PhD Nutrition Test Matrix - Optimizing Natural Testosterone Production

The topic of testosterone and its role in the world of sport and sports performance can be one of controversy. But this naturally occurring hormone plays a key part in the health of men and women alike. The biosynthetic pathway of testosterone production is tenfold. The addition of “test boosters” can theoretically enhance someone's ability to facilitate the increase in natural testosterone production and its concentrations within the body, and subsequently improve resistance exercise performance.

Discussed below are the three main contributors in optimizing natural testosterone production.

  1. Training

The effects of physical activity on the endocrine system and testosterone included vary. This is inter-individual with changes both acute and long-term as part of the adaptive process. That is, intensity, duration, fitness level and nutritional-metabolic status can dictate serum testosterone levels. Generally speaking, relatively short, intense bouts of exercise such as HIIT (High Intensity Interval Training – see barbell complex below) and weight training, increase testosterone concentrations, while more prolonged endeavours, such as marathon running, lower levels.1

  • Perform 12 reps of each movement as fast as possible;
  • Record time taken to perform entire complex;
  • To begin, take three times the amount of rest taken to perform the complex, for example, 1 minute of work, 3 minutes of rest;
  • Perform 5 sets;
  • As fitness and strength levels improve, reduce rest period and increase weight used.

Barbell Complex

  • SLDL;
  • Bent-over row (pronated grip);
  • Hang clean;
  • Push press;
  • Back squat;
  • Alternating lunges (12 each leg).
  1. Diet

Nutritional status and diet are key contributors to naturally occurring testosterone concentrations. Prolonged periods of being in a hypocaloric state (caloric deficit – especially with reference to sometimes extreme and severe dieting) and aggressive dieting can negatively affect associated hormonal function such as testosterone. Drastically reducing calories or “quick fixes” involving meal replacement shakes or juice “diets” involving dramatically reducing calories and increasing expenditure are unfortunately the norm, within modern day society. People want results, and fast! A more astute diet, if weight and fat loss are the goal, would therefore be better achieved over longer and steadier periods of time, slowly reducing caloric intake and gradually increasing expenditure if needed.

  1. Contributory nutrients and supplementation

Dietary fats

Fatty acid levels are determined primarily by dietary intake and genetics, and long-term restriction from those following low fat diets exacerbates essential fatty acid (EFA) deficiencies, and can be related to several disease conditions. Providing the body with enough dietary fat can significantly influence the fatty acid status in men and women, along with variations in testosterone levels.2 & 3

Testosterone is synthesized from cholesterol, again reiterating the importance of enough dietary fat within the diet. Those of particular importance are saturated and monounsaturated fats, such as:

Saturated fats

  • Meat, poultry, butter, cheese, cream, whole milk, coconut, egg yolks and dark chocolate.

Monounsaturated fats

  • Olives, canola and peanut oils, nuts and avocados.


Of the plethora of supplements available that claim to boost testosterone, zinc is possibly one of the most well researched. Symptoms of mild and severe low levels of zinc include depressed growth, teratogenesis, poor carbohydrate metabolism, altered cognition, poor immune function, alopecia, impotence, eye and skin lesions, and diarrhea.4 Low dietary zinc has also been associated with hypogonadism, low testosterone,5 low free T4 and low IGF-1, revealing the importance of zinc in steroid-hormone gene transcription. More than 100 different enzymes are involved in catalytic reactions and zinc dependent, one of which is testosterone. It is therefore important that sufficient zinc levels are achieved, particularly for those involved in frequent and intense bouts of exercise, whether that is through diet or supplements.6

D-Aspartic Acid

Also referred to as D-Aspartate, DAA, D-AA has shown to be a contributor to the rise in natural testosterone production. Studies researching the effects of DAA have been “cyclic” in nature, that is, it is suggested that use of products containing DAA should be used over a set period of time and then subsequently cease use for the same amount time in order to see the full effects of supplement.8

Vitamin D

There are many different forms of vitamin D, but vitamin D3 is the primary form used by the body. Although ultraviolet light is responsible for the conversion of vitamin D3 in the skin, we unfortunately have minimal exposure in the UK. The addition of vitamin D3 supplementation has been demonstrated to significantly (statistically) alter testosterone levels in males. Vitamin D3 has also been demonstrated to aid the prevention of osteoporosis in women.9

In conclusion

Taking into consideration the previous, training and nutritional status are of primary concern, and the addition of minerals and nutrients found in some “test boosting” products can assist an individual reaching their maximum, natural potential.8

Although an interesting topic, it’s important to state that natural testosterone production and maximal threshold that can be obtained is genetically predetermined. The addition of test boosting products and ingredients within, such as PhD’s Test Matrix, can contribute to an individual's ability to optimize testosterone serum concentrations within their natural and genetics capabilities.


  1. Siff M. 2003. Supertraining Sixth Edition. Denver. Supertraining Institute.
  2. Hurtado de Catalfo GE, de Gomez Dumm IN. Influence of testosterone on polyunsaturated fatty acid biosynthesis in Sertoli cells in culture. Cell Biochem Funct. 2005;23(3):175-180.
  3. Melmed S, Polonsky KS, Reed Larsen P, Kronenberg HM. 2011. Williams Textbook of Endocrinology 12th Edition.Philadelphia. Elsevier Saunders.
  4. Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Institute of Medicine (US). Zinc. In: Dietary Reference Intakes for Vitamin A, Vitamin K, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington DC: National Academy Press; 2000:442-501.
  5. Prasad AS, Mantzoros CS, Beck FW, et al. Zinc status and serum testosterone levels of healthy adults. Nutrition. 1996;12(5):344-348
  6. Antonio J, Kalman D, Stout JR, Greenwood M, Willoughby DS, Haff GG. 2008. Essentials of Sports Nutrition and Supplements. Humana Press. Totowa.
  7. Topo E1, Soricelli A, D'Aniello A, Ronsini S, D'Aniello G.Topo E, Soriicelli A, D’Aniello et al. The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and rats. Reprod Biol Endocrinol. 2009 Oct 27;7:120.
  8. Moradi F. Changes of Serum Adiponectin and Testosterone Concentrations Following Twelve Weeks Resistance Training in Obese Young Men. Asian J Sports Med. 2015 Dec; 6(4)\
  9. Pilz S, Frisch S, Koertke H, et al. Effect of vitamin D supplementation on testosterone levels in men. Hormone and Metabolic Research. 2011 Mar;43(3):223-9

About the Author

Dan Osman BSc (Hons), Dip. ISSN, CISSN, ASCC An experienced personal trainer, strength and conditioning coach, CISSN sport and exercise nutritionist, and PhD Nutrition sponsored athlete. “Growing up I wasn’t very sporty or athletic, and as a teenager I was never comfortable in my own skin and in all honesty carried a little too much puppy fat with the low self-esteem and confidence that went with it. Somewhere between 16 and 17 I discovered weight training and focused more on my nutrition, which brought about a new self-confidence and the rest, as they say, is history. After a spell of developing a passion for health and fitness, I was introduced to Brazilian Jiu-Jitsu (BJJ), Mixed Martial Arts (MMA) and Muay Thai – I was hooked! I can proudly say that the old school methods of training are still alive and well today and, with reference to BJJ and MMA, sink or swim! Being constantly paired with and, quite frankly, manhandled by stronger, heavier and more experienced guys made me long to be stronger, faster and more powerful to keep up with them, which is where my passion for strength, conditioning and nutrition evolved.” Dan is focused on getting results for his clients and combines a down-to-earth approach, with an unprecedented and asserting passion for fitness, health, nutrition and performance. Empowerment is a key method of Dan’s approach to coaching, giving his clients the tools they need to achieve real, tangible, life-changing results. Because of this Dan ‘lives the life’ and is as serious about his own training as he is with his clients, continually improving his methods of coaching and training through education and self-development. Dan is a first class BSc in Sports Studies (Hons.) graduate, as well as being certified with the International Society of Sports Nutritionists (CISSN) and a UKSCA (ASCC) as an accredited Strength and Conditioning coach. He has built on this foundation by working with a range of professional athletes and clients, from his postgraduate appointment at Saracens Premiership Rugby Union Club in preparing the senior squad for their 2008-2009 season, followed by his post within the University of Hertfordshire’s Performance Team working with talented, amateur and elite level athletes, included within sports initiatives such as the national Talented Athlete Scholarship Scheme (TASS), Elite Athlete Support Programme (EASP), Norwich City Football Development Centre, England Women’s FA, Batchwood Tennis High Performance Centre, Gosling Tennis High Performance Centre, Badminton England and Mavericks Netball Club. Dan has nearly 12 years' experience in the industry and now continues to work within the east of the country, predominantly within Essex. He worked with a wide range of clientele from those who wish to transform bodies and improve their health, fitness levels, recover from injury, lifestyle, to physique, TASS, MMA and powerlifting athletes, to name a few. Furthermore, Dan has been a consultant for the ASA’s diving talent programme and an England Netball London & South-East Academy Coach and Coach Educator. Dan recognizes that every client is an individual, and knows because of this every client requires a bespoke nutritional and training programme to achieve their goals. Dan’s training philosophy “Assisting individuals in reaching their goals through specific and effective training practices. Education and empowerment are key outcomes of my training interventions, giving you the tools needed to take control of your own body composition and performance and health goals”
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