Exactly what do you mean by improving blood cells? All cells in your body are protected by getting sufficient nutrients for the body to do what it does, by living a healthy lifestyle, getting enough sleep, exercising (or more properly moving), the luck of your genetics, and staying away from toxins in the environment and in food and medicine that degrade your immune system and cause cell mutagens to go nuts. The latter you can only avoid by working to change the world we live in, as economic activity as currently conducted values earning money over health. So you do the best you can or, if you're rich, move away from as much of this pollution as you can. Don't know what you mean by container food -- some food in containers is as natural as any other food and some food not in containers isn't very natural at all, such as GMOs which may or may not be harmful but certainly aren't natural. I would guess you mean food sold that contains a lot of additives that are not food, but again, some food sold in the produce aisle at your supermarket has this in it as well. You can minimize this by shopping only in health food stores that only sell organically grown produce. As for the strength of blood cells, obviously all nutrients that are essential are essential to everything, but B12 and iron are especially important in food. B12 can be hard to get in a vegetarian diet, as it's mostly found in animal food, but you can find it if you work hard at it. The other nutrient hard to get in a vegetarian diet is methionine, an amino acid, so again, you need to work to get it but it can be done. Iron you only need what you need -- too much isn't better as it can affect the heart adversely -- and as with most minerals can be found in many green leafy vegetables, beets, and in foods that grow in the ocean. One other substance that can help build blood cells is chlorophyll, which is one of the things that makes green foods green. It's quite high in fresh water algae such as spirulina, which is also quite high in B12, so is a good vegetarian source for that. Chlorophyll has almost the same makeup as hemoglobin, which is why the body can use it to make stronger blood cells. Do you have any special reason to worry about the strength of your blood cells?