This depends on the B12 status the person had initially, and probably on other unknown individual factors. While there are no proven natural wholefood sources of B12 that are vegan, it's possible that some people obtain small quantities of B12 from unrecognised or incidental sources (since B12 is produced by soil bacteria) while others do not, so it's ...
From the Vegan Society:
To get the full benefit of a vegan diet, vegans should do one of the
Eat fortified foods two or three times a day to get at least three
micrograms (mcg or µg) of B12 a day OR
Take one B12 supplement daily
providing at least 10 micrograms OR
Take a weekly B12 supplement
providing at least 2000 ...
To make it short, veg*an athletes should follow the same recommendations as veg*ans that are not athletes. Indeed, several studies have been done on the topic and here I summarize the most important ones, stating which considerations have been done for each subject:
State of the art
Medical science has no final assessment on veg* diets and sport.
It is very easy to get adaquate protein from whole plant based products. Below is an excerpt from an article in scientific literature.
... Protein needs are the nutritional issue for which there is
probably the least reason for concern. The fact is that all essential
and nonessential amino acids can be supplied by plant sources alone,
assuming that ...
While I appreciate the orientation towards an analytical, scientific and health perspective here, I have not ignored culinary considerations where they seemed important.
This post is a work in progress. I will try to keep updating it as I learn more.
Beans, legumes, grains, nuts and, uh, seeds are all the seeds of the plant they come from. ...
There are several investigations assessing this issue. In several clinical trials (1, 2) Dr. Barnard has prooved that a low-fat vegan diet can improve serum values of HbA1c and requirements for medication of patients affected by type 2 diabetes. The same studies found significant improvements in plasma lipids (LDL and total cholesterols), ...
Here's what's in 100g of banana according to Wikipedia (percentages based on recommendations for adults)
Nutritional value per 100 g (3.5 oz)
Energy 371 kJ (89 kcal)
Carbohydrates 22.84 g
Sugars 12.23 g
Dietary fiber 2.6 g
Fat 0.33 g
Protein 1.09 g
Thiamine (B1) (3%) 0.031 mg
Riboflavin (B2) (6%) 0.073 mg
Niacin (B3) (4%) 0.665 mg
1. General vegetarians (Non-vegans)
For non-vegans, dairy products seems to be the best source, as mentioned in other answers as well. List of top 4 (I'm excluding eggs):
The amount of vitamin B12 in cheese depends on type and variety, Swiss cheese provides the most with 3.34μg per 100g serving
(56% DV), followed by Gjetost(40% DV), Mozzarella(39% ...
The truth about the natural diet is that our ancestors were eating whatever they could get their hands on. They could digest meat as well as vegetables. Some humans have been fed mainly bread their whole life. Some people were eating only meat like some game-following nomads in the north of Canada, and some people were strictly vegetarian (maybe in India?). ...
Vegan omega 3 supplements are widely available. In the UK they can be found in any "health food" type store, for example.
Typically these supplements are flaxseed oil or linseed oil in non-gelatine capsules.
You can also use liquid flaxseed/linseed oil. You get a much higher dose from a teaspoon of oil than a capsule. I find the flavour quite vile, so when ...
Here's some of the UK NHS's advice on feeding babies, with the non-vegan bits edited out.
Your baby's first foods can include mashed or soft cooked fruit and
vegetables like parsnip, potato, yam, sweet potato, carrot, apple or
pear, all cooled before eating. Soft fruits like peach or melon, or
baby rice or baby cereal mixed with your baby's usual ...
This answer would be most likely the same for a non-veg*n question, since there is nothing specific that you should look out for as a result of your diet.
The bones are made mostly out of rigid form of collagen, which is a protein and composes the organic part of the bone and calcium phosphate and other salts, which create the hard outer layer.  Based ...
I personally do not worry about the EPA and DHA intake that I have. When I used to care about my Omega 3 (ALA) intake, I consumed a lot of flax seeds and chia seeds which are both pretty high in Omega 3 and also have a good Omega 3 and Omega 6 ratio.
Since you specifically asked for non-ALA answer though, they only feasible way for most vegans to get their ...
What are vegan sources of Omega 3 that are not algae, seeds, or nuts?
It seems you're in luck - it should be easy to obtain from these sources:
Vegetables, especially green leafy ones, are good sources of ALA, one
form of omega-3 fatty acids. Although ALA isn't as powerful as the
other omega-3 fatty acids, DHA and EPA, these vegetables also have
Nutritional yeast is best consumed in small amounts daily.
Nutritional yeast is a very high source of niacin (Vitamin B3). The tolerable upper limit (TUL) for niacin is set at 30 mg per day because some people experience uncomfortable facial flushing after consuming anywhere from 30-1000 mg of niacin per day. One tablespoon of nutritional yeast provides 28 ...
This is pretty much the same goal that Rob Rhinehart (the founder of Soylent) set out to accomplish.
He created a highly engineered recipe of soy protein isolate, maltodextrin, isomaltulose, soy lecithin, soluble corn fibre, gellan gum, cellulose salt, sucralose, and a vitamin/mineral premix. The recipe is specified to be a nutritionally complete meal ...
It's not the oxalic acid, it's the calcium:
Potassium oxalate did not influence iron absorption in humans from a kale meal and our findings strongly suggest that OA in fruits and vegetables is of minor relevance in iron nutrition.
In short, calcium is extremely digestible in chloridric acid (some people even use it to polish marble)...
I've never seen a doctor recommend meat for pregnant women, even non-vegans/non-vegetarians. Meats have above-average rate of food poisonings, and most farm animals are raised with hormones. If anything, eating meat during pregnancy is a liability and should be done with caution for every mother-to-be. NHS has a whole guide on foods to be avoided and, other ...
Vitamin D is often treated generically, sometimes even not specifying the index. According to this article, there are five Ds (D1, D2, D3, D4 & D5) and only D2 (ergocalciferol) and D3 (cholecalciferol) can be used by our bodies.
This article goes further and makes a difference between D2 and D3. D3 is clear winner (my emphasis):
The majority of ...
Animal products in general are really good sources of B12. This applies to milk and the products that are made from it and I would argue that eggs are a good source of it too, although your definition might be different.
This RDI for B12 was previously set to be 6µg but is now being changed to 2.4µg. Based on this, following can be said:
Milk is a very ...
For vitamin B12 oral intake, 1,000 mcg daily is both safe and sufficient.
Update: A recent randomized controlled trial of vegetarians and vegans who were marginally B12 deficient showed that 50 mcg B12 taken daily was sufficient to correct B12 status. Effect of two different sublingual dosages of vitamin B12 on cobalamin nutritional status in vegans and ...
Simple and Less Tempting
For the purposes mentioned in the question (clarity of mind, weight loss, mental reward by not worrying too much about food), it is enough to have some sort of simple, but nutritionally sufficient, diet, not necessary limited to a single recipe.
Vegan or vegetarian diets are already simpler than omnivore diets. To make it even ...
If you are having issues reaching your protein goals, you can supplement your diet with soy protein powder. It's cheap, a source of all 9 essential aminoacids, and it has a bland taste, so you can mix it into smoothies, shakes, salads, or even your lunch.
About "which quantity", we can't get the right number for you without knowing your weight, height, age,...
Sources of Vitamin A
There are two dietary sources of vitamin A:
Taking up retinoids (vitamers of vitamin A) directly, which occurs in animal based, non-vegan food.
Converting a form of provitamin A into vitamin A. Provitamin A is abundant in lots of vegetables.
A quick note on supplements
Both forms can also be taken as a food supplement. Retinol ...
An answer has been given on the Health Stack Exchange:
A vegan diet is based only on vegetal foods. If we analyze the amino
acid content of different food protein sources (animal and plant
proteins), lysine is consistently at a much lower concentration
in all major plant-food protein groups than in animal foods (1,
2). Lysine is one of the ...
I think there are no studies yet on this topic (if someone finds something I would be happy to read them). Macronutrient needs are simply statistics collected for a big number of people over several years. The real need of macronutrients is different for every person, the tables just show averages based on gender / country / age.
In general, a diet can ...
I would try an answer from the medical point of view.
This short article (a free account is required in some countries) summarizes the risks that a vegetarian/vegan lifestyle poses during pregnancy.
B12 deficiency during pregnancy can lead to "infants having developmental delays even with repletion of B12".
long-chain omega-3 fats deficiency
I agree with GabrielF in that there is no reason to needlessly complicate veganism.
When you start a new diet, it is definitely good idea to monitor the changes this may induce in your body and so if you just became vegan, I would say a blood test after few months and then one after a year since becoming vegan (for example because of the B12 and other fat-...
I ran my personal best of 2:49 at the Boston Marathon after one year of training under a pretty strict vegan diet. (I'm still vegan but running less these days). My diet wasn't complicated at all, I had three rules of thumb:
A smoothie consisting of various types of fruit combined with soy milk, a spoonful of 'good' fats (mostly flax) and some extra hemp ...
A common rule of thumb I've always heard is by Michael Pollan, a food author:
Eat food, not too much, mostly plants.
Don't eat anything your great grandmother wouldn't recognize as food. "When you pick up that box of portable yogurt tubes, or eat something with 15 ingredients you can't pronounce, ask yourself, "What are those things doing ...