Collagen for beautiful skin and healthy joints
Effect, deficiency, dosage, side effects, overdose
- What is collagen?
- Types of collagen
- Collagen as a dietary supplement
- Collagen in the cosmetics industry
- Collagen requirement
- How does collagen work in the body?
- Collagen and the skin
- Collagen and connective tissue
- Collagen and muscles
- Collagen and the skeleton
- Collagen and bone metabolism
- Collagen and joints
- Collagen and cartilage formation
- Collagen and arthritis
- Collagen and rheumatism
- Collagen and blood vessels
- Which foods stimulate the collagen production?
- Collagen side effects and overdose
Collagen, also known as collagen, is a structural protein that is found in many multi-cellular animals and therefore also in humans in the body. It is, among other things, part of the tendons, ligaments or bones.
Parts of the skin also consist of collagen. The substance plays an important role in both medicine and cosmetics. The structural protein is used in body care and make-up to improve the complexion or as a dietary supplement to promote bone and cartilage health.
What is collagen?
Collagen is one of the so-called structural proteins. Structural proteins are all the proteins that primarily serve as a scaffold in the cells and tissues of the body. In contrast to other proteins, they do not act as enzymes, but have the task of giving the cells and tissues their shape and tension. They keep the structures elastic, but at the same time ensure a certain strength. In addition to creatine and elastin, collagen is one of the most important structural proteins in the body.
Collagen always consists of long protein chains, the collagen molecules. These form a left-handed helix, also called a helix. Three of these structures are arranged in a so-called superhelix. Hydrogen bridges between the individual strands ensure the necessary stability.
The collagen fibers are tightly wound so that they have an enormous tensile strength. However, they are hardly stretchable.
Types of collagen
The collagens can be divided into different subspecies. Type I is mostly found in humans. That is why the term collagen is often used synonymously for type I collagen in general usage. A total of 28 different types of collagen are known. 10 other proteins also have collagen-like structures.
Type I collagen
Type I collagen is a fibrillar collagen. This means that the protein is able to form fibrils. These are quite thick and have cross striations. Type I mainly occurs in the following body structures:
- Leather and cornea in the eye
Type II collagen
Type II collagen is also a fiber-forming protein. It is part of the hyaline and elastic cartilage and is also found in the fibrous cartilage and in the vitreous body of the eye.
Type III collagen
Type III collagen is often associated with type I collagen. Like this form, type III is also fiber-forming and therefore belongs to the fibrillary collagens.
Collagen III is an important component of the reticular fibers and thus also of the reticular connective tissue. Reticular fibers are particularly fine strands that are arranged in a reticulated structure. The reticular tissue is part of lymphoid organs such as lymph nodes, spleen or tonsils and palate tonsils. But type III can also be found in the following body structures:
- Bone substance
Collagen IV is a network-like collagen that is mainly found in the basal membrane. The basal membrane, also called the border membrane, separates all of the body's epithelial tissue from the underlying connective tissue.
This protein is a fiber-associated collagen. It is mainly found in the extracellular matrix of the skeletal muscle. Tendons, bone tissue, cartilage tissue, fat tissue, nerve tissue and the skin also contain this type of collagen.
Other types of collagen
Various other fiber-forming, reticular or transmembrane collagens are found in the body. For example, they are part of the placenta or fetal tissue. They are also found in the internal organs, the skin, the growth areas of the cartilage or in the eyes. The exact functions of many types of collagen are still unclear.
Collagen peptides and collagen hydrolyzate
In addition to the forms such as collagen I, collagen II or collagen IV, the names collagen hydrolyzate or collagen peptides are often read in food supplements.
Collagen hydrolyzate is obtained from collagen. In contrast to gelatin, this hydrolyzate is enzymatically modified so that it is readily water-soluble. Collagen peptides are not another form, they are just another name for hydrolyzed collagen.
Collagen as a dietary supplement
Hydrolyzed collagen, also called collagen hydrolyzate, is mostly used in food supplements. It is collagen that has been made water-soluble by certain enzymatic processes. Collagen hydrolyzate is therefore bioavailable and can be processed accordingly by the body.
Most products use collagen derived from animals. Possible sources are, for example, chicken bones or fish skin. But there are also synthetic collagens that can be used as food supplements.
Collagen types in nutritional supplements
If you want to buy a collagen dietary supplement in a shop, you should pay close attention to the type of collagen contained. Dietary supplements with collagen I or collagen II are available. While type I is mainly found in the skin and bone, type II collagen is found particularly in cartilage.
Those suffering from joint complaints are therefore more likely to resort to dietary supplements with type II collagen. Someone who wants to tighten their skin from the inside or strengthen their nails should buy a type I dietary supplement. In reality, however, the separation is not so strict because the types always appear mixed in the body.
Collagen supplements forms
Basically, collagen is available in the form of powder, tablets or capsules. Each dosage form has advantages and disadvantages. Collagen hydrolyzate in powder form is mostly odorless and tasteless and can be easily dissolved in water.
If you don't want to mix it, you can take the collagen in tablet or capsule form. This dosage form is particularly practical on the go and when traveling.
Collagen in the cosmetics industry
Collagen is part of many moisturizing and skin-tightening creams. The structural protein is particularly popular in the areas of beauty and anti-aging due to its firming effect. Shower gel, mascara, lipstick or after-sun lotion are also popular products in the cosmetics industry that contain collagen.
Collagen is not only found in cosmetics, but also in many hair care products. It is supposed to put a film around the hair so that it appears smoother and is also easier to comb.
Collagen in skin care products
In the case of cosmetic products, however, the question arises as to whether the collagen contained can penetrate the top layers of the skin at all. The skin consists of three layers: epidermis, dermis and hypodermis.
In the dermis there are interwoven fine collagen and elastin strands. They keep this middle layer of skin elastic and also store moisture. So that collagen-containing cosmetics can develop their effect, they have to penetrate the epidermis to reach the dermis.
However, this is not possible because collagen as a molecule is too large to penetrate the skin. Nevertheless, the skin can feel better after using cosmetics containing collagen. After drying, cosmetics with collagen contract on the skin, increase the tension and, at least for a short time, eliminate small bumps and/or dents.
The exact need is not known. The body is fundamentally able to independently produce collagen from amino acids. But with increasing age, the body's own production decreases.
You should also know that everyone's need is different. Someone who has joint problems or even cartilage damage has a greater need than someone whose joints are healthy and fit.
In studies carried out on the effects of collagen, the dosage was mostly between 2500 and 10000 milligrams a day, the average intake was around 8000 milligrams.
How does collagen work in the body?
People owe the firmness of their body primarily to the fiber-forming proteins. Collagen is made up of several molecules. Three chain-like proteins twist around each other, forming a helix. Many of these "protein ropes" in turn combine to form collagen fibrils.
The neighboring collagen molecules are offset, so that the fibril itself consists of less dense and dense zones. Bundling of fibrils is called collagen fiber. Collagen can bind water, around 60 percent of its weight is due to the water content.
The bound water plays a role both for passive, mechanical stabilization and for the active role of collagen. For example, researchers have found that collagen contractions caused by water deprivation in the bone compensate for tensile stresses and thus prevent breaks or cracks in the brittle bone structure.
Collagen provides structure
Depending on its nature, collagen in the body's connective tissue makes up a large part of the so-called extracellular matrix. It is the part of the tissue that lies between the cells in the intracellular space. These fine strands in the body also serve to shape organs.
They help regulate the water content of the tissues and keep them elastic. Without collagen, ligaments and tendons would not be as stable and tear-resistant, and the articular cartilage would be less pressure-resistant.
Without collagen, humans could not see either. The filigree collagen fibers ensure the firmness and clarity of the cornea. If the arrangement of these fine strands in the cornea is disturbed, this leads to reduced strength. With such a keratoconus, the cornea bulges forward, so that vision is significantly restricted.
Collagen and the skin
The skin is not only one of the largest organs, it also takes on many tasks:
- Protection from cold and heat
- Protects against pressure, shocks and friction
- Offers protection against chemical damage and radiation
- Prevents loss of heat and moisture
- Prevents pathogens from penetrating through the protective acid mantle
- Acts as a sense organ
It has a special structure, so that the skin can do all these tasks. The top layer of skin, the epidermis, consists of 5 different layers.
The underlying dermis is an elastic layer of skin, which mainly consists of loosely woven connective tissue. The network layer, an important part of the dermis, is formed by a dense network of collagen fibers, which is filled with elastic tissue. This construction creates the firmness, tension and elasticity of the skin.
The lowest layer of skin is the subcutis. It consists of a loose tissue in which fat pads are embedded. The firm strands of the dermis run through this layer as a branch. They also act as straps because they are also attached to the fascia under the skin. The general body fascia, which lies under the skin, also consists of very firm collagen fibers.
Collagen against skin aging
The skin structure changes with increasing age. The individual skin layers become thinner and the number of collagen fibers decreases. This also reduces the fat and water content of the skin. Wrinkles form and the skin is prone to dryness and cracks. All in all, there is a clear loss of elasticity with wrinkles, the skin is no longer as regenerative as before.
Various studies show that collagen can reduce the signs of aging. Song et al. Mice daily collagen hydrolyzate in a dosage of 400 to 800 milligrams per kilogram of body weight. This substitution increased the activity of antioxidant enzymes in the skin. The collagen also counteracted the sagging of the skin, stimulated the formation of fibers in the dermis and thus gave the skin more elasticity.
Collagen and photo-aging
Collagen hydrolyzate may play a crucial role in the treatment and prevention of photo-aging, e.g. skin aging from the sun's rays. Excessive exposure to UV rays can cause the skin to prematurely age. Free radicals are generated in the skin by the UV rays. These damage the skin cells and destroy the supporting structure made of collagen and elastin fibers.
The skin loses moisture and becomes increasingly dry. Photo-aging characters include:
- A sagging complexion
- Light calluses
- Rough wrinkles
- Noticeable pigmentation
Taking collagen hydrolyzate can counteract these symptoms. For example, collagen peptides from fish skin have a positive influence on UV-damaged skin.
Collagen hydrolyzate can increase the moisture content of the skin and contribute to the repair and regeneration of the elastin and collagen strands. Skin dryness and wrinkles are reduced and the skin becomes more elastic again. Red light therapy, an exposure to red light, can support this effect.
Collagen and skin cancer
Various skin cancers are summarized under the umbrella term skin cancer. In addition to black skin cancer (melanoma), this also includes basalioma or squamous cell carcinoma.
Every year in Germany alone, around 20,000 people contract new malignant melanoma. The frequency increases steadily. Two thirds of all melanomas are discovered at a very early stage and accordingly have a good chance of healing.
The main cause of black skin cancer is UV light. Repeated sunburns significantly increase the risk of skin cancer. If you value tanning in summer, you should only stay protected in the sun. There is also a certain hereditary disposition for this type of skin cancer.
Since taking collagen hydrolyzate can stimulate the activity of antioxidant enzymes in the skin, it also protects against the harmful effects of free radicals. In this way, collagen-containing dietary supplements may also help prevent cancer. Further research with this focus could generate more knowledge and expand the possibilities for cancer prophylaxis.
Collagen and connective tissue
The connective tissue is a basic tissue of the body, which consists of connective tissue cells and intercellular substances. The mobile and also the local cells of the connective tissue are embedded in an extracellular matrix, which is largely formed from collagen and other structural proteins. These form a network, in the interstices of which so-called proteoglycans sit.
The collagen fiber structure makes the tissue resistant to tensile forces, whereas the proteoglycans regulate compression forces. In this combination, the tissue serves, among other things, to maintain the shape of the organs.
Conjunctive tissue strengthening
A variety of signs can indicate that the connective tissue is weak. If the skin surface is no longer properly supported, visible dents form in the skin. These are mainly on the buttocks or on the thighs and are also known as cellulite or orange peel.
Stretch marks are also a sign of a connective tissue weakness. These are tissue injuries that occur when the skin is overstretched. They are initially bluish in color, but gradually fade until a light, scar-like streak remains. Many people do not know that weak connective tissue on the legs can also lead to broom tear or varicose veins.
Various articles from current research show that women with connective tissue weakness can benefit from collagen intake. In a placebo-controlled double-blind study from 2015, 105 women with moderate cellulite received 2.5 milligrams of bioactive collagen peptides or a placebo preparation daily.
After a period of 6 months, the group taking the collagen hydrolyzate showed a clear effect. The skin had fewer dents and was much firmer. Normal-weighted women achieved the best results, but the cellulite was also reduced in overweight women.
Collagen and muscles
Many people know that collagen plays an important role in joint and skin health. But the structural protein also has an impact on the muscles.
Because of its low biological value, collagen hydrolyzate was long considered a “useless” protein in weight training. The biological value is a marker of how well the body can convert a food protein into an endogenous protein. It has a good biological value, though collagen lacks amino acids.
Muscle build-up with collagen
The conclusion was drawn that collagen is not suitable for supporting muscle build-up. A wrong conclusion, as an article from 2015 reveals. The aim of this study was to find out whether collagen is suitable for strengthening the muscles.
Study participants were older men who had grade I or II sarcopenia. Sarcopenia is the technical term for age-related muscle loss that affects about 10 percent of all 60 to 70 year olds and up to 50 percent of over 80 year olds.
Half of the study participants received a placebo preparation, while the other half took 15 grams of collagen peptides daily. In addition, all subjects underwent instructed strength training three times a week.
The results were surprising. The participants who supplemented the collagen gained 4.2 kilograms of muscle mass in 12 weeks. In the control group, muscle growth was only 2.9 kilograms. Muscle strength also improved significantly in the collagen group.
Similar results could only be achieved in comparable studies by administering the hormone testosterone. However, taking testosterone is associated with significantly more side effects.
It has not yet been clarified why collagen has such a positive effect on muscle building despite the lack of an essential amino acid. It is believed that the substance contained, hydroxyprolyglycine, activates anabolic signaling pathways in the muscles, which in turn stimulates muscle-building processes.
Collagen and the skeleton
The human skeleton consists of more than 200 skeletal bones. Skulls, spine, pelvic bones, chest and many other bones support the body and are extremely stable. They also serve to protect important organs. Even an upright walk would not be possible without the skeleton.
In order to understand the importance of collagen for bone health, it is important to take a closer look at the bone structure. The outer layer of bark (Compacta) can be distinguished macroscopically from the inner sponge-like framework (cancellous bone).
The tissue that gives the bone its stability is called bone tissue. It consists of bone cells, the so-called osteocytes, which are encased in an extracellular matrix. 95 percent of the organic parts of this bone matrix consist of collagen. Most of these are type I collagens.
Crystals made of the mineral hydroxyapatite are attached to these tensile collagen fibrils. Due to the attachment in a defined orientation, the collagen fibers in combination with the mineral give the bone its compressive strength. Without collagen, the bones would not be stable and resilient.
Collagen and osteoporosis
Osteoporosis, popularly known as bone loss, is a disease characterized by the loss of bone mass. The bones lose stability and strength and break faster.
Osteoporosis is particularly common in women after the menopause. This is probably due to hormonal processes. According to recent research findings, oxidative stress and changes in the collagen structure also seem to play a decisive role.
Oxidative stress, such as that which arises when there is an increased accumulation of harmful free radicals, but also an increased supply of blood sugar accordingly leads to an increase in the development of so-called advanced glycation end products (AGEs). These glycated reaction products impair the cross-linking of the collagen strands and thus cause an unstable bone structure.
In addition, the body's collagen production decreases with age. This also affects the stability of the bone.
Collagen and bone metabolism
Scientific studies suggest that taking collagen can improve bone health. A 2004 study in mice showed a significant increase in bone density after four weeks of collagen administration.
Collagen can also be combined with other medications for osteoporosis therapy. The hormone calcitonin is used to treat osteoporosis, which can lower the increased rate of bone loss. Supplementing with collagen can be useful here to counteract bone loss.
Collagen and joints
A mobile connection of two or more bones is called a joint in medicine. There are around 360 joints in the human body. The largest joints include the knee and hip joint.
A joint always consists of two bones that are shaped so that they mesh well. The end of one bone is called the condyle, the end of the other bone is called the socket. Both bone ends are covered with a thin layer of cartilage.
The joint gap is located between the bone ends. This is filled with synovial fluid, also called synovial fluid. Together with ligaments, tendons and muscles, the joint capsule that surrounds the entire joint forms a protective shell.
The cartilage layer and the joint lubrication enable smooth and, above all, painless movements of the joint. If there are impairments here, the joint can often only be moved with pain.
The cartilage tissue on the articular surfaces consists of cartilage cells (chondrocytes) and the extracellular cartilage matrix. This consists of a basic substance in which collagen fibers are embedded like a net. A loss of collagen is always accompanied by a loss of cartilage.
Collagen and cartilage formation
Once removed, cartilage cannot be rebuilt. Many doctors still hold this opinion. But recent studies suggest that regeneration of the damaged cartilage is quite possible.
If the cause of the cartilage abrasion is removed, the cartilage substance can rebuild itself. The interesting question is to what extent collagen can support cartilage build-up.
In the event of cartilage damage, more and more cartilage precursor cells, so-called chondrogenic progenitor cells, migrate into the damaged region. These ultimately transform into cartilage cells to compensate for the cartilage damage. For this regeneration, however, the cells need the right nutrients and building blocks.
Studies show that collagen hydrolyzate can increase the activity of the chondrocytes so that they produce more cartilage. At the same time, collagen also serves as a building block for this cartilage substance.
Collagen and arthritis
Arthritis is the medical term for joint wear. Arthritis is one of the degenerative joint diseases that are associated with a decrease in cartilage tissue. In principle, arthritis can develop in every joint. However, the knee and hip are particularly often affected.
Typical symptoms of osteoarthritis are the pain when starting and the morning stiffness of the joints. The first movements after a long break are painful, but after a short period of activity, the symptoms subside quickly. The stiffness of the joints in the morning usually lasts no longer than 30 minutes. Other symptoms include:
- Tenderness of the joints
- Limited joint mobility
- Rubbing or grinding noise in the joint when moving
- Joint swelling
The exact cause of arthritis is controversial. On the one hand, mechanical abrasion helps reduce cartilage. But it also seems that misdirected chondrocytes play a role in the development of the joint disease.
When the cartilage is worn out, it can no longer adequately protect the bone structures of the joint from impact and friction. In order to protect itself, the bone increasingly forms bone substance. As a result, the joints deform and also thicken.
It isn't uncommon for the affected joint to become inflamed with overheating, reddening of the joint and joint effusion. This is called activated arthritis.
There are several risk factors for arthritis:
- Gender (women become ill more often)
- Injuries that cause joint instability
- Joint-stressing hobbies or joint stress at work
- Genetic family history
Treat arthritis with collagen
The primary goal of conservative osteoarthritis treatment is to slow the wear and tear of the joints and to alleviate the joint complaints. In addition to various medications or orthopedic aids, physiotherapy also helps. To prevent surgical intervention, the additional intake of collagen-containing food supplements can be useful.
Several studies have found that supplementation helps improve the quality of life for osteoarthritis patients. The structural protein also shows a better effect than chondroitin or glucosamine, which are also often recommended for the treatment of arthrosis.
Crowley et al. used the Western Ontario McMaster Osteoarthritis Index (WOMAC) in their 2009 study to correctly assess their subjects' complaints. After taking Type II collagen for 90 days, the score on this scale was reduced by around 30 percent. The patients themselves assessed their pain by around 40 percent less than before the treatment using the visual analogue scale.
Collagen and rheumatism
Even though the term rheumatism is popularly used for joint complaints, it is not a single disease, but a whole group of diseases. The rheumatic type includes complaints on the musculoskeletal system, which are associated with pain and often with functional restrictions.
In addition to the bones and muscles, collagens and organ functions are also affected. Around 400 individual diseases are now known that can be assigned to the rheumatic type. Known rheumatic diseases are:
- Rheumatoid arthritis (chronic polyarthritis)
- Ankylosing spondylitis
- Collagenoses such as scleroderma or lupus erythematosus
The exact causes of rheumatism are unclear. It is common to many diseases of the rheumatic type that the immune system attacks the body's own structures. It is therefore an autoimmune disease. In collagenosis, for example, the immune system considers the collagen in the connective tissue to be foreign and forms antibodies against it.
Since collagen occurs in many organs, various organ systems such as mucous membranes, vessels, skin, lungs or the heart can be affected.
Collagen in rheumatoid arthritis
One of the most common diseases of the rheumatic type and also the most common chronic arthritis is rheumatoid arthritis. Worldwide, up to 1 percent of the population is affected by the disease.
Rheumatoid arthritis can develop gradually or suddenly. The main symptoms include swelling and overheating of the joints as well as morning stiffness. The symptoms typically appear symmetrically on the basic and central joints of the fingers or toes. However, other joints such as the hip or ankle joints can also be affected.
Rheumatoid arthritis has not yet been curable. The aim of treatment is therefore to stop the progress of joint destruction and to relieve the pain. Scientific research suggests that collagen may help here.
60 patients with rheumatoid arthritis participated in a study by Harvard University. Before the study, they discontinued all immunosuppressive drugs and were divided into two groups. One group received a placebo preparation, the participants in the other group took collagen over a period of 90 days.
There were no changes in the blood count of the two groups after these three months, but the differences in the state of health were clear. The joints were less swollen and less sensitive to pressure. While the mobility of the participants in the placebo group deteriorated, this could be prevented in the collagen group. The study participants who took collagen also needed pain relievers less often.
Collagen and blood vessels
A dense network of blood vessels supplies the organs of the body with blood that is rich in oxygen and nutrients. The same number of blood vessels are used to remove the venous blood. The arteries of the body must be elastic for optimal care and to compensate for fluctuations in blood pressure.
Elastin and collagen are responsible for the elasticity of the vessels while at the same time being stable against mechanical stress. With increasing age or with diseases such as diabetes mellitus, the elasticity of the blood vessels decreases. This makes them susceptible to the development of vascular calcification (arteriosclerosis).
Atherosclerosis caused by collagen deficiency
So-called arteriosclerotic plaques arise from oxidative stress, which leads to a chronic inflammatory process in the vessel walls. The vascular endothelium normally produces substances that prevent blood cells or platelets from adhering to the vascular wall.
If the endothelium malfunctions, for example due to risk factors such as smoking or being overweight, the endothelial cells release adhesive molecules. These cause certain cells from the blood to penetrate into the wall of the vessel and convert there into phagocytes, which in turn store fats and cholesterol components. This sets in motion an inflammatory process that ultimately contributes to the breakdown of collagen and thus to the development of vascular calcification.
Atherosclerosis prevention with collagen
A scientific article from 2017 provides evidence that collagen could be suitable for the prevention of arteriosclerosis and thus also for the prophylaxis of diseases such as heart attacks or strokes.
When taking 16 grams of collagen per day, an improvement in cholesterol levels was observed in the study participants after 6 months. While the "harmful" LDL cholesterol decreased, the values of the "good" HDL cholesterol improved. There was also a significant reduction in the cardio-ankle vascular index (CAVI). This index is an indicator of the stiffness of the joints. The higher the value, the greater the risk of cardiovascular events such as heart attack or stroke.
Igase et al came up with a similar result in their study from 2018. They wanted to find out whether the supply of collagen has an effect on the pulse wave velocity (brachial-anke pulse wave velocity). This value provides information about the speed at which a pressure wave passes through the artery. The more rigid the vessel walls and the smaller the vessel volume, the higher the value. Increased values in the measurement of pulse wave speed are found in arteriosclerosis but also in other diseases that are associated with changes in the vascular system.
In the study, half of the participants received placebo, while the test group consumed 2.5 grams of collagen per day. According to the study, the test group showed a significantly lower pulse wave speed as compared to the placebo group.
Which foods stimulate the collagen production?
The body needs various vitamins and minerals for collagen production. With a balanced diet or a targeted supplementation you can support the organism in this important collagen production.
Vitamin E can inhibit the activity of collagenase and thus counteract the breakdown of collagen. Vitamin C, on the other hand, is one of the most important free radical scavengers and an essential co-factor in collagen production. In addition, vitamin C activates the opponents of collagenase and thus also prevents collagen breakdown. Foods that are rich in vitamin C and vitamin E and therefore play an important role in the collagen production include:
- Superfoods like acai
- Rose hip
- Sea buck-thorn
- Brussels sprouts
- Vegetable oils
Silicic acid is important for the formation of connective tissue fibers in the skin and other tissues. It supports the activity of the enzyme prolyl hydroxylase, which is of great importance in collagen biosynthesis. Grains such as oats, barley or millet, as well as nettle and field horsetail are important sources of silica.
Collagen side effects and overdose
No toxic effects were found in animal experiments, even at a dosage of 5000 mg/kg body weight. The use as a dietary supplement is therefore considered safe. The following side effects can occur in rare cases:
- Stomach pain
If you are unsure if you can tolerate the collagen well, you should order online from a shipping company that offers a satisfaction guarantee. Here, the customer can contact the shop if he/she is not satisfied with the quality of the product and receive a refund or a new item in exchange.