The question of whether to take nutrition supplement is no-brainer for most vegan, or vegetarian - when I decided to become vegetarian and an uncommitted vegan I did little research regarding taking supplements. This is due in large part because of lack of research prior to becoming vegetarian and on the other hand driven by my unwillingness to taking medicines that seems unnecessary when I can obtain the nutrition from fruits or vegetables.
Over the years I’ve had physics recommend I take supplements, particularly for my low iron level - while I respected their opinion since they are the expert, it only lasted for two to three months, and I usually stop taking it.
I always thought it was unnecessary because I eat enough fruits, vegetable, got decent exposure to the sun, get my 6-7 hours of sleep every night, stay well hydrated and workout often - so the idea of taking supplements seemed like a waste of money, and unnecessary. However, last year while training for another half marathon I found my self experiencing sharp pain in my chest while breathing, whether I was running or stop running, I had difficulty breathing constantly, and some days it felt like I had rib fracture, or someone was stepping on my chest , while I am trying to breath. At first i took it as sign of over training, so I took few weeks off. However, the symptoms continued. After much thinking, I decided to go see a doctor about it - after a number of breathing test, they could not figure out what was wrong with me. So they sent me to get a chest x-ray and blood tested. After few days of waiting, I finally heard back - and to my surpriseall my sympathies were caused by the lack of B12, iron and others nutrition that I am lacking my diet.
Against my belief and values I realizes that I needed to try and help myself as much as as I can . So, against my strong belief on taking medicine for nutrition that you can find in fruits or vegetables I decided to take supplements again. From Omega-3, vitamins B12, calcium, to Zinc. Whether the supplement are working is open to question, I guess I won’t know until i start training again. Despitetake supplements again I am still of the belief thata whole-food, planet-based diet can easily meets all the daily nutrient requirement, provided you plan your diet out and consume the necessary greens on a daily basis to make up for the deficit - one of my biggest mistake is that I sometimes don't consume as much as an average person, so it's natural that I find some weeks where I might consume food that may not have the necessary nutrition.
So, should you take supplement? this is a question that I cannot answer or give you a justification - The first thing to ask yourself is whether you need them in the first place. I also recommend consult with your physician before taking any supplement because if you take the wrong one it can have adverse impact to your health. If you are planning on changing your diet by becoming vegetarian or vegan make sure to consult your physician and have a discussion on how to supplement for the missing nutrition that your diet will be depriving you of. Your diet should not cause you more harm, so make sure to do your research before deciding to take any supplement, but most importantly make sure to get an expert opinion.