I’m not a nutrition specialist (I’m toxicologist) although I’m interested in nutritional aspects. I’ve often asked myself about your question. Certainly, in the discovery phase of new drugs the extrapolation of in vitro efficacy concentrations to the predicted therapeutic doses, by using different methodologies, is crucial. As far as I know, the minimal effect concentrations of most of the individual nutrients (antioxidants, for example) in in vitro experiments are orders of magnitude higher than the plasma concentration levels as nutrients. This is the consequence of two factors: the majority of individual nutrients like as antioxidants are found in few amounts in food and these nutrients are often extensively metabolized in vivo. The difficulties for the in vitro to in vivo extrapolations make questionable some claims about the benefits of some foods based on their individual nutrients.

Kind regards.

I think that discussion does not happen frequently for personal or corporate convenience. The techniques of in vitro digestion are a hyper simplification of the digestive process, and even more so in the nutrition of ruminants. Only for example, the presence of a complex nervous system in the gastro-intestinal tract connected to the central nervous system and that plays an important regulatory role at the hormonal level, especially when there is a toxicological risk, could never be replicated in vitro, converting said techniques in mere tools of partial diagnosis.

Thank you all for the comments, and Yes, Dr. Tranchant, it is a combination of in vitro and animal testing that is often done in nutritional sciences if we need to investigate effects at the cellular level. What we have for essential nutrients are DRIs with ,somehow, a broad range between deficiency and toxicity, but If we spot a certain optimum level/effect of a nutrient using an in vitro cell approach, how can we translate that to an oral intake with equivalent in vivo effect, without using animals. I think the concept of using in vitro and in silico approaches to extrapolate conclusions to the human intake level in nutritional sciences is just not addressed enough, up to my knowledge.

Thanks a lot.

it's a related discussion not exactly the answer to your question but , I don't think in vitro effect of nutrients can be extrapolated to in vivo. for example the whole IG stuff is not at all pertinent in vivo cause you never eat one food alone : the glycemic index is modified by when you eat it (before or after exercise) and what you eat with the carbs (ie bread + butter, pasta + meat etc) so I do not find it relevant. Calories intakes could be discussed too ... for the same reasons