DEAR DR. BLONZ: A famous medical doctor does these videos where he recommends the elimination of all corn from the diet for optimal mental and physical health. He doesn't refer merely to corn syrup, which I would understand needing to limit, but all corn, in any amount. One of the reasons he gave was the fatty acids in corn. This is all a bit shocking, as this is the time of year I look forward to enjoying fresh, sweet corn on the cob. Is there any basis for such concern? -- H.K., Tulsa, Oklahoma
DEAR H.K.: With the obvious exception of individuals who are allergic to it, the answer is no: You do not need to eliminate corn from your diet. Just like you, I consider it a harvest treasure that can be enjoyed in any healthful diet.
Fresh, sweet corn is a whole food that provides fiber, vitamins and minerals, as well as phytochemicals that are good for our vision (lutein and zeaxanthin). Are corn's fatty acids an issue? Maybe, if your diet was 100% corn. As with most individual foods, corn does not provide every fatty acid and all other nutrients the body needs. But that is a disingenuous argument, and it makes one wonder where these concepts originate -- certainly not with any evidence I have seen.
DEAR DR. BLONZ: I am wondering about nutrient losses when cooking carrots. In one class I took, the instructor mentioned that, when cooking carrots in water to soften them for a recipe, the best way to retain their nutrients was to keep the temperature just below boiling and keep the lid on tight to prevent evaporation. I wanted to question this, but it was presented as family advice passed down through generations, so it did not seem appropriate. -- J.S., Anderson, South Carolina
DEAR J.S.: The primary nutrient that is lost through evaporation is ... water. Higher temperatures can cause some nutrient destruction; the most heat-sensitive nutrients include vitamin B12, thiamine (vitamin B1), riboflavin (B2), niacin (B3), pyridoxine (B6), folate, pantothenic acid and vitamin C.
During cooking, water-soluble nutrients are distributed in the total volume of water, including that found naturally in the food. With increases in water temperature and food surface area, more nutrients end up in the cooking water. For example, being in water helps keep plant cells hydrated and intact. Virtually all the nutrients in intact carrots (greens removed) sitting in ice water remain in the vegetables. Some slicing and steaming, just until tender, will bring more nutrients into the water, but most still remain in the carrot. More will be lost if you do some fine dicing, followed by boiling, and then discard the cooking water. This is one reason that some recipes suggest saving the cooking water for use in a sauce.
Most fat-soluble substances, including vitamin A, vitamin K and any minerals, will remain in the carrot. Other healthful fat-soluble phytochemicals would also remain, as would all the fiber.
Carrots remain a healthful food, even when cooked. Best to be less concerned about minor nutrient losses and more focused on having a variety of healthful ingredients in all your dishes -- prepared in a way that helps you enjoy every bite.
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