I don't think anyone has the certain answer to this question. Many nutritionists recommend 15 to 20 grams per day. Based on the results of this study, I have extrapolated a formula for calculating the daily need for collagen:
Ideal weight* x 0.14 : 0.25
The result indicates the daily grams to be taken
*Ideal weight: our weight without excess body fat. If you don't know your ideal weight there is a VERY homemade method to get an idea: subtract 10 from the inches of your height. Here is an example:
Height 1 meter 60 cm
Ideal weight 60-10 = 50 kg

It needs to be diluted in a liquid: hot or cold drink, smoothie, soup, yogurt, omelet. The more liquid there is, the better it will dissolve and the less you will perceive its taste. Although in truth, our collagen is almost tasteless.

Our supplier manufactures in Turkey, which falls under European regulations for collagen production, so it must comply with all relevant European regulations. Companies that produce in Brazil or China are not required to comply with these regulations.

By law, any European collagen producer must comply with the following regulations:
EC 853/2004, which requires, among other things, sterilization with UHT
EC 852/2004
EC 178/2002

The supplier also has a production facility in Switzerland, but the production capacity is MUCH smaller, so we would not have the ability to guarantee almost totally tasteless and odorless collagen. The Turkish production capacity, on the other hand, allows us to always have batches of virtually tasteless collagen.

In addition, our supplier is FSSC 22000 certified, a certification scheme recognized by the Global Food Safety Initiative (GFSI). GFSI certifications are globally recognized food safety standards developed to improve food safety throughout the supply chain. FSSC certification is voluntary

It is also ISO 9001 and ISO 22000 certified

Our supplier has very high quality standards as it also supplies the world's largest food company-Nestlé, which with Vital Proteins is also the market leader in collagen. The accreditation process to become a Nestlé supplier is very complex as the quality standards required are very high. I give an example understandable even to non-technical people: collagen packaging must take place in a clean room. A clean room is a highly controlled work environment designed to minimize the presence of particulate contaminants. Simply put, it is a space characterized by highly filtered air, controlled temperature and humidity, and strict procedures to limit the introduction of foreign particles.

I realize that to some people reading Turkey may generate doubts, but they are just prejudices. Turkey is a great nation, just look at their beautiful television series. We had Cinecittà, and today? On the biggest channel in the world, Netflix, it is the Turkish series that are depopulated, not the Italian ones.

Absolutely not.
Collagen is a protein and only needs to be digested to be absorbed. Vitamin C is needed by our body to synthesize new collagen.

Is it necessary to supplement it? No one currently has a definite answer to this question. When in doubt, since it has no harmful effects and if it is not needed it is simply excreted with the urine, I take it. I use Dr. Giorgini's “pure vitamin C.”.

How much vitamin C to take? It depends on when it is taken and whether it is taken together with carbohydrates, since the transporter within the cell for vitamin C is the same as that used by glucose, and glucose has precedence for use.

All collagen on the market is hydrolyzed. If it were not it would be called gelatin. These are the two products you get from animal collagen.

Let's start at the beginning: collagen is the "glue" that holds the bodies of animals together. In its natural form it is insoluble. Gelatin, what we call "isinglass," is made by partially dredging collagen with heat. Gelatin is soluble in hot water. Collagen powder is obtained through the process of hydrolyzing animal tissues such as bone, skin, and cartilage (our collagen is produced exclusively from the skin of pasture-raised cattle. Collagen powder is soluble in both hot and cold water.

Gelatin forms a gel; collagen does not because it is composed of smaller molecules. Our gelatin has a molecular weight of about 50,000 Da (dalton). Gelatin can have different molecular weights from 20,000 Da to 100,000 Da. The molecular weight of gelatin determines its Bloom, or gelling power; the higher the bloom, the higher the gelling power. Our collagen has a molecular weight between 1,800 Da and 2,000 Da. In contrast, the native collagen molecule (found in animal tissues) has a molecular weight of 300,000 Da.

Why am I telling you all this? During digestion, proteins must be broken down in order to be absorbed; if a protein is smaller in size it is absorbed faster because it is easier to break it down.

I wrote a this insight On all objections to collagen.

A couple of points here: one of the most popular objections is “the molecule is not absorbed whole.” These people believe that you supplement collagen by thinking that the collagen molecule (bovine, porcine, or marine) is absorbed whole from the gut and goes whole into the skin to plump it up. This is nonsense and shows the ignorance of these people on the subject.
1) Any protein to be absorbed must be digested, that is, “cut” into smaller pieces that can be absorbed by the intestines. No company selling collagen claims that it is absorbed whole, partly because they all sell collagen hydrolyzed.
2) All collagen is hydrolyzed: this means that the original molecule is “cut” into smaller molecules, the peptides. In this way it is as if it were pre-digested and thus is more easily and quickly digested. So the collagen was not whole to begin with either.

The reason I supplement collagen is glycine. There are several evidences that glycine is a conditionally essential amino acid: our body cannot produce enough of it for daily needs. This happens especially in certain physical conditions: people with metabolic disorders (obesity, type 2 diabetes, fatty liver) have low levels of glycine. These low glycine levels are also often found in cases of inflammation, insulin resistance, high oxidative stress, advanced pregnancy, and exposure to xenobiotics (substances foreign to an organism's normal metabolism, whether of natural or synthetic origin).

Taking collagen (the absolute richest food in glycine) provides our body with this very important amino acid. Glycine accounts for 33% of the amino acids of which collagen is composed and is necessary for the production of glutathione (one of the most powerful antioxidants produced by our bodies) and many other compounds: heme group, purines, creatine, and bile salts.

Important: You don't have to take collagen, just incorporate foods that contain it into your daily diet: gelatin, nerves, joints, or animal skin. Bone broth, contains interesting levels of collagen only if it becomes gelatinous when it cools.

The absolute richest natural food (which has not undergone processing) in collagen is pig skin.

Our collagen is produced only from cattle skin

“I was advised to take type II collagen for my joints, what type of collagen does yours contain?”
It does not matter to our bodies what type of collagen we take in, because when we ingest collagen in order for it to be absorbed by the intestines it must be “broken down” into the individual amino acids of which it is made or into small groups of them. Whether these amino acids come from type I, II or other collagen makes no difference. Our body will then use some of these amino acids to build new collagen.
However: our collagen contains mainly type I collagen and to a small extent type III collagen, as it is obtained from the skin of (pasture-raised) cattle.

There are multiple types of collagen in our bodies, to date 29 are known, but let's look at just the two main ones:
Type I: about 90% of the collagen found in the human body. It is found in skin, bone, tendons, arteries, fibrous cartilage and cornea.
Type II: hyaline cartilage, vitreous body.

Hyaline cartilage is smooth and flexible but less resistant to traction than fibrous cartilage. It is found in joints (articular cartilage), the ends of long bones (growth cartilage), trachea, bronchi, and nose. It reduces friction in joints, cushions shocks and is involved in bone growth. It is the most common type of cartilage.

Fibrous cartilage is dense, very resistant to compression and traction, and is stiffer than hyaline cartilage. It is found in knee menisci, intervertebral discs, pubic symphysis, and some joints (e.g., temporomandibular). It absorbs shock and provides mechanical strength in areas subjected to high stress or pressure.

Osteoarthritis is a condition related to the deterioration of cartilage. In most cases it is due to aging (more than 70% of people over 55 suffer from it) but it can also be caused by poor posture that makes the joint work poorly. For example, after an accident if we do not properly recover the muscles in the knee, it can work out of alignment and wear down the knee cartilage. Another cause can be vare or vague knees. Obesity also contributes to cartilage deterioration.

Can collagen help? There are several studies (1,2) where collagen intake is observed to be beneficial for joints, but proving that collagen intake can decrease the incidence of osteoarthritis would require very long and very expensive studies because you would need a large group of people for decades. Who knows, maybe someday the Live Better foundation will have us the money to fund this study... It would also be nice to do a study on the incidence of osteoarthritis in ancestral living populations, like the Hadza.

What is certain is that there is plenty of anecdotal evidence: thousands of people around the world report that taking collagen has improved their joints. Unfortunately, anecdotal evidence, however, is not scientific evidence, as it is personal experience that could be influenced by many factors.

You don't have to necessarily take collagen, just habitually consume collagen-rich foods such as: gelatin, ribs, animal skin (the richest one is pig skin), collagen-rich cuts such as bovine tail. (3)

BIBLIOGRAPHY
1) https://pmc.ncbi.nlm.nih.gov/articles/PMC8521576/
2) https://pubmed.ncbi.nlm.nih.gov/30368550/
3) https://fdc.nal.usda.gov/food-search?component=1225

In Europe, the production of gelatin and collagen must comply with strict purity standards. The final product must have a conductivity and therefore a salt content below 2000 µS at 1% concentration. To reach this level of purity, manufacturers use ion exchange resins. These include cationic resins, which remove positively charged ions (cations), and anionic resins, which remove negatively charged ions (anions). This process has a direct impact on the overall purity of the product, ensuring that the heavy metal content is practically zero.

In addition, the limit content of heavy metals is subject to EU reg. 853/2004.

No, there is no such thing as organic collagen because part of the process by which it is produced, hydrolysis, is not allowed in the organic protocol. This is the setssa reason why organic stevia does not exist: one step of production is hydrolysis.

No, that’s incorrect. The claim is based on a misreading of this study. What the study really shows is that marine collagen retains 1.5 times more water than collagen from mammals.

No, there is no such thing as vegan collagen. Collagen is the structural protein found in all animals. In plants this role is filled by cellulose, which is indigestible to us humans. What is sold as “vegan collagen” is a mix of amino acids similar to what is found in animal collagen. Similar but not the same: for example, plant collagen lacks hydroxyproline, one of the most+ abundant amino acids in plant collagen The amino acids used to create “vegan collagen” can be extracted from plants or synthesized in the lab.

It depends. It seems that in order to initiate protein synthesis, it is necessary to consume at least 30 grams of protein or 12 grams of essential amino acids in a single meal. As a reminder, collagen does not contain all the essential amino acids, so throughout the day it is essential to consume foods that contain them: eggs, fish or meat, which are called noble proteins precisely because they contain all the essential amino acids.

If taking it all at once you have a hard time digesting it, you may have a problem with protein digestion. You could try taking a smaller amount and gradually increase it. We made a live on how to improve digestion.

Studies suggest that the best times to consume protein are at breakfast and dinner. To stimulate protein synthesis, it's important to consume at least 30 grams of complete protein (containing all essential amino acids) or 12 grams of essential amino acids in a single meal. Since collagen is not a complete protein, it’s ideal to combine it with other high-quality protein sources such as eggs, fish, or meat in the same meal.

No, collagen provides our body with the amino acids necessary for our body's collagen synthesis. Our body's proteins are constantly renewing themselves, and since collagen is the most abundant protein in our body, we constantly need amino acids to renew it.

In addition, collagen is a food. In fact, I remember that collagen is nothing but hydrolyzed gelatin (which means "cut into smaller molecules").

My personal hypothesis is that our body does not produce enough glycine (read the the study) because throughout human evolution, people consumed all parts of the animal including those rich in collagen. These parts provided a natural source of glycine, which makes up about 25% of collagen. As a result, the body didn't need to produce much of it on its own. Today, however, when we eat meat, we mostly consume muscle tissue, which contains only small amounts of collagen. This means the body no longer receives the same glycine supply it was used to getting for over 2.5 million years. By supplementing with collagen, we're simply restoring a source of glycine that was once a natural part of the human diet.

The study mentioned above suggests that we may face a daily glycine deficit of around 10 grams. Glycine is essential for collagen synthesis and collagen, as a reminder, is the most abundant protein in the human body. Could this glycine shortfall be one of the reasons why, as we age, our skin loses elasticity and our bones become more fragile? I don’t know for sure but it seems logical to think it might be. Glycine is also critical for the synthesis of glutathione (the study) one of the most powerful antioxidants produced by our bodies. Since aging is also linked to increased production of free radicals, could a glycine deficiency lead to lower glutathione levels and therefore a reduced ability to neutralize free radicals? I can’t say for sure, but once again, logic seems to point in that direction.

Indeed!

MAPs contain only essential amino acids, whereas collagen contains mainly glycine, proline, and hydroxyproline, which are nonessential amino acids.

Yes of course. Collagen is a protein, and children need more protein than an adult because they are growing.