DEAR DR. BLONZ: I enjoy tuna, and have found a water-packed brand where the fish are caught in a way that provides a lower risk of contaminants. Does tuna packed in water still have high levels of omega-3 essential fatty acids? If it has less than tuna packed in oil, how much less? -- M.M., San Leandro, California
DEAR M.M.: The oil used for canned tuna is usually soy or canola oil, not fish oil (check the list of ingredients). As a result, oil-packed tuna contains extra fat, but little in the way of extra amounts of the healthful omega-3 fats. A typical can of light tuna in water (drained) contains 0.5 grams of fat and 111 milligrams of omega-3 fats. A can of light tuna in oil (drained) contains 8.1 grams of fat and 128 milligrams of omega-3 fats.
For higher levels of omega-3 fats, use albacore (white) tuna. One 3.5-ounce serving of water-packed albacore (drained) contains 2.5 grams of fat and 706 milligrams of omega-3 fats. The difference between “light” and “white” tuna stems from the fact that the yellowfin and skipjack varieties used to make light tuna contain fewer omega-3 fatty acids than albacore.
DEAR DR. BLONZ: I eat a variety of veggies, grains and legumes with my vegan diet, and beans are the biggest source of protein that I rely on. A close friend told me that fiber could hamper protein absorption, and I wanted your view on this. -- R.S., Martinez, California
DEAR R.S.: There can be a slight decrease in protein absorption on a high-fiber vegan diet, but this would only become an issue with a marginal protein intake. You have stated your interest in legumes; this means that having rice and other grains will make a complementary protein. Aside from this, there are lots of high-protein plant foods, such as soy and other legumes, along with nuts and seeds. All considered, it is doubtful that your fiber intake would be sufficient to cause problems.
DEAR DR. BLONZ: I read your article on protein for the elderly and want to add my sixpence worth of comment. A good source of protein is whey, as in whey powder. It is highly bioavailable and can be added to milk or yogurt or even in cooking. I read that whey protein is good not only for athletes, but also for the elderly and for people about to have surgery. -- M.N., Walnut Creek, California
DEAR M.N.: Thank you for that suggestion. Whey is a natural protein found in milk. It’s what’s left after milk is coagulated and the curd is removed. It may contain a small amount of lactose, that carbohydrate in dairy that many folks have trouble digesting. A pure whey protein isolate will contain only about 0.1 gram of lactose per tablespoon (20 grams of protein). This is the same amount of lactose that would be in one half-teaspoon of milk.
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