Important future developments will include selective androgen receptor modulators (SARMs). These drugs will be able to produce isolated effects of testosterone at androgen receptors. They are likely to become useful clinical drugs, but their initial worth may lie in facilitating research into the relative importance of testosterone’s action at the androgen receptor compared to at other sites or after conversion to other hormones. Testosterone will remain the treatment of choice for late onset hypogonadism for some time to come.
Free testosterone (T) is transported into the cytoplasm of target tissue cells, where it can bind to the androgen receptor, or can be reduced to 5α-dihydrotestosterone (DHT) by the cytoplasmic enzyme 5α-reductase. DHT binds to the same androgen receptor even more strongly than testosterone, so that its androgenic potency is about 5 times that of T.[114] The T-receptor or DHT-receptor complex undergoes a structural change that allows it to move into the cell nucleus and bind directly to specific nucleotide sequences of the chromosomal DNA. The areas of binding are called hormone response elements (HREs), and influence transcriptional activity of certain genes, producing the androgen effects.

Vitamin D supplementation may potentially boost testosterone levels, but further research is needed to determine if it really has an effect on the testosterone levels of young people and athletes. The truth is likely similar to zinc and magnesium — being in a deficient state causes your testosterone levels to drop below baseline, and supplementing it just takes you right back to baseline (but not any higher).
There is increasing interest in the group of patients who fail to respond to treatment with PDE-5 inhibitors and have low serum testosterone levels. Evidence from placebo-controlled trials in this group of men shows that testosterone treatment added to PDE-5 inhibitors improves erectile function compared to PDE-5 inhibitors alone (Aversa et al 2003; Shabsigh et al 2004).

It seems that adequate testosterone levels are an important influence on sexual symptoms in the aging male and also influence the response of men to PDE-5 inhibitors, the first line treatment for erectile dysfunction in men. Many would now suggest screening for testosterone deficiency in all men presenting with erectile dysfunction (Gore and Rajfer 2004; Shabsigh 2005). This would seem appropriate because, in addition to benefits on sexual function, identification and treatment of hypogonadal men with testosterone could improve other symptoms of hypogonadism and protect against other conditions such as osteoporosis.


These are the 4 primary methods in which the best test boosters increase testosterone production. It is important to realize, that many of these pathways can be incorporated at the same time. For example, Nutrient Optimization should always be a consideration when promoting testosterone production. As well, most men prefer sticking to an Alpha-5-Reductase regimen year-round to promote better prostate health as well as preventing hair loss.
Mínguez-Alarcón, L., Chavarro, J. E., Mendiola, J., Roca, M., Tanrikut, C., Vioque, J., ... Torres-Cantero, A. M. (2017, March–April). Fatty acid intake in relation to reproductive hormones and testicular volume among young healthy men [Abstract]. Asian Journal of Andrology, 19(2), 184–190. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/27834316
Most studies support a link between adult criminality and testosterone, although the relationship is modest if examined separately for each sex. Nearly all studies of juvenile delinquency and testosterone are not significant. Most studies have also found testosterone to be associated with behaviors or personality traits linked with criminality such as antisocial behavior and alcoholism. Many studies have also been done on the relationship between more general aggressive behavior/feelings and testosterone. About half the studies have found a relationship and about half no relationship.[66]
Although, most studies on TT have been conducted on animals, the results appear promising. One study that looked at sexually sluggish male albino rats found that having been given extracts of TT, the rats "mount frequency, intromission frequency, and penile erection index" all increased, while "mount latency, intromission latency, and ejaculatory latency" all decreased. Who said romance was dead?
Disclaimer: The entire contents of this website are based upon the opinions of Dr. Mercola, unless otherwise noted. Individual articles are based upon the opinions of the respective author, who retains copyright as marked. The information on this website is not intended to replace a one-on-one relationship with a qualified health care professional and is not intended as medical advice. It is intended as a sharing of knowledge and information from the research and experience of Dr. Mercola and his community. Dr. Mercola encourages you to make your own health care decisions based upon your research and in partnership with a qualified health care professional. If you are pregnant, nursing, taking medication, or have a medical condition, consult your health care professional before using products based on this content.
Below, we have the runners up. They are still potent supplements and we’ve had great runs with them. Keep in mind though, there are a LOT of test boosters we’ve tried that are not making this list. We wish we could talk poorly about specific supplements, but that’s a legal issue; so instead we only focus on the best supplements we’ve taken. If we took it and didn’t like it – we wont write about it.
The group's 2010 clinical practice guidelines make it clear that "the threshold testosterone level below which symptoms of androgen deficiency and adverse health outcomes occur and testosterone administration improves outcomes in the general population is not known." They also clearly advise against screening men in the general population to avoid "labeling and medicalization of otherwise healthy men for whom testing, treatment, and monitoring would represent a burden with unclear benefit."

The sexual hormone can encourage fair behavior. For the study, subjects took part in a behavioral experiment where the distribution of a real amount of money was decided. The rules allowed both fair and unfair offers. The negotiating partner could subsequently accept or decline the offer. The fairer the offer, the less probable a refusal by the negotiating partner. If no agreement was reached, neither party earned anything. Test subjects with an artificially enhanced testosterone level generally made better, fairer offers than those who received placebos, thus reducing the risk of a rejection of their offer to a minimum. Two later studies have empirically confirmed these results.[71][72][73] However men with high testosterone were significantly 27% less generous in an ultimatum game.[74] The Annual NY Academy of Sciences has also found anabolic steroid use which increase testosterone to be higher in teenagers, and this was associated with increased violence.[75] Studies have also found administered testosterone to increase verbal aggression and anger in some participants.[76]
Falling in love decreases men's testosterone levels while increasing women's testosterone levels. There has been speculation that these changes in testosterone result in the temporary reduction of differences in behavior between the sexes.[53] However, it is suggested that after the "honeymoon phase" ends—about four years into a relationship—this change in testosterone levels is no longer apparent.[53] Men who produce less testosterone are more likely to be in a relationship[54] or married,[55] and men who produce more testosterone are more likely to divorce;[55] however, causality cannot be determined in this correlation. Marriage or commitment could cause a decrease in testosterone levels.[56] Single men who have not had relationship experience have lower testosterone levels than single men with experience. It is suggested that these single men with prior experience are in a more competitive state than their non-experienced counterparts.[57] Married men who engage in bond-maintenance activities such as spending the day with their spouse/and or child have no different testosterone levels compared to times when they do not engage in such activities. Collectively, these results suggest that the presence of competitive activities rather than bond-maintenance activities are more relevant to changes in testosterone levels.[58]
That testosterone decreases with age has been clearly established by many studies over many years in several different populations of men (Harman et al 2001; Feldman et al 2002; Araujo et al 2004; Kaufman and Vermeulen 2005). Of even greater significance is the steeper fall of the most biologically active fraction of total testosterone, non-sex hormone binding globulin (SHBG)- bound testosterone, or bioavailable testosterone (bio-T). The classical, but not the only approach to measuring bio-T, is to precipitate out SHBG (and hence the testosterone which is strongly bound to it as well) and measure the remainder as total testosterone (Tremblay 2003). Vermeulen et al (1999) have devised a less tedious and less expensive method of measuring a surrogate for bio-T, namely calculated bio-T, inserting total T, albumin, SHBG and a constant into a mathematical formulation. There is a strong correlation between actual bio-T and calculated bio-T (Emadi-Konjin et al 2003).
Are you getting enough vitamin D? Vitamin D is an essential nutrient, but it can be difficult for people to know if they are getting the right amount. Some people will be able to get enough vitamin D from sunlight. Others may need to make dietary changes or take supplements. Here, we explain how to get vitamin D from sunlight, food, and supplements. Read now
Every vitamin, mineral, and ingredient that affects the human body can be taken in enough quantities that they are harmful, or toxic, even the ones that — at lower levels — are beneficial or necessary. Unfortunately, testosterone boosters contain a lot of ingredients that are not well understood. This means in addition to not being able to confirm whether certain ingredients increase testosterone, the scientific and medical communities also don’t know at what levels many ingredients become toxic. On the up side, you might need to eat several pounds of a particular leafy plant before it becomes harmful. On the down side, it could be significantly less that pushes you over your body’s limit. We simply don’t know how little or how much the human body can tolerate. We recommend keeping your doctor in the loop when you add any supplement with unproven ingredients into your diet — they’ll be able to help you find and track any undesired side-effects that these ingredients might cause.

Dixon Troyer is the President of Operations at 3 Elements Lifestyle, LLC., a Fitness and Weight Loss company that specializes in YOU! With more than 15 years of gym and club experience, owning, operating and managing clubs of all sizes, Dixon lectures, delivers seminars and workshops on the practical skills required to successfully help you with your health and fitness goals. Dixon also helps you build the teamwork, management, and training necessary to open your own fitness center.
A number of research groups have tried to further define the relationship of testosterone and body composition by artificial alteration of testosterone levels in eugonadal populations. Induction of a hypogonadal state in healthy men (Mauras et al 1998) or men with prostate cancer (Smith et al 2001) using a gonadotrophin-releasing-hormone (GnRH) analogue was shown to produce increases in fat mass and decreased fat free mass. Another experimental approach in healthy men featured suppression of endogenous testosterone production with a GnRH analogue, followed by treatment with different doses of weekly intramuscular testosterone esters for 20 weeks. Initially the experiments involved men aged 18–35 years (Bhasin et al 2001) but subsequently the study was repeated with a similar protocol in men aged 60–75 years (Bhasin et al 2005). The different doses given were shown to produce a range of serum concentrations from subphysiological to supraphysiological (Bhasin et al 2001). A given testosterone dose produced higher serum concentrations of testosterone in the older age group (Bhasin et al 2005). Subphysiological dosing of testosterone produced a gain in fat mass and loss of fat free mass during the study. There were sequential decreases in fat mass and increases in fat free mass with each increase of testosterone dose. These changes in body composition were seen in physiological and supraphysiological treatment doses. The trend was similar in younger versus older men but the gain of fat mass at the lowest testosterone dose was less prominent in older patients (Bhasin et al 2001; Bhasin et al 2005). With regard to muscle function, the investigators showed dose dependent increases in leg strength and power with testosterone treatment in young and older men but there was no improvement in fatigability (Storer et al 2003; Bhasin et al 2005).
Before taking any supplements, at either end of the spectrum, you need to check whether it’s low testosterone that is actually causing the problem. Taking something that you don’t need could potentially cause irreversible issues. For that reason, steroid hormones like DHEA should never be prescribed without having blood tests first. Roked also recommends regular blood monitoring to make sure you’re taking the correct dosage.
The bones and the brain are two important tissues in humans where the primary effect of testosterone is by way of aromatization to estradiol. In the bones, estradiol accelerates ossification of cartilage into bone, leading to closure of the epiphyses and conclusion of growth. In the central nervous system, testosterone is aromatized to estradiol. Estradiol rather than testosterone serves as the most important feedback signal to the hypothalamus (especially affecting LH secretion).[115] In many mammals, prenatal or perinatal "masculinization" of the sexually dimorphic areas of the brain by estradiol derived from testosterone programs later male sexual behavior.[116]

There is an increased incidence of hypogonadism in men with rheumatoid arthritis. Tengstrand et al (2002) studied hormonal levels in 104 men with rheumatoid arthritis and 99 age-matched healthy men. They divided their subjects into 3 age groups: 30–49, 40–59, 60–69. Mean non-sex hormone binding globulin-bound testosterone (bioavailable testosterone) was lower in men with rheumatoid arthritis for each of the three groups. LH was also found to be lower in the patients with rheumatoid arthritis suggesting a hypothalamic-pituitary cause of the reduced bioavailable testosterone. Of the 104 men with rheumatoid arthritis, 33 had hypogonadism compared to 7 of the 99 healthy controls.
Nutrient Optimization– Testosterone production can often be increased by nutrient optimization. This is the supplementation of excess key vitamins and minerals which are required to produce testosterone. This allows your test pathway to keep producing away, as opposed to someone with a key vitamin or mineral deficiency- which slows down or stops testosterone production.
When your testosterone levels go up, so does your libido. Unfortunately, the inverse is not true — your libido levels can go up without your testosterone levels also going up. And that’s how most supposed T-boosters “work”: they make you feel ornery, leading you to think that your T levels are appreciably higher, when they actually aren’t. In rare cases, supplementation will result in a 20% testosterone increase. This kind of improvement may sound impressive, but is irrelevant for practical purposes.

Afrisham, R., Sadejh-Nejadi, S., SoliemaniFar, O., Kooti, W., Ashtary-Larky, D., Alamiri, F., … Khaneh-Keshi, A. (2016, November 24). Salivary testosterone levels under psychological stress and its relationship with rumination and five personality traits in medical students. Psychiatry Investigations, 13(6), 637–643. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5128352/
Bisphenol-A also known under the name of BPA is a chemical compound which is very widespread for manufacturing a wide spectrum of plastic items and aluminum cans. Many studies have already proven the fact that even the smallest amount of BPA is very harmful to the human health. This compound causes hormonal imbalance and even may lead to prostate cancer.
Hooper, D. R., Kraemer, W. J., Saenz, C., Schill, K. E., Focht, B. C., Volek, J. S. … Maresh, C. M. (2017, July). The presence of symptoms of testosterone deficiency in the exercise-hypogonadal male condition and the role of nutrition [Abstract]. European Journal of Applied Physiology, 117(7), 1349–1357. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/28470410
Testosterone is more than a “male sex hormone”. It is an important contributor to the robust metabolic functioning of multiple bodily systems. The abuse of anabolic steroids by athletes over the years has been one of the major detractors from the investigation and treatment of clinical states that could be caused by or related to male hypogonadism. The unwarranted fear that testosterone therapy would induce prostate cancer has also deterred physicians form pursuing more aggressively the possibility of hypogonadism in symptomatic male patients. In addition to these two mythologies, many physicians believe that testosterone is bad for the male heart. The classical anabolic agents, 17-alkylated steroids, are, indeed, potentially harmful to the liver, to insulin action to lipid metabolism. These substances, however, are not testosterone, which has none of these adverse effects. The current evidence, in fact, strongly suggests that testosterone may be cardioprotective. There is virtually no evidence to implicate testosterone as a cause of prostate cancer. It may exacerbate an existing prostate cancer, although the evidence is flimsy, but it does not likely cause the cancer in the first place. Testosterone has stimulatory effects on bones, muscles, erythropoietin, libido, mood and cognition centres in the brain, penile erection. It is reduced in metabolic syndrome and diabetes and therapy with testosterone in these conditions may provide amelioration by lowering LDL cholesterol, blood sugar, glycated hemoglobin and insulin resistance. The best measure is bio-available testosterone which is the fraction of testosterone not bound to sex hormone binding globulin. Several forms of testosterone administration are available making compliance much less of an issue with testosterone replacement therapy.

"I am very cautious about committing someone for life to medication," said Dr. Kathleen L. Wyne, who directs research on diabetes and metabolism at Houston's Methodist Hospital Research Institute and serves on the Sex Hormone and Reproductive Endocrinology Scientific Committee for the American Association of Clinical Endocrinologists. "That does frustrate patients because they have heard about [Low T] from TV and friends."
Low testosterone levels may contribute to decreased sex drive, erectile dysfunction, fragile bones, and other health issues. Having low testosterone levels may also indicate an underlying medical condition. See your doctor if you suspect you have low testosterone. A simple blood test is all it takes to check if your testosterone falls within the normal range.
"The Journal of Clinical Endocrinology and Metabolism" published that males who switched from a high-fat diet to a low-fat diet also saw a decrease in their testosterone levels. If you want to put some fat back into your diet without fearing cardiac implications, plant-based saturated fat like coconut is just the ticket. Meat-based fat is also acceptable if kept to less than 10% of your dietary fat intake.

After bombarding consumers with advertising, and massaging physicians with free meals and medical "information," the stage is set to seal the deal. "The fat guy has been seeing the ads on TV," said Fugh-Berman. "The doc has just come from a medical meeting where they were talking about how using testosterone can fight depression, etc., and they are being primed in a different way."
Beast Sports recommends taking four capsules twice per day. The pills are about the same size as a multivitamin or a Tylenol liquid gel pill — not tiny tablets, unfortunately, but they aren’t horse pills. They smell like the boxes of raisins your Mom packed into your school lunch, but stale, like they were forgotten in the pantry for a few years, and a little spicy, like she sprinkled curry powder on them. If you follow this eight pills per day regime, your $46 bottle will last you twenty-two days, and cost you about $2 per day.
Testosterone is the main hormone associated with muscle mass, strength gains, and libido. But that's far from the only thing it does in the body. As Chris Lockwood, Ph.D., explains in the article "All About Testosterone," it impacts everything from mood and memory to bone health—but yes, to be clear, it also makes muscles bigger and stronger, and helps increase endurance and athletic performance.
Barbara Mintzes, at the University of British Columbia, said in a Skype interview, "Androgel was approved for a real condition—men who have a number of clinical or acquired conditions that affect testosterone, either through the testes or pituitary gland. So testosterone replacement therapy makes sense, and producing it in a gel makes sense. Where there is an actual need for the product, there's nothing wrong with that." But, she added, "When this gets marketed for what is essentially healthy aging, the antennas go up."
Smith and colleagues (2005) undertook a prospective study on the contribution of stress to coronary heart disease. Their study, which involved 2512 men aged 45 to 59 years, looked at a number of metabolic parameters. They found that an increased cortisol to testosterone ratio was associated with a high risk of coronary artery disease and that this risk was mediated by components of the insulin resistance syndrome. They reported that high cortisol and low testosterone levels are associated with a worsening of insulin resistance and that there is evidence to support the possibility of improving this pattern by treatment with testosterone.
While it would be nice to buy a testosterone pill from the local supplement store and have your testosterone levels go up, such a magic pill does not exist. As you can see from the above rundown, while a few supplements may be somewhat effective if your T levels are already low, none will significantly raise your testosterone above a baseline level. Thus, the basics of keeping your T levels high remain pretty simple:
Ashwagandha is sometimes included in testosterone supplements because of the hypothesis that it improves fertility. However, we couldn’t find sufficient evidence to support this claim (at best, one study found that ashwagandha might improve cardiorespiratory endurance). WebMD advocates caution when taking this herb, as it may interact with immunosuppressants, sedative medications, and thyroid hormone medications.

A number of research groups have tried to further define the relationship of testosterone and body composition by artificial alteration of testosterone levels in eugonadal populations. Induction of a hypogonadal state in healthy men (Mauras et al 1998) or men with prostate cancer (Smith et al 2001) using a gonadotrophin-releasing-hormone (GnRH) analogue was shown to produce increases in fat mass and decreased fat free mass. Another experimental approach in healthy men featured suppression of endogenous testosterone production with a GnRH analogue, followed by treatment with different doses of weekly intramuscular testosterone esters for 20 weeks. Initially the experiments involved men aged 18–35 years (Bhasin et al 2001) but subsequently the study was repeated with a similar protocol in men aged 60–75 years (Bhasin et al 2005). The different doses given were shown to produce a range of serum concentrations from subphysiological to supraphysiological (Bhasin et al 2001). A given testosterone dose produced higher serum concentrations of testosterone in the older age group (Bhasin et al 2005). Subphysiological dosing of testosterone produced a gain in fat mass and loss of fat free mass during the study. There were sequential decreases in fat mass and increases in fat free mass with each increase of testosterone dose. These changes in body composition were seen in physiological and supraphysiological treatment doses. The trend was similar in younger versus older men but the gain of fat mass at the lowest testosterone dose was less prominent in older patients (Bhasin et al 2001; Bhasin et al 2005). With regard to muscle function, the investigators showed dose dependent increases in leg strength and power with testosterone treatment in young and older men but there was no improvement in fatigability (Storer et al 2003; Bhasin et al 2005).
Bodybuilding.com sells science-backed testosterone support from top brands so you can continue to crush your goals. Our customer reviews will give you a snapshot of how each of these products works on real people living real lives, so you can make the best decision for your body. Ready to feel powerful again? Let’s find the test booster that’s right for you.
Male sex characteristics greatly depend on testosterone synthesis in your body. If you keep the levels of this hormone normal, you will prevent sexual potency issues. Accordingly, the elevation of testosterone levels helps combat the impairment of erectile function. The levels of this hormone also affect male fertility. If these levels grow, fertility improves. Aging has a negative impact on testosterone secretion. Such hormonal imbalance is inevitable and permanent. But it’s still possible to positively change the situation and stimulate hormone production by using the high-quality testosterone boosters.
This nutritious veggie is loaded with indole-3-carbinole, a chemical that gets rid of girly hormones from your blood. It was found that healthy men who took 500mg of this chemical daily for 1 week had their levels of estrogen reduced by half, making testosterone more effective. If you have not done so already, it is time to start making cabbage a regular part of your diet to get your T-levels boosted.
“I see people who've been doing things in the gym and they've never been told that it can shut off your own production and it can also irreversibly lower your sperm count,” says Roked. “These are all quite serious issues that even though they may be rare if it happened to you it would cause a big impact on your life, so I'd say it's always best to do things with a specialist, but also for anyone it's not a great idea to take things that aren't needed."
Keep in mind that you can use virtually any type of equipment you want for this – an elliptical machine, a treadmill, swimming, even sprinting outdoors (although you will need to do this very carefully to avoid injury) -- as long as you're pushing yourself as hard as you can for 30 seconds. But do be sure to stretch properly and start slowly to avoid injury. Start with two or three repetitions and work your way up, don't expect to do all eight repetitions the first time you try this, especially if you are out of shape.

Dr. Anthony’s Notes: Magnesium is best to take at night as it is relaxing. Supplemental magnesium can cause loose stools at high doses. If you experience loose stools, you'll know to back off your dose. This is a really useful supplement for overall health – not JUST for testosterone. Verdict: this is one of the natural testosterone supplements that work. Best Food Sources: pumpkin seeds, spinach, swiss chard, black beans, cashews, quinoa, quality whole gains like Ezekiel bread How To Take Magnesium: 200-400mg capsule form at night before bed.
Fenugreek, which is scientifically known as Trigonella foenum-graecum, is a popular medicinal herb used in India and areas of the Middle East. Studies on fenugreek suggest that it can increase testosterone levels by acting as an aromatase inhibitor. Aromatase is the enzyme responsible for converting testosterone into estrogen. Studies show that subjects supplementing fenugreek experienced a boost in testosterone as well as reduced fat loss and increased strength and muscle mass.
A related issue is the potential use of testosterone as a coronary vasodilator and anti-anginal agent. Testosterone has been shown to act as a vasodilator of coronary arteries at physiological concentrations during angiography (Webb, McNeill et al 1999). Furthermore men given a testosterone injection prior to exercise testing showed improved performance, as assessed by ST changes compared to placebo (Rosano et al 1999; Webb, Adamson et al 1999). Administration of one to three months of testosterone treatment has also been shown to improve symptoms of angina and exercise test performance (Wu and Weng 1993; English et al 2000; Malkin, Pugh, Morris et al 2004). Longer term studies are underway. It is thought that testosterone improves angina due its vasodilatory action, which occurs independently of the androgen receptor, via blockade of L-type calcium channels at the cell membrane of the vascular smooth muscle in an action similar to the dihydropyridine calcium-channel blockers such as nifedipine (Hall et al 2006).
^ David KG, Dingemanse E, Freud JL (May 1935). "Über krystallinisches mannliches Hormon aus Hoden (Testosteron) wirksamer als aus harn oder aus Cholesterin bereitetes Androsteron" [On crystalline male hormone from testicles (testosterone) effective as from urine or from cholesterol]. Hoppe-Seyler's Z Physiol Chem (in German). 233 (5–6): 281–83. doi:10.1515/bchm2.1935.233.5-6.281.
After bombarding consumers with advertising, and massaging physicians with free meals and medical "information," the stage is set to seal the deal. "The fat guy has been seeing the ads on TV," said Fugh-Berman. "The doc has just come from a medical meeting where they were talking about how using testosterone can fight depression, etc., and they are being primed in a different way."
Zinc plays a variety of roles in regulating the functions of enzymes and chemicals as well as your immune system. Zinc is also a potent antioxidant and can reduce the frequency of illnesses. Studies show that zinc may actually increase testosterone production. Large doses of zinc have actually been found to inhibit aromatase, thus reducing estrogen levels and increasing the effects of testosterone.
Phthalates are found to cause poor testosterone synthesis by disrupting an enzyme required to create the male hormone. Women with high levels of DEHP and DBP (two types of phthalates) in their system during pregnancy were found to have sons that had feminine characteristics Phthalates are found in vinyl flooring, detergents, automotive plastics, soaps and shampoos, deodorants, perfumes, hair sprays, plastic bags and food packaging, among a long list of common products. Aside from phthalates, other chemicals that possess gender-bending traits are:
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