Too much of a specific vitamin can put other vitamins out of balance.

I don’t know that I answer that right–oh–I know–if you take too much vitamin A, it’s called hypervitaminosis A. Hyper means too much. It could cause hypovitaminosis of another vitamin. Hypo means too little. It may not cause hypovitminosis of all your other vitamins, just the one it competes with. Vitamins have their own intricate balance.

It’s been years since I studied that, so hypervitminosis A may now be called Avitminosis. Hope I have you one the right track.
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there are many, many causes of weakness. it its related to diet, it could be hypoglycemia, anemia, viruses. so eat every 3-6 hours. get enough iron, copper, folic acid. lentils have iron, cashews have copper, whole grains have folic acid.

look for gelatin, glycerine, or stear in the ingredients. they are common animal ingredients.
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"weakness and near passing out" is something I’ve never experienced during many years on a vegan diet, Are you eating enough food and drinking enough water in general? This is really something you should see a physician for as it could be related to your diet, but unrelated to veganism.

As for vitamins and supplements, if you’re eating a balanced diet, this isnt really something you need to worry about. Protein is literally found in every food. Iron is found in many vegetables, my favorite source is spinach. If you’re concerned about other nutrients search google with the term "Vegan sources of _______."
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