Yes you do. I supposed it is possible to be "healthy" on an all meat or all veg diet, but that's not optimal. Especially for veg diet since they need tons of supplements and/or have to track down all kinds of exotic veg, nuts, etc to stay sane and healthy.
It's like walking on all fours. Sure I can get from point A to point B on all fours, but it's not optimal. We were built to walk on our legs. The same goes for food. We were built to be omnivores.
The fact that no human society ( or pre human society ) existed on an all meat or all veg diet should be a dead giveaway.
Frankly, as a one time vegan myself, veganism should be labeled an eating disorder. Human beings should be eating a balanced diet.
You can absolutely be healthy, and not require any supplements, on a vegetarian diet. I don't eat anything exotic and have no health issues at all as a vegetarian.
Veganism is a different story, as you well know. I think that it's unfair and wrong to call veganism an eating disorder though. If you're a vegan for moral/philosophical reasons, and ensure that you keep your vitamin and mineral levels healthy, whether by supplements or dietary choices, how is that an eating disorder? That's like saying that conscientious objectors to the draft had a mental disorder.
All the major dietetics and health organizations in the world agree that vegan and vegetarian diets are just as healthy as omnivorous diets. Here are links to what some of them have to say on the subject:
Academy of Nutrition and Dietetics
It is the position of the Academy of Nutrition and Dietetics that appropriately planned vegetarian, including vegan, diets are healthful, nutritionally adequate, and may provide health benefits for the prevention and treatment of certain diseases. These diets are appropriate for all stages of the life cycle, including pregnancy, lactation, infancy, childhood, adolescence, older adulthood, and for athletes.
Dietitians of Canada
A healthy vegan diet can meet all your nutrient needs at any stage of life including when you are pregnant, breastfeeding or for older adults.
The British National Health Service
With good planning and an understanding of what makes up a healthy, balanced vegan diet, you can get all the nutrients your body needs.
The British Nutrition Foundation
A well-planned, balanced vegetarian or vegan diet can be nutritionally adequate ... Studies of UK vegetarian and vegan children have revealed that their growth and development are within the normal range.
The Dietitians Association of Australia
Vegan diets are a type of vegetarian diet, where only plant-based foods are eaten. With good planning, those following a vegan diet can cover all their nutrient bases, but there are some extra things to consider.
The United States Department of Agriculture
Vegetarian diets (see context) can meet all the recommendations for nutrients. The key is to consume a variety of foods and the right amount of foods to meet your calorie needs. Follow the food group recommendations for your age, sex, and activity level to get the right amount of food and the variety of foods needed for nutrient adequacy. Nutrients that vegetarians may need to focus on include protein, iron, calcium, zinc, and vitamin B12.
The National Health and Medical Research Council
Appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthy and nutritionally adequate. Well-planned vegetarian diets are appropriate for individuals during all stages of the lifecycle. Those following a strict vegetarian or vegan diet can meet nutrient requirements as long as energy needs are met and an appropriate variety of plant foods are eaten throughout the day
The Mayo Clinic
A well-planned vegetarian diet (see context) can meet the needs of people of all ages, including children, teenagers, and pregnant or breast-feeding women. The key is to be aware of your nutritional needs so that you plan a diet that meets them.
The Heart and Stroke Foundation of Canada
Vegetarian diets (see context) can provide all the nutrients you need at any age, as well as some additional health benefits.
Harvard Medical School
Traditionally, research into vegetarianism focused mainly on potential nutritional deficiencies, but in recent years, the pendulum has swung the other way, and studies are confirming the health benefits of meat-free eating. Nowadays, plant-based eating is recognized as not only nutritionally sufficient but also as a way to reduce the risk for many chronic illnesses.
British Dietetic Association
Well planned vegetarian diets (see context) can be nutritious and healthy. They are associated with lower risks of heart disease, high blood pressure, Type 2 diabetes, obesity, certain cancers and lower cholesterol levels. This could be because such diets are lower in saturated fat, contain fewer calories and more fiber and phytonutrients/phytochemicals (these can have protective properties) than non-vegetarian diets. (...) Well-planned vegetarian diets are appropriate for all stages of life and have many benefits.
There have been ovo-lacto-vegetarian societies throughout history (e.g. some religious orders in both Christianity and India, the “Pythagorean diet”).
I think you’re right that veganism is modern, as without modern scientific knowledge eating a healthy diet without milk, cheese, or eggs is very difficult.
It's not really difficult at all. You need to make sure you get adequate b-12, iron, omega-3 but many foods are fortified (at least in Canada where I live) and many people are already taking a multivitamin.
The only required supplement for vegans is B12, and that's not because of lack of meat. B12 is produced by bacteria and most of us live in sanitized environments, so there is no reliable sources of B12 any longer. It's possible that even the animals you eat are low in B12 due to cobalt deficiency in the soil[1], so I encourage you to check your levels and supplement if necessary.
Also, your argument is a classic example of an appeal to nature[2].
There's a perfectly valid argument to be made that as we are able to get full nutrition from non-animal sources, even if that requires supplementation, that it's unethical and immoral to use animals as a source of nutrition.
To say "no, being a vegan is wrong because you can't get full nutrition from eating plants" is an invalid argument, because most vegans aren't arguing only on a health basis.
