Agreed, tumor decline is greater on melatonin alone. No dispute there, like I said. But the text of the authors is what I misunderstood. This is what they said, that made me conclude that there is no tumor reduction if melatonin and glycine are combined.
Melatonin and glycine alone significantly reduced the tumor volume by 63.2% (p = 0.002) and 43% (p = 0.044) over time, respectively, while tumor volume increased by 8.7% in the controls. Moreover, treatment with melatonin and glycine alone reduced the tumor proliferation index. Most interestingly, the combination therapy did not have any influence on the above-mentioned tumor parameters.
I thought it meant no tumor reduction from the combo. But their numbers show the following:
3.3. Change in Tumor Volume
We observed an 8.7% (−17.5; 40.9) increased tumor volume in the control group and a 63.2% (−3.1; 71.1) decreased tumor volume in melatonin, 43% (−12.6; 70.1) in glycine, and 47.7% (−116.9; 60.6) in combined supplementation with melatonin and glycine at day 8 vs. day 14.
So I summarized that as:
a decrease in tumor volume of
63.2% for melatonin,
43% for glycine; and
47.7% for the combo.
Based on the numbers, II take the sentence “Most interestingly, the combination therapy did not have any influence on the above-mentioned tumor parameters” to mean the combo did not provide synergistic effects, such that it did not improve over melatonin alone, or only marginally improved over glycine alone. They actually state that in their conclusion.
the combined supplementation with these nontoxic substances did not yield additive effects.
But there is a 47.7 reduction in tumor volume by the combo (in rats). So I opined above, that I am happy with that, but want to chase the other benefits of glycine, shown in human studies. So I am willing to forego the additional benefit (in rats) of melatonin alone (63% versus 47.7%).
The sample size is too small
The rats were randomly assigned to either sham groups (n = 10/group) or experimental groups (CRLM; n = 15/group).
to make any conclusions, except
This study suggests an inhibitory function for melatonin and glycine alone in the case of CRLM growth by acting as natural antiangiogenic molecules, with a following angiogenesis-dependent cancer proliferation and immunomodulation. In spite of the fact that dietary melatonin and glycine given separately exert anticancer effects, the combined supplementation with these nontoxic substances did not yield additive effects. To explain these findings, further investigations are warranted.
