Are Old Testament Dietary Laws God’s Prescription for Good Health Today?

No.

1 Timothy 4:1-5:
Now the Spirit speaketh expressly, that in the latter times some shall depart from the faith, giving heed to seducing spirits, and doctrines of devils;
Speaking lies in hypocrisy; having their conscience seared with a hot iron;
Forbidding to marry, and commanding to abstain from meats, which God hath created to be received with thanksgiving of them which believe and know the truth.
For every creature of God is good, and nothing to be refused, if it be received with thanksgiving:
For it is sanctified by the word of God and prayer.

The passage above shows that everything is now lawful (with the slight exceptions in Acts 15:20, though I doubt that you were planning to eat meat offered to idols or drink blood anyway).

Acts 15:20:
But that we write unto them, that they abstain from pollutions of idols, and from fornication, and from things strangled, and from blood.

The Law of Moses was never given to the Gentiles.  God never told Gentiles not to eat pork products.  For that matter, He never gave the Ten Commandments to the Church, either, though you can see parallels of all but one of them in the New Testament.  You still don’t have the right to run out and commit adultery!  The law of love in the New Testament precludes that, as do the multiple warnings to flee fornication or even the appearance of evil.  The law of love actually goes beyond the Law because men look for loopholes where there are laws to try to justify wrong actions that they want to do.  Doing everything under the umbrella of love precludes harmful actions even if they are NOT specifically addressed in the Law of Moses.

However, what you eat has nothing to do with the law of love unless what you’re eating makes someone eating with you stumble.  Beyond that, it is clear that we can eat whatever we want.  The whole idea of having to keep the Law today is vigorously disproved in Acts 15:24 and elsewhere; much of Acts 15, the book of Galatians and the book of Colossians are devoted to this topic.)

Even in Peter’s rooftop vision, he was told to arise, kill and eat ceremonially unclean animals (as far as the Law was concerned).  If God were still enforcing the ceremonial “uncleanliness” laws concerning diet, He would have been telling Peter to sin in the vision!

Acts 10:9-16:
On the morrow, as they went on their journey, and drew nigh unto the city, Peter went up upon the housetop to pray about the sixth hour:
And he became very hungry, and would have eaten: but while they made ready, he fell into a trance,
And saw heaven opened, and a certain vessel descending unto him, as it had been a great sheet knit at the four corners, and let down to the earth:
Wherein were all manner of fourfooted beasts of the earth, and wild beasts, and creeping things, and fowls of the air.
And there came a voice to him, Rise, Peter; kill, and eat.
But Peter said, Not so, Lord; for I have never eaten any thing that is common or unclean.
And the voice spake unto him again the second time, What God hath cleansed, that call not thou common.
This was done thrice: and the vessel was received up again into heaven.

The question then could be asked, “Why would God forbid certain foods that aren’t really harmful under the Law?”  The answer is that these observances were part of the ceremonial laws concerning ritual uncleanness.  There were many other forced actions if you wanted to stay or become ceremonially clean.  Many of these laws were hygiene-related, even going to great extremes. But the statement that you don’t have to refuse meats today because every creature is good means that you can have all the lobster meat you want without it being a sin under the New Covenant.  (This is good, because I really like lobster!)  If lobster (and all the other “unclean” meats) were harmful, then they would NOT be good (contrary to what Paul told Timothy) and God would surely have extended the dietary prohibitions for our own good.

It is still possible to overdo things and eat or drink too much of something.  For example, you would not want your sole source of hydration to be “energy drinks” and your sole food to be hot fudge brownie sundaes.  But God leaves such matters up to our discretion rather than legislating them in the New Covenant.

People keep writing books on the supposed health benefits of the Old Covenant dietary laws, but NOTHING in the New Testament validates the idea that Old Testament eating is the healthiest eating.