Is Taurine a Conditionally Essential Amino Acid?

Taurine is the most abundant intracellular amino acid in humans, and this relates directly to its numerous physiological and biochemical functions. In the presence of pyridoxine (vitamin B6), taurine can be synthesised from methionine and cysteine. However, for most individuals, the diet is the main source of the amino acid. Some of the roles of taurine include bile conjugation and the prevention of cholestasis; an antiarrhythmic, chronotropic and inotropic effect (in effect stabilising the beating of the heart); central nervous system effect including neuromodulation; the development and protection of the retina; as well as endocrine and metabolic effects. There is also significant evidence that taurine can act as an antioxidant and anti-inflammatory agent in humans. 

Taurine is present in breast milk, and this is an essential component for the growing infant as the infant cannot synthesise enough taurine for full physiological and biochemical needs. Certain adults may also be unable to synthesise enough taurine, particularly those who are ill, and these people may benefit from supplements. In addition, people on restricted diets may also not be able to obtain enough taurine in the diet, and so supplements may be necessary in such cases.  However, doses are not fully understood and so it is difficult to make individual general recommendations. Consideration of taurine as a conditionally essential nutrient should therefore be given but with care being taken to match intakes to individual needs.  

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RdB

Lourenco, R. and Camilo, M.E 2002. Taurine: a conditionally essential amino acid in humans? An overview in health and disease. Nutrición Hospitalaria. 17(6): 262-270
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How Does D-Aspartic Acid Cause Testosterone Release?

In mammals, D-Aspartic acid has been shown to have a significant effect on the hypothalamo-pituitary-testicular axis. In this regard, D-aspartic acid may cause the release of luteinizing hormone from the brain, and also testosterone release from the testes. In rats, D-aspartic acid is found in high concentrations in testicular venous blood, indicating it might be released from the testes. Lower levels of D-aspartic acid are found in other areas of the testes including the extracellular fluid. However, all the areas of the testes have higher concentrations of D-aspartic acid compared with other tissues, indicating that the testes are a significant site of concentration. It is suggested that the secreted D-aspartic acid that enters the testicular venous blood, passes to the rete testicular fluid and then is incorporated into the spermatozoa. This is quite different from the distribution of testosterone, and so it is unclear how D-aspartic acid causes the release of testosterone from the testes. However, evidence today suggests that this amino acid is highly important in male reproductive function with a central role in regulating testosterone in adult males.  

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RdB

D’Aniello, A., Di Fiore, M.M., D’Aniello, G., Colin, F.E., Lewis, G. and Setchell, B.P. 1998. Secretion of D-aspartic acid by the rat testis and its role in endocrinology of the testis and spermatogenesis. FEBS letters. 436(1): 23-27
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D-aspartic Acid

D-aspartic acid is unusual in that amino acids normally utilised in the human body are the levo L-forms. Other D-forms of amino acids sound in humans include the free forms of D-alanine, G-glutamate and D-serine. Most D-aspartic acid in mammals is found in the brain, eyes and testes. D-aspartic acid has a number of functions in humans. In particular, d-aspartic acid can activate the N-methyl-D-aspartic acid receptor and thereby initiate impulses in the glutamate system of neurones. The general effect of this is to cause excitatory effects in the brain. D-aspartic acid may also increase cyclic AMP in neurones, and the subsequent cyclic AMP may travel through the neurone to the terminal of the cell, when it can act as a second messenger. D-aspartic acid may also cause the release of gonadotropin releasing hormone and in the pituitary gland it may cause the release of prolactin (PRL), luteinizing hormone (LH) and growth hormone (GH). In the testes, D-aspartic acid may cause the release of testosterone and progesterone, meaning that D-aspartic acid appears to play a significant role in the hypothalamic-pituitary-testicular axis. 

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D’Aniello, A. 2007. D-Aspartic acid: an endogenous amino acid with an important neuroendocrine role. Brain research reviews. 53(2): 215-234
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Ginger: Phytochemistry

Ginger (Zingiber officinale) is an angiosperm (flowering) plant that produces a large edible rhizome or root. The rhizome is used in cuisine for its distinctive taste, as well as its antioxidant and preservative properties. Ginger is a plant that is related to turmeric, cardamom, and galangal. Chemically ginger is an interesting mixture of chemicals, many of which are responsible for the unique taste of ginger. Some of the main chemicals isolated from ginger include gingerol, shogaol, paradol, beta-sitosterol palmitate, isovanillin as well as metabolites of these chemicals. Ginger also contains vitamin C and the B vitamins thiamine, riboflavin and niacin.  The chemical composition of ginger can be altered significantly by the growing conditions, the storage conditions, the growing time, the harvest time, and the storage length. Powdered ginger may also have a slightly different chemical composition compared to fresh ginger.  

As well as its use in cuisine, ginger has a number of particular medicinal uses. One well known action of ginger is that of inhibiting inflammation. This makes ginger useful against conditions of chronic inflammation like arthritis. Subclinical conditions associated with inflammation including obesity, cardiovascular disease and cancer may also be modified in their progression by use of ginger although the effects will be less obvious and much longer in their manifestation. In terms of its biochemical effects, ginger may inhibit the synthesis of certain proinflammatory prostaglandins, particularly 5-lipoxygenase, through inhibition of the cyclooxygenase 1 and 2 enzymes. Ginger has also been shown to interfere with the vanilloid nociceptor. Ginger may also inhibit the expression of certain genes associated with inflammation including genes encoding cytokines, chemokines and cyclooxygenase 2. Ginger therefore modulates multiple pathways that can lead to inflammation, and this explains its highly effective anti-inflammatory effects. 

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RdB

Agrahari, P., Panda, P., Verma, N.K., Khan, W.U. and Darbari, S. 2015. A brief study on zingiber officinale – a review. Journal of Drug Discovery and Therapeutics. 3(28): 20-27
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Magnesium in Health

Magnesium is an essential macromineral, and the role played by magnesium ions in optimal nutrition is becoming increasingly evident. A deficiency of magnesium is not uncommon, and low intakes of magnesium have been becoming increasingly frequent in Western nations, where the diet tends not to contain magnesium rich foods. In cases of magnesium deficiency, supplements can be beneficial, and magnesium is generally cheap and relatively well absorbed. One of the most common symptoms of low magnesium intake is muscle tremors and twitches. Serious cases of magnesium deficiency can result in myocardial infarction. Magnesium is used in the body as the magnesium ion, and in this form magnesium can bind to cell membranes due to the negatively charged proteins within the membranes. This effect provides stability to membranes, and these membrane stabilising effects may be one of the most physiologically important functions of magnesium in humans. It is though that once bound to the membranes, the positive charge on the magnesium ion is able to electrically stabilise the membrane through interaction with proteins as well as by inhibiting phospholipase A2, an enzyme that can cause cleavage of the fatty acids from phosphates in phospholipids present in the membranes.  

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Saris, N.E.L., Mervaala, E., Karppanen, H., Khawaja, J.A. and Lewenstam, A. 2000. Magnesium: an update on physiological, clinical and analytical aspects. Clinica Chimica Acta. 294(1-2): 1-26
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A Nice Cup of Tea

George Orwell wrote about tea in the Evening Standard in 1946. In this article Orwell made observations about tea that are insightful and interesting. Firstly, Orwell suggested that a “nice cup of tea” really refers to Indian tea. In relation to this he suggested that China tea is cheaper and of lesser quality. Evidence today suggests that tea quality varies considerably, and cheaper tea tends to be of lesser quality and taste, corroborating Orwell’s observations. Lesser quality tea, often referred to as brick tea may also have much higher levels of fluoride. Another observation he made was that tea should be made in small quantities, with army tea from a cauldron tasting like grease and whitewash, and tea from an urn being tasteless. In terms of teapots, Orwell suggests that earthen teapots are superior, with silver and Britannia Ware pots producing a poor taste, something evidently even worse for enamel pots. Orwell also suggests that pots should be warmed before use, something that is often stated as improving the taste of tea, perhaps because it increases the brewing temperature which enhances the flavour. 

In his article, Orwell clearly prefers strong tea, and in this regard clearly makes his tea with loose leaf black tea. The idea that the pot should be taken to the kettle, as suggested by Orwell, is claimed to increase the temperature of the water as it makes contact with the tea, and this likely relates to the same benefit as warming the pot. Orwell also suggests that the cup from which the tea is drunk can considerably impact taste, an anecdote shared by many who favour a particular cup or mug. In this regard, Orwell recommends a good breakfast cup. The last comment by Orwell relates to drinking tea without sugar, and this is perhaps his best advice. Orwell’s reasons for this are the negative effects on the taste that sugar has, which is evidently true, because sugar is very sweet, whereas tea is quite bitter. However, further than this, sugar is unhealthy and can cause disease, whereas tea is healthy and can treat disease. Adding sugar is therefore the antithesis to drinking tea, whether one is interested in the taste, or its health effects. 

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RdB

Orwell, G., 2017. A nice cup of tea. SFCB.
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Broccoli: Stability of Its Nutrients During Digestion

Broccoli (Brassica oleracea) is a rich source of phytochemicals that may have significant health benefits. In particular, broccoli contains high amounts of polyphenols, glucosinolates and vitamin C, and these nutrients may explain its ability to reduce the risk of certain diseases including cancer. However, the presence of nutrients does not guarantee health effects, as the nutrients must survive digestion and then be absorbed. For example, around 69 % of glucosinolates may be lost during digestion in the stomach, although the remaining glucosinolates remain relatively stable in the intestine. In contrast, the vitamin C content of broccoli may be more stable with only 7 % loss during digestion in the stomach. During digestion, polyphenols are extensively degraded with an 80 to 84 % loss in the intestine, but much lower degradation in the stomach of around 6 to 25 %. The losses associated with nutrients in broccoli are determined by the exact conditions of digestion, and therefore losses may differ depending on the presence of other foods, as well as showing differences between individuals. Further, while phytochemicals can be degraded during digestion, it might be that the breakdown products are in turn also able to confer health effects. For example, the breakdown products of polyphenols may be absorbed and may provide many of the effects attributed to polyphenols themselves. Bacterial degradation of polyphenols in the small and large intestine is likely extensive. 

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RdB

Vallejo, F., Gil-Izquierdo, A., Pérez-Vicente, A. and García-Viguera, C. 2004. In vitro gastrointestinal digestion study of broccoli inflorescence phenolic compounds, glucosinolates, and vitamin C. Journal of agricultural and food chemistry. 52(1): 135-138
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Vitamin C in Carrots

Carrots are perhaps best known for their orange colour which derives from their high concentrations of carotenoids (60 to 134 mg per kg). In particular, carrots are high in alpha-carotene and beta-carotene, and both of these carotenoids are bioavailable and act as antioxidants in humans. Carotenoids have been linked to reductions in the risk of cancer in human studies. However, like most vegetables, carrots are also a good source of vitamin C and this improves their antioxidant capacity somewhat. For example, in one study, the vitamin C content in the cultivars of carrots tested ranged from 54 to 132 mg per kg. Higher levels of vitamin C were found in cultivars of carrots that are harvested late in the season, and storage of the carrots for 30 days resulted in a 47 % decrease in vitamin C content. Therefore the best place for carrots, if vitamin C content is a priority, is the ground, and picking them only when needed for cooking might be the best option in order to preserve the high vitamin C content. 

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RdB

Matejkova, J. and Petrikova, K. 2010. Variation in content of carotenoids and vitamin C in carrots. Notulae Scientia Biologicae. 2(4): 88-91
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Can Green Tea Increase Equol Production

Equol is a degradation product of the isoflavone daidzein. Daidzen is degraded to equol in the gut of humans under the influence of a number of bacteria. Current evidence suggests that equol may have health effects that include protection from certain cancers. Foods high in daidzein, the presence of particular bacteria in the gut, as well as genetic make-up may all influence how much equol is produced. In terms of dietary factors, foods may be able to influence equol production because they can supply daidzein, or because they alter the bacteria in the gut to a more favourable profile. Studies have suggested that one food that may be beneficial in this regard is green tea. For example, in one study, researchers assessed the diet of hospital patients and found that those with a greater ability to make equol had significantly higher levels of green tea in their diet. Of course, this does not prove cause and effect, and green tea drinkers may also make other changes to their diets that favour equol production, such as having lower sugar intakes. However, it is known that green tea can alter bacteria profiles in the gut microbiota and in this way may be able to favourably increase synthesis of equol. 

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RdB

Miyanaga, N., Akaza, H., Takashima, N., Nagata, Y., Sonoda, T., Mori, M., Naito, S., Hirao, Y., Tsukamoto, T. and Fujioka, T. 2003. Higher consumption of green tea may enhance equol production. Asian Pacific Journal of Cancer Prevention. 4(4): 297-301
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Antioxidants in Cabbage

Cabbage is a healthy food that is available in a number of different varieties and cultivars. Cabbage is healthy because of the high fibre and low sugar content which support optimal blood sugar levels and reduce the risk of insulin resistance developing. This makes cabbage a great way to prevent weight gain and diseases such as diabetes and cardiovascular disease. However, cabbage also contains a number of phytochemicals, and many of these are antioxidants which have their own health effects. For example, cabbages contain vitamin C, and the amount varies between cultivars and between individual cabbages. Vitamin C is an essential nutrient and can improve extracellular antioxidant defences and increase cellular glutathione levels. Lutein is another antioxidant present in cabbages that belongs to the carotenoid family of nutrients and lutein may protect eyesight. Cabbages are not high in vitamin E, but contain reasonable amounts of alpha-tocopherol, the most important antioxidant for cell membranes. Lastly, polyphenols are also present in cabbages, as they are in all plant foods. Of the polyphenols in cabbages, anthocyanins in red cabbage are the most noticeable as they provide them with their red colour. Eating a range of cabbage varieties and cooking cabbage to help release the antioxidants from the cells is perhaps the best strategy to optimise antioxidant intake from them. 

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RdB

Singh, J., Upadhyay, A.K., Bahadur, A., Singh, B., Singh, K.P. and Rai, M. 2006. Antioxidant phytochemicals in cabbage (Brassica oleracea L. var. capitata). Scientia Horticulturae. 108(3): 233-237
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