PhD Nutrition Test Matrix

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.


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.


  • 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.


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


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 AD’Aniello ARonsini SD’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 ratsReprod 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

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