Archive for the ‘Zinc Nutrition’ Category

Oyster Extract for Peak Performance

Wednesday, October 10th, 2012

In this article I will be  extoling the virtues of making oyster extract powder part of your heath programme. However there are still many more virtues to be discussed but this article will look at oyster extract from the bodies biochemistry perspective, in particular the concept of balancing trace mineral levels in the body to maintain peak hormonal and enzymatic functioning.

Have you ever had that feeling that you are missing something in your diet, that you are just not up to par, knowing there is some imbalance in there that you just can’t figure out? Well this is a frequent reason many of us attend our GP or therapist. However in some countries certain physicians take a very holistic approach to this and work by a process of elimination to try and figure the problem out, rather than going down the orthodox prescribed medication route straight away.  Oyster extract is one of the tools they often try to eliminate other possibilities.

Many people will present with a biochemical imbalance. Doctors and therapists will try to identify this by various means. They may opt for blood tests, hair analysis and use various other diagnostic tools and methods to reach a conclusion. Some therapists however will use oyster powder.

By advising their clients to try oyster extract powder they know that each and every one of the 59 trace elements the body needs are present in sufficient and extremely bioavailable quantities.  They can begin to out rule certain nutrient deficiencies at which stage if they do not see an improvement then investigations of a different nature become necessary.  This has been observed many times in our clinical experience from clients presenting with trace element deficiencies like zinc, copper, manganese, selenium and so forth.

Furthermore, where deficiencies are identified by the more traditional analytical methods and micro-nutrients are subsequently administered, certain imbalances may result which can lead to more symptoms. With oyster extract capsules this does not happen, as the total array of trace elements are presented in a balanced biochemical matrix. Each and every one of the trace elements we need are presented in the relative concentrations as nature intended.

The results speak for themselves. Improved energy levels, stronger immunity, smoother complexion and better sexual health. All these benefits come from ensuring the trace elements necessary for  peak performance in all these biochemical systems are balanced, by nature-as nature intended. You only get this from oyster extract.

With winter fast approaching and many of use reaching for the zinc lozenges, consider taking a course of oyster extract capsules. Not only are they the highest natural source of zinc, they also contain each and every one of the 59 trace elements we need to get us through the winter months.

Make sure you discuss your oyster extract with your supplier and choose a potent product. Some cheap oyster extract products on the market can have up to 60% tapioca starch mixed in along with other bulking agents. Only choose pure,  high zinc, oyster extract capsules. Think before you zinc!

Natural Zinc Supplement vs. Synthetic Zinc Supplement. Which should I choose?

Wednesday, October 6th, 2010

It’s that time of the year again when we reach for the medicine cabinet and decide what supplement regime we will follow to ward off illness in those dark winter months. As the leaves fall and our sun tans fade, we are conscious of getting enough of the right nutrients to keep our immunity in top condition so as to minimise the threat of flu season and all the plethora of winter ills. One nutrient however that most of us recognise as vital in this fight is zinc. However with so many brands of zinc supplements on the market and so much confusion out there, how do we know if we are taking enough and how do we know if the quality is sufficient to get results?

Let’s start with facts and some recent research. Zinc is a vital trace element in the body and is vital in over 300 enzyme reactions. It has a role in the biochemistry of physiological processes that govern everything from the way we look and feel, to our immunity, to our sexual health. While severe zinc deficiency is rare in developed countries it is sometimes seen in groups with no animal protein intake who are not careful to find suitable vegetable sources in their diet. However, the World Health Organisation estimates that up to 80% of us are mildly zinc deficient and there are very definite symptoms associated with this. Fatigue, lowered immunity, loss of libido, macular degeneration and a host of skin conditions can manifest in this zinc deficient state.

The RDA in the USA for zinc can vary between government agencies but the National Institutes for Health states that it is 11mg for adult men and 8mg for adult women. This figure is also used by the Linus Pauling Institute in OSU which is at the forefront of zinc research. Scientists at this institute found little evidence that zinc lozenges decreased the duration of the common cold and they also found that too much zinc was damaging to the immune system in the same way that too little is. So how much should we take?

Given that the food we eat contains some zinc it is reasonable to figure we need a small amount by way of supplementation to make sure we get enough. Lifestyle is a big factor also. Athletes and sexually active men have an increased need for zinc nutrition as do pregnant and lactating women. However when you take zinc elementally like in lozenges such as zinc gluconate or zinc acetate, you risk interfering with the body’s delicate balance of trace elements. Too much zinc can, for example, lead to copper deficiency. Copper deficiency can affect energy production and neurological processes in the brain. So you take zinc for fatigue, then copper uptake is affected, then we get problems with energy production. Back to square one.

I digress for a moment: This problem exists every time we take minerals elementally. i.e. on their own. Our bodies have never been used to getting minerals or vitamins individually. They come in a matrix in the food we eat. This matrix is usually some kind of protein or fat which is broken down into small sub units during digestion. These sub units with their associated minerals and vitamins are then used to build the complex molecules our bodies need for normal functioning. For those with a limited knowledge of  biochemistry it is not easy to understand. To use an analogy, let’s say you wanted to make a bicycle and I handed you 2 wheels, a saddle, pedals, a chain, brakes, handle bars and a frame, you would put it all together pretty quickly and ride away. It’s like this when you get your minerals and vitamins from a natural, unprocessed, organic source. The body has the building blocks it needs to maintain us. However, imagine  if I handed you instead of 2 wheels, some wire and rubber to make the tyres, some bits of metal to make the spokes, some ball bearings, some nuts, a wheel rim, some rubber for the tube, the different components for the valve etc. Then I did this for all the other parts of the bicycle, you would then have literally thousands of components to put together to make your bike. Think you could manage that? Well it’s a bit like that when we fill our bodies with individual minerals and vitamins and expect to maintain good health.

The lesson: Taking our nutrition from healthy natural sources is always going to be the best way to stay healthy. When it comes to maintaining zinc levels, synthetic zinc supplements should be taken with caution. Pumpkin seeds are a good vegetable source for the vegetarians among us while oysters are the best animal source, 10 times higher in fact than the next source which is beef.

This brings me to a close as I want to tell you what I believe to be the best way to supplement zinc in your diet. Oyster extract is the zinc supplement of choice in my house. It contains not only very high levels of organic zinc but all the 59 trace elements our bodies need. All these minerals are already bound in amino acids ready to go to work in our bodies, just like the wheels on the bike. Four capsules of a good quality oyster extract will provide roughly 3mg of top quality zinc. This is a safe supplemental amount. However because all the minerals are bound and balanced, one can take more without the associated risks when you use synthetic alternatives. Caveat emptor – All oyster extracts do not have this zinc potency, some can have as little as 0.1mg in four capsules, not very effective. Always check the amount of zinc with the manufacturer before you make a purchase. Think before you zinc!

Ten reasons why Oyster Capsules are a superior Zinc Supplement.

Wednesday, June 9th, 2010

Zinc deficiency affects over 80% of the adult population. It is a vital trace element required in over 300 enzyme reactions in the body. Athletes, pregnant and lactating women, sexually active males and anyone feeling the stresses and strains of modern life all have increased demands for zinc. The clinical range of the symptoms of zinc deficiency vary from decreased immunity to low libido, from poor skin, hair and nails to macular degeneration, from prostate health issues to hormonal balancing.

However, for those of us who feel they need more zinc than their diet provides the job of choosing the right zinc supplement can be daunting as there are so many brands and stories on the market. Choosing oyster capsules is not something many may have considered, but as natures highest source of naturally occurring zinc, they are certainly worth a try. The rest of this article will give you ten reasons why oyster extract capsules are the superior zinc supplement on the market today.

  1. Oysters are the highest NATURAL source of zinc, tens times higher in fact than the next source which is beef.
  2. Oyster capsules not only contain zinc, they contain all of the 59 trace elements our body needs for the correct physiological functioning of all the biochemical pathways.
  3. The zinc in oyster capsules is naturally bound to amino acids which makes it very bioavailable. This is more effective than chelated zinc supplements and far superior to synthetic zinc supplements.
  4. The zinc in oyster capsules is balanced with other key co-factor elements such as copper, manganese and selenium in a way that makes them work better together. This balancing is done by nature, as nature intended. No other zinc supplement can boast this fact.
  5. Oyster capsules are not only high in zinc, they contain many other interesting compounds which benefit general health. Clinical work has shown they can increase glutathione levels counteracting fatigue, increase immunity and improve sexual health.
  6. Oyster capsules are classed as a Superfood. Because they are not synthetic there is no danger of upsetting the body’s biochemistry by taking more if you so wish. People taking 12-16 capsules daily have reported zero fatigue. Many athletes take higher doses due to their increased demands with amazing results.
  7. The holistic effect on the body’s biochemistry of using oyster capsules has been well documented since ancient times. In traditional Chinese medicine oyster extract has been used for centuries for liver cleansing and sexual health.
  8. Oyster capsules are cutting edge nutrition. Research is currently being carried out in several institutions around the world to investigate what other bio active compounds they contain and to better understand the positive health benefits users report.
  9. Oyster capsules are cost effective. Taking them ensures your body’s biochemistry is well balanced. Taking lots of synthetic, elemental trace element supplements in the hope of achieving the same result is more risky and more expensive.
  10. The production of oyster capsules is sustainable and because the oyster shells lock carbon out of the atmosphere there is a net reduction in atmospheric carbon from the process. The best oyster extract capsules do not include shell. It is usually traded on for other manufacturing processes.

A cautionary note: Not all oyster extracts are the same. Some can be up to 20 times more potent in terms on zinc concentration than others. This is due to differences in region and seasonal harvesting applied by the different manufacturers. This difference is also usually reflected in the price. Check with your supplier before you make a purchase to ensure they are selling a high zinc oyster capsule. Think before you zinc!

The Caviar of Zinc Supplements

Wednesday, May 19th, 2010
There are many, many zinc supplements on the market. So much so that buying the right one can be a very time consuming affair and with so many brands, how do you know which is the right one for you. However, as with all purchasing decisions, there is quality and there is quantity. There is fast food and there is gourmet food. There are synthetic zinc supplements and there is Oyster Extract Powder.

Despite all the marketing blurb, there is only one science of zinc supplementation, and this is it. Zinc is the most ubiquitous element in the body. It is required in and therefore controls over 300 enzyme reactions in the body. It maintains everything from immunity and sexual health to gene expression and neurobiology. Zinc deficiency has been shown to cause a diverse range of conditions from fatigue to poor sexual health, prostate issues, lowered immunity, macular degeneration and many, many more. Having adequate zinc intake is vital to our over all general health and mental and sexual well being. Too much or too little has been shown to have adverse affects on our health. This is a very important point for people taking zinc supplements.

Most zinc supplements give significantly higher amounts of zinc than our body needs. This interferes with the absorption of other key elements such as copper, calcium and iron. This can cause an imbalance in the body’s biochemistry interfering with the many biochemical pathways in the body. There is however one source of zinc that is perfectly balanced for our needs. Balanced by nature, just as nature intended. It not only has zinc in abundance but also each and every one of the 59 trace elements our body needs. This is the caviar of zinc supplements; this is oyster extract powder.

Oysters contain 10 times more zinc than the next highest source which is red meat. However this zinc, unlike the synthetic versions on the market, is to be found bound in amino acids and other large molecules which makes it very bio available. In order for zinc to be absorbed it has to first bind to such ‘ transport molecules ‘. This is not no easy for the synthetic supplements, but in oyster extract powder the job is already done.

Beware, not all oyster extract powders are the same. The cheaper brands from Korea, China and New Zealand tend to be mainly glycogen starch. Not many of us are starch deficient. The zinc content can be as low as 0.1g per kilogram of powder in such brands. Brands such as OysterMax™ have over 3.0g of zinc per kilogram of powder and are therefore 30 times more potent in terms of zinc concentration. To explain this more succinctly, there is the extracted meat of over 50 large oysters in a bottle of Oystermax™. There is the meat of 4 or 5 large oysters in some other brands. With this you can start to understand the price and quality difference issues.

This 3.0g potency level means 4 capsules (1g of powder) will provide 3mg of zinc. This is a safe supplemental amount of zinc. The high zinc oyster extract powder products are, by default, also more potent in all the other trace elements. This is because these high zinc extracts are mainly protein in nature and all these elements are bound to the amino acids in the proteins and ready for absorption. Combined with the rest of your daily food intake a supplemental amount of zinc of this order should be sufficient to ensure adequate supply. The beauty of oyster extract powder is that you have the peace of mind of knowing that each and every other trace element your body needs is there too. Athletes, sexually active people and those feeling fatigued or stressed can safely up their intake knowing that they will not upset the body’s delicate biochemical balance. Oyster Extract powder is balanced in levels of all trace elements the way nature intended.

Be careful to ask your supplier how potent their oyster extract powder is before you make a purchase. Ask the geographical source of the oysters, the quality of the water the oysters were grown in and how much zinc is contained in each gram of powder. If it is less than 1.5mg it can be considered a cheap brand. If it is over 3mg you are buying caviar. Think before you zinc!

New look website

Tuesday, October 6th, 2009

Oystermax will have a new look website from today. To coincide with the launch we will be giving customers a very special offer. Details to follow later.

Zinc supplements and Zinc deficiency.

Tuesday, September 2nd, 2008

As summer rolls on and winter draws near for some us thoughts will turn to making it a time as comfortable as possible in spite of the inclement weather we might expect. For a lot of us this means making sure that our health is in top shape and the medicine cabinet is stocked with all the necessary items to beat the winter blues.

Prospects of the common cold, influenza, sore throats and a plethora of aches and chills are just a few weeks away and this is a good time to think about some strategies to beat the winter blues. However recent studies into one major area of prevention has thrown up some very interesting facts that people should be aware of. It is the whole area of zinc supplements and zinc deficiency.

Many of us run for the zinc lozenges zinc tablets and zinc sprays and gels at the first sniffle or the first sign of a flu or cold. But wait here a moment. Research has found that we may be doing more harm than good. While zinc is indeed important for a healthy immune system in that zinc stimulates the thymus gland to produce thymulin. Thymulin in turn stimulates T-cell and T4 helper cells to fight infection. These cells can be present in low numbers when individuals are zinc deficient, increasing the risk of contracting infections during the winter.

The problem is, as recent research has shown, is that the immune system is sensitive to zinc concentrations in the blood. Too little or too much zinc can have a negative effect on the immune system response. So before you race to the cabinet and take 25 or 50 mg of zinc remember that fact and also remember that excessive zinc consumption can lead to neuro degenerative problems as it is toxic in high doses.

So how much is enough I hear you say? Firstly remember that the WHO (World Health Organisation) estimates that up to 80% of Western society may be zinc deficient. This is mainly due to the poor nutrient availability in processed foods and fast food which are so common place nowadays and also to poor eating habits that are associated with modern lifestyles and corporate advertising. Meanwhile, the RDA for zinc is 11mg per day for men and 9 mg per day for women. This RDA actually varies between Governments and some set it as high as 15mg for both men and women and slightly higher again for pregnant and lactating women.

Based on this these facts alone a daily supplement of zinc should really provide no more than 3 or 4 mg of zinc with the rest coming from diet. Then one has to assume how bio available the zinc supplement in question is. If it claims to be highly bio available and a tablet contains 25 mg of zinc gluconate or zinc sulphate or some chelated form of zinc then one can immediately see the problem. How can one be sure of how much of the zinc they take is actually absorbed?

The bio availability issue is a very pertinent one and the bioavailability of many synthetic zinc supplements is very questionable. However there is a solution that many may not consider and it comes from beneath the waves of an ocean near you. It’s called oyster extract powder. Oysters are the highest natural source of zinc. This zinc in oyster extract powder is highly bio available as it is already bound to active transport molecules making it easily absorbed. Another important aspect is also that along with the zinc you have zinc co-factors like manganese, copper and selenium and all the other 59 trace elements the body needs for proper physiological functioning.

If you want to try an oyster extract powder supplement email the manufacturer and ask them how much zinc is in each capsule of the product. Only the more conscientious brands will know this, be aware of this and be able to recommend a daily dosage based on this. With some brands you may have to take 20 capsules to get 3 or 4 milligrams of organic zinc while with some of the better brands this could be only 3 or 4 capsules daily assuming they have manufactured the powder with zinc potency in mind.

The bottom line is that taking an oyster extract powder supplement to increase the immune system response in winter is probably one of the safest and most effective ways to augment what should be a healthy lifestyle during those months when we are at risk.

Zinc & Testosterone in Healthy Adults

Wednesday, June 25th, 2008

This article, co-authored by a team of five researchers headed by Ananda S. Prasad, M.D., Ph.D., has enormous implications for all bodybuilders, especially those who are “natural.” It was originally published in the peer-reviewed medical journal Nutrition, Volume 12, No.5, 1996, pp. 344-348.

Dr. Prasad is considered to be the world expert on the trace mineral zinc and its metabolic effects on human beings. He has somewhere between 200 and 300 peer-reviewed publications to his credit and knows very well how to design a research project. He notes at the beginning of the research report’s abstract that “Zinc deficiency is prevalent throughout the world, including the USA.”

In this article, Dr. Prasad discusses an investigatioin of the effect of “mild zinc deficiency” on the serum testosterone levels of men.

BACKGROUND: Testosterone, as the reader may know, is the male sex hormone that many steroids are formulated to mimic. It is produced naturally in men and signals the body to develop male characteristics, including increased muscle mass. Certain background information here is very important. At BALCO Laboratories, Inc., of Burlingame, California, where the trace mineral levels of more than 200,000 people, including thousands of athletes, have been measured, a test called multi-element analysis has shown that approximately 70% of all athletes tested have been shown to have either a depletion (which is what Prasad calls a “mild deficiency”) or an outright deficiency. In either case, in one or more ways health and performance may be impaired. In the case of a deficiency, the individual will have one or more overt symptoms identifiable by any knowledgable physician.

Let us emphasize this point more strongly. Over 70% of the serious athletes BALCO has tested have proven depleted or deficient in zinc. This includes entire professional football and basketball teams, many amateur and professional bodybuilders, hundreds of Olympic athletes scattered among many different events, karate champions, and even elite tennis players.

By and large, these athletes are people who pay careful attention to their diet, yet the majority are still they are depleted or deficient in zinc.

According to a conversation we have had with Dr. Prasad, bodybuilders are prone to zinc depletion or deficiency for a number of reasons.

First, one of the best sources of zinc is red meat. Many bodybuilders eat a reduced amount of meat, concentrating instead on chicken and fish as their main protein sources.

Second, bodybuilders lose more zinc than do non-exercisers. Zinc exits the body in a number of ways, including through sweat. On an exercise day, an athlete will lose 50% more zinc through sweat than on a non-exercise day.

Third, bodybuilders require significantly more zinc than do non-exercisers.

In fact, because bodybuilding involves the infliction of a great deal of micro-damage to cells and tissues that must be repaired, and because the muscle are stimulated through exercise to grow, the director of BALCO Labs estimates that bodybuilders may require up to twice as much zinc as do non-exercisers.

This means that if you are a bodybuilder, you are very likely to have either a zinc depletion or deficiency. And if you are using steroids, which depress the body’s zinc, magnesium and copper levels, you are even more likely to be zinc deficient.

Dr. Prasad’s study involved several different populations.

The most important for bodybuilders is the group of four normal adult men approximately 27 years old. He measured their serum testosterone levels, then fed them a diet low in zinc for six months, thus inducing a “mild zinc deficiency” in them. As they progressed through the diet, he measured their serum testosterone levels two more times, once after eight weeks and once again after 20 weeks. As these men became progressively zinc depleted, their serum testosterone concentrations dropped. The chart Dr. Prasad has included on page 347 of the study indicates that by the end of the 20 weeks they had approximately ¼ the testosterone that they had had at the study’s beginning.

The implictions of this for bodybuilders and other athletes is clear. If you are depleted or deficient in zinc—and BALCO’s clinical experience indicates that you probably are—you can significantly increase your testosterone level through zinc supplementation.

In another group of nine older men 55 to 73 years old, Prasad and his fellow researchers measured serum testosterone levels. These men, he notes, were “marginally zinc deficient” (what BALCO calls “depleted”) at the time of the first measurement. After three to six months of zinc supplementation, he measured their serum testosterone levels again. Their testosterone levels had approximately doubled.

For many bodybuilders, this also has important implications. As you get older, your testosterone levels decline. That’s one reason why older bodybuilders have more difficulty adding muscle mass than the younger men in the gym. Many bodybuilders begin to sense at the age of 35 or 40 that adding muscle has become more difficult. For someone around this age who is zinc depleted or zinc deficient, supplementation with a highly absorbable form of zinc (monomethionine or asparate or a combination of the two) can make a noticeable difference.

Warning: Do not buy an ineffective zinc supplement. Do not buy tablets. Capsules are more absorbable. Do not buy zinc oxide. This is not a very absorbable form of zinc. Do not buy any zinc supplement that lists any calcium compound in the ingredients because the presence of calcium will reduce your absorption of zinc.

If the capsule contains a filler, it is probably a calcium compound, which will reduce your absorption of the zinc. Fillers are often not mentioned on the list of ingredients. If you are buying a supplement from a health food store and the clerk doesn’t know what the filler of a product is, ask him or her to call the company to find out.

Zinc – Natures Most Precious Metal

Wednesday, June 25th, 2008
Zinc, often described as the most ubiquitous trace element in the body, is of great importance in human nutrition. The World Health Organisation (WHO) estimates that up to 80% of western society may be mildly zinc deficient. More severe zinc deficiency can be seen in developing countries where the population eats less meat and more vegetables.

Who is at risk?

In Western society moderate to severe zinc deficiency is restricted to certain groups. These include the elderly who have a reduced ability to absorb zinc, vegetarians who are not diligent on zinc intake, alcoholics who excrete a lot of zinc via the kidneys, and athletes and body builders who loose more zinc through sweat and have an increased demand to their exercise regimes.However, most of us at some time or other experience stress, fatigue, overwork and may not eat, or may not have time to eat, a proper balanced diet. It is at these times that we all run the risk of becoming zinc deficient. As zinc is involved in over 300 enzyme reactions in the body, the symptoms of zinc deficiency are very diverse.

What are the symptoms?
One of the first areas to suffer from zinc deficiency is our immune system. Zinc helps the thymus gland to produce thymulin which in return promotes T cell and T4 helper cell production. For this reason zinc is very beneficial for anyone with compromised immunity. It is also the reason a large percentage of the population decide to take zinc lozenges and zinc supplements of all kind coming into the winter to help off set the common cold and the flu.

Zinc helps the skin to maintain it’s elastin and collagen supply. It can improve wound healing and in certain conditions like acne, psoriasis and dermatitis it has proven benefits to help prevent flare-ups. It has a triple role in the case of acne as:

  1. It controls the production of sebum, the oily liquid which clogs the pores before a flare-up.
  2. It can help prevent or control the ensuing infection by stimulating the immune response.
  3. It can improve wound healing and therefore reduce scarring from any such flare-ups.

Zinc is very important for keratin production and both nails and hair are the first to suffer, even in mild zinc deficiency. Brittle nails, spilt ends, lack lustre hair, falling hair and nails that peel are but a few symptoms of zinc deficiency.

One of the very common symptoms of zinc deficiency is fatigue. Zinc is very important for testosterone production and when levels of the hormone fall in both men and women fatigue and exhaustion can result, especially when coupled with a hectic modern lifestyle. Because zinc is so important for testicular health it can help increase free testosterone in the blood and thereby re-invigorate and increase energy levels. It is also essential for prostate health and the prostate gland has more zinc in it than any other organ in the body. In women, whose testosterone levels are about one tenth that of males, the increase in testosterone not only improves energy levels but it can help prevent osteoporosis.

How do I know if I have a zinc deficiency?
Zinc deficiency is very hard to quantify. It varies from individual to individual and depends a lot on life style and diet. A normal adult consuming a well-balanced diet and not abusing alcohol or drugs should at worst be very mildly zinc deficient. For most of us it gets worst from there.
What are the best sources of zinc?
The best sources of zinc are from diet. For correct absorption of zinc into the bloodstream, that zinc must first bind to active transport molecules during the process of digestion. Zinc uptake is also inhibited by compounds called phytins ( phytic acid) which are found in wholegrains and plant fibres. This is where the efficacy of many synthetic zinc supplements is questioned. These large pills have to disintegrate and bind to transport proteins before leaving the stomach or the zinc is useless. The zinc receptor cells are located in the duodenum and once it passes here very little uptake can occur.

This is why eating foods rich in zinc is the best policy. These foods have the zinc already bound to active transport molecules such as amino acids and certain acids. Red meat and poultry provide much of the zinc in the Western diet but fish, nuts and some cereals are also good sources, just don’t forget the phytic acid dilemma.

The world is your oyster!
One of the best sources of zinc are oysters and oyster extract powder is an excellent supplemental source of zinc. However not all oyster powders are the same. Most use oysters harvested when the oysters meat yield is high and this is when the zinc concentration is lowest. These tend to be the cheaper ones from New Zealand, China and Japan. Water quality from the growing areas is also something not easily traced in countries who do not have trade agreements with the US and Europe. Other oyster extracts are in pill form so half the weight is binding agents and excipients with no nutritional value.
Which brand is best?
There are however some very potent ones on the market who harvest the oysters at the right time and process the oysters with this same potency in mind. While more expensive, they far out weigh the synthetic alternatives on the market and are ultimately money well spent. If you feel you are zinc deficient or have any of the symptoms of zinc deficiency consult your health adviser and decide on a zinc replenishment plan that is suitable for your lifestyle. Think before you zinc!