Vitamin B12 is probably the most controversial one. It is only made by bacteria most of which live in the soil. The only foods that contain B12 are animal products and soil residues on plant-food (and a little in some fungi). Since we have a high degree of hygiene and wash our food extensively there is no significant amount of B12 on the surface of plant-food. The other important information about B12 ist that it is not only about the intake but more about the uptake of it in the gut. Some vegans develop severe deficiencies while others live healthily for decades without supplementing. The origin of these differences being the individual differences in the ability of taking up B12. The uptake efficiency largely depends on your gut health. See GUT HEALTH. Since most people don’t know anything about the state of their guts it is advisable to consider supplementing B12 and find the right dose by checking your blood values if possible.
Vitamin D is not contained in plant-food but it can be made by our skin upon exposure to sunlight. It is important to expose your skin without any protection for as long as it is healthy for your skin type and you don’t get sunburned. Many people, including myself, claim that by eating a plant-based whole foods diet with a significant amount of raw fresh produce they could reduce their skin’s sensitivity towards sunlight and can now stay in the sun longer whithout getting sunburned.
Great sources of omega-3-fatty acids are flax seeds, chia seeds and hemp seeds. Flax and chia have to be either soaked or grounded for good uptake. Nuts, seeds and almonds contain omega-3-fatty acids as well. Vegetables, especially dark leafy greens, whole grains and nuts and seeds contain great amounts of minerals such as iron, calcium and zinc. Iodine is contained in sea lettuce.