September 01, 2009
Optimal DHA Daily Dosage?

Can blood and urine tests point toward the ideal daily dosage of the omega 3 fatty acid DHA.

A team of French scientists have found the dose of DHA (docosahexaenoic acid) that is "just right" for preventing cardiovascular disease in healthy men. In a research report appearing in the September 2009 print issue of The FASEB Journal (, the scientists show that a 200 mg dose of DHA per day is enough to affect biochemical markers that reliably predict cardiovascular problems, such as those related to aging, atherosclerosis, and diabetes. This study is the first to identify how much DHA is necessary to promote optimal heart health.

"This study shows that regularly consuming small amounts of DHA is likely to improve the health status of people, especially in regards to cardiovascular function," said Michel Lagarde, co-author of the study.

Now, the press release above is not clear. Do they see the optimal response at 200 mg of DHA per day? Does the response stay the same, get worse, or get better above 200 mg? Well, okay, so lets move on to the abstract.

Twelve healthy male volunteers (aged 5365 yr) were assigned to consume an intake of successively 200, 400, 800, and 1600 mg/d DHA, as the only omega-3 fatty acid, for 2 wk each dose. Blood and urine samples were collected before and after each dose of DHA and at 8 wk after arrest of supplementation. DHA was incorporated in a dose-response fashion in platelet phospholipids. After supplementation with 400 and 800 mg/d DHA, platelet reactivity was significantly decreased. Platelet vitamin E concentration increased only after 200 mg/d DHA, while p38 MAP kinase phosphorylation decreased. Urinary isoprostane was also significantly lowered after 200 mg/d DHA but was increased after 1600 mg/d. Therefore, supplementation with only 200 mg/d DHA for 2 wk induced an antioxidant effect.

Okay, that's still not perfectly clear. I can imagine why vitamin E would drop at higher DHA levels as DHA gets oxidized and vitamin E gets depleted reducing it. What happened with isoprostane between 200 and 1600 mg? What is urinary isoprostane? Turns out isoprostanes are an indication of free radicals reacting with fats. Higher isoprostanes probably mean more bad stuff going on.

Isoprostanes are prostaglandin-like compounds produced primarily from esterified arachidonic acid in tissues by non-enzymatic reactions catalysed by free radicals in vivo.

Higher circulating concentrations of F2-isoprostanes are associated with coronary artery calcification (CAC) and CAC is definitely a bad thing.

So maybe there's an ideal dose level of DHA and maybe it is in the hundreds of milligrams per day. I emphasize the maybe.

Share |      Randall Parker, 2009 September 01 09:00 PM  Aging Diet Heart Studies

coldequation said at September 2, 2009 5:32 AM:

This study was flawed in that they gave the different doses sequentially to the same patients. DHA builds up over time so the old doses would have still affected the patients.

If you look at fig. 2 here: it looks like DHA is beneficial if you're lacking it, not so much if you already have enough. But I haven't heard of clinicians measuring it.

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