Nature's Wealth on the seven species of Israel

Shirat Devorah has an interesting excerpt from a book called Nature's Wealth, about the seven species of Eretz Yisrael, in honor of Tu BeShvat. She writes at the bottom her source:

Source: "Nature's Wealth" -  Rabbi Moshe Cohen Shaouli and Rabbi Yaakov Fisher - based on the teachings of the Rambam

Also available here, perhaps for a bit less. It does look rather nice, and an interesting idea, though I wonder whether it is indeed based on the teachings of the Rambam. The Rambam's son said that we need not believe and defend every medical statement mentioned by Chazal:

…We are not obliged, on account of the great superiority of the sages of the Talmud, and their expertise in their explanations of the Torah and its details, and the truth of their sayings in the explanation of its general principles and details, to defend them and uphold their views in all of their sayings in medicine, in science and in astronomy, or to believe them [in those matters] as we believe them regarding the explanation of the Torah… we find that they made medicinally related statements in the Gemara which have not been justified or validated...

and the Rambam himself made a statement about Chazal relying on contemporary science, such that it may not be correct:

You must, however, not expect that everything our Sages say respecting astronomical matters should agree with observation, for mathematics were not fully developed in those days; and their statements were not based on the authority of the Prophets, but on the knowledge which they either themselves possessed or derived from contemporary men of science. 

If so, it might not be wise, or within the shitta of the Rambam, to cite statements from Chazal about the medicinal properties of various foodstuffs as if this is Torah miSinai, especially if any such statement is not also backed by present-day science.

To give two examples from Shirat Devorah's excerpt, first we will consider what it has to say about figs:

Our ancestors found figs to be of great medicinal value. The Bible mentions dried whole figs as a cure for boils. Rabbi Abraham Ibn Ezra writes that "fresh or dried figs stimulate blood circulation, and thus preserve life". Our Sages said that "one gripped with a powerful hunger should be given figs to eat" because they increase the flow of blood and are rejuvenating.

I am not sure where Ibn Ezra writes this. However, as we have seen several times in the past, Ibn Ezra repeats many things we find in Galen, presumably via Avicenna. This is not Torah miSinai but rather ancient Greek medicine. And often, the now-discredited theory of the four humours is the basis of certain statements. And note that he talks about stimulating blood circulation, where blood is one of the four humours.

Indeed, we find the following statement by Galen on the properties of foodstuffs:

So call it Ibn Ezra and it is suddenly kosher and divine revelation about the nature of these figs.

Further, what does it mean that

 The Bible mentions dried whole figs as a cure for boils. 

? Presumably, this is a reference to 2 Melachim 20:7, where Chizkiyahu had boils, and Yeshayahu instructed how to cure him:

ז  וַיֹּאמֶר יְשַׁעְיָהוּ, קְחוּ דְּבֶלֶת תְּאֵנִים; וַיִּקְחוּ וַיָּשִׂימוּ עַל-הַשְּׁחִין, וַיֶּחִי.

7 And Isaiah said: 'Take a cake of figs.' And they took and laid it on the boil, and he recovered.

These were not mere boils, but Chizkiyahu was near death at this point. But see what Rashi and Radak say about this, citing Chazal:

"In the words of Chazal, is it not that if you place fig sap upon flesh, immediately the flesh is smitten? Rather, this is a miracle within a miracle. Similarly, 'and Hashem showed him wood'. It was bitter wood. Such is the way of Hashem -- with bitter, he sweetens the bitter."

If so, this is not proof that the Biblle mentions dried whole figs as a general cure for boils. This was in fact a miracle.

Even Ralbag does not think it is a cure for boils, though as a rationalist, he sees this as Hashem performing the miracle in a way that one can point out other, quasi-natural causes:

"It is known that Hashem, when He performs wonders, seeks for them some causes, as it is possible, so that it is slightly less strange via the rule of nature. And therefore he commanded to take a cake of figs. For even though it does not have the power to effect this, behold, there is in it some effect in healing abscesses and in their בישול {?}."

And so the statement stands on slightly firmer ground, though it is still a bit shaky. The book might well give its sources, but I am not sure where the statement

Our Sages said that "one gripped with a powerful hunger should be given figs to eat" because they increase the flow of blood and are rejuvenating.

comes from, other than Yoma 83b, or whether this explanation, outside quotes, about increasing the flow of blood is in the Talmud or is the authors' interjection.

Second, in terms of barley, they write:

The Talmud warns that barley may cause intestinal worms. Also, because it is difficult to digest, barley should be avoided by those with gastrointestinal problems.

I don't think the authors mean to conflate the two. But the idea that it causes intestinal worms is find in Berachot 36a:

Over raw cabbage and barley-flour we say the blessing 'by whose word all things exist', and may we not infer from this that over wheat-flour we say 'who createst the fruit of the ground'? — No; over wheat-flour also we say 'by whose word all things exist'. Then let him state the rule for wheat-flour, and it will apply to barley-flour as a matter of course?⁷  — If he had stated the rule as applying to wheat-flour, I might have said: That is the rule for wheat-flour, but over barley-flour we need say no blessing at all. Therefore we are told that this is not so. But is barley-flour of less account than salt or brine, of which we have learnt:⁸  Over salt and brine one says 'by whose word all things exist'? — It was necessary [to lay down the rule for barley-flour]. You might argue that a man often puts a dash of salt or brine into his mouth [without harm], but barley-flour is harmful in creating tapeworms, and therefore we need say no blessing over it. We are therefore told that since one has some enjoyment from it he must say a blessing over it.

If it indeed means that barley-flour causes tapeworms, then this would, in all likelihood, be based on Chazal's belief in spontaneous generation. (The phrase used in the gemara, BTW, is that it is 'difficult for kukyanei'. This in turn is related to the anasakis worms found in fish. And it makes sense that it means that it causes them to exist, similar to how certain other activities are kasha for davar acher, meaning tzaraas.) One could plausibly explain that the tape-worm eggs were laid in the barley flour, and so ingesting it uncooked would allow those tapeworm eggs to hatch inside one's body. But if so, wouldn't the same be true for uncooked wheat-flour?

But one should not simply repeat the Talmudic advice as if it were a certainty. And even more so, one should not malign barley in general, where the Talmud only spoke about barley-flour causing this.

So I don't know that I would rely on this book to accurately and completely tell me about what Chazal said, or to learn practical information from Chazal about the medicinal properties of these foodstuffs. As a coffee-table book, an/or as a place to start (especially if they do have footnotes), it looks nice.

However, it looks like this book might be intended to offer practical medical advice, based on outdated medicine from the time of the Rambam an earlier. Thus:

Nature's Wealth is a unique treasure, discussing Health and Healing plants, based on the teachings of the Rambam! This book is recommended by Professors of Science and Medicine. It features many preventions of illnesses and their care. Compiled by: Rabbi Moshe Cohen Shaouli and Rabbi Yaakov Fisher.

If it is indeed practical advice, I would warn people to stay away. We are commanded by the Torah (Devarim 4:15) "And you shall guard yourselves very well...". Following medical advice from people using medieval medicine, and who even seem to misunderstand / accidentally misrepresent some basic sources in the Torah and Chazal, would not be keeping with that Biblical commandment, IMHO.