effect on cholesterol risk is zero. The other part of the equation is fish oil lowers triglycerides levels – the other artery-hardening blood fat, and this is protective. The strong cardio-protection afforded by the long chain omega-3s is by a separate mechanism to cholesterol – it works by reducing inflammation, clot formation and irregular heartbeats called arrhythmias."

How much flax seed would you need: "To get your entire daily quota of 2g short chain omega-3 (ALA) all from flax seeds, you would need 2 heaped teaspoons (1 teaspoon weighs 3.4g and yields 0.8g ALA), however remember there are other sources such as nuts and canola oil as well. Be sure to crush the seeds fresh each morning before adding to your muesli (or chew them very well), or else the much of the ALA will pass straight through your gut locked inside the hard seed shell."

Anonymous said...

Hi Nicole

Re: LDL cholesterol

You mentioned that: '... Taking fish oil capsules may increase LDL slightly ...'

How so? I'm of the belief that fish oil (in capsules) is good for health.

GI Group said...

Nicole says:

"Please do not worry. Supplementation with fish oil can increase LDL slightly, but as I said it also increases the good HDL and does not pose any increase in risk. The effect is academic rather than significant to health and has to do with VLDL and IDL being converted to LDL by the fish oil, as well as testing calculation shortcomings. It is the ratio of total: HDL ratio that is most indicative of risk (see http://www.americanheart.org/presenter.jhtml?identifier=4503 for more on cholesterol ratios). Fish oil is protective against cardiovascular disease as well as beneficial for many other aspects of health."

Anonymous said...

What can vegetarians and vegans and others who don't eat fish take to get the long chain Omega 3?

Anonymous said...

I'm with Anonymous -- I'm vegetarian, and unless fish hve been re-classified as vegetables...


GI Group said...

For the vegetarians, here's what Nicole suggests:

"I recommend you take a long chain omega-3 supplement (DHA/EPA) derived from marine algae, for example Vega brand Vegan omega-3 DHA. Ask your search engine to find a product near you, or ask your local supplement store. Aim to take around 500mg daily (often 2 capsules, but check the label for the dose)."

Anonymous said...

Hi Nicole , I take 2 tablespoonsful of flaxseed oil everyday , is that too much and is it harmful? Thanks