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Query about efficiency of fish oil and its benefits.

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I'm wondering your opinion on fish oil dosage for cardiovascular and brain health, as well as help for joints, dry eye, blood pressure, anxiety, etc. This is largely preventative - I'm overweight (but exercising), trying to eat healthy, getting my blood pressure down (I'm pre-hypertensive currently, though sometimes reading normal...sometimes a tad high), and generally trying to live a healthy lifestyle.

I'm currently taking ~2g/day of fish oil (that's 1.8g active DHA/EPA from fish oil; it'd be more like 3g of actual total oil in 4 capsules). This equates to 613mg DHA, 1187mg EPA, 800 mg phytosterols, and an additional 300 mg Krill oil. Quite honestly, I'm not sure if the Krill oil has "separate" DHA/EPA levels or is included in the levels I just mentioned, but I think it's probably separate. From other labeling (standalone Krill products in the same product line), they don't tend to list DHA/EPA individually, so that would push me closer to 2g a total DHA+EPA a day if true and give me some extra protection in the form of astaxanthin (the antioxidant) right in the Krill oil (plus I take 200mg CoQ10 and 100% RDA Vitamin E as part of my vitamin regimen). Since starting this, my cholesterol numbers have improved a great deal over the last year+.

I'm wondering if this is a good dosage to maintain. I've seen one argument that up to 1g is beneficial, but more than that is a waste (or could potentially be harmful via oxidative damage or prostate cancer risk). While I've seen others recommend up to 4g per day to get the maximum benefit for cardiovascular protection, blood thinning, join health, anxiety management, etc.)

I'm especially concerned about possible oxidative damage from too high a dose of fish oil. Some studies (for example see and ) seem to indicate that high doses (in the latter case, 6g, which is higher than I'm considering) can lead to oxidative stress damage from long-term usage. On the other hand, I've seen arguments that the anti-inflammatory effects and other benefits outweigh this risk, and if you take antioxidants like CoQ10 (200 mg for me) and astaxanthin (50 mcg in my vitamin + whatever amount is in the Krill oil), that helps ameliorate any oxidative damage concerns.

I also know fish oil has been recently linked to prostate cancer, but I'm less concerned with this as there's not yet any causality proven...just an association with higher plasma levels of DHA and EPA and prostate cancer.

Unfortunately, getting the proper amount of oily fish in my diet is very difficult where I live. At best, I only eat oily fish very occasionally (1-2 times a month, and that's probably generous).

Finally, I know while several early studies showed fish oil is very beneficial, some more recent ones have cast some doubt on the benefit, so the jury is still out in some regards. But some of the other benefits (lower blood pressure, anxiety alleviation, dry eye relief, anti-inflammation affects) are more well-established, so I'd ideally like to continue taking it.

My main two questions are:

1.) Would you recommend I stay at the around ~2g I'm currently taking or change dosage (up or down)? My doctor said up to 4g should be fine (before I found the oxidation articles), but I'm not able to see her again until May.

2.) If oxidative damage was indeed happening, would that show up in blood tests? For example, would my LDL go up if oxidative damage was happening, letting me know there's a problem, or could I be doing damage "silently" over the long term and not realize it through tests?

I'd like your opinion on what I'm doing and what you think as an expert in the field. Thank you!

Category: Internal Medicine Specialist

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Category: HIV- AIDS Specialist
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Hello and thankyou for approaching DoctorSpring with your query.

Fish oil dosage around 3-4 gms is found to be beneficial in lowering triglycerides, LDL by 25 to 30 percent and increases HDL Thus having a benefit on the cardiovascular system in preventing Coronary heart disease. It is not that effective in lowering triglycerides when used in levels less than 2gms though has benefits.
Fish oil is also use by the brain cells, helps in anxiety. It is good for the joints too due to its anti-inflammatory effect.
It has shown to decrease systolic B.P by 3-5mmHg and diastolic b.p by 2-3 mmHg due to decrease in the resistance of the blood vessels in the body.
It helps in dry eye, by contributing to the lipid layer of the eye, therefore decreasing evaporation and of the maintaining the tear film.

Krill is supposed to be similar to DHA / EPA and provides similar benefits as well.

In small trials , fish oil capsules upto 12gm/day have been administered for more than 2 years without any serious adverse effects. However US FDA recommends general population to take upto 2g/day , and in patients with high triglycerides upto 4g/day. This recommendation is taking into consideration of all major evidence based studies. 2gm would be your safe bet. There is just not enough data for higher dosage.

Systematic reviews and meta analysis of numerous large studies have found no significant effects of fish consumption on any type of cancer. Hence the current overall study supports that fish or fish oil does not put you at the risk of cancer.

1) I would recommend you can continue your current dose. If your triglycerides are high , you can increase to 3gms, else the present dose is fine.

2) There is no way to test for oxidative damage. But fish oil is safe overall. And you need not worry if you taking around 203gm / day. Oxidative damage is a micro cellular process which can be measured.

Just a note regarding Vitamin E " Current evidence does not support a role for vitamin E supplementation in the prevention or treatment of cancers, cardiovascular disease, dementia, and infection. Since the best available evidence, while not conclusive, suggests that high-dose vitamin E (=400 units/day) might increase all-cause mortality ".

My recommendation is that you should NOT take Vitamin E supplement as there is possible risk (and no proven benefit). Another factor to be kept in mind is that Supplements have only a very small when compared to a good diet , exercise and weight loss. So make sure you are not overlooking the other factors

I hope this has helped.
Feel free to ask followups.


Patient replied :

Thanks so much for your thorough and excellent reply! A few remaining points/questions:

You said "And you need not worry if you taking around 203gm / day." I'm assuming you meant to write 2 gm/day, but just want to make sure.

As far as Vitamin E, I get 30 IU in my multivitamin, but that's all I take, not megadoses (and there's none added in the fish oil as listed on the label). Good to know the risks of too much, though; I will make sure not to take any extra, but I'm getting nowhere close to the 400 IU you mention!

Finally, does it matter at all the "other" content in fish oil? For example, the caplets seem to contain ~3g of *total* fish oil, but EPA+DHA is 2g. The latter number (2g) is the one I need to be concerned about, correct? Is there no additional worries about oxidation as far as the "extra" gram not counted in EPA+DHA?

Thanks again.

Sorry I meant 2gm only.
30 mIU of Vitamin E is not a concern. No issues there
The additional components may contribute EPA + DHA content in a non significant way. Many food items will also do the same. But that is acceptable since 2gm is the 'supplementary' dosage which takes other other possible sources into account.

Hope this clarifies
Feel free to ask followups
Thank you

Patient replied :

Great thank you very much for the information! I will continue on the 2g fish oil as directed and feel much more comfortable about staying at that level!

I do have one followup about some additional supplements I'm taking if you don't mind. I'm currently taking Magnesium Oxide (~500mg) and Potassium Gluconate (99mg). I had read that some versions of these supplements, in particular Aspartate and Glutamate, can cause exocitation and neurotoxicity and should be avoided. I think I'm probably safe with Oxide and Gluconate against this side effect, but I'd like to make sure. Are Oxide and Gluconate indeed safe versions of these to be taking (over Aspartate or Glutamate)? There's a chance I might switch in the future to Glycinate, Citrate, or Malate due to gastric issues - what about the safety of these versions? I guess what I'm asking is, are Aspartate and Glutamate the only ones I should actively avoid?

Thanks again!

In my opinion (which of course based on evidence and guidelines ) if you are a healthy individual ( WITHOUT - alcoholism, malabsorption, a vegan diet, a history of gastric bypass surgery, or some inborn errors of metabolism, hemodialysis , or a proven Vitamin deficiency) the only supplement to be considered is Fish Oil.

Now days testing for Vitamin D3 also makes sense. If Vitamin D3 is low then a Calcium _ Vit D supplement can be considered. There is no solid data which says extracted antioxidants in isolation are beneficial. Instead antioxidants in whole form as in fruits, vegetables, tea etc are the ones to be included.

So I would recommend any of them.

Hope this helps
Feel free to ask followups
Thank you

Patient replied :

Thanks much for the detailed response!

Understood regarding isolated antioxidants. I do get 1,600 IU D3 in my multivitamin, but you think I should ask my doctor to test for deficiency?

To clarify the reason I'm taking magnesium and potassium, I have had IBS for years, and that, along with some muscle twitching I was getting, prompted my doctor to recommend magnesium since the Miralax I take at night for the IBS can deplete electrolytes. (So I supplement a small amount of the potassium as well).

My question was more about the gluconate, oxide, or glycinate components of these minerals after reading that aspartate and glutamate are potentially unsafe due to excitotoxicity and neurotoxicity concerns. So I guess what I'm asking is, are mineral supplements based on gluconate, oxide, and glycinate safer?

Additionally, I discovered last night my multivitamin has an amino acid blend of four (L-Glutamine, L-Taurine, L-Carnitine, and L-Methionine; I'm guessing 25mg of each as the blend total is 100mg). I also get 250mg of L-Arginine and 250mg of L-Carnitine in my blood pressure supplement.

I know glutamate is potentially excitotoxic/neurotoxic, and that arginine can potentially boost nitric oxide, which if increased could be both neurotoxic and neuroprotective, but I'm hoping in these small amounts, that's not really too much of a concern. Do you think at these relatively small does, this is also safe?

Thanks. That should be all the questions should I understand your answers - I really appreciate your time!


At smaller doses Glutamine and Arginine are safe. At Least there is no evidence of any adverse effects. Many body building supplements have high levels of Glutamate , Arginine, L-Taurine, L-Carnitine, and L-Methionine. No adverse effects are usually reported. I really doubt the benefits , but I no issues taking them.

Vitamin D3 supplement is better taking after checking the Vit D3 levles. If you are not taking calcium you SHOULD NOT take this level of Vitamin D3 for sure.

In my opinion there is no reason for Magnesium and Potassium as the body will be able to adjust for any excess demand or loss. You can also check the Magnesium levels in the body to be sure.

Hope this helps
Thank you

Dr. Jaydeep Tripathy
Category: HIV- AIDS Specialist
MBBS from Sri Ramachandra University in December 2011
M.Med (Family Medicine) - TNMGR University, Chennai
MBA-MPH in Public Health in March 2016, SRM University
Finished AFIH in March 2016, SRM University
MRCP ( UK ), Internal Medicine, Royal College of Physicians, June 2016
Fellowship in Diabetology from Martin Luther University in January 2017

Currently Resident Physician, in MD Radiodiagnosis - Kamakshi Memorial Hospital, Chennai
Dr. Jaydeep Tripathy and 4 other Medical Specialists are ready to help you

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