Here we answer the questions we receive most frequently about plant-based nutrition and health.

What about protein?

Protein originates in plants, and all plants contain protein that our bodies can use. Protein is made up of small ‘bricks’ called amino acids. The body clips these bricks together in different combinations to create various proteins. When you consume plants, you consume the bricks. When you consume animal products like meat, you consume the whole protein structure from the literal flesh/muscle of the animal, which the body breaks down into these bricks anyway.

Do you need to eat specific food combinations at each meal to get complete protein on a plant-based diet?

There are essential and non-essential amino acids. Non-essential means the body can make them, while essential amino acids cannot be made by the body and must come from the food we eat. There are nine essential amino acids, and all of them originate from plants and are found in plant foods. As long as you eat enough calories and include a variety of plant foods throughout the day, it’s easy to get all the protein you need without worrying about combining specific foods at each meal.

Can you build muscle on a plant-based diet?

Yes, you can build muscle on a plant-based diet. Research shows that when total calorie and protein needs are met, plant-based diets support muscle growth and strength just as effectively as diets that include animal products. Studies comparing vegetarian and omnivorous diets during resistance training have found no significant differences in strength or muscle gains.

Plant proteins provide all the essential amino acids required for muscle building, and recent clinical trials demonstrate that protein-rich vegan diets can promote muscle growth to the same extent as omnivorous diets.

When it comes to building muscle, three key factors matter most:

1. Calorie surplus
2. Resistance training
3. Adequate protein intake

It’s also important to understand that gaining visible muscle typically requires a calorie surplus, while weight loss requires a calorie deficit—so doing both at the same time is more difficult. However, it is possible to build strength while losing weight, even if visible muscle gain is limited. Some muscle loss during weight loss is normal, so the focus should always be on what best supports your health and goals right now.

Aren’t carbohydrates unhealthy?

Not all carbohydrates are the same. There are two main types: simple and complex.

Simple carbohydrates are digested quickly and provide a rapid burst of energy. They include sugars found in candy, soda, and processed foods like breakfast cereals, white bread, pasta, and energy bars. While some simple carbs like those in whole fruit are healthy, highly processed simple carbs are just added sugars and offer little nutrition. 

Complex carbohydrates, found in whole foods like legumes, fruits, vegetables, whole grains, and starchy vegetables (sweet potatoes), contain fibre and are digested more slowly. This slower digestion provides a steady, lasting release of glucose, the body’s preferred and most efficient fuel source. Complex carbs help you feel full longer and support stable blood sugar levels. Complex carbohydrates have been unfairly demonised, but research shows that diets highest in unprocessed complex carbs are linked to the best health outcomes, including lower risks of heart disease and better weight management.

In summary, carbohydrates—especially complex carbs from whole plant foods—are essential for energy and overall health.

Are there any nutrients of focus on a plant-based diet?

Vitamin B12

Vitamin B12 is an essential nutrient made by certain bacteria, not by plants or animals themselves. In nature, B12 is produced by the digestive systems of animals, particularly ruminants like cows and sheep. For these bacteria to make B12, the animals need enough cobalt in their diet. In modern farming, soils and animal feeds can be low in cobalt, so it’s common practice to supplement farm animals with either cobalt or B12 directly. As a result, B12 found in animal products today often comes from supplementation.

Due to improved hygiene, food safety, and changes in how food is produced, B12 is no longer reliably found in plant foods, and it can be hard to obtain enough B12 from fortified plant foods alone. For this reason, it’s recommended that anyone following a plant-based diet—and those taking certain medications like metformin, which depletes B12 levels—take a B12 supplement. B12 supplements are safe, effective, and affordable.

Key points:

• B12 is made by bacteria, not by plants or animals
• In modern farming, animal products contain B12 because animals are supplemented
• B12 is not naturally present in plant foods due to modern food production and hygiene
• Plant-based eaters should take a B12 supplement

For more information on supplementation, visit NutritionFacts.org.

Omega-3 fatty acids

Just like protein, omega-3 fatty acids originate in plants in two forms. One form is known as marine omega-3 and comes from algae. Fish eat the algae and store the omega-3 from the algae in their flesh, which is how humans get omega-3 from fish (or algae). The other is plant-based omega-3, which the body makes from ALA, found in chia, flax, or hemp seeds. Evidence shows that 1–2 tablespoons of flax, chia, or hemp seeds daily is all that is needed to meet the recommended daily intake of omega-3.

Click here for more information.

Iron

Iron enters the food chain through plants. The type of iron found in plants is called non-heme iron. There is another type called heme iron—heme meaning blood—so heme iron means ‘iron from blood’. Heme iron is the iron you get when you consume the blood of another mammal, which occurs when a person eats meat. When consuming meat, only 40% of the iron is heme iron, with the other 60% non-heme iron (or iron from plants). Why? Because the animals people eat, for iron, get their iron from plants.

Data shows that vegetarians who eat a varied and well-balanced diet are not at any greater risk of iron deficiency anaemia than non-vegetarians—though vegetarians tend to have lower iron stores, and need to be more intentional about consuming iron-rich plant foods and optimising absorption.

“Iron deficiency is considered one of the most common nutritional deficiencies in the world. It is most common in countries where diets lack food variety and include regular sources of iron inhibitors such as phytic acid and tannins. In Western countries like Australia, research suggests that vegetarians are no more likely to suffer from iron deficiency anemia than non-vegetarians.” – Dietitians Australia  

What about calcium and bone health?

Humans are unique among animals because we are the only species that:

• Consume milk after infancy
• Consume the milk of another species

Humans have no need for milk after infancy, but we do need calcium.

Like iron, calcium enters the food chain through plants. It is found in plant foods such as leafy greens (collards, kale, bok choy, mustard greens), calcium-set tofu, beans, lentils, nuts, seeds, and fortified plant milks. Notably, countries like Canada have removed specific daily recommendations of dairy (milk, cheese) from their dietary guidelines because there is no dietary need for dairy itself—what we need is calcium, which plants can provide.

Some studies have shown that calcium supplementation did not reduce bone fractures in the elderly (in those already getting enough dietary calcium), and some have even suggested possible heart health risks with high-dose supplementation. 

It is worth noting that, while the Australian Dietary Guidelines recommend 1,000-1,200 mg of calcium daily, the World Health Organization has a recommended daily intake of 500 mg and the UK government guidelines recommend 700 mg. 

When it comes to bone health, getting enough calcium is important, but it’s not the whole story. Research shows that strength training is one of the most important factors for maintaining healthy bones, especially for women. Regular weight-bearing exercise helps build and maintain bone density.

Vitamin D plays a key role in calcium absorption and bone strength. Vitamin D is a hormone that regulates calcium levels in the blood. While small amounts of vitamin D can be obtained through food, it is difficult and not recommended to rely on food alone. The best natural source is ultraviolet (UV) radiation from sunlight, which is also the main cause of skin cancer. Therefore, it’s important to speak with your doctor about the best times, duration, and amounts of natural sunlight exposure for you, based on your skin tone and health history. Vitamin D supplementation is also an option to discuss. Since vitamin D is fat-soluble, it should only be supplemented after a blood test to check your levels and under the guidance of a qualified professional. Vitamin D deficiency is quite common in Australia and New Zealand, so discussing this with your doctor is important.

What about soy?

Plants don’t produce the same hormones found in mammals like humans, cows, and horses. Instead, plants like soy contain compounds called phytoestrogens (phyto means plant), which have a chemical structure similar to the hormone estrogen—but they are not the same thing. These phytoestrogens can attach to estrogen receptors in the body, but instead of activating them like estrogen does, they often block estrogen from binding. This is why soy consumption is thought to be protective against hormone-related cancers, such as breast cancer, and may help improve menopausal symptoms like hot flashes.

Regarding men, a meta-analysis of 41 studies showed that soy consumption did not impact testosterone or estrogen levels in men, no matter how much soy was eaten or how long the study was.

Overall, soy is safe to consume and in fact has many positive health effects.

What if I can’t tolerate certain foods?

We suggest starting with the plant foods you can tolerate and gradually building from there. Plant foods—and fibre in particular—are very beneficial for gut health, but restoring your gut can take time and sometimes guidance. Dr Alan Desmond is a world-renowned plant-based gastroenterologist, and we highly recommend reading his book, listening to his podcast, and even taking his gut health course. You can access all of this via his website. Working with a qualified health professional can also be helpful and may be necessary to support your journey.

This PDF has information on addressing constipation. Speak with your doctor or a qualified health professional if you are experiencing any bowel issues or changes in bowel habits.

What if I am feeling hungry? How do I know I am getting enough nutrients?

It’s important to make sure you’re eating enough calories and choosing foods that keep you full. Ideally, each meal should have a base of oats or grains, along with legumes and starchy vegetables like potatoes. From there, add plenty of fruits and other vegetables. Grains, beans, and potatoes help you feel satisfied and provide the calories your body needs.

One helpful way to track your intake and ensure you’re meeting your nutrient and calorie needs is to use an app or website like Cronometer. Many people find this especially useful when they’re starting a plant-based diet. Note that tracking is not advised for those with a current or past history of disordered eating.

What if I would like more guidance on how to add more plants to my diet?

We highly recommend our Make the Switch course. Make the Switch is unlike anything we’ve developed before. It’s for individuals who want to ‘dip their toes’ into a plant-based lifestyle while getting expert advice on how to transition in a way that fits their unique needs. It’s also something many healthcare professionals have requested for their patients who need an easy, sustainable way to start improving their diet without feeling overwhelmed. Access your free preview today!

If you have any other questions, please don’t hesitate to email us at contact@doctorsfornutrition.org