Glucosamine is an amino sugar and a prominent precursor in the biochemical synthesis of glycosylated proteins and lipids. Glucosamine is part of the structure of the polysaccharides chitosan and chitin, which compose the exoskeletons of crustaceans and other arthropods, as well as the cell walls of fungi and many higher organisms. Glucosamine is one of the most abundant monosaccharides. It is produced commercially by the hydrolysis of crustacean exoskeletons or, less commonly, by fermentation of a grain such as corn or wheat. Oral glucosamine is a dietary supplement and is not a pharmaceutical drug. It is illegal in the US to market any dietary supplement as a treatment for any disease or condition. Glucosamine is marketed to support the structure and function of joints, and the marketing is targeted to people suffering from osteoarthritis. Commonly sold forms of glucosamine are glucosamine sulfate, glucosamine hydrochloride, and N-acetylglucosamine. Of the three commonly available forms of glucosamine, only glucosamine sulfate is given a "likely effective" rating for treating osteoarthritis. Glucosamine is often sold in combination with other supplements such as chondroitin sulfate and methylsulfonylmethane. Glucosamine, along with commonly used chondroitin, is not routinely prescribed to treat people who have symptomatic osteoarthritis of the knee, as there is insufficient evidence that this treatment is helpful. One clinical study over three years showed that glucosamine in doses of 1500 mg per day is safe to use. Glucosamine with or without chondroitin elevates the international normalized ratio (INR) in individuals who are taking the blood thinner, warfarin. It may also interfere with the efficacy of chemotherapy for treating cancer symptoms. Adverse effects may include stomach upset, constipation, diarrhea, headache, and rash. There are case reports of people who have chronic liver disease and a worsening of their condition with glucosamine supplementation. Glucosamine is naturally present in the shells of shellfish, animal bones, bone marrow, and fungi. D-Glucosamine is made naturally in the form of glucosamine-6-phosphate, and is the biochemical precursor of all nitrogen-containing sugars. Specifically in humans, glucosamine-6-phosphate is synthesized from fructose 6-phosphate and glutamine by glutamine—fructose-6-phosphate transaminase as the first step of the hexosamine biosynthesis pathway. The end-product of this pathway is uridine diphosphate N-acetylglucosamine (UDP-GlcNAc), which is then used for making glycosaminoglycans, proteoglycans, and glycolipids. As the formation of glucosamine-6-phosphate is the first step for the synthesis of these products, glucosamine may be important in regulating their production; however, the way that the hexosamine biosynthesis pathway is actually regulated, and whether this could be involved in contributing to human disease remains unclear.

Xylitol is a naturally occurring alcohol found in most plant material, including many fruits and vegetables. Xylitol is widely used as a sugar substitute and in "sugar-free" chewing gums, mints, and other candies. As a medicine, xylitol is used to prevent middle ear infections (otitis media) in young children, and as a sugar substitute for people with diabetes. Xylitol is added to some chewing gums and other oral care products to prevent tooth decay and dry mouth.

L-serineThe is a non-essential amino acid. L-serine and the products of its metabolism have been recognized not only to be essential for cell proliferation, but also to be necessary for specific functions in the central nervous system. The findings of altered levels of serine and glycine in patients with psychiatric disorders and the severe neurological abnormalities in patients with defects of L-serine synthesis underscore the importance of L-serine in brain development and function. L-serine supplementation is in trials for the treatment of several CNS diseases such as Alzheimer's disease, Hereditary sensory and autonomic neuropathy type 1 and Amyotrophic Lateral Sclerosis

Amygdalin is a naturally occurring cyanogenic glycoside derived from nuts, plants, and the pits of certain fruits, primarily apricots. Bitter almonds containing amygdalin are used in Traditional Chinese Medicine to remove “blood stasis” and to treat abscesses. Amygdalin was first used as a cancer treatment in Russia in 1845, and in the United States in the 1920s. Laetrile is another name for the natural product amygdalin. Hydrogen cyanide is thought to be the main anticancer compound formed from laetrile (Amygdalin) via in situ release. Cyanide from the hydrolysis of amygdalin is believed to be cytotoxic with actions selective against cancerous cells, but results from animal studies were mostly negative. Other animal studies suggest it may help to relieve pain due to its anti-inflammatory and analgesic effects. One study suggested amygdalin can inhibit tumor growth, but subsequent tests were unable to confirm this observation. Laetrile (Amygdalin) has shown little anticancer activity in animal studies and no anticancer activity in human clinical trials. In 1970, an IND application to study laetrile was filed by the McNaughton Foundation (San Ysidro, California). This request was initially approved but later rejected because preclinical evidence in animals showed that laetrile was not likely to be effective as an anticancer agent. The side effects associated with laetrile toxicity mirror the symptoms of cyanide poisoning, including liver damage, difficulty walking (caused by damaged nerves), fever, coma, and death. Laetrile (Amygdalin) is not approved for use in the United States.

Pyridoxamine (PM) is one of three natural forms of vitamin B6. It is a critical transient intermediate in catalysis of transamination reactions by vitamin B6-dependent enzymes. In preclinical or clinical trials PM has demonstrated pharmacological potential for treatment of diabetic nephropathy, diabetic retinopathy, and hyperlipidemia, and for use in kidney stone preventive therapies. Although its precise mode of action in vivo is not yet clear, it is likely that at least three mechanisms are at play: inhibition of post-Amadori steps of the Maillard reaction; scavenging of reactive carbonyl compounds; and inhibition of toxic effects of ROS. Pyridoxamine was marketed as a dietary supplement, often as the hydrochloride salt, pyridoxamine dihydrochloride. However, in the United States, the FDA ruled in January 2009 that pyridoxamine must be regulated as a pharmaceutical drug because it is the active ingredient in Pyridorin, a drug designed to prevent the progression of diabetic nephropathy.