https://glorian.org/learn/courses-and-lectures/healthy-spirituality/dietary-guidelines
Dietary guidelines state to avoid modern diets such as those that add synthetic vitamins to foods.
Alexis (Gnostic Instructor), mentioned in one answer to a question that
"Supplements and other medicinal treatments should only be short term help, not long term treatment, because the body will stop trying to go on its own, and learn to depend on the substances you are giving it. This will result in long term harm." - https://glorian.org/connect/ask-instructor/24041-constipation
He also mentioned:
Personally, I do not take vitamins, or really, pills of any kind. I prefer to be nourished from natural sources rather than a factory. So, I do my best to eat a diversity of fresh vegetables, fruits, and grains. If you need vitamin A and D, they are plentiful in easy to find foods, and even sunlight." https://glorian.org/connect/ask-instructor/7802-vitamins#reply-7808
Samael Aun Weor mentioned in one of his books/lectures that scientists were able to make a cell with the same physical components as an organic cell. But it did not have life. This is because it is missing the etheric aspect. Likewise, when we eat food, it is not just the physical aspect we are consuming. We are also nourishing other aspects as well. This is why synthetic foods and grafted vegetables are not recommended.
"Modern scientists are very far from even suspecting that when any plant is grafted it cannot capture the special type of cosmic vibratory waves that are fundamental and necessary for life; therefore, it is logical that within the vital depths of such fruits an adulteration is produced." - Samael Aun Weor https://glorian.org/books/social-transformation-of-humanity/cultivated-fruit
We need to nourish all our bodies, not just the physical. That is why this instructor states:
"Well the mantra Krim is the mantra that you utilize in order to extract the energies of what we eat and to place them not only in the physical body but in the vital body, in the astral body, in the mental body and even to God. That is why it is written when we eat it has to be like a ritual mostly when we eat we have to remember God and pronounce the mantra Krim in order for that energy to go to the higher level of the seventh body. The human being has to be nourished in the seven bodies. That is why we say if you eat a grafted fruit, you are only feeding your physical body because an adulterated fruit does not have the energy necessary for the astral body, for the mental body, for the causal body, for the spiritual body. This is why when humanity eats this kind of fruit they lose their morals because they are not feeding their heart (emotions), their head (mind) only their physical body." - Gnostic Instructor, https://glorian.org/learn/courses-and-lectures/the-transformation-of-energy/the-transformation-of-energy