I realize this is an older post, but I came across some information recently that might be helpful.
I have always been sensitive to fish oil and fish that are high in omega 3 fatty acids (flax oil, also). I would feel awful after ingesting either but never knew why.
After I had a near-fatal episode of heart failure from a hemolytic episode I saw an excerpt from a book by Dr. Dean Ornish (cardiologist) that gave a warning regarding fish oil. I'll paste it in below along with a link to the article.
I'm sure most people with thalassmia would have no problem with fish or flax oil, but if you have a nitric oxide deficiency causing pulmonary hypertension, severe anemia, or heart failure from any cause it's probably best to avoid them.
Jan
The Dark Side of Good Fats
(excerpt from article)
However, like many wonderful things in life, there is also a dark side to the omega-3 fatty acids. A recent British Medical Journal analysis of nearly 100 studies of omega-3 fatty acids found mixed benefits. In most people they were beneficial, but not in everyone. Some people actually got worse.
When Dr. Leaf first learned of these puzzling findings, he thought they were a little, well, fishy. But, after reviewing the data from his studies and others, and communicating with other investigators, he identified the subgroup of people who actually got worse: those with congestive heart failure or chronic recurrent angina (chest pain) due to insufficient blood flow to their heart. Dr. Leaf wrote in a forthcoming article in the August issue of the scientific journal Fundamental & Clinical Pharmacology, "Any patient with an advanced state of impaired cardiac function should not be prescribed fish oil fatty acids or be urged to eat fish!" As he told me in a telephone conversation, "For these people, it may kill them."
Why? When part of a person's heart receives insufficient blood flow due to coronary artery disease, that part of their heart becomes starved for blood and the oxygen that it carries. If it's temporary, they may get angina. If the deprivation is for more than a few hours, that part of the heart muscle begins to die and turns to scar tissue—in other words, a heart attack. If it's a small part of the heart, the person may live; if not, they may die.
If a moderate to large part of the heart muscle turns to scar tissue, then that person may suffer from what's called congestive heart failure. This means that the heart is barely able to pump enough blood to keep the person alive. Also, cells that are only barely receiving enough blood flow become hyperexcitable. This, in turn, can lead to an increased risk of irregular heartbeats, which, in turn, can cause sudden cardiac death.
The omega-3 fatty acids stabilize the rhythm of your heart by effectively removing these hyper-excitable cells from functioning, thereby reducing the likelihood of irregular heartbeats and sudden cardiac death. For most people, this is a very good thing and accounts for most of the large reduction in the likelihood of sudden cardiac death.
However, if you have congestive heart failure, your heart is barely pumping blood well enough to keep you alive. The omega-3 fatty acids may eliminate from function enough of these pumping cells that your heart is no longer able to pump sufficient blood to live, causing an increased risk of cardiac death.
For most people, omega-3 fatty acids remain highly beneficial. I still take them. But if you have congestive heart failure, chronic recurrent angina or evidence that your heart is receiving insufficient blood flow, talk to your doctor. If so, it may be prudent to avoid taking omega-3 fatty acids or eating foods that contain them.
http://www.pmri.org/publications/newsweek/The_Dark_Side_of_Good_Fats_Dean_Ornish.pdf