A wealth of information on this is available on the internet. The below is just to put light from a different perspective.
In the juice of the plant, photosynthesis makes for the interaction of light, warmth and physical substance (ie hydrogen, carbon dioxide, oxygen, nitrogen) to synthesize organic substances into proteins, fats and sugars.
E. Pfeiffer explains  that two processes take place, a darkness and a light process:
- the darkness process (night activity of the plant) leads to formation of starch and sugar. When sugar breaks down it releases warmth.
- a light process: When warmth is liberated, light comes free in the body. This light formation will occasion the formation of protein substances. protein is formed out of light. Enzymes give plants their capacity to combine these forces with mediating substances so protein can be build up. Enzymes contain phospor compounds (adenosine, tryptosine, etc). all substances in which phosphorous and to a small extent magnesium play a role. Note Phosophor was called by the alchemist the carrier of light. Enzymes means or can be read as : 'tremendous transformation at tremendous speeds', they are key to metabolism and life, to health and youthfullness. Fats are formed in plants as a kind of enhancement of the sugar process: when the sugar process makes a somersault and connects several compounds, and then gets rid of some water, the fatty acids appear.
Now mineral science speaks about caloric energy of the combustion of sugar to carbohydrates that gives off warmth energy to the body, but doesn't speak of the light energy given off when proteins are digested under influence of enzymes (and warmth).
This is the important point: Light is absorbed, then liberated in digestion, and we receive light. When we have broken down the protein we receive the light which is released in the body and this has an extremely important effect: it is this that maintains life for the body, especially in the nerveous system (and the brain). When the light metabolism (ai phosphate enzyme transformation) is affected, it affects the life power as well as consciousness.
 - Subnature and supernature in the physiology of plant and man, lecture by Ehrenfried Pfeiffer on 10 Oct 1958 (published 2005)