Ask The Experts: Our Medical Panel Answers Audience Questions###
We received hundreds of questions and comments from listeners about the health benefits of fatty acids. Our experts include Thomas Sherman, Ph.D.,, associate professor in the Georgetown University Department of Physiology and Biophysics., Majid Fotuhi, MD, Ph.D., chair of the Neurology Institute for Brain Health and Fitness, and Paul M. Coates, Ph.D., director of the Office of Dietary Supplements at the National Institutes of Health. Some questions have been edited for space and clarity.
Q: My eye doctor told me that fish oil supplements can help with dry eyes. Is this correct? — From Facebook user Eric V.
A: Dr. Sherman: Although there is an observation from the Nurses’ Health Study that there is an association between fish oil intake and decreased risk of dry eye syndrome, there is no clinical trial evidence to support this yet. What evidence there is mostly anecdotal or from studies in which there is a clear financial conflict of interest by the researcher.
Q: I am confused. Does Algal DHA replace Omega-3 fish oil or does one take both? — From Facebook user Janice D.
A: Dr. Sherman: Algal DHA is simply an alternative source of DHA. Essentially, now both you and the fish would be getting their DHA from algae.
Dr. Fotuhi: Yes. I am in favor of Algal-DHA. There is no need to take both.
Dr. Coates: Fish oil contains DHA as well as the Omega-3 fatty acid EPA. Algal DHA contains only DHA and is a vegetarian source of this Omega-3 fatty acid. Most research, particularly for heart health, has been conducted with formulations containing both DHA and EPA; studies examining infant neurodevelopment sometime use formulations containing DHA only. If you take fish oil only, you’ll get both DHA and EPA, and if you take algal DHA only, you’ll only get DHA. Taking both algal DHA and fish oil would effectively double the dose of DHA (assuming each product contains about the same amount of DHA).
Q: Can you get Algal DHA without the fishy taste? Also, does it harm the Omega-3 fatty acid supplement to freeze it? I am concerned about the oxidation of these fatty acids given the number of double bonds. Also, freezing may help prevent the burping with the associated fishy taste. — From Facebook user Amy A.
A: Dr. Sherman: I have never tried Algal DHA (or krill oil!). It is not uncommon to store DHA gels in the freezer, both to preserve freshness and to help avoid burping for those prone to that unfortunate side effect.
Dr. Coates: Algal DHA is a vegetarian source of DHA. Nevertheless, some people still find that it has a fishy aftertaste. Whether you take fish oil or algal DHA, you can try different brands, particularly those that are manufactured to dissolve lower down in the GI tract. This may help with the fishy aftertaste and burping. As far as storage, many dietary supplements have recommended storage guidelines listed on the product label, such as “Store in a cool, dry place”. Refrigerating or freezing products may be fine for some products but not others. It’s best to follow the manufacturer’s guidelines and contact the manufacturer if you’re not sure.
Q: I became severely allergic to fish and shellfish about 15 years ago. I used to eat fish between three and five times per week. Now I can’t eat it at all or take fish oil supplements. How can I get enough Omega-3 fatty acids? I am very concerned about this missing element in my diet. I eat healthy otherwise, lots of leafy greens, olive oil, etc. — From Facebook user Dale W.
A: Dr. Sherman: You should be able to safely take an Algal-sourced DHA if you wish. I would think that any certified vegan source of DHA would be safe. On the other hand, a good diet rich in walnuts, ground flaxseed or chia seed, and your leafy greens should be good.
Dr. Fotuhi: A person who is allergic to fish may not be allergic to Algal-DHA or other forms of DHA supplements. You can check with an allergy specialist.
Dr. Coates: We would recommend talking with your healthcare provider about other options to get Omega-3 fatty acids into your diet. There are two main types of Omega-3 fatty acids – short chain and long-chain. The Omega-3 fatty acids found in seafood and fish oil (EPA and DHA) are long-chain Omega-3 fatty acids, while those in plant products such as flaxseed and walnuts (alpha-linolenic acid) are short-chain Omega-3 fatty acids. Our bodies can convert short-chain Omega-3 fatty acids into long-chain Omega-3 fatty acids. Although this conversion process isn’t very efficient, it does mean that we don’t actually have to eat the long-chain Omega-3 fatty acids. So your health care provider may suggest incorporating more plant-based foods into your diet that contain alpha-linolenic acid, the short-chain Omega-3 fatty acid. Some foods are also fortified with these fatty acids.
Q: I heard this briefly mentioned on the show, but it is true that flax, chia and hemp need to be ground in order for their nutrients to be absorbed? — From Facebook user Jenna N.
A: Dr. Sherman: Yes. Flaxseed in particular is an effective laxative when consumed whole or ineffectively chewed. Its shell is composed of lignans that gel in the presence of water: try putting a spoonful in a small glass of water. This is probably not the effect you are aiming for, however, so ground flaxseed or flaxseed meal is best. If you don’t want to grind it yourself, purchase a bag of flaxseed meal and portion it into sealable sandwich bags and store them in the freezer. Use each bag for a week or two. A careful sniff will tell you if the meal is beginning to oxidize (turn rancid).
Dr. Coates: Our bodies have to break down both foods and dietary supplements to make the nutrients available for absorption in the GI tract. If you consume whole seeds such as flax, chia and hemp, it’s likely that some of the seeds will pass through your body without being broken down. Chewing or grinding the seeds probably makes the nutrients they contain more accessible by the body, but there’s nothing wrong with consuming the seeds in whole form. They provide dietary fiber, among other things, which has many health benefits.
Q: I’ve heard that recent studies suggest that Omega-3 obtained through food may have a benefit, while Omega-3 obtained via supplements (e.g. fish oil pills) don’t carry the same benefits. I was wondering if your guests could comment on these findings. — From Facebook user Will C.
A: Dr. Sherman: I am unfamiliar with these studies and would be surprised if they were anything more than anecdotal reports. It is not clear to me who would fund such a study other than a supplement manufacturer, and their results would surely not denigrate their own product! On the other hand, fish and other foods rich in Omega-3 and DHA are more than simply oil; they contain iodine, fat soluble vitamins, protein, etc. So there is no reason to assume fish oil supplements and fish are the same either.
Dr. Fotuhi: I believe that the Omega-3 fatty acid molecules have the same benefits, whether they are from food or from supplements.
Dr. Coates: It’s always preferable to get nutrients from food first because foods contain other compounds such as fiber and phytochemicals that also have health benefits. The Dietary Guidelines for Americans states that consuming about 8 ounces per week of a variety of seafood (providing about 250 mg per day of DHA and EPA) is associated with reduced cardiac deaths.
However, a lot of research has also been conducted on fish oil supplements providing both DHA and EPA. The FDA has approved a qualified health claim for both foods and dietary supplements that contain DHA and EPA, stating that “Supportive but not conclusive research shows that consumption of EPA and DHA Omega-3 fatty acids may reduce the risk of coronary heart disease.” Our fact sheet on Omega-3 fatty acids summarizes some of the research on these fatty acids.
Q: If we take a supplement of DHA and also eat organic free-range Omega-3 rich eggs, do we need to be worried about too much DHA? (For a nursing mother as well as young children.) — From Facebook user Amanda V.
A: Dr. Sherman: No. And you are doing a great service to your growing little one. Breast milk derives its DHA and other long-chain polyunsaturated fats from your diet, so the more, the better.
Dr. Fotuhi: The amount of Omega-3 in eggs is very small, and so taking it with a DHA supplement cannot become toxic. Taking DHA 900 mg/day has been shown to improve memory in one double-blind placebo-controlled study. Doses up to 1,500 mg are quite safe.
Dr. Coates: DHA itself does not have an established upper limit, but the Institute of Medicine of the National Academies states that it’s acceptable to consume between 0.6 – 1.2 grams per day of the short-chain Omega-3 fatty acid alpha-linolenic acid. If you are following the manufacturer’s recommended serving for the DHA supplement and eating a reasonable amount of Omega-3 rich eggs, there’s probably nothing to worry about. In most cases, people get into trouble when taking doses of supplements that are higher than the recommended amount listed on the label. This is true for most nutrients, including vitamins and minerals.
Q: What does the panel recommend for pregnant women? — From Twitter user @SilviaRdz
A: Dr. Sherman: this is certainly a conversation to have with your physician, but most recommendations include frequent fish intake. The biggest concern, of course, is the heavy metals and other contaminates of fish, which is why many pregnant and nursing mothers opt for pure fish oil supplements. On the other hand, cultivating a taste for small fishes offers enormous benefits and will serve you well for the rest of your life. Sardines, anchovies, smelt, wild-caught pacific salmon, trout, etc., are safe and tasty choices. Personally, I love canned sardines on toast or sardines or anchovies on a sandwich or in a salad. I cannot get my wife or kids to join me, however.
Dr. Fotuhi: I am in favor taking DHA for pregnant women. DHA is highly important for developing brain.
Dr. Coates: Consuming moderate amounts of seafood, largely due to its Omega-3 fatty acid content, may have a variety of health benefits including improved infant health outcomes. Therefore, the Dietary Guidelines for Americans recommends that pregnant and breastfeeding women eat 8-12 ounces of a variety of seafood per week from choices that are lower in methyl mercury. Women who are pregnant or breastfeeding should not eat four types of fish because they are high in methyl mercury. These are tilefish, shark, swordfish, and king mackerel. All types of tuna, including white (albacore) and light canned tuna are fine, but white tuna should be limited to 6 ounces per week because it is higher in methyl mercury.
Q: With daily Omega-3 fish oil supplements I get tinnitus and have heard similar reports, but no information on why. If the dose is reduced, ringing is too. Why? — From Twitter user @brrrrgrr
A: Dr. Sherman: I have also heard this, but have encountered both sides of this issue, with those who take fish oil to treat tinnitus and those who stop taking it because fish oil seemingly caused tinnitus. I have never heard of anyone saying that eating fish caused tinnitus, however. I should look into this, for it is commonly reported.
Q: What are the effects of DHA and Omega-3 from birth versus taking them up later in life? Do children benefit in ways adults cannot recover later? — From Twitter user @clayheaton
A: Dr. Sherman: There is a very nice paper published in 2005 from the EPIC-elderly prospective cohort study (BMJ 330: 991) that enrolled almost 75,000 men and women, aged 60 or more, across Europe. They were asked to adhere to a modified Mediterranean diet and the extent to which they adhered was scored on a 10-point scale. Those who increased their diet score, meaning that they changed their diets to better adhere to the Mediterranean diet, had a lower overall mortality. It is never too late to start.
Dr. Fotuhi: DHA is an important factor for growth and neuroplasticity in the brain. Children’s brains are in a constant state of rapid development and so it is possible that DHA may be particularly beneficial for kids. However, new research shows neuroplasticity and growth of new synapses continues in adults as well and so it is never too late to start taking DHA.
Q: What is the bioavailability of Omega-3’s from supplements? How much actually makes it into our systems without breaking down? — From Twitter user @trianglman
A: Dr. Sherman: unless you have some sort of fat malabsorptive condition, which is typically associated with many chronic GI ailments such as Crohn’s or Celiac disease, sufficient uptake of Omega-3 fatty acids is not a concern.
Q: My daughter and I are vegan and we get our Omega-3 from supplements from algae, flax seeds and chia seeds. Are these as effective as those sourced from fish oil? Also talk about the mercury problems with fish sources. — From Sara G. via Website
A: Dr. Sherman: Algae oil is very rich in DHA, but all other plants, including flax and chia seeds and walnuts, contain the precursor to DHA called ALA (alpha-linolenic acid). ALA is the dietary “essential Omega-3 fatty acid” for making the longer, more unsaturated, Omega-3 fatty acids, such as DHA (and EPA) that are so important. The problem is that we convert ALA to DHA ineffectively: on the order of 1–4% conversion in men and 8–10% in women (the enzymes that conduct this conversion are estrogen regulated). The other problem is that these enzymes are also responsible for converting the Omega-6 essential fatty acid, LA (linoleic acid) to its longer form (arachidonic acid). If your diet is very rich in LA, as most American diets are given our dependence on corn, this will impede the conversion of ALA to DHA. Eating or taking DHA directly from algal or fish sources obviates this concern.
Dr. Coates: There are two main types of Omega-3 fatty acids – short chain and long-chain. The Omega-3 fatty acids found in seafood and fish oil (EPA and DHA) are long-chain Omega-3 fatty acids, while those in plant foods (alpha-linolenic acid) such as flaxseed and walnuts are short-chain Omega-3 fatty acids. Algal DHA is another source of the long-chain Omega-3 fatty acid DHA. Research indicates that long-chain Omega-3 fatty acids have somewhat greater health benefits (particularly for heart health) than short-chain Omega-3 fatty acids. Our bodies can convert short-chain Omega-3 fatty acids into long-chain Omega-3 fatty acids, but the process isn’t very efficient, so consuming long-chain Omega-3 fatty acids directly is a more effective way of getting them into your body.
Some forms of seafood are higher in methyl mercury than others, but research indicates that the health benefits of consuming a moderate amount of seafood outweigh the possible detrimental effects of the methyl mercury. The Dietary Guidelines for Americans recommends consuming at least 8 ounces per week of a variety of seafood (less for young children). Even women who are pregnant or breastfeeding should consume 8-12 ounces per week of seafood, though they should choose varieties that are lower in methyl mercury and should not eat tilefish, shark, swordfish, and king mackerel because they are high in methyl mercury. All types of tuna, including white (albacore) and light canned tuna are fine for pregnant or breastfeeding women, but white tuna should be limited to 6 ounces per week because it is higher in methyl mercury.
Q: Is there a difference in Omega-3 from wild salmon versus farmed salmon? And if so, does the benefit from the Omega-3 from farmed salmon outweigh the chemicals in the fish? — From Jan via Website
A: Dr. Sherman: No, there is no significant difference in the chemical forms of Omega-3 fatty acids, but there can be in their amounts. Farmed fish is very dependent on the food source, and if they are fed good sources of DHA, they will be an excellent source of DHA for those who eat them. The problem is that many farmed fish are fed the fish meal byproducts of fish oil production. Not only are these sources already somewhat depleted of the essential oils, but often they are sourced from big fish rich in toxins. This “reverse-food chain” or “reverse protein factory” as Francis Moore Lappé (“Diet for a Small Planet”) referred to it, is creating a very unsafe product. So no, the DHA does not outweigh the chemicals. Find clean sources of fish or fish oil.
Q: In fresh or canned salmon, is there more Omega-3 in the skin than in the flesh? Most people don’t eat the skin. Should they? — From lynnlc via Website
A: Dr. Sherman: Omega-3’s are in the fat, whether it is the fat in the flesh or in the skin. If prepared properly – if that is the goal – fish skin can be just as tasty as the crispy chicken skin many are more accustomed to. I am not sure that we “need” to eat the skin, however. Trout is an example of a fish where I typically eat the skin; both because the skin of trout is thinner and more palatable, and because trout is not as fatty as other fish and its skin offers a bit more fat.
Q: What brand of supplements do you recommend for Omega-3, fish oil and DHA? — From bneupane via Website
A: Dr. Fotuhi: DHA from all supplements are equally effective. You need to read the label and make sure to get about 900-1000 mg of DHA/day. If you prefer a vegetarian form, you can take Algal-DHA. You can watch my interview with Dr. Oz for more information.
Q: I have a question about DHA and its use for a child who has had a brain injury at birth. Can DHA improve his brain function? He has cognitive, language and motor delays. Also, what would be a recommended amount? He also has apraxia of speech and some parents are using it for that. Is there a danger of giving a child too much DHA? What would that amount be? — From Sara M. via Email
A: Dr. Fotuhi: There is no scientific evidence that DHA can reverse the effect of brain injury at birth. However, DHA is critical for brain development and has no side effects. In a recent placebo-controlled clinical trial, children given 600 mg Algal-DHA improved their reading skills.
Q: Is whole fish-based DHA superior to algae based-DHA for health benefits (i.e., Does the DHA have more beneficial properties when obtained from eating whole fish as compared to taking algae-based supplements?) — From Susan E. via Email
A: Dr. Sherman: Remember, fish get their DHA from algae. Remember also, however, that fish are more than their DHA, and are a great food, perhaps the perfect food. Given a choice, I would rather eat fish than algae.
Dr. Fotuhi: DHA has the same benefits, whether it is from eating fish or from taking algal-based supplements.
Dr. Coates: Seafood and fish oil contain both DHA and EPA, while most algal-based products contain only DHA. DHA is the same compound whether sourced from fish or algae. Much of the Omega-3 fatty acid research has been conducted with formulations containing both EPA and DHA, so it is very difficult to separate the health effects of each.
Q: I am curious about how diet affects meat and milk. I have heard that if cows eat grass their meat has a better balance of Omega-3 and Omega-6. Is this true? Does it apply to milk also? Also, do walnuts rival salmon for content of beneficial fatty acids? — From JoAnn N. via Email
A: Dr. Sherman: It is definitely true that wild animals and grass fed animals have significantly more Omega-3 fatty acids in their meat and milk than do grain fed animals. That being said, they still do not represent a significant source of Omega-3 fatty acids, but it is much better than grain-fed meat. Personally, I think that feeding corn to cows is one of the worst things we have ever developed.
I love walnuts, but as I mentioned earlier, walnuts and salmon deliver very different kinds of Omega-3 fatty acids. Salmon has pre-formed DHA, whereas walnuts have the precursor to DHA, alpha-linolenic acid (ALA). The effectiveness of ALA is completely dependent on our ability to convert it to DHA, which is dependent on many other factors.
Dr. Coates: Just like humans, the foods that cows and other animals eat affects the levels of nutrients in their bodies and their milk. Chickens who eat feed high in Omega-3 fatty acids for example, lay eggs that are higher in Omega-3 fatty acids.
The Omega-3 fatty acids found in seafood like salmon and fish oil (EPA and DHA) are long-chain Omega-3 fatty acids, while those in plant products such as walnuts are short-chain Omega-3 fatty acids.Our bodies can convert short-chain Omega-3 fatty acids into long-chain Omega-3 fatty acids, but the process isn’t very efficient, so consuming long-chain Omega-3 fatty acids directly is a more effective way of getting them into your body.
Q: Is there a blood study, urine study, etc., that can be done to monitor Omega levels in the cells? I understand that it is very easy to get the ratio of Omega-3 and 6 thrown off with diet, resulting in too much Omega-6. Is it possible to have too much Omega-3? — From Cynthia via Email
A: Dr. Sherman: There are blood analyses that can measure red blood cell composition of Omega-3 fatty acids, that offer some sort of indirect measure of the level of Omega-3 fatty acids in our diet. I understand that these tests cost about $100 to $150. And yes, it is easy to have a lot of Omega-6 in our diets, but the consequences of a lot (too much) of Omega-3 are unclear.
Dr. Fotuhi: There are now commercially available blood tests to measure the amount and ratio of Omega-3 and Omega-6 fatty acids. At the doses of 500 mg to 1,500 mg, Omega-3 fatty acids are safe (except for people who take blood thinner medications such as Coumadin/Warfarin).
Q: The labels on most of the Omega-3 and fish oil supplements I see in the drugstore show the total amount of oils along with the amounts specifically of EPA and DHA. For example, the daily supplement I have been taking contains 1200 mg of fish body oils (marine lipid concentrate), with 400 mg of EPA and 200 mg of DHA. What should I be looking for by way of an adequate daily dose for an adult? — From Charles G. via Email
A: Dr. Fotuhi: My usual recommendation to my patients is 900-1000 mg of DHA per day.
Dr. Coates: Recommended dietary allowances (RDAs) have not been established for EPA or DHA because they are not “essential” nutrients (our bodies can make them from alpha-linolenic acid, the short-chain Omega-3 fatty acid). The RDA for alpha-linolenic acid is 1.1 – 1.6 grams per day for adults depending on age, gender and whether pregnant or breastfeeding. The American Heart association makes the following recommendations, but these are not government-issued recommendations: “The American Heart Association recommends that people without documented coronary heart disease (CHD) eat a variety of fish, preferably oily fish (salmon, tuna, mackerel, herring and trout), at least twice a week. People with documented CHD are advised to consume about one gram of EPA and DHA (eicosapentaenoic and docosahexaenoic acids, EPA and DHA) per day, preferably from oily fish, although EPA+DHA supplements could be considered in consultation with a physician. People who have elevated triglycerides may need two to four grams of EPA and DHA per day provided as capsules under a physician’s care.”
Q: You didn’t answer the caller’s question about Omega-3’s in dairy sources. Please address. — From Jennifer K. via Email
A: Dr. Sherman: Dairy is a poor source of Omega-3 fatty acids, but it is a source. Some types of milk are supplemented with DHA, which makes is a better source. Although the amounts are trivial compared to eating fish, I still recommend it.
Dr. Coates: Some foods, including some dairy products, are fortified with Omega-3 fatty acids.