The following is taken from two comments by Michael James on the https://happinessofbeing.blogspot.com blog regarding the importance of being vegan in today's age:
The way that milk is produced nowadays means that the principle of ahiṁsā leaves us no choice but to be vegan, both because of the way dairy cows are treated like milk-producing machines, whose superfluous offspring are slaughtered for meat, and which are themselves slaughtered as soon as they cease producing milk at an optimally profitable rate, and also because the environmental impact you refer to (which is arguably the greatest hiṁsā of all) is caused not just by the meat industry but by the livestock industry in general, which includes its two closely intertwined branches of meat and dairy production.
The meat and dairy industries have both been very successful at promoting myths that serve their cause. One of their favourite myths is the ‘protein myth’, according to which animal protein is superior to plant protein, so to get adequate protein we need to eat animal products (meat or milk). This is totally false for two reasons: firstly because most plant foods (including most fruit) have adequate quantities of protein, so it is almost impossible to consume sufficient calories without also consuming sufficient protein (unless we manage to get all our calories from ‘refined’ sources such as white sugar or alcohol), and secondly because there is no such thing as ‘superior protein’ in the sense they mean, since our bodies cannot use protein without first breaking it down into its constituent amino acids, from which we build our own proteins, and by eating a variety of plant foods we get all the amino acids we need. Animal proteins are actually more complex and hence more difficult to break down and assimilate, so for our needs the simpler and more easily digestible plant proteins are superior. This is why protein malnutrition hardly ever occurs except among alcoholics or people who are starving for want of sufficient calories, or very rarely among people suffering from metabolic diseases that prevent normal digestion and assimilation.
One of the favourite myths of the dairy industry is the ‘calcium myth’, according to which we need to consume milk in order to get sufficient calcium. This is a total fabrication, because epidemiological research shows that osteoporosis is most prevalent in societies that consume most animal protein, particularly in those that consume most dairy products. The reason for this is that though milk does contain calcium, the net effect of consuming milk is a loss of calcium, because when a human body (particularly one that has passed the age of natural weaning) digests the complex proteins in cow’s milk, it has an acidifying effect on our blood, so to neutralise that acidity our bodies need to leach calcium from our bones and teeth.
Plant foods are not deficient in either protein or calcium, and for human bodies they are the most suitable sources of these and other nutrients. Where do cows get all their protein and calcium from? Only from eating green grass. Likewise, for humans green leafy vegetables are the richest and most suitable source of both protein and calcium.
Regarding GI (gastrointestinal) health, most GI problems are caused by eating animal-derived foods, so vegans who eat balanced whole-food plant-based diets generally have the healthiest gastrointestinal systems and seldom suffer from the common GI problems that meat or dairy eaters suffer from. Curd, yogurt and buttermilk do provide beneficial gastrointestinal flora (bacteria), but if we eat a healthy plant-based diet our naturally occurring gastrointestinal flora will thrive, so there would be no need for us to supplement it by consuming curd, yogurt or buttermilk.
Regarding vitamin B12, animal bodies do not produce it, so we normally need to get it from food. It is naturally produced by bacteria and micro-fungi that live on the surface of plants, so in the past dietary deficiency of it was not an issue. What has primarily caused a deficiency of B12 in our diets nowadays is the widespread use of pesticides and fungicides in modern agriculture, and we cannot necessarily bypass this problem by consuming organic produce, because even such produce is affected by the prevalence of pesticides and fungicides in the environment. B12 deficiency is a problem nowadays not only for vegans but for many other people also, but vegans tend to be affected by it the most. Not all vegans are deficient in B12, but for those who are it is fortunately easy nowadays to buy vegan B12 tablets, which are a simple way of avoiding any deficiency.
Incidentally, after posting the first of these two comments I read your latest one, in which you wrote ‘the dairy industry has responded well by removing bGH and other growth hormones and by treating cows very humanely’. I am afraid this is another myth, because there is actually very little humanity in the modern dairy industry, and a huge amount of cruelty all the way from birth till slaughter. For example, how many dairy cows nowadays are allowed to live their natural lifespan? At best only a tiny percentage. Like almost every other industry, greed for profit trumps compassion every time, and greed for profit demands the profitable disposal of any waste or surplus, which in the dairy industry means slaughter for meat, both of surplus calves (particularly male ones) and of dairy cows as soon as their productively begins to decrease.