Oxalate in plants

Posted on October 3, 2023 by Robert Barrington

Oxalic acid is a metabolite of plants and is found in many plant tissues. High intakes of oxalates are present in some diets and they may have detrimental effects in humans. The main problem with oxalates is they can bind to calcium and other minerals and thus prevent their absorption. Some authors have claimed that oxalates in the diet may contribute to kidney stones, but the evidence for this happening in healthy normal individuals is not strong. Some removal of oxalates though soaking in water can occur as the oxalate can leach into the water. In a typical English diet the intake of oxalates is around 70-150 mg per day. The biggest contributor to oxalate intake in the English diet is tea, beetroot, spinach and rhubarb. People with more plants in their diet consume more oxalates compared to those with lower intakes, and this may affect mineral absorption. However, this is rather theoretical and based on models, and real world data does not support a damaging effect for high plant food diets. Further, the binding of minerals to oxalates could be considered a benefit as it prevents oxalate absorption. 

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RdB

Noonan, S. N. and Savage, G. S. 1999. Oxalate content of foods and its effect on humans. Asia Pacific Journal of Clinical Nutrition. 8(1): 64-74
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Spinach: Safety and Effects

Posted on October 2, 2023 by Robert Barrington

Spinach leaves are commonly consumed in human nutrition and the leaves have been shown to possess a number of phytochemicals that may be biologically active. These include a number of flavonoids and carotenoids that have been shown to have beneficial effects. These compounds have been shown to have significant antioxidant and antiinflammatory effects and extracts of spinach leaves have been used to treat a number of diseases for this reason. However, despite the growing number of studies that show beneficial effects for spinach leaves in human health, anecdotes of damaging effects persist relating to spinach. In particular oxalates can inhibit the absorption of calcium and so very high concentrations of spinach leaves may reduce calcium intake. Further, spinach also contains nitrates, high intakes of which may increase gastrointestinal cancer. However, a lack of empirical evidence in the literature attests to any detrimental effect for spinach when eaten in moderation as part of a healthy diet. 

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RdB

Lomnitski, L., Bergman, M., Nyska, A., Ben-Shaul, V. and Grossman, S. 2003. Composition, efficacy, and safety of spinach extracts. Nutrition and cancer. 46(2): 222-231
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Vitamin D from Fish Oil or Multivitamin Capsule?

Posted on October 2, 2023 by Robert Barrington

Vitamin D is an important hormone that can be synthesised from cholesterol in the tissues of the skin, and which is also present in a number of foods. Vitamin D is difficult to obtain in the diet as it is such a limited range of foods and as such the main source of vitamin D is through the action of sunlight on the skin via endogenous synthesis. However, supplements are useful during winter months in latitudes that recluse sun exposure, and as a result supplements can be used to optimise vitamin D levels. Vitamin D is available as both a dry tablet form and an oil based form, and both appear to be well absorbed. For example, in one study, researchers administered either a dry form vitamin D supplement or oil based fish oil form to subjects at a dose of 10 micrograms per day. After 4 weeks both supplements had significantly raised blood levels of vitamin D but there was no difference in the effectiveness of the supplements. Therefore both dry form and oil form vitamin D appear to be equally effective at raising blood levels of vitamin D. 

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RdB

Holvik, K., Madar, A.A., Meyer, H.E., Lofthus, C.M. and Stene, L.C. 2007. A randomised comparison of increase in serum 25-hydroxyvitamin D concentration after 4 weeks of daily oral intake of 10 μg cholecalciferol from multivitamin tablets or fish oil capsules in healthy young adults. British Journal of Nutrition. 98(3): 620-625
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Shilajit: Cognitive Effects

Posted on September 29, 2023 by Robert Barrington

Shilajit, also known as salajit, shilajatu, mimie, or mummiyo is a black powder that excudes from rocks in high mountain regions. A number of organic substances in shilajit have been identified including the compound called fulvic acid, which may give shilajit some of its properties. In addition, a number of minerals including selenium have been identified in the shilajit. Another possible source of the physiological effects of shilajit are a group of compounds called the dibenzo α-pyrones. Four main physiological effects of shilajit have been identified including antioxidant, anti-inflammatory, memory enhancing and anti-aggregation of tau proteins. These effects provide protection from general aging and from dententia and neuronal damage. The ability of shilajit to enhance neuronal activity has been evidenced in studies where cognitive effects were observed. However, it is not clear how shilajit works on a cellular level and so more research is needed in this area. 

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RdB

Carrasco-Gallardo, C., Guzmán, L. and Maccioni, R.B. 2012. Shilajit: a natural phytocomplex with potential procognitive activity. International Journal of Alzheimer’s disease. doi:10.1155/2012/674142
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The Beneficial Effects of Glycine

Posted on September 28, 2023 by Robert Barrington

G;ycine is the smallest and simplest of the amino acids and the only proteinaceous amino acid not to display chriality. Glycine has a number of functions in humans aside from its use in forming proteins and these include the synthesis of glutathione. Glycine can also exert a number of physiological effects that occur through its ability to attach to a number of receptors including the glycine anion channel protein and the N-methyl-D-aspartate (NMDA) receptor. Activation of the NMDA receptor may lead to neuroprotective effects in the case of glycine. Normal blood levels of glycine in man are 300 micromolar, but taking dietary supplements can raise plasma levels to 900 micromolar. In studies up to 90 grams of glycine per day over several weeks have been used in man without harmful side effects, evidencing its safety. Glycine may also stimulate the release of growth hormone in man, and in this regard may have certain fat oxidising and tissue regenerative effects. 

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RdB

Pérez-Torres, I., María Zuniga-Munoz, A. and Guarner-Lans, V., 2017. Beneficial effects of the amino acid glycine. Mini reviews in medicinal chemistry. 17(1): 15-32
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Branched Chain Amino Acids and Brain Function

Posted on September 27, 2023 by Robert Barrington

Branched chain amino acids are amino acids with a structure that contains a branch. In this regard they are structurally unique amongst the amino acids. Branched chain amino acids are found in high concentrations in skeletal muscle and their main function is to provide structure to muscle to allow the skeleton to move. However, branch chain amino acids can affect the brain because they have the ability to interfere with the large neutral amino acid transporter. This has an effect on the brain because many of the amino acids that can affect the brain also use this transporter. By interfering with the transporter, the branch chain amino acids may therefore be able to moderate the uptake of important amino acids to the brain, and this may affect the ratios of amino acids in the brain. That is not to say the modification is detrimental, just that branched chain amino acids can clearly affect this system. Branched chain amino acids supplements may therefore have neurological effects in humans. 

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RdB

Fernstrom, J.D. 2005. Branched-chain amino acids and brain function. The Journal of Nutrition, 135(6): 1539S-1546S
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Aphrodisiac Properties of Eurycoma longifolia

Posted on September 26, 2023 by Robert Barrington

Tongkat Ali (E. longifolia) is a traditional herb that is considered to possess aphrodisiac properties. For this action to occur the herb must be consumed, although bioavailability of some of the phytochemicals within the herb may be poor. Many studies on the effects of Tongkat Ali of sexual parameters have been performed on animals. However, these studies consistently show a beneficial effects on reproductive behaviour and sexual function in anaimals models. The mechanism of action is not understood, and studies have suggested that increases in testosterone may play a role. However, other studies have been less clear. Some evidence suggests that the herb may increase the release of luteinizing hormone, which in turn may stimulate testosterone synthesis from the testes. Other mechanisms may relate to activation of the nervous system or a general health effect from the presence of antioxidants. However, more studies need to be performed on humans if the beneficial effects are to be confirmed. 

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RdB

Bhat, R. and Karim, A.A., 2010. Tongkat Ali (Eurycoma longifolia Jack): a review on its ethnobotany and pharmacological importance. Fitoterapia. 81(7): 669-679
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Tongkat Ali (Eurycoma longifolia): Reproductive Function

Posted on September 25, 2023 by Robert Barrington

Tongkat Ali (Eurycoma longifolia) is a herb that is sometimes called Malaysian ginseng on account of its similar properties to Panax ginseng. Evidence suggests that Tongkat Ali has a number of biochemical effects in humans that include a significant ability to improve reproductive function. Tongkat Ali contains a number of phytochemicals that may contribute to its reproductive effects and these include bioactive compounds such as phenolic compounds, polypeptides, diterpenoids, alkaloids, and quassinoids. In one study Tongkat Ali was significantly able to improve erectile dysfunction in human males. One line of reasoning is that Tongkat Ali is able to increase testosterone levels, and this causes beneficial reproductive effects. This may suggest that the effects of the herb may only become apparent in those who have deficiencies in testosterone. The testosterone raising effects of Tongkat Ali may also make the supplement of interest to athletes during intense training. 

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RdB

Kotirum, S., Ismail, S.B. and Chaiyakunapruk, N. 2015. Efficacy of Tongkat Ali (Eurycoma longifolia) on erectile function improvement: systematic review and meta-analysis of randomized controlled trials. Complementary therapies in medicine. 23(5): 693-698
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Niacin and Paresthesia

Posted on September 22, 2023 by Robert Barrington

Niacin is a B vitamin that can be taken in high amounts to reduce plasma cholesterol. When used for this purpose, niacin is highly effective. However, niacin also causes paresthesia as a side effect and this describes a flushing or redness in the skin that is associated with a skin itching sensation. The reason for this effect is that niacin can activate G protein coupled receptors in skin immune cells and vasodilation. In this regard, niacin may cause keratinocytes to release prostaglandin D2 which is the cause of the effect. The effect appears to be harmless and is considered a side effect of the compound’s main effects on the lipids in the blood. That niacin is so effective at reducing the lipids in the blood and normalising cholesterol levels throws up a dilemma in that anyone wishing to take advantage of this effect must also put up with the paresthesia that is associated with it. However, over time the effect does diminish, this making the long term use of niacin a viable alternative to other cholesterol lowering agents. 

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RdB

Dunbar, R.L. and Gelfand, J.M. 2010. Seeing red: flushing out instigators of niacin-associated skin toxicity. The Journal of Clinical Investigation. 120(8): 2651-2655
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β-alanine and Paresthesia

Posted on September 21, 2023 by Robert Barrington

β-alanine is a supplement that may have particular effects beneficial in resistance training on account of its ability to raise muscle concentrations of carsosine. Carnosine acts as a significant buffer to reductions in pH during intense exercise and this is the mechanism that is thought to be responsible for the performance effects of β-alanine. However, β-alanine can, as a side effect, induce paresthesia, which is an itching or tingling sensation in the skin when consumed in reasonably high concentrations. The exact reasons for this are not clear but may involve the innervation of neurons in the skin that are activated by G-protein coupled receptors that are sensitive to β-alanine. Evidence suggests this itch is not related to the release of histamine, and the circuits involved in the itch are likely independent of the histamine system. This may suggest that β-alanine has effects beyond those of the increase of carnosine in muscle and one of these effects may be neuronal in nature.

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RdB

Liu, Q., Sikand, P., Ma, C., Tang, Z., Han, L., Li, Z., Sun, S., LaMotte, R.H. and Dong, X. 2012. Mechanisms of itch evoked by β-alanine. Journal of Neuroscience. 32(42): 14532-14537
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