Well rounded ..variety is the key to a healthy diet.
Photo: Marco del Grande
MELBOURNE (The Age), October 28, 2007:
Vegetarians must double their portion size and kilojoule intake to achieve recommended daily levels of iron, zinc and omega-3 fatty acids, a study has found. Substituting foods such as nuts, seeds and legumes for a meat, chicken and fish-based diet can lead to a dangerous shortfall in essential nutrients, particularly for pregnant and menstruating women, the study found.
Study author Professor Katrine Baghurst, from the department of medicine at the University of Adelaide, said the findings had implications for Australian dietary guidelines, which groups "meats and alternatives" together.
"People need to be aware that they should not simply substitute a portion of a plant-based food for a portion of meat and expect to receive the same nutritional benefits," she said.
"Legumes, nuts and seeds undoubtedly provide valuable nutrients and variety should be included in a healthy diet, but our data shows they are not direct substitutes for foods of animal origin."
The study was funded by Meat and Livestock Australia and will be published in Nutrition And Dietetics next month. It analysed 10 diets based on the Australian Guide to Healthy Eating.
In each, a serving of meat was exchanged for a serving of chicken, fish, legumes, nuts or seeds.
Computer simulation found that even though a diet with plant alternatives provided the same amount of protein, it did not meet the recommended dietary intake for vitamin B12 and long chain omega-3s in all people, for zinc in men and pregnant women, and iron in women.
For example, to absorb the required iron and zinc from pine nuts, peanuts and sunflower seeds, 50percent more kilojoules would need to be consumed than the equivalent meat serving in the guidelines, she said.
Vegetarian Network Victoria president Mark Berriman disputed the findings. He said many other studies had linked a vegetarian diet to health benefits, such as a lower risk of developing heart disease, cancer and osteoporosis.
"The average person on a Western diet is the one who needs to be looking at whether they're getting the right nutrients," Mr Berriman said. Another study found that zinc protects against age-related macular degeneration (AMD), the nation's main cause of blindness.
A study of 3654 people in the Blue Mountains conducted over 10 years found those with a zinc intake of 15.8milligrams per day - equivalent to a 200-gram grilled rump steak - were significantly less likely to develop AMD than those who had a lower intake.
The Centre for Vision Research at the University of Sydney also found a diet high in lutein and zeaxanthin - present in green beans, silver beet, broccoli and eggs - protected against AMD, which affects one in seven Australians aged over 50.
By Louise Hall, Health Reporter
Copyright © 2007. The Age Company Ltd
