DEAR DR. ROACH: I was diagnosed with atrial fibrillation a year ago. A week after that, I had an MRI that showed I'd had a ministroke and probably several others in the past. I love ribeye steak, and eat it maybe two or three times a year. Is this safe? — R.A.
ANSWER: Atrial fibrillation is a rhythm problem of the heart. The natural rhythm is lost, so the heartbeat becomes irregular. Because of the lack of normal movement in the heart, the blood can pool and form clots in the left atrium; these clots can travel downstream to lodge in a blood vessel. Clots can cut off the blood supply to the area where they lodge. It's most critical when it happens in the brain, since if brain cells die, function is lost.
A stroke is just a focal area of cell death in the brain. The size and location of the area in the brain where cell death occurs determines how significant the stroke is. Strokes can range from unnoticeable to devastating to fatal. Most people with atrial fibrillation take medication to reduce the risk of stroke.
Eating poorly can increase the risk of heart disease and stroke as well, but most commonly this happens via a different mechanism. High amounts of saturated fat — such as in ribeye steak, which is fattier than many cuts of beef — increase the risk of damage to blood vessels through buildup of cholesterol plaques. These plaques cut off blood supply, and this causes a heart attack if the plaques are lodged in the arteries of the heart, a stroke if in the brain and various problems if in other parts of the body.
In people who have a history of stroke, it's particularly important to take steps to reduce further risk. That means a discussion with your doctor about whether you are on the best treatment for atrial fibrillation and whether you have evidence of cholesterol plaques.
Even if you don't have any evidence of plaques, a healthy diet of mostly plants, with whole grains, nuts and seeds, some fatty fish if you enjoy that and sparse amounts of meats reduces many health risks. However, two or three steaks a year is not going to cause harm. The best data available shows that people who have 100 grams (just over 3 ounces) of red meat a week are at the lowest risk of developing blood vessel problems. It's not clear that zero is better than that small amount.
In any event, I am a firm believer that enjoying life is the goal. If having a steak a few times a year is truly enjoyable, the risk is small, and you should enjoy those meals without guilt.
DEAR DR. ROACH: What is the body's rate of absorption for calcium? — A.
ANSWER: The textbook answer is 20% to 40%, but in reality, the answer is very complicated, as it depends on total body and intracellular calcium, vitamin D levels, presence of phosphates in food and other factors. The short answer is that it's usually exactly what it needs to be when things work properly. If the body is deficient in calcium, then absorption is maximal, but still most calcium in food is not absorbed.