Vitamin K and Testosterone

Hormonal interactions are difficult to quantify as there are so many variables at play. This makes it very difficult to determine the effects of nutrients on hormones, and giving advice on which nutrients may affect testosterone levels is therefore replete with caveats. Another problem with studies that investigate the effects of nutrients on hormones is that many of the studies are performed in animals. For example, in one study, researchers investigated the effects of vitamin K deficiency in testosterone production in rats. The results of the study showed that a vitamin K deficiency decreases testosterone synthesis through a downregulation of the Cyp11a enzyme, one of the key regulatory steps in the testosterone synthesis pathway. Further, the levels of Cyp11a mRNA correlated with the amount of vitamin K in the testis. Therefore in rats at least, vitamin K deficiency can cause sub-optimal synthesis of testosterone. However, in humans it is not clear if this effect is the same, or how it affects overall testosterone levels in the blood. 

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RdB

Shirakawa, H., Ohsaki, Y., Minegishi, Y., Takumi, N., Ohinata, K., Furukawa, Y., Mizutani, T. and Komai, M. 2006. Vitamin K deficiency reduces testosterone production in the testis through down-regulation of the Cyp11a a cholesterol side chain cleavage enzyme in rats. Biochimica et Biophysica Acta (BBA)-General Subjects. 1760(10): 1482-1488
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Canned Tuna

Tuna is a salt water fish that makes a significant contribution towards human nutrition. Fresh tuna is an oily fish and in this respect can supply significant amounts of omega-3 long chain marine oils in the diet. However, fresh tuna is expensive and perhaps not freely available to most consumers outside of coastal locations in tropical areas. Canned tuna is however much more widely available, but the canning process removes the oil and the fish tissue becomes rather dry. This means that canned tuna is a poor source of omega-3 fats. Further, tuna is available in different forms in tins. Firstly, tuna steak is the form that most closely resembles the fresh tuna structurally as it is in effect fresh tuna that has been canned. Another form of canned tuna are tuna chunks, which are broken down in structure from steaks to form chunks, and this process can be further extended to form flakes. The price of the tuna reflects this processing and tuna steak can be almost twice the price of tune flakes. Tuna tends to be more expensive than both sardines and mackerel in tins, but is cheaper than salmon, particularly if the salmon is wild. However, salmon, mackerel and sardines (and pilchards which are the same fish) are all rich in omega-3 fats. Therefore tuna is a good option as a source of protein, but other forms of fish may provide a more practical balance of protein with fat. 

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RdB

Jaffry, S. and Brown, J. 2008. A demand analysis of the UK canned tuna market. Marine Resource Economics. 23(2): 215-227
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L-Theanine: Hormonal Effects

Evidence suggests that green tea can inhibit steroidogenesis and may decrease testosterone levels in rats. However, it is not clear if this effect is common to humans, or whether there are special considerations regarding the methods of the studies that have evidenced this. One counter argument to the contention that green tea may lower testosterone comes from the fact that many studies show an anti-anxiety and stress lowering effect for green tea, as well as L-theanine, an amino acid present within the tea. This likely relates to the evidence that L-theanine is able to interact with the neurones of the brain to increase the alpha wave state, and this has a significant calming effect, lowering the excitability of the central nervous system. This is relevant to testosterone because stress, and in particular cortisol release, is a significant factor at inhibiting testosterone synthesis. Therefore L-theanine and green tea (because of its L-theanine content) may indirectly be able to affect testosterone synthesis, through a general effect that lowers the stress response and initiates an environment more conducive to normal hormonal balance. 

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RdB

Wang, L., Brennan, M., Li, S., Zhao, H., Lange, K.W. and Brennan, C. 2022. How does the tea L-theanine buffer stress and anxiety? Food Science and Human Wellness. 11(3): 467-475
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Combining Food To Improve Health: Starch

Certain foods in isolation could be considered to be detrimental to the health. For example, foods high in starch derived from wheat such as bread, breakfast cereals and other baked products could be considered unhealthy because they tend to cause rapid rises in blood sugar, and this can lead to oxidative stress and insulin resistance if the foods are eaten regularly in large amounts. However, in many cases combining these starchy products with other types of food can reduce these negative effects. For example, bread combined with protein as might be found in a tuna sandwich, can significantly reduce the absorption of the glucose from the starch, and this slows the speed of the blood sugar rise that occurs following consumption. Adding vegetables (such as cucumber) or tomatoes to the sandwich will add fibre and water, and this will further slow absorption. That is not to say the bread becomes healthier, but its detrimental effects are lessened. Further, the other foods, particularly the vegetables, will increase the nutritional content of the meal as a whole. Likewise, adding milk and dried fruit or nuts to breakfast cereal will improve the quality of the overall meal, and at the same time lessen the detrimental effects of the cereal on blood sugar levels. In this way, by combining food, the nutritional content of the meal, and its overall effects, are more important than the individual effects of each food when taken in isolation, and this is the basis of a balanced diet. 

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Bioavailability of Beta-Carotene in Carrots and Spinach

Carrots and spinach are rich sources of β-carotene. Beta-carotene is a plant pigment that is used in the photosynthetic process. As part of this role in plants, β-carotene is required to act as an electron acceptor during times of high light levels. The ability of β-carotene to accept electrons makes it an important antioxidant for plants. Beta-carotene is bioavailable in humans, and in humans it serves the same antioxidant role, preferring to accumulate in cell membranes because of its lipid soluble properties. The bioavailability of β-carotene from plants has been shown to be influenced by a number of factors including the location in the plant source, the presence of other influencing dietary components, as well as the type and extent of processing. With regard to the latter, cooking and pureeing carrots and spinach significantly increases the bioavailability of β-carotene because it breaks open the cells and this releases the β-carotene ready for absorption. Therefore processed sources of spinach and carrots offer enhanced bioavailability compared to unprocessed and raw forms of the vegetables. 

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RdB

Rock, C.L., Lovalvo, J.L., Emenhiser, C., Ruffin, M.T., Flatt, S.W. and Schwartz, S.J. 1998. Bioavailability of β-carotene is lower in raw than in processed carrots and spinach in women. The Journal of Nutrition. 128(5): 913-916
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Rose Hip Antioxidants in Marmalade and Jam

Marmalade is a preserve made from citrus fruit, and in this regard is similar to jam, which is in turn made from berries. Marmalade is a popular food in developed Western culture and has been a staple food for many centuries because it is an effective way to transfer the beneficial properties of a perishable fruit, into a functional food that can be stored almost indefinitely. Rose hip “marmalade” is not a true marmalade as it is not made solely from citrus fruit but rose hips can be added to orange marmalade to add flavour.  Alternatively rose hips can be used on their own to create jam, as the rose hip is technically a berry. Rose hips are rich in a number of vitamins including A, B and K, but are particularly high in vitamin C. In addition, rose hips are also high in phenolic antioxidants, especially flavonoids. Adding rose hips to marmalade is therefore a way of enriching an already vitamin C rich preserve with additional vitamin C, and this was perhaps an important consideration before oranges were widely available in the countries at higher latitudes and before the advent of refrigeration. As a result of the phenolic antioxidants and vitamin C, rose hip marmalades and jams are evidenced to have excellent antioxidant properties and in this regard can be considered a healthy food choice. 

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Yildiz, O. and Alpaslan, M. 2012. Properties of rose hip marmalades. Food Technology and Biotechnology. 50(1): 98
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“Healthy” Foods that Should Be Avoided: Pasta and Rice Cakes

A number of foods that are considered to be healthy by the mainstream are demonstrably damaging to the health. One such food that is often considered as a healthy food is pasta. Generally pasta is quite heavily processed and even whole grain pasta does not really retain the original composition of unprocessed wheat grain. This means that consuming pasta can cause rapid elevations in blood glucose due to the rapid absorption rates, and this can lead to oxidative stress and in the long term, insulin resistance. Eating pasta with protein can slow the absorption, but the fact remains that pasta has the potential to cause blood glucose problems. Further, pasta is often overconsumed, and this exacerbates the problem. Rice cakes are also highly processed and retain little of the original composition of the wheat grain, and in a similar way to pasta, rice cakes can cause rapid elevations in blood glucose levels, with the same detrimental effects. One of the main problems with these foods is they are often used on weight loss diets because they are “low in fat”, but in reality, they are detrimental to weight loss because they elevate insulin levels. Lastly, neither rice cakes nor pasta have any real meaningful content of micronutrients, and as such, they are empty calories. This means they provide little in the way of nutritional value. 

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Forskolin Against Obesity

Coleus forskolin is a plant that grows in Nelap, India and Thailand. The plant has a number of medicinal effects and these likely relate to the presence of a diterpene molecule within the plant tissues called forskolin. Forskolin has been shown to stimulate the enzyme cyclic adenosine monophosphate (cAMP), which is a key regulator of cell function. Cyclic AMP may have different functions in different cell types, and this explains the wide number of uses of forskolin. In terms of weight loss, cyclic AMP is able to trigger the breakdown of triglycerides from adipose tissue, and can also upregulate fatty acid oxidation. Therefore forskolin may have weight loss effects by regulating these two key cellular functions, thus increasing the amount of fat oxidised for energy. Studies on humans show that forskolin has relevant and measurable clinical effects and can significantly decrease body fat in overweight humans subjects. Studies also suggest that forskolin is safe and effective for long term use, and in fact taking it over the long term may elicit the best results in terms of improvements in body composition and decreases in body fat. Health effects from reduced body fat, particularly from the abdomen, include reductions in blood pressure and this may decrease the risk of cardiovascular disease. 

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Lieberman, S. 2004. A new potential weapon for fighting obesity: forskolin – the active diterpene in Coleus. Alternative & Complementary Therapies. 10(6): 330-333
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The Main Differences Between Tea and Coffee

Tea and coffee are two of the most commonly drunk beverages after water. Both tea and coffee have some interesting health properties, and are quite similar in this respect. However, the chemistry of tea and coffee reflects some of the differences between the two drinks. The first major difference between tea and coffee is that whilst tea is usually consumed only in its raw state, albeit after being dried or fermented, coffee can be more processed. Filter coffee is perhaps more akin to tea because it is the use of the whole beans to generate a drink, whereas instant coffee is more highly processed. Further, tea is available as fermented black tea as well as dried green tea, and this means there are also more than one form of tea. Therefore comparisons can only be done in the context of the particular drink being consumed. Further, the addition of milk and sugar to tea or coffee can also change the health properties significantly. 

One similarity between the two drinks is that they are both high in polyphenols, and these may explain some of the health effects of the two drinks. Polyphenols are antioxidants and may significantly reduce oxidative stress. However, the polyphenols differ between coffee and tea with the former being dominated by the polyphenol chlorogenic acid, whereas the later is dominated by the polyphenol catechins. Another key difference is that tea contains lower amounts of caffeine than coffee, but at the same time also contains the structurally similar theophylline. Tea is also rich in the amino acid L-theanine, something that is not present in coffee. L-theanine is able to cross the blood brain barrier and here it activates alpha waves in the brain, producing a calming effect. The present of L-theanine, and the lower caffeine content may explain the calming effects of tea, compared to the more stimulatory effects of coffee. 

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Honey as an Antibacterial

Honey is an important food and medicine. Its culinary effects are well known, and relate largely to its sweet taste, something that results from its very high concentration of sugars. The medicinal effects of honey are more complex, and relate in part to the sugars present, but also to the high concentrations of phytochemicals that are collected by the bees from the flowers they visit. These phytochemicals are concentrated into the honey by the bees, and this may provide much of the internal medicinal effects. One external effect of honey that is reasonably well reported is that of its antibacterial effects. Bacteria such as Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, Enterococcus faecalis, and Micrococcus luteus are vulnerable to the topical application of honey, but Gram negative bacteria such as Escherichia coli, Pseudomonas aeruginosa, and Salmonella typhi are more sensitive. As Gram negative bacteria have the potential to be more pathogenic, this is a major advantage for honey over other antibacterial methods. It is likely that the high sugar content in honey causes osmotic problems in bacteria killing them through desiccation, but that the phytochemicals may also disrupt their metabolism. Because bacteria are not resistant and cannot get resistant to osmotic desiccation, honey holds a major advantage over many drug-derived alternatives. 

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Mohapatra, D.P., Thakur, V. and Brar, S.K. 2011. Antibacterial efficacy of raw and processed honey. Biotechnology Research International. Article ID 917505
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