No matter which dietary choices we follow as individuals, regular blood work and supplmentation is always a good idea. Even veganism or a vegetarian diet has it's shortfalls and as we are all creatures of habit who usually eat to taste and not for what are body "needs" we'll have a habit of being deficient in one nutrient or another. Typical shortfalls for a vegan/vegetarian diet is Vitamin D, B12, calcium among other things, there are no perfect diets and certainly no perfect individuals following them so supplmenting just makes sense.

Personally RDA's should be thrown out the window (they are typically very low in the first place) and a nutrition plan set in place by working with your PCP and a nutritionist using blood tests to see where you are naturally deficient. Serious athletes live and die (or should) by their nutrition plan and depending on your activity levels getting everything you need through food is a massive chore even eating 6x per day which I personally do.

Those of us on a liquid diet especially should be mindful as malnutrition is a very easy place to get to if we are just drinking Ensure or Jevity. I make sure I'm juicing fresh fruits and vegies along with the protien powders, vitamin and herbal supplements that I take (which includes vitamin D). It is possible to OD on certain vitamins and minerals so working with your Dr and a nutritionist is important, even if it's just to get you started in the right direction. I don't believe I could work or workout at the pace I keep without proper nutrition, it just gives your body the best environment to be healthy.

Sorry for the book, nutrition is a passion and I think if our bodies are to have the best chance of fighting this disease or any type of infection it has to be running at it's peak.

Eric