When choosing to eliminate or reduce a dietary component, that for many of us has been instilled in our dietary culture, there is understandable uncertainty and factors to consider. Plant-based eating has received a backlash for its suspected inability to meet nutrient demands. Here we debunk some of the biggest misconceptions that exist surrounding a plant-based diet.
1. Can I get enough protein from a vegetarian or vegan diet?
Perhaps the most common accusation made towards plant-based diets is that they do not provide sufficient protein. This is an understandable concern considering the great amount of digestible protein that animal food provides. However, animal protein is by no means an essential nutrient for the human body. A plant-based diet is more than capable of supplying sufficient dietary protein, provided it is well-planned and energy requirements are being met. Protein is found in the likes of beans, rice, tofu, lentils, hummus and grains. A diet that combines a number of these foods will provide an adequate supply of amino acids (the building blocks used to make proteins), and therefore prevent protein deficiency.
One of the biggest challenges people face when deciding to go plant-based is they don’t have a repertoire of protein-rich recipes or they may be the only person in their family that is eliminating meat. As a result, they cut meat out of their meals without replacing it with a plant-based high-protein alternative. A slow transition to a plant-based diet, or allocating time to plan and follow protein-rich plant-based recipes, is a great way to ensure the diet is well-planned and protein requirements are being met.
2. Will a plant-based diet make me low in iron?
Iron is a mineral found in food. Its job is to carry oxygen around the body (1). The American Dietetic Association states that iron-deficiency is rare, even in individuals who follow a plant-based diet. Though it is true meat provides a great bioavailable source of heme-iron, plant-based foods contain iron too, just in a different form. Plant foods contain what is called nonheme iron, this type of iron is more susceptible than heme iron to other factors in food that lower its absorption.
To get the most iron out of food on a plant-based diet, consuming iron-rich foods like nori, seeds, grains, leafy greens, beans, tempeh and fortified cereals and flours, should be done alongside vitamin-C containing foods. Vitamin C rich foods help the absorption of iron and include blackcurrants, orange juice, kiwifruit, capsicum, broccoli, berries and kale.
Tannins, found in tea, reduce the absorption of iron. Drinking tea between meals, or waiting at least 30 minutes to 1 hour after eating is recommended to optimise iron absorption. Phytate, a compound found in plant foods like beans, grains, nuts, and seeds, also reduces the absorption of iron. Tricks like soaking beans and grains and heating food will help to reduce some of the effects of phytate on iron absorption.
As a result of reduced iron bioavailability in plant-based foods, the recommended iron intakes of vegetarians is 1.8 times higher than for non-vegetarians (2).
3. Will I always be hungry on a plant-based diet?
Some people fear that without including meat or other animal-based products in their diet, they are never going to feel truly satisfied. The theory behind such a thought process is that animal products are high in protein, which has a satiating effect. On top of that, plant-based products are typically lower in calories. However, as previously mentioned, plant-based foods also contain protein, alongside one of the most satiating food components - fibre.
Fibre is the parts of plant foods such as vegetables, fruits, grains, beans and legumes, that can’t be digested by the body. It slows the digestion of food through the gut helping you feel fuller for longer (3).
If you’ve switched to a plant-based diet and are experiencing hunger, it is likely your consumption of nutrients is a little out of balance - ask yourself am I getting enough protein, fat and fibre?
4. Will a plant-based diet provide me with all the nutrients I need?
Zinc, calcium, vitamin D, riboflavin (vitamin B2), vitamin B12, vitamin A, and essential fatty acids are the most discussed nutrients when it comes to the adequacy of a plant-based diet. The only vitamin you are unable to obtain from a diet strictly derived from plants (vegan) is vitamin B12. All other nutrients can be obtained through plant foods in a well-balanced plant-based diet. The key is variety! Aim to include as many different plant foods in your diet each week as possible.
If you’re worried, have a chat to your GP about getting your blood tested every so often.
5. Does a plant-based diet contain complete protein?
The American Heart Association states that “plant proteins alone can provide enough of the essential and non-essential amino acids, as long as sources of dietary protein are varied and caloric intake is high enough to meet energy needs.” The main consideration when switching to a plant-based is, therefore, the quality of the protein. Protein quality is determined by the composition of the amino acids (building blocks) and the digestibility of that protein. Plant-based proteins are less digestible than animal proteins because of the “anti-nutritional” factors including tannins, glucosinolates (found in mustard and canola products), trypsin inhibitors (in legumes) and more (4). Treatments such as soaking food, heating it, boiling, steaming and fermenting do reduce the effects of “anti-nutritional” factors but don’t eliminate them.
One of the downfalls of consuming less digestible protein is that more protein, and consequently energy, must be consumed to reach protein requirements. This is where plant-based protein powders may have a role. Protein powders have a complete amino acid profile and are clear of anti-nutritional factors.
Plant proteins also contain lower concentrations of the essential amino acids, which can’t be produced by the body, than animal proteins do. Of particular interest is lower concentrations of the essential amino acid Leucine, which has an important role in working as a signal to start and monitor muscle protein synthesis (muscle growth).
