Vegan diet/ veganism is rapidly rising in the world because of various reasons like- health/ animal welfare or environmental concerns. Research also states that, plant-based diets are linked to lowering the risk of cardiovascular diseases/ type-2 diabetes/ cancers because of its low saturated fat content (1). 

Plant based diets are broadly classified into three types: 

• Vegetarian diets – which includes no meat, but allows the intake of dairy products like milk, curd, cheese etc.
• Vegan diet – it not just excludes meat but also any animal products like milk and milk products etc.
• Pescatarian diet – it’s a kind of vegetarian diet which includes sea food also.

Now what is a vegan diet?
Vegan diets  strictly exclude   the consumption of any  animal products – meat, eggs, milk and its products. Some, go a step further and also exclude honey, however, harvesting excess amounts of honey that is stored in a hive can make it non-vegan. It is not just followed as a dietary choice, but some make it part of their lifestyle as well.
People who follow the vegan diet mostly include fruits, vegetables, grains and legumes, nuts and seeds predominantly in their diet. However, one should also focus on nutrients such as vitamin D, omega-3 fatty acids, proteins, iron, calcium and vitamin B12 while following a vegan diet as they can be more prone to these deficiencies. These nutrients are commonly found in animal products.
Benefits of a vegan diet:

• Lowered risk of heart disease
• Lowered risk of cancers
• Weight loss
• Lower risk of type-2 diabetes.

While the benefits may seem promising for health, these are potential downsides to this kind of a diet.

• Can cause leaky gut issues – because of excess phytates and lectin which increases intestine permeability.
•  A steady consumption of soy and its products can cause hormonal disruptions – these contains phytoestrogens which mimics  oestrogen in the body.
• Iron/ haemoglobin deficiency – plant foods contain non-heme iron which does not get absorbed in the body completely which can lead to iron deficiencies.
• Vitamin B12 deficiencies – animal products are the primary sources of vitamin B12 and vegans are at notable risk for developing an irreversible deficiency of this important nutrient which is essential to maintain your body’s optimal function. The deficiency symptoms can be easily mistaken for weight loss, constipation, anaemia etc.,
• Vegans are at risk of developing depression because of significant decrease in omega-3 fatty acids like ALA, EPA and DHA and an increase  in omega-6 fatty acids like linoleic acid etc.
• Could lead  to eating disorders especially like orthorexia where people have unhealthy obsession of healthy eating which leads to a highly restrictive eating pattern.

There are also some social downsides of following a vegan diet apart from the health front.

• It might limit food options in social gatherings and can lead to social isolation because of the food restriction and carefully navigating the situations where they are unable to eat.
• Requires continuous diligence while eating.
• Might not be practical at all the time.
• Vegan diet can be expensive
• Difficult to manage physically demanding jobs that require stamina.
• May not be practical and sustainable  for people with busy schedules. 

While veganism supports the environment and enhances ethical beliefs, this needs to be followed carefully. Following a vegan diet leads to nutrient deficiencies like vitamin B12, D, calcium, iron, omega-3 fatty acids etc. Supplements used to compensate for these nutrients could have  side effects. Also,  nutrients are better absorbed in their natural forms [from whole foods] when compared to their chemical substitutes. 

References:
https://www.ahajournals.org/doi/10.1161/JAHA.119.012865
https://timesofindia.indiatimes.com/life-style/food-news/7-dangerous-side-effects-of-vegan-diet/photostory/77717097.cms?picid=77717141 
https://www.insider.com/the-potential-risks-of-being-vegan-2019-4 
https://environmental-conscience.com/veganism-pros-cons/ 
https://www.medicalnewstoday.com/articles/149636#nutrients-to-consider 
https://www.health.harvard.edu/blog/plant-based-diets-are-best-or-are-they-2019103118122 
https://www.nature.com/articles/s41398-019-0552-0 
https://www.verywellfit.com/health-benefits-and-risks-of-eating-vegan-4104567 
https://webber-nutrition.co.uk/vegan-diet-pros-and-cons/