While you can’t argue the endless benefits of a plant foods, “it takes a lot of work to be a healthy vegan,” where the diet is entirely plant-based, GP Dr Jill Gamberg of Double Bay Doctors said.
“It is of utmost importance for those following a vegan diet to get the nutrients needed for good health and to prevent deficiencies [down the track].
“The amount of protein you need depends on your weight and in general people eat too much protein, however vegans may not get enough.” While a 100-gram chicken breast has around 30 grams of protein, the equivalent amount of chickpeas provides about 19 grams. 100 grams of cooked quinoa provides around 4 grams of protein.
According to Nutrition Australia, the recommended protein intake to maintain healthy muscle in the average man is 56 grams per day and 46 grams per day for a woman.
“Vegans often fail to obtain enough dietary vitamin B12, needed for cell division, making red blood cells, DNA synthesis, and normal nerve function. A deficiency may cause anaemia and neurological symptoms.
“A fist-sized piece of chicken, fish or meat would contain approximately the daily amount needed.”
Green vegetables do contain B12, but in less concentrated amounts than animal products. “It is recommended that all vegans and some vegetarians take vitamin B12 supplements.”
Dairy foods are the best source of calcium, “needed to maintain bone health and for important metabolic functions, including muscle function and vascular control.”
Calcium is available in various plant-based foods, but while a glass of milk contains about 300 milligrams of calcium, a cup of kale contains 95 milligrams. The recommended daily intake for adults is 1,000 to 1,200 milligrams. Vegans might need to consume calcium-fortified tofu and plant-based milks to bump up their intake, Gamberg said.
Vitamin D is needed for calcium absorption, yet “most vegan diets contain little or no vitamin D.”
Produced in the body when the sun’s ultraviolet rays hit the skin, vitamin D is also in oily fish, with small amounts in cheese, egg yolks and certain mushrooms. Vegans with little sun exposure may need a vitamin D supplement, Gamberg said, recommending 15 minutes of daily sun exposure on top of this.
Although plant foods can contain iron, they contain nonheme iron only. The other form of dietary iron, heme iron, found in meat, poultry and seafood has higher bioavailability, Gamberg said.
“In other words it is absorbed better. Iron is an essential component of haemoglobin, a red blood cell protein that transfers oxygen from the lungs to the tissues. Iron deficiency can cause anaemia, with symptoms of fatigue, weakness, lightheadedness, a fast heartbeat or shortness of breath.”
Women 18 to 50 need about 18 milligrams of iron per day, and men, around 8 milligrams. A fist-sized serve of beef contains 2 milligrams, one cup of white beans contains 8 milligrams, and half a cup of spinach contains 3 milligrams. Supplementation may be needed if iron levels are low, Gamberg said.
Vegans also need to consider their intake of essential anti-inflammatory omega-3 fatty acids, she said.
EPA and DHA are omega-3 fatty acids found in oily fish such salmon and sardines. Alpha-linolenic acid (ALA) is an omega-3 fatty acid found in walnuts and flaxseed oil, and a good alternative for vegans.
Gamberg recommended a vegan diet be implemented under the supervision of a doctor or dietitian to ensure all nutritional requirements are met and so nutrient status can be monitored.
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