Pet Food Glossary of Ingredients
Are the building blocks of proteins, the biological workhorses of nearly every structural component of the body (see protein). Proteins are found in all living things including animals, plants and fungi. Dogs require 10 essential amino acids and cats 11 and these can only be provided by the diet. The essential amino acids are arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. In addition, taurine is an essential amino acid in cats. As well as the biological building blocks of life, amino acids are also an important source of energy. Obtaining the right balance of amino acids depends on the quality of protein in the diet (see protein).
Aniseed is a powerful plant that is rich in many nutrients and boasts a wide array of health benefits. It is recognised as having anti-fungal, antibacterial and anti-inflammatory properties and can support a healthy gut.
Antioxidants work to ‘mop up’ free radicals, which are the waste by-products of oxidation reactions during normal cell metabolism. Free radicals are also produced when the body’s cells are damaged by disease, and external factors such as toxins and radiation are thought to be contributing factors in ageing, cancer, arthritis and many other degenerative diseases. Vitamin E and Pro-Vitamin A, Vitamin C and flavonoids are all good examples of powerful antioxidants found naturally in fruit and vegetables. Other antioxidants include selenium and zinc.
All dry pet foods require an antioxidant in order to prevent the fat components in the formula from becoming rancid on exposure to air. OSCAR pet foods are preserved naturally using tocopherols derived from fruit and vegetables.
Considered a highly digestible, highly palatable meat source for dogs. Besides protein beef is an excellent source of zinc (see zinc), iron (see iron), selenium (see selenium) and vitamins providing the dog and cat with essential nutrients and amino acids (see amino acid).
A group of red, orange, and yellow pigments called carotenoids found in fruits, vegetables, and whole grains, such as spinach, sweet potato and carrots. Beta-Carotene and other carotenoids have antioxidant properties.
Is the dried residue from the production of sugar from the sugar beet plant. It is an excellent source of both soluble and insoluble fibre. Certain fibres can help an animal feel fuller for longer helping to reduce obesity, prevent constipation and diarrhoea. OSCAR use beet pulp sourced in the UK.
Recognised as a ‘superfood’ it contains anthocyanins (the purple colour pigment),
An excellent source of the B-complex vitamins (see Vitamin B) and amino acids (see amino acid). OSCAR source their brewer's yeast from Germany.
Recognised as a ‘superfood’ it is a great source of Vitamin K and C, a good source of Folic acid and also provides Potassium and Fibre.
Required to maintain the bones and teeth, the nervous system and the clotting ability of the blood. Growing and nursing animals require higher levels of calcium in the diet. Calcium levels in the body are critically linked to the levels of phosphorus. Too high phosphorus and too low calcium will lead to brittle bones that are easily fractured. Growing animals are particularly sensitive to excess amounts of calcium which can lead to bone and joint deformities. Calcium is found in eggs, milk, cheese, green vegetables and whole grain foods.
Derived from the pulp of fibre rich plants. In cat formulas, it can help reduce the formulation of hairballs. It can also improve stool quality in your dog and cat.
Considered to be a prime source of protein because it is highly palatable, highly digestible and has a high biological value, meaning that it is easily broken down once consumed into its constituent amino acids (see amino acid). OSCAR use meat from chickens reared in the UK that does not contain the heads, feet or feathers, except in trace amounts which is unavoidable.
Made by simmering the meat in water to create a nutrient rich stock. OSCAR use stock in their foods to add flavour.
Chicken oil has a high and consistent level of the essential fatty acids that are necessary for a healthy skin and coat and is considered to be the highest quality fat source available. OSCAR use only pure chicken oil and it is an excellent source of energy.
A sulphated glycosaminoglycan (GAG), and an important structural component of cartilage found within the joints that allows the free movement of one bone against another. All the joints in the body, especially those of the limbs such as the shoulders, elbows, hips and knees, undergo gradual degenerative changes due to wear and tear. This is what causes osteoarthritis, a disease where the joints and surrounding tissues become inflamed, less mobile and painful.
Supplementing the diets of dogs and cats with chondroitin (for example as chondroitin sulphate derived from cattle cartilage or mussels) can help increase mobility and decrease the pain associated with osteoarthritis. Generally, chondroitin supplements are more effective when combined with glucosamine.
Copper (as Copper sulphate pentahydrate)
An essential trace mineral that is a source of copper. Copper is essential for many functions in your pet’s body including the health of the immune system and iron absorption.
Rich with antioxidants and nutrients that can help support your pet’s immune system and decrease inflammation. The red berry is high in Vitamin C, fibre and potassium. Cranberries can improve bladder health and fight bacteria amongst other benefits.
Egg yolks are a good source of fat, whilst egg whites contain a highly digestible source of protein with a high nutritional value. Eggs are also a valuable source of vitamins and minerals. OSCAR source dried egg from France.
Contains B vitamins and several dietary minerals such as calcium, iron, magnesium and manganese. It is a culinary herb and has antioxidant properties.
A valuable foodstuff supporting glucose metabolism and maintenance of intestinal health. It is also recognised as being an antioxidant.
Comes from the processing of oily fish like salmon. As well as providing energy fish oil contains omega-3 and omega-6 (essential fatty acids). Fish oils can help support many health conditions including joint and skin conditions.
A source of high-quality protein, energy, minerals, vitamins and other nutrients. Fish meal derived from oily fish is also a rich source of the omega-3 essential fatty acids.
Fibre in the diet is a carbohydrate which is important for maintaining normal gastrointestinal transit time and motility. There are 2 kinds of fibre: soluble and insoluble. Soluble fibre is a good food source for the ‘friendly bacteria’ in the large intestine, which is why it is called a prebiotic. Soluble fibre is used for the production of short chain fatty acids that provide energy to the cells in the intestine. Fibre helps to slow down gastric emptying enabling more time for absorption and digestion of food. It also helps with peristalsis (the contractual movements that move food along the digestive tract).
Fructo-oligosaccharides, derived from the chicory plant, favour the growth of beneficial bacterial colonies whilst reducing the colonies of potentially harmful bacteria in the small intestines.
A natural disaccharide sugar and one of the building blocks of glycosaminoglycan found in the cartilage within joints. Like chondroitin, glucosamine is an important structural component of joints, and along with chondroitin supplementation, it can help increase mobility and decrease the pain associated with osteoarthritis.
Glucosamine is used to support the prevention and treatment of osteoarthritis and contributes to joint cartilage elasticity. It helps to stimulate the formation of new cartilage and works together with chondroitin and MSM.
A composite protein (or multiple proteins), specifically gliadin and glutenin, that can be responsible for causing gluten sensitive gastrointestinal/skin diseases in humans and dogs. Present in wheat, barley, rye, and some oat-flour grains.
(Chicken, Lamb and Salmon) are broken down into smaller chains of amino acids in order to make the end product more digestible and nutritious (less allergenic and highly digestible). The hydrolysis of proteins in hypoallergenic diets can help minimise dietary intolerances in cats and dogs.
A general term used to describe foodstuffs that are less likely to induce dietary-related allergic responses in cats and dogs with specific food sensitivities. Hypoallergenic diets can consist of a novel (a source of food the dog or cat has not been exposed to previously) protein and or carbohydrate source and can also be foods that contain hydrolysed protein.
(also known as Ash) refers to the amount of minerals present in our recipes such as calcium, phosphorus, and magnesium. It is determined by burning all the rest of the contents and looking at the minerals (inorganic substances) that are left behind. They are needed to balance body fluids and used to support strong bones and teeth.
Iron (as Iron sulphate monohydrate)
An essential trace mineral. Iron is needed for the formation of haemoglobin, the molecule within red blood cells responsible for carrying oxygen around the body which fuels every living cell. Low levels of iron affect the formation of red blood cells, leading to anaemia. The best sources of iron are organ meats, such as liver and kidney; other meats such as fish and whole grains are also adequate sources.
Iodine (as Calcium iodate anhydrous)
A dietary source of the mineral iodine, a mineral essential for thyroid health. It can be found naturally in seaweed and ocean fish.
Derived from seaweed and is a rich source of iodine (see iodine).
Often used in hypoallergenic diets (see hypoallergenic, hydrolysed protein). It is a good source of protein (see protein) and also rich in calcium (see calcium). Lamb is produced from meat trimmings and the clean parts of the carcass which is cooked and dried. OSCAR source Lamb from the UK.
A non-essential amino acid (see amino acid) or vitamin like substance. It plays an important role in the production of energy by transporting fatty acids to the mitochondria (the energy areas in the cells). Supplementation of L-carnitine may help boost fat metabolism in the skeletal and cardiac muscle, thereby supporting healthy weight loss and aiding heart function. L-carnitine may also benefit working dogs by helping overall performance and improving stamina.
An essential amino acid (see amino acids). Along with its role in the synthesis of proteins in the body, it is also used to synthesise melatonin and serotonin. Melatonin is a hormone that plays a role in daily sleep-wake cycles and serotonin is a neurotransmitter that plays a role in the regulation of mood states and emotions. Low levels of available serotonin in the brain are associated with reduced feelings of well-being, anxiety, depression and aggression.
A dietary fibre that can be found in the cell walls of all plants and offers a range of benefits, including supporting hairball defence by aiding the movement of unwanted hair through the digestive system. Lignocellulose can also help to improve digestive health and improve stool quality.
Linseed (Flax seed)
A good source of fibre, omega-3 fatty acids and Lignan (known to have antioxidant properties). It is also rich in Vitamin B1, B3, and many minerals including Manganese, phosphorus and Magnesium. OSCAR use Linseed produced in the UK.
Contains Lutein (an amino acid). Rich in chlorophyll, carotene, protein, calcium and other minerals. Also, vitamins from the B group as well as Vitamin C, Vitamin D, Vitamin E, and Vitamin K.
A naturally occurring carotenoid. Lutein is found in the lens of the eye where it filters blue light and protects the retinal cell from light damage. Lutein is found in many fruits and vegetables including dark green leafy plants, kale and spinach. OSCAR lutein is sourced from Lucerne.
Required for more than 300 biochemical reactions in the body. It is a key element for the conduction of nerve impulses along nerves and for the electrical activity of heart muscle that controls the beating of the heart. It also helps to regulate blood glucose levels and aid in the production of energy and protein. Magnesium is found in meat, fish, and cereals.
A starch, and therefore a member of the polysaccharide family of carbohydrates. Its primary function is to supply a steady source of energy throughout the day to help maintain stable blood sugar levels. Uncooked starches are not easily digested, but when well-cooked they are almost 100% digestible. Potatoes and sweet potatoes are also a good source of starch.
Required in many metabolic processes such as the conversion of amino acids, conversion of glycerol to glucose, producing energy, health and maintenance of bone and cartilage in joints. Manganese is also associated with free-radical scavenging by antioxidants. To ensure dogs get enough manganese in their diet, most manufacturers add it as a supplement.
A dietary source of the mineral manganese.
Carbohydrate in the diet providing fibre which is important for maintaining normal gastrointestinal transit time and motility. There are 2 kinds of fibre, soluble and insoluble. Soluble fibre is a good food source for the ‘friendly bacteria’ in the large intestine, which is why it is called a prebiotic. Soluble fibre is used for the production of short chain fatty acids that provide energy to the cells in the intestine. Fibre helps to slow down gastric emptying enabling more time for absorption and digestion of food. It also helps with peristalsis (these are the contractual movements that move the food along the digestive tract). Mannan-oligosaccharides, derived from the cell walls of yeasts, have similar effects on the intestinal flora.
Made up of meats that have been ground down and cooked. This reduces the fat content and provides a protein rich source. It is a good source of glucosamine for joint health and helps to strengthen and maintain pets’ muscles. Meal does not include feathers, heads, feet or entrails.
A form of organic sulphur which shows effectiveness in reducing pain and inflammation associated with osteoarthritis. MSM works well alongside Glucosamine and Chondroitin.
Inorganic compounds used for many different metabolic processes in the body such as the formation of bones and teeth, the conduction of nerve impulses, the activation of enzymes and the maintenance of electrolyte balance.
There are 2 categories of minerals based on the quantities found in the body. Macro minerals are present in significant amounts and include calcium, chloride, iron, magnesium, phosphorus, potassium, sodium and sulphur. Trace minerals are present only in tiny amounts and include chromium, copper, cobalt, iodine, manganese, selenium and zinc. The mineral requirements of cats and dogs vary depending on factors such as age, size, gender and activity.
Indicates the relative water content of the food.
Nucleotide Yeast Extract
Nucleotides are the structural units of DNA and RNA (just as amino acids are the building blocks of proteins). They are derived from a special type of nutritional yeast. Nucleotides are involved in the maintenance of a healthy immune system as they help the defence cells to replicate more quickly when challenged. They interact with some of the B vitamins where they facilitate the absorption of nutrients in the small intestine that can improve the efficiency of digestion.
OSCAR use an inactive yeast as a carrier for nucleotides, and this is also a good source of essential B vitamins. Nucleotide Yeast Extract can significantly increase the effectiveness of vaccination programmes for dogs.
Dogs and cats are incapable of producing Omega-3 fatty acids on their own, so they must get them through their diet. The most common fatty acids added to pet food are Docosahexaenoic acid (DHA) and Eicosapentaenoic acid (EPA). Whilst not essential for adult cats and dogs, Omega-3 fatty acid is required for vision and brain development in young puppies, helping manage inflammation in skin and joints, and a whole host of other physiological functions.
In the ageing animal, Omega-3s can help prevent deterioration of cognitive function by improving brain oxygenation. Rich sources of Omega-3s include flaxseed oil, whilst the most abundant source of DHA and EPA is marine fish oil.
Arachidonic acid and linoleic acid are essential fatty acids belonging to the Omega-6 family of polyunsaturated fatty acids. Dogs can synthesise arachidonic acid, but cats are unable to do this, making arachidonic acid an essential nutrient in the diet of cats.
Omega-6 fatty acids are essential for healthy reproduction, growth, immune function, and skin and coat health. Arachidonic acid can be found in animal fats such as beef tallow and poultry skin. Linoleic acid can be found in vegetable oils such as sunflower oil.
Contains polyphenols, including numerous flavones. It is a culinary herb and has antioxidant properties.
A source of flavonoids and antioxidants and a culinary herb. It also has breath freshening properties.
Rich in essential vitamins and antioxidants. Peas are a grain free source of carbohydrate. OSCAR use peas sourced in the UK.
A good source of Vitamin A and C. Also contains minerals such as calcium, magnesium, manganese, phosphorus and potassium. It is also recognised as a powerful antioxidant.
Required to maintain the bones and teeth. Other roles include its presence in cell membranes and the supply of energy at cellular level. Growing and nursing animals require higher levels of phosphorus in their diet. Phosphorus levels in the body are critically linked to the levels of calcium, too high phosphorus and too low calcium will lead to brittle bones that are easily fractured. Growing animals are particularly sensitive to calcium / phosphorus imbalances which can lead to bone and joint deformities. Phosphorus is found in meat and bones, dairy products and cereal grains.
A rich source of Vitamin C, polyphenols and anthocyanins, which have antioxidant and anti-inflammatory properties.
An excellent source of carbohydrate, which, when cooked, is highly digestible and therefore ideal for dogs with sensitive digestion. Potatoes are gluten free and rich in Vitamin C, B6 and potassium.
Poultry oil has a high and consistent level of the essential fatty acids that are necessary for a healthy skin and coat and is considered the highest quality fat source available. OSCAR use only pure poultry oil. It is an excellent source of energy.
A dry, sterile product derived from processing poultry meat such as chicken.
White rice is high in energy and low in protein. Brown rice is often perceived as the healthier option, but white rice is simply brown rice with the husk removed. Rice husks are of little nutritional value in dogs and are therefore excluded from OSCAR diets. Rice is a very digestible energy source and is used to promote a steady energy release throughout the day which also helps stabilise blood sugar levels. Rice is gluten free.
Can be a great source of omega-3, which may decrease inflammation, support the immune system, support cognitive function and help keep your dog's coat looking healthy and shiny. Salmon is also a good protein source and can be used as an alternative to meat sources.
A rich source of minerals and vitamins.
Selenium (as Sodium selenite)
is required for the activation of thyroid hormone from its precursors. It also supports the immune system and is involved with Vitamin E as an antioxidant. Sources of selenium include meat, fish and some cereal grains.
Recognised as a ‘superfood’ it is an extremely nutrient rich vegetable. It contains high amounts of carotenoids, Vitamin C, Vitamin K, Folic acid, Iron and Calcium.
An excellent source of gluten free carbohydrate. Sweet potato also contains beta-carotene, an antioxidant, giving the flesh its orangey colour.
is one of the most important macro minerals because, along with potassium and chloride, it is responsible for the conduction of nerve impulses within the brain, nervous system and for the maintenance of acid-base electrolyte balance in all the bodily fluids. Sodium is constantly being excreted by the kidneys into the urine, so a constant supply is needed in the diet, usually in the form of sodium chloride, or in some other form such as sodium bicarbonate (baking soda). Sodium chloride, or common table salt, is not added to pet foods as a palatability enhancer, but it may be added to some foods where there is insufficient present naturally in other ingredients. Sodium is found in meat, fish, bone and blood meal.
A source of gluten free carbohydrate.
An amino acid that is essential for cats and must be provided in their diet from meat. Taurine is a particularly important amino acid for heart function and a deficiency may result in dilated cardiomyopathy (DCM) where the heart becomes weakened and enlarged. It is also important for healthy vision and reproduction. Taurine is found in meat and fish, and concentrations are particularly high in heart and skeletal muscle.
An essential oil that can have antiseptic properties. It is a culinary herb and contains Vitamin C, A and K, iron, manganese, and calcium.
Antioxidants of natural origin. OSCAR pet foods are preserved naturally using a tocopherol blend of fruits and vegetables in addition to Vitamin E. All dry pet foods require an antioxidant to prevent fat components in the diet from becoming rancid on exposure to air – thus prolonging their shelf life.
A rhizomatous herbaceous perennial plant of the ginger family, Zingiberaceae. Turmeric contains curcumin: a polyphenol that has antioxidant and anti-inflammatory properties.
Also known as ghost probiotics, they are defined as inactivated (non-viable) microbial cells, which, when administered in sufficient amounts, can offer health benefits to the animal that are similar to their probiotic counterparts. Tyndallised bacteria are paraprobiotics that support digestive health and immunity. They help to reduce intestinal inflammation and improve well-being and stool quality.
The most important nutrient in the body making up approximately 70% of an animal's live weight. An animal could lose almost all of its body fat and a quarter of its protein and still survive; yet a 15% loss of water is likely to result in death.
Water within the cells is necessary for most metabolic processes and chemical reactions. It is important for temperature regulation and is an essential component of normal digestion. Elimination of waste products from the kidneys also requires a large amount of water.
There are 2 main sources of water, drinking and ingested water (from the food), and metabolic water produced during the metabolism of protein, carbohydrates, and fats.
A great source of energy and protein, that also contain fibre and B vitamins. The energy from grains is the slow-release kind that is good, it takes time to enter the bloodstream which means your pet gets a steady supply of energy instead of spikes and drops in blood sugar. Wheat contains gluten. OSCAR source a top-quality wheat grown in the UK.
A group of nutrients that are required for many metabolic processes within the body. There are 2 categories of vitamins based on their solubility, the water-soluble vitamins (B and C) and the fat-soluble vitamins (A, D, E, and K). Water-soluble vitamins are not stored in the body so they must be readily available in the diet, ideally on a daily basis to avoid deficiencies. Fat-soluble vitamins can be stored in fat tissue and in the liver, so a daily availability is not so crucial. However, young animals have a limited capacity to store fat-soluble vitamins and this needs to be taken into account in their diets.
Vitamin A (Retinol)
Required for healthy vision, synthesis of reproduction hormones and synthesis of protein as well as regulating the growth of skin cells and regulating sebum. Pure carnivores, such as cats do not have the ability to convert plant carotenoids to Vitamin A.
Vitamin B1 (Thiamine)
This vitamin is a member of the water-soluble vitamins and concentrated in the heart, the liver, the kidneys and the brain. Thiamine is involved in many complex biochemical reactions that help generate energy for the cell. It is essential for healthy functioning of the nervous system, where it assists in transmission of sensory impulses. The daily requirements of thiamine in cats is about 3 times that of dogs. Yeast and wheat germ have the highest thiamine content, but it is also found in meat, bran and cereals.
Vitamin B2 (Riboflavin)
Another water-soluble vitamin, contributes to skin and coat health. It is very common in nature, being found in yeast, liver and eggs. Riboflavin is very sensitive to light. Vitamin B2, along with Vitamin B3, is involved in energy production.
Vitamin B3 (Niacin) A
member of the water-soluble B vitamins. Niacin is involved in many metabolic pathways in the body such as amino acid (see amino acid), glucose (see carbohydrate) and fatty acid (see essential fatty acids) metabolism. In dogs, but not cats, niacin can also be synthesised from tryptophan (see Vitamin B2, Vitamin B6, amino acid). Niacin is found in many foods, particularly good sources include muscle and organ meat, beans and lentils.
Vitamin B7 (Biotin)
A water-soluble vitamin that is part of the B vitamin family. The body needs Biotin to help convert certain nutrients into energy. It also plays an important role in the health of your pet’s hair, skin and nails as it supports formation of keratin. Foods that contain biotin consist of eggs, fish, meat and certain vegetables such as sweet potato.
Vitamin B9 (Folic acid)
A member of the water-soluble B vitamins. Folic acid is involved in the development of the tissues in the nervous system and can help to prevent anaemia. Stored in the liver, folic acid is essential for fast cell multiplication (e.g., in the fetus) and is involved in the synthesis of essential DNA components. In the dog, some folic acid is produced by intestinal bacteria. However, it is not known whether this is sufficient for daily requirements and therefore a dietary source is required. Cats require a dietary source of folic acid. Yeast is a good source of folic acid, along with liver, and green vegetables such as spinach, broccoli and eggs.
Vitamin C (Ascorbic acid)
With the exception of humans and guinea pigs, most animals can synthesise ascorbic acid from glucose, so there is no dietary requirement for this vitamin. Ascorbic acid is a good antioxidant, Sources of ascorbic acid include fruits and vegetables such as Broccoli, Spinach and Pomegranate.
Vitamin B12 (Cobalamin)
a member of the water-soluble B vitamins. Cobalamin is the only vitamin that incorporates a mineral (cobalt) in its composition. It is a coenzyme in many essential biochemical reactions, and also plays a primary role in the synthesis of proteins and the production of red cells. Cobalamin is an essential dietary vitamin. It is only fond in animal products such as liver, kidney, heart, lung fish and meat. There is no cobalamin present in non-meat nutrients so in animals fed vegetarian diets, supplementation is especially important.
Vitamin D3 (Cholecalciferol)
must be provided in the diet for dogs and cats. To be active in the body Vitamin D must be modified in the liver and kidney. Vitamin D plays an important role in the regulation of calcium and phosphorus metabolism by increasing intestinal absorption of both minerals, optimising calcium incorporation into bone and reducing the loss of calcium and phosphorus in the urine. Good sources of Vitamin D include oily fish and liver.
A generic term that covers several substances of which alpha tocopherol is the most common form that has the greatest biological activity. Vitamin E is stored in fat tissue, within the liver and muscles. Vitamin E is recognised as an antioxidant and helps to protect the cells from the action of free radicals. Free radicals are produced by cells through normal metabolism, and consequently contribute to the ageing process. Free radicals are also produced as a result of external factors that affect the body such as exercise, pollution and sunlight. Vitamin E helps to protect the cell membranes from free-radical damage and strengthens the immune system. Sources of Vitamin E are of vegetable origin and include oils, grains and cereals. Vitamin E is also found in some animal products such as liver.
Vitamin K is a co-factor for many enzymes, meaning that Vitamin K has to be present to enable enzyme activity. It is essential for some blood coagulation processes (preventing excessive bleeding) and also has a role in protein metabolism and helping calcium incorporation into bone. Vitamin K is usually stored in the liver. The intestinal bacteria of cats and dogs produce Vitamin K. However, this process may not provide the full daily requirement in all circumstances, so a dietary source is required. The main sources of Vitamin K are liver, meat and vegetables such as spinach.
Yucca Schidigera Extract
An evergreen shrub found in the deserts of the American Southwest and Northern Mexico. It is used in pet food to help reduce the odour of stools. The plant was used in traditional Native American medicine to treat a variety of health issues, including arthritis.
Zinc (as Zinc chelate of protein hydrolysate)
An essential trace element (mineral) required by over 300 enzyme systems in the body that control many metabolic processes such as carbohydrate and protein synthesis and metabolism, tissue growth and repair. A zinc deficiency causes a dull harsh coat, hair loss, reddening of the skin, crusting of the skin, delayed wound healing, stunted growth and a weakened immune system. Chelated zinc is more readily adsorbed into the body than any other form of zinc and is therefore better at supporting pets’ zinc levels.