Polyunsaturated Fatty Acids and Thyroid Health
Published March 23 2015
There is a lot of controversy over polyunsaturated fatty acids, also known as PUFAs. These fatty acids contain more than one double bond, and include omega-3 fatty acids, omega-6 fatty acids, omega-9 fatty acids, and conjugated fatty acids. They also include omega-7 fatty acids, although I won’t be discussing these here. Although many people reading this know that the average person consumes too many omega-6 fatty acids on a daily basis, some healthcare professionals seem to be opposed to people consuming other types of PUFAs in supplement form, such as omega-3 fatty acids.
Even though many people reading this are probably familiar with the different types of PUFAs, for those who are unfamiliar with them I’ll go ahead and briefly discuss the major categories.
Omega-3 Fatty Acids. These are also known as n-3 fatty acids, and they get their name (omega-3) from having their double bond at the third carbon atom from the end of the carbon chain. There are three types of omega-3 fatty acids, which are alpha linoleic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Different sources of ALA include walnuts, flaxseed oil, hemp oil, and chia seeds. On the other hand, sources of EPA and DHA include fish, krill oil, calamari, eggs, and meat.
Omega-6 Fatty Acids. These are also known as n-6 fatty acids, and they get their name (omega-6) from having their double bond at the sixth carbon atom from the end of the carbon chain. Some examples of omega-6 fatty acids include linoleic acid, gamma-linolenic acid (GLA), and arachidonic acid. Some food sources of omega-6 fatty acids include nuts and seeds, whole grain cereals and breads, meat, and vegetable oils.
Omega-9 Fatty Acids. These are also known as n-9 fatty acids, and you probably have guessed that they get their name from having their double bond at the ninth carbon atom from the end of the carbon chain. Oleic acid is the most well known omega-9 fatty acid. Some food sources of oleic acid include olive oil, avocados, and macadamia nuts. Erucic acid is another type of omega-9 fatty acid, and is commonly found in rapeseed and mustard seed. Without question oleic acid is the healthier omega-9 fatty acid, as erucic acid has been shown to cause health issues in both human and animal studies.
Conjugated Fatty Acids. In conjugated fatty acids, at least one pair of double bonds are separated by one single bond. Some of the beneficial effects of conjugated fatty acids include antitumor, antiobese, antiatherogenic and antidiabetic activities (1). Conjugated linoleic acid (CLA) falls under this category, is primarily consumed by humans in the form of meat and dairy products, and has been shown to have many biological effects, including anticarcinogenesis, antiatherogenesis, immune modulation, and changes in body composition (2).
Are Omega 6 Fatty Acids Bad For Your Health?
All of the fatty acids I listed are important for optimal health. The problem is that most people eat too many omega-6 fatty acids. The optimal ratio of omega-6 to omega-3 fatty acids should be somewhere between 1:1 and 4:1, but most people eat somewhere in the range of 10:1 to 20:1. The main reason for this has to do with vegetable oils, as well as nut and seed oils. Canola oil, safflower oil, sunflower seed oil, and peanut oil are the primary types of oils used in processed foods, fast food, and even in fancy restaurants. As a result, if you eat a lot of processed foods and/or eat out a lot then chances are you are eating a lot more omega-6 fatty acids than you should. Keep in mind that not all omega-6 fatty acids are bad for you. Gamma linolenic acid (GLA) is an omega-6 fatty acid, and numerous studies have shown this fatty acid to have anti-inflammatory effects (3) (4) (5).
On the other hand, most people don’t eat enough foods that are high in omega-3 fatty acids. Another issue is that many people can’t efficiently convert ALA into EPA and DHA. So for example, someone might consume a lot of flax oil and chia seeds, but might be unable to convert the ALA into EPA and especially DHA (6) (7), both of which have many important functions. Some claim that EPA isn’t nearly as important as DHA, and while DHA is definitely important for optimal health, studies also show that EPA is important in helping with inflammation and lipid metabolism (8) (9).
As a result, most people need to minimize their consumption of omega-6 fatty acids, while trying to increase their consumption of foods rich in EPA and DHA. The main source of EPA and DHA is fish, although in my opinion, due to the toxins most people should limit their consumption of fish. This is yet another controversial topic, as some claim that as long as you avoid those fish high in mercury (i.e. shark, swordfish, king mackerel), and stick with the smaller, wild fish (i.e. wild Alaskan salmon) then it is fine to freely eat fish. I don’t agree with this, as I feel most people should limit their fish consumption to two or three times per week. And due to the mercury and other toxins (i.e. PCBs, radiation due to Fukushima, etc.) some feel that fish should be avoided altogether. I spoke about fish and other types of seafood in another article I wrote entitled “Seafood and Thyroid Health“. Micro-algae might be another food-based option for getting omega-3 fatty acids in those people avoiding consumption of fish, as this does seem to convert to DHA (10) (11).
Are Fish Oil Supplements Good Or Bad For Your Health?
Another controversial area is the consumption of fish oil supplements. Some healthcare professionals advise people not to supplement with fish oils. The main reason for this has to do with something called lipid peroxidation. Lipid peroxidation involves the oxidation of lipids (fats). What happens is that reactive oxygen species (free radicals) attack the polyunsaturated fatty acids of the fatty acid membrane (12). Since lipid peroxidation is self-perpetuating, the initial oxidation of only a few lipid molecules can result in significant tissue damage (12). Because PUFAs are susceptible to oxidation, there is a concern that consuming fish oils can cause lipid peroxidation, which will lead to an increase in inflammation and tissue damage.
I agree that the consumption of low quality, or even excessive amounts of good quality fish oils can be problematic. On the other hand, there is plenty of research on the anti-inflammatory benefits of EPA and DHA. I have recommended higher doses (although not excessive amounts) of good quality fish oil supplements to many of my patients for years, and I wouldn’t continue doing so if my patients didn’t receive good results overall. However, keep in mind that just about all of my patients are dealing with some type of chronic health condition, as most of the people I work with have either Graves’ Disease or Hashimoto’s Thyroiditis, which involve high levels of pro-inflammatory cytokines. Although I do think that healthy people can benefit from taking an omega-3 fatty acid supplement due to the fact that most don’t get enough omega-3 fatty acids from their diet, I don’t recommend taking very high doses of omega-3 fatty acids on a wellness basis.
In addition, when taking a fish oil supplement, antioxidants can help to protect the person from the negative effects of lipid peroxidation. In fact, some fish oil supplements include alpha or mixed tocopherols to help with this. Glutathione and CoQ10 can also offer protection against lipid peroxidation. Although taking antioxidants alone won’t always provide protection from lipid peroxidation, it will greatly reduce the risk of oxidative stress.
Are Your Fish Oil Supplements Third Party Tested?
You also want to be careful where you get your fish oils from. One small randomized controlled trial looked at the effect of omega-3 supplements with different oxidation levels, and found that the ingestion of less oxidized omega-3 supplements reduced triglyceride and cholesterol levels, while highly oxidized omega-3 supplements had a negative effect on cholesterol levels (13). The authors concluded that the level of oxidation of the supplements is a key factor in controlling circulating lipid profile, and that manufacturers should pay attention to the quality of the product. There are many companies which sell fish oil supplements, and many of these supplements have high oxidation levels, and as a result, rancidity is something to look out for. But how can you determine if a fish oil supplement is rancid? One method of doing this is to cut a few of the fish oil supplements in half and see if there is a strong fishy odor, which is usually indicative of a high oxidation level and/or rancidity.
Another suggestion is to see if there is a certificate of analysis for any fish oil supplement you’re thinking about taking. The International Fish Oil Standards Program (IFOS) is a third party testing and certification program for fish oils, and it tests fish oils for their potency, purity, heavy metal content, etc. Recently they began testing for radiation as well. But it also tests the stability of the product to see how easily it can turn rancid, which can happen if the fish oil supplement isn’t manufactured properly, or if the company stores or transports the fish oils in areas with excessive heat or humidity.
Is Krill Oil A Better Option Than Fish Oil?
Although there aren’t nearly as many clinical trials on the benefits of krill oil when compared to those studies on fish oil, most of the studies on krill oil show that it is just as good as fish oil supplements, and perhaps even better. It might also be less likely to go rancid due to astaxanthin, which is a powerful antioxidant. One downside is that krill oil supplements usually contain lower amounts of EPA and DHA than most fish oil supplements, and so it might not be as effective in helping to reduce pro-inflammatory cytokines associated with autoimmune thyroid conditions.
There are numerous studies which show that fish oil supplements can inhibit NF-kappaB (14) (15), which is a big factor when it comes to chronic inflammation. I couldn’t find any studies which showed that krill oil inhibits NF-kappaB, although to be fair, I didn’t come across any studies which showed that krill oil didn’t have the ability to inhibit NF-kappaB. Some claim that the omega-3 fatty acids in krill oil are more bioavailable than fish oil, although this is controversial (16). Recently I attended a conference from the Institute of Functional Medicine, and one of the presenters who routinely does fatty acid profiles on his patients mentioned that he hasn’t noticed a change in the fatty acid profiles of his patients who consume krill oil, but he has seen positive changes when consuming fish oil. But of course this is just based on the clinical experience of one healthcare professional, and it’s difficult to make a conclusion until actual studies are conducted.
Can Other Anti-Inflammatory Supplements Be Used Instead Of Fish Oil?
Before I talk about other anti-inflammatory supplements, you might be wondering why supplements are necessary to take at all when dealing with chronic inflammation. After all, isn’t eating an anti-inflammatory diet sufficient? Obviously anyone dealing with chronic inflammation should eat a whole foods diet, avoid the refined foods and sugars, etc. And it’s probably wise to mention that the quality of the whole foods someone eats is also important. For example, grass-fed beef has a higher amount of omega-3 fatty acids than grain-fed beef. And the same concept applies to pasture raised chickens. Although some nuts can be good sources of omega 3 fatty acids (i.e. walnuts), they still have a higher ratio of omega 6 to omega 3 fatty acids. Although this isn’t problematic for someone who has a healthy ratio of omega-6 to omega-3 fatty acids, as mentioned earlier, most people have high omega-6:omega-3 ratios, and therefore should minimize their consumption of nuts and seeds. In past articles I’ve also spoken about people with gut problems limiting their consumption of nuts and seeds due to the lectins and phytic acid, but of course this is unrelated to the topic of polyunsaturated fatty acids.
Although eating an anti-inflammatory diet is important, doing this alone usually isn’t sufficient to inhibit the chronic activation of NF-kappaB in someone who has Graves’ Disease or Hashimoto’s Thyroiditis. Obviously one needs to remove the autoimmune trigger, but even when this is done it is usually necessary to do things to inhibit NF-kappaB. Omega-3 fatty acids aren’t the only nutrients which can accomplish this, as vitamin D, green tea, turmeric, and resveratrol can help to accomplish this as well. One can make a good argument that someone who has “healthy levels of vitamin D (above 50 ng/mL), drinks a few cups of green tea each day, and takes a good quality turmeric supplement might not need to take any fish oils in order to suppress the inflammation. This might be true if someone has a healthy omega 3 index and/or a healthy omega-6 to omega-3 ratio. In order to confirm this one can choose to obtain a fatty acid profile, as this will evaluate the levels of omega-3 and omega-6 fatty acids, and can specifically measure the levels of ALA, EPA, DHA, GLA, arachidonic acid, etc. Although I usually don’t recommend for my patients to obtain such testing, this is an option to consider, and then perhaps those who have a healthy omega-3 index and omega-6 to omega-3 ratio would be better off taking some of the other nutrients I mentioned to combat the inflammation.
In summary, although both omega-3 and omega-6 fatty acids are important for optimal health, most people consume too many omega-6 fatty acids, and are deficient in omega-3 fatty acids. Although fish is an excellent source of omega-3 fatty acids, they are also a major source of toxins. Because of this, millions of people take purified fish oil supplements as their primary form of omega-3 fatty acids. However, since polyunsaturated fatty acids are more likely to undergo oxidation, there is a concern that taking fish oil supplements can lead to an increase in inflammation and tissue damage. Although taking excessive amounts of fish oils and/or low quality oils can cause more harm than good, for those people with autoimmune thyroid conditions, taking fish oils can help greatly to control the inflammatory component.