Monday, April 20, 2009

Omega-6 And Omega-3 Content Of Common Foods

I often say one of the best ways to increase relative omega-3 in the body is to reduce the amount of omega-6 fat consumed. It's the ratio of the two that's important. (Note: It's 2012 and I'm changing my mind on this.)

Here are amounts of omega-6 (N6) and omega-3 (N3) fatty acids in some common foods:

Click to enlarge.

If you're trying to hold your omega-6 intake at bay, lots of nuts and seeds probably won't help. But they're not the primary culprit in American's soaring N6:N3 ratio. Many processed foods and baked goods contain some form of omega-6-rich corn or soy oil.

Why Reduce Omega-6?
  1. Omega-6 (N6) fatty acids are precursors to pro-inflammatory compounds in the body. Inflammation is good, it protects against infection. But high levels of omega-6 (relative to omega-3) have been linked to a range of inflammation-based conditions. Think of illnesses with "-itis" at the end of them, e.g. arthritis, bursitis. A pro-inflammatory environment has also been linked to cardiovascular disease, diabetes, certain cancers, and mental health problems.
  2. Omega-3 (N3) fatty acids are precursors to anti-inflammatory compounds in the body. Here's the thing: N6 and N3 compete for the enzymes that convert them into more biologically active compounds. So, when you have a lot of omega-6 around, it may use proportionately more of those enzymes, leaving you with a pro-inflammatory environment.
Both of these polyunsaturated fats are considered essential for humans. Essential, meaning, we have to eat them, our bodies don't make them.

The Institute of Medicine says that an Adequate Intake (AI) for N6 (linoleic acid) is about 10 to 15 grams a day. The AI for N3 (alpha-linolenic acid) is about 1 to 2 grams a day. AIs are estimates, and as always they vary depending on age, gender, life stage, activity level, so many things. There's thinking that an optimum N6:N3 ratio is closer to something smaller, 4:1 or less. Some of us are eating a ratio of 20:1 and higher.

N6 and N3 often occur together in foods. Many foods that are good sources of N3 are also good sources of N6. Walnuts are a good example. They're a respectable food, but eating lots of them won't go very far in improving N6:N3 ratio.

(Walnuts have more N6 than N3, in a ratio of about 4:1. You can click through to the Excel spreadsheet I made to generate this graph, where I have the N6:N3 ratio listed for each food, along with saturated fat and calories. Look at that almond ratio: 1689:1!)

Another thing I learned doing this - When it comes to omega-3 content, there's hardly a difference between grass-fed beef and conventional beef. And neither of them provide more than a few milligrams in the raw state, probably negligible amounts after being cooked.  (NutritionData's figures are based on USDA's figures which may or may not reflect the state of modern livestock production.)

One more thing - Greens (Romaine, spinach, kale, broccoli, rapini, etc.) have proportionately more N3 than N6 (anything less than 1.0 in the Ratio column in my Excel sheet). Now that's a food where the more you eat, the more improved your ratio.
Chart: Bix


Angela and Melinda said...

That's extremely interesting. Certainly contradicts the common wisdom re nuts, and also re grass-fed meat. Are there any anti-nutrients in the greens (yay, broccoli raab!) that would prevent your body from utilizing the N3s in them?
Also nice to know that kidney beans rank well vis-a-vis N3s!

Jennywenny said...

Very cool, thanks! I didnt realise about the grass fed meat, and it was confusing me a little about the walnuts too, I was always under the impression they were a good source of omega 3 oil, so I guess they are, but they still have lots of omega 6 oil so they are not good for the ratio.

Bix said...

The grass-fed meat surprised me too, as did the walnuts. And peanuts!... 1540 mg of omega 6 for every ONE mg of omega 3.

Bix said...

By the way, I'm loving this Google Documents application. It's how I linked my Excel data. Anyone can edit this data and make their own charts, right there online.

caulfieldkid said...

The canned Tuna surprised me a little, and the grass fed beef (just like everyone else).

Google docs = very nice.

I guess I'll just keep on eating my beans. :)


Bix said...

To shaun, the bean man ... Tuna! What are we going to do about the tuna? and other fish? Fish is a really, really good source of omega-3, and an excellent source of mercury.

Mark my words, in twenty years from now, by 2030, we'll all be eating farmed fish.

Carrie Oliver said...

WOW! We eat walnuts and other nuts all the time. Plus, chicken? This is a really helpful chart, did I miss where you sourced the data?

Carrie Oliver said...

WOW. We eat walnuts and other nuts all the time. Plus, chicken? I had no idea. Did I miss how you sourced this data? Really illuminating.

caulfieldkid said...

I really, really hate the idea of eating farmed fish. The health benefits are not there. The environmental benefits are not there. The taste is not there. It's a terrible scam.

If that becomes my only choice (which you are probably right in your prediction) then I will no longer eat fish.


Bix said...

Carrie, All the data I looked up at

Lots more there.

RB said...

I find the omega 3 / 6 chart interesting. However, should we simply concentrate on omega 3 / 6 in each individual food or in the entire diet? In the previous post about long lived cultures, it looked at the total diet. I wonder what the omega 3 / 6 ratio is in the diets of these cultures? In Michael Pollan's book "In Defense of Food", he discusses the wisdom in traditional diets. These diets were evolved over dozens generations without the aid of nutritional information. We need to look at total diets and not just individual foods and individual nutritional elements. The question should be do we have the right mix of foods in out diet?

Unknown said...

This is a really nice chart. It's very useful for planning shopping!

@CaulfieldKid - I agree with you on farmed fish. I think there's even more mercury in farmed fish than wild fish. It's due to the "kibble" that they are fed, I believe.

Also, I learned from talking to a boutique tuna canner (disclosure: no monetary or other connection) that YOUNG tuna has much less mercury than the open ocean-caught tuna. It's also more sustainable. He told me you can tell which one is young by looking at the fat content: young tuna is much higher fat, i.e., ~7% or so compared to the older, ocean-caught tuna.

RB: I think you make a great point. You do yourself no favor by eating almonds every day if you also gorge yourself on processed & baked goods the rest of the day. How would you ever catch up? That said, it is probably easier to maintain a balanced n3/n6 diet if you don't eat anything that is too out of balance. Kind of like avoiding foods that are made up of more than 1/3 saturated fat.

Anyway, thanks again for the great post!

Rob said...

Could this be right?

Whopper has a N6:N3 ratio of 0.26

Seems contrary to the conventional and unconventional wisdom.

Bix said...

You're right, seemed odd. I had a look.

Their total of 9.9 grams of total polyunsaturated fatty acids was too high to be made up of just 800mg of omega-3 and 212mg of omega-6. After I expanded the details (a tab at the bottom), I saw 8024 mg of omega-6 (18:2 n-6), not 212. So, their addition looks questionable.

I'd say this Whopper is closer to (from their data) 8024 N6 / 800 N3, or an N6:N3 ratio of about 10:1.

Marty McWhirter RN said...

You need to research your info on grassfed beef a little further. "Diet can significantly alter the fatty acid composition in fed cattle. Cattle fed primarily grass enhanced the omega-3 content of beef by 60% and also produces a more favorable omega-6 to omega-3 ratio. Conventional beef contains a 4:1 6:3 ratio while grass-only diets produce a 2:1 6:3 ratio (French et al., 2000; Duckett et al., 1993; Marmer et al, 1984; Wood and Enser, 1997)."

Bix said...

Hi Marty,

I think you need to look a little closer at the chart, which shows that feeding cattle grass enhanced the flesh's omega-3 content by ~50%, and also produced a more favorable N6:N3 ratio. (Data source: USDA) This is not dissimilar from the numbers you cite.

Many factors contribute to these numbers, which make them vary, including the breed of cow, age and health of the cow when tested, the season when tested (spring different from fall), the time spent in field vs. on feed (many grass-fed cows are grain finished), the metabolism of the cow (absorption, digestion, incorporation of N3 into tissues), the N3 content of the grass (which varies) and of the non-grass feed combination (which varies). The USDA uses a protocol, a way to standardize ... test from certain muscles/organs, an average of so many tests, etc.

It's difficult, given this variability, to state a number, especially a number to a decimal place. These data are useful for comparing food sources, as relative indicators.

Anonymous said...

It should be noted that despite the high ratio of omega-3 to omega-6 in flax seed and oil, numerous studies have confirmed that it actually feeds prostate cancer tumors. Consequently, it's a good source for women, a questionable source for men, something to avoid by men with an elevated PSA, and a definite no-no for men with prostate cancer.

(The Google Account identity log-in appears to be broken.)

Bix said...

Re: Access to the Excel spreadsheet:

I received an email about this access not working, in addition to the comment above. I went into Google Docs and re-shared it. Hope that works.

If anyone wants access and can't get it, just send me ( your email address and I'll add it to the view list.

Jayne said...

I've looked through foods at the Nutrition Data website, and am now confused. They list a raw egg as having NO omega 3 and NO omega 6 in it. But boil it, and all of a sudden, it has 106 grams of omega 3 and 1616 grams of omega 6. How can this be? Am I missing something here? Anyone's words of wisdom much appreciated here!

Bix said...

Hi Jayne,

I looked it up...

Egg, whole, raw, fresh, 1 large
omega-3: 37.0 mg
omega-6: 574 mg

Egg, whole, cooked, hard-boiled, 1 large
omega-3: 39.0 mg
omega-6: 594 mg

That looks in the ballpark to me. I think the 106 mg and 1616 mg are for the default, 1 cup chopped. Not sure why raw said 0.

Jayne said...

Hi Bix, Thank you for your reply. Turns out, I thought that "Egg, white, raw" meant the color of the shell, not sans yolk! Silly me!
I guess it helps to read the chart correctly!
This is my first time at it, so forgive the Newbie!
"Food for thought" here -- I've found that the Inflammation Factor shown on the chart is much simpler to use, and "factors" in more than just the O3s and O6s. Saves a whole lot of numbers work!
BTW, I see you're from Philly! My old home town. :) And you've got some awesome credentials! Thank you for sharing your expertise in this area. Much needed, since the Docs are not so helpful as we try to improve quality of life for the 2nd half.

Jayne said...

Hi Bix, I'm back again. Would you give your 2-cents' worth on the dilemma I have found:
1 cup of fresh raw nectarine has a 2.9/159 Omega 3/Omega6 ratio. Similarly, 1 c of fresh raw peaches has a 3.1/129 O3/O6 ratio. Seemingly bad ratio. Inflammation factor on these 2 fruits is -26 & -22 respectively. Are we to avoid these fruits?
A different situation: 1 cup raw banana has a good 60.8/103 O3/O6 ratio, but an IF of -115. Why is the IF so high?
I enjoy a banana daily, and peaches and nectarines when they are in season. I'm told to eat my fruits and veggies. How do I balance that common wisdom with these numbers?
I know, I know, a little knowledge is a dangerous thing! Can you shed any light on the seeming bad numbers for these common fruits?
Appreciatively, Jayne

Bix said...

Hi Jayne,

My opinion? Eat the peach ... and the banana and nectarine. The benefits outweigh the costs. There are other factors to consider besides polyunsaturated fats. There is lots of good fiber and phytochemicals/antioxidants in produce.

I wouldn't eat several at a sitting though. As produce goes, fruits tend to be higher in sugars and calories. Although nothing like a soda.

I don't know how NutritionData arrives at their IF. Consumption of sugars (glucose, fructose, sucrose) generally increases free radicals (ROS: reactive oxygen species) and initiates an inflammatory response. But foods such as fruits that are accompanied by antioxidants can stem this rise in ROS.

Anonymous said...

Why has no one mentioned chia? It has an omega 3 ratio of 3.4:1. It is also high in protein and fiber. I ingest a few tablespoons daily. I am not aware of any negatives relating to chia, unlike flaxseed.

Hank Roberts said...

> I don't know how NutritionData
> arrives at their IF

Apparently it's a secret.

I found no published research supporting the rating. Odd.

Helen said...

What about butter? Milk? Cheese? I would love the know the ratio.

Bix said...

Hi Helen,

You can find the amounts of omega-6 and omega-3 in foods at or other data base.

Here's butter:

2 tablespoons: n6:n3: 764mg:88.2mg is a ratio of 8.7 to 1

That's similar on this chart to white meat chicken. A ballpark figure though, since it depends on what the cow ate, among other things.

(These figures do not reflect amounts of saturated fat, only 2 types of polyunsaturated fat: n6 and n3.)

Anonymous said...

Google Chia seed.

Anonymous said...

I too was on the hunt recently for sources of Omega-3 that aren't fish-derived because my husband is allergic to fish and chia, and found the same things you did, plus avocados and macadamia oil are also higher in O-6 than O-3.

I found a way around for hubby: vegetarians get their DHA from algae oil, and now he does too--about 500 mg./2X daily.

If farm-raising fish ever takes over wild-caught, I'm going to chia and hubby's continuing his algae oil. Flax is useless for obvious reasons.

martinla said...

I don't understand the IF ranks at all. There appear to be healthy food at the top of both the Lowest and Highest IF charts. Peppers and ginger and turmeric, for example near the top of the Highest IF rankings.

Thanks for a very helpful post - and a great blog!

Anonymous said...

Great article - i have a question maybe someone could help. 1000mg of Omega three supplement contains ~400mg EPA, ~100mg DHA and the reainder when i asked was 'other fish oil'
Do you thin the remainder of the oil would be n3 or n6. i presume its a combination of n6 & 9 whci would make the supp almost 1:1. is there any point in taking this?

Bix said...

I think the remainder would be some combination of other polyunsaturated fat (including omega-6), monounsaturated fat, saturated fat, and cholesterol.

Out of curiosity I looked up some fish oils on NutritionData:

4g Sardine oil has 1gm omega-3, 0.1gm omega-6, (and some other poly) 1.5gm monounsaturated, 1.3 saturated, 32 mg cholesterol.

4g Salmon oil has 1.6gm omega-3, 0.07gm omega-6, (and some other poly) 1.3gm monounsaturated, 0.9 saturated, 22 mg cholesterol.

So it probably isn't an omega-6-to-omega-3 ratio of 1:1. It has more omega-3.

If you consume no other source of EPA and DHA, which are found mostly in animal food, and of that mostly in seafood, then this fish oil pill may be supplying you something you wouldn't get from food otherwise, regardless of the ratio of omega-6-to-omega-3.

Our body does make its own EPA and DHA from the omega-3 in plants like flax, but it's not a lot and there is a raging debate as to how much we need.