What is a vegan diet?
Put simply, a vegan diet is one which excludes all animal products. People who eat a vegan diet can consume:
- Nuts and seeds
- Pulses and legumes
- Other plant-based products, such as coconut yoghurt and vegan cheese
But vegans avoid the following:
Technically, a vegan doesn’t use any animal products either. This means they wouldn’t wear leather shoes, or use cosmetics with animal-derived ingredients (such as shellac).
With that in mind, it’s probably more accurate to say that there’s been a recent explosion in plant-based eating, rather than true veganism. Last year, the demand for vegan food spiked by 140% .
What’s good about a plant-based diet?
While there’s lots of research looking into the benefits of vegetarianism (in which people avoid meat, but still eat eggs and dairy), there’s actually not much high-quality research investigating the benefits of 100% plant-based eating.
Here’s what we know from the few studies available:
- Plant-based eaters have a lower average BMI. In other words, they tend to weigh less . There’s a suggestion that this is because plant-based diets cause people to burn more calories after eating, though this theory needs to be further substantiated .
- Plant-based eating protects against high blood pressure, type-2 diabetes and death from heart disease . Interestingly, this effect is more pronounced in men. It’s worth mentioning that these results relate to the study of Adventists in the USA—people who generally lead modest lives, and who don’t drink or smoke.
- Plant-based eaters have a lower risk of cancer. A meta-analysis (a study of studies) found that plant-based eaters had a 15% reduced risk of developing cancer .
There are lots of ways to eat a plant-based diet, and it’s still possible to eat a lot of ‘junk’ food. Chips and coca cola, for example, are vegan foods!
However, if a plant-based eater does indeed eat more plants, these confer benefits too:
- High intake of antioxidants and polyphenols. Fruits and vegetables are brimming with these powerful compounds, which help to fight inflammation in the body . Polyphenols can also encourage the growth of good bacteria in the large intestine.
- Higher fibre intake. Plant foods are generally rich in fibre, which performs lots of functions in the body, including fighting leaky gut . Of course, some people with dysbiosis may benefit from eating less fibre for a while.
What are the drawbacks of a plant-based diet?
It’s possible to eat well on a plant-based diet, but it requires a little more planning. Without proper attention, a plant-based eater could find that they’re not getting enough of the following macro and micronutrients:
- Protein. Plant foods simply aren’t as high in protein as animal-based foods. If you aren’t getting enough protein, it will impact virtually every bodily process, including immune and muscle function.
- Vitamin B12. This vitamin is not found in plant-based foods. The only reliable sources for plant-based eaters are foods that have been fortified and supplements. A deficiency of vitamin B12 can result in a higher level of inflammatory homocysteine, and even lead to nerve damage .
- Iron. There’s iron in plant foods, such as spinach and sesame seeds, but it’s in the non-heme form, which is less bioavailable (usable) to the body. A lack of iron can lead to anaemia and fatigue.
- Calcium. The mineral is bound to oxalates in plant foods, which means it’s difficult for the body to use it. We need calcium not only for our bones, but also for our hormonal function and nerve transmission.
- Omega 3 fats. Oily fish is the best source of the essential fatty acids EPA and DHA. Plant-based eaters can consume omega 3 fats in the form of walnuts, chia seeds and flaxseeds, but their body still needs to convert it into EPA and DHA.
- Iodine. One study showed that up to 80% of vegans are deficient in iodine . The mineral is essential for thyroid function.
In addition to not eating enough of the right nutrients, plant-based eaters can also find themselves eating too many anti-nutrients. These substances—such as lectins, phytic acid and protease inhibitors—are found in seeds, grains and legumes.
They are the plants’ way of protecting themselves, kind of like their own immune system. However, when we eat them, they can prevent other nutrients from being absorbed, further contributing to deficiencies. This substances can be particularly problematic in people who suffer from an autoimmune disease.
Is a plant-based diet right for everyone?
Some people feel they thrive on a plant-based diet, while others seem to struggle. Genetic testing can go some way to explaining why. We are all different in a number of ways, such as:
Our ability to convert vitamin A. Plant foods don’t contain true vitamin A (known as retinol) but a pre-cursor to vitamin A, called beta-carotene. If everything is working well, the body can convert beta-carotene into retinol—which essential for eyesight, growth and fertility.
However, we now know that some people have a genetic SNPs that means their conversion is reduced by 69%, or even up to 90% .
What this means is that if a poor converter decided to eat a plant-based diet, they could come to find themselves suffering from symptoms of inadequate vitamin A: night blindness, poor immunity and thyroid problems.
Differences in our gut microbiomes. The mass of bacteria, viruses and other microorganisms that live in our gut plays a huge role in how we respond to certain foods. One example of this is vitamin K2. This vitamin is present in animal products, but a healthy microbiome can also make it .
However, not everyone has a healthy microbiome. If a person with minimal vitamin K2-producing bacteria switched to a plant-based diet, they may find themselves running low on this crucial vitamin. This can show up as nasty dental problems, and even bone fractures.
Our carbohydrate tolerance. There’s a gene called AMY1, which codes for amylase—an enzyme that breaks down starch. Generally speaking, people from cultures with a more starch-heavy traditional diet (such as Japan) will have more copies of this gene (and thus more amylase), while those from a culture with a fat and protein-heavy traditional diet will have less .
A plant-based diet is naturally higher in starchy carbohydrates. If a person with low levels of amylase starts to eat a starch-heavy, plant-based diet, they may find themselves at greater risk of developing metabolic syndrome and obesity .
Of course, not everyone is going to know which of these applies to them, unless they undertake genetic testing or microbiome profiling.
Should you eat a plant-based diet?
There are moral and even political considerations of a vegan diet, which are too complex to go into here. From a purely nutritional standpoint, it’s fair to say that a plant-based diet might not be right for everyone, all the time.
However, our relationship with food is multi-faceted, and everyone’s diet is personal to them. Instead of focusing on labels, every individual should pay attention to which foods make them feel healthy and well—and which don’t. For some, that will include animal products, and for others it won’t.
Even if you don’t eat an entirely plant-based diet, you can still benefit from eating more plants. Load your plate with colourful fruits and vegetables, try different nuts and seeds, and include pulses if you tolerate them. You could even enjoy vegan dessert.
A healthy diet begins with fresh, whole, unprocessed foods—whether you identify with being plant-based or not.