Plant oils, particularly seed and nut oils, contain ALA.[43] Food sources of EPA and DHA are oceanic fish, whereas dietary supplement sources include fish oil, krill oil and marine algae extracts. The European Food Safety Authority (EFSA) identifies 250 mg/day for a combined total of EPA and DHA as Adequate Intake, with a recommendation that women pregnant or lactating consume an additional 100 to 200 mg/day of DHA.[45] In the United States and Canada are Adequate Intakes for ALA and LA over various stages of life, but there are no intake levels specified for EPA and/or DHA.[46]
As the science of nutrition continually evolves, researchers recognize that nutrients needed to maintain a healthy lifestyle must be tailored to the individual for maximum effectiveness. Recognizing that people are not all alike and that one size does not fit all when it comes to planning and achieving a healthful diet, the Institute of Medicine's dietary guidelines, titled "Dietary Reference Intakes for Macronutrients," stress the importance of balancing diet with exercise and recommends total calories based on an individual's height, weight and gender for each of four different levels of physical activity.
"Often the enthusiasm for these vitamins and supplements outpaces the evidence. And when the rigorous evidence is available from randomized controlled trials, often the results are at odds with the findings of the observational studies," explains Dr. JoAnn Manson, chief of preventive medicine at Brigham and Women's Hospital, professor of medicine at Harvard Medical School, and principal investigator of a large randomized trial known as VITAL (Vitamin D and Omega-3 Trial).
Go nuts for nuts (and seeds). From protein and healthy fats to vitamins and minerals, these superfoods pack a serious nutritional punch. Similarly, seeds like chia, flaxseed and pumpkin seeds are nutritional powerhouses too. They are an excellent source of vitamins, antioxidants, and minerals like calcium, zinc, and magnesium. You can add them to your favorite baking recipe, sprinkle them over your cereal or simply munch on them instead of a candy bar.
The use of dietary supplements is widespread. High doses of vitamins are thought to be helpful because they help the body recover from damage and maintain itself long-term. Many vitamins are not harmful in doses even 10 to 100-fold higher than officially recommended. Some governments warn about possible negative side effects, even including increased mortality from "excessive" intake of certain supplements. However, supplements of essential nutrients have been available for more than 80 years. They are known to be safe, and the observed side effects are generally mild with few exceptions.
^ Jump up to: a b Committee on the Framework for Evaluating the Safety of Dietary Supplements, Food and Nutrition Board, Board on Life Sciences, Institute of Medicine and National Research Council of the National Academies (2004). Dietary supplements a framework for evaluating safety. Washington, D.C.: National Academies Press. p. ES-1-ES-3. ISBN 978-0-309-09206-7.
Nutritional supplements may be designed to provide specialized support for athletes. Some of these consist of high-protein products, such as amino acid supplements, while other products contain nutrients that support metabolism, energy, and athletic performance and recovery. People engaging in intense athletic activity may have increased needs for water-soluble vitamins, antioxidants, and certain minerals, including chromium. Sports drinks contain blends of electrolytes (salts) that the body loses during exertion and sweating, as well as vitamins, minerals, and performance-supporting herbs.
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