Effective probiotics

When it comes to choosing the right probiotics for PERKii micro-shield technology, we start with scientific research. All the strains used in our products are backed by multiple, independent studies to ensure they may have a substantiated benefit to our health once in the gut.

Did you know? The human body consists of approximately 37 trillion cells encoded by 23,000 human genes. We are, however, outnumbered by the human microbiome – the bacteria living on and in us.

What are probiotics?

Derived from Greek, ‘probiotics’ literally translates as ‘for life’ (as opposed to antibiotics which means ‘against life’). By definition, probiotics are “live microorganisms that when administered in adequate amounts confer a health benefit on the host” (Hill et al., 2014). 

Based on this definition, it is evident that to achieve true ‘probiotic’ status, a microorganism must fulfil the following criteria:

1. The microorganism must be alive at time of ingestion

2. Ingested in a dosage high enough to cause an effect

3. The ingested live microorganisms need to grant a beneficial effect to the host in order to be a probiotic

Lactobacillus and Bifidobacterium species colonize the gastrointestinal tract and the urogenital tract of humans. They are found in a wide variety of food products and fermented products. They are listed as GRAS (generally recognized as safe) by the United States Food and Drug Administration (FDA), and they are listed as QPS (qualified presumption of safety) by the European Food Safety Authority (Hill et al., 2018; Jungersen et al., 2014).

Why do we need probiotics?

Probiotic levels can be affected by a wide range of factors including poor diet (too many fats or processed foods or too little fibre), excess stress, toxic substances (including antibiotics) and excess alcohol intake. While a good diet and exercise is the first line of defence, the large demands of the modern-day life can limit our ability to achieve our goals. Understanding the potential benefits of probiotics, can help you consider how adjusting your intake (of probiotics) may best benefit you.

Lactobacillus casei

One of the world’s most documented probiotic strains, Lactobacillus Casei is a dairy derived probiotic, which has been described in over 90 scientific publications and more than 20 clinical studies.

The substantial amount of clinical data from these studies has indicated that lactobacillus casei may have beneficial effects in the gastrointestinal and immune areas at a recommended dosage of 1 billion CFU/day over a period of 5-6 weeks.

May support the body’s immune function. 

Three clinical studies (1,2,3) directly investigated the administration and immune function of lactobacillus casei in humans. All three studies are published, randomised, double-blind and controlled trials (1262 participants). The length of probiotic supplementation during these studies was 5-6 weeks.

The available evidence from the studies indicated that there was a ‘causal relationship between intake of lactobacillus casei and immune function in adults’. It was evident that there are benefits to the immune system in adults consuming a daily intake of lactobacillus casei (intake is defined as, at least 1x 109 CFU). 

May support the body’s response to vaccines. 

A trial undertaken in 2012 (Rizzardini et al.) , reported in the British Journal of Nutrition, found significant enhancing effects of both bifidobacterium and lactobacillus casei on the levels of antibodies (IgG, IgG1, IgG3 and vaccine specific secretory IgA) to Influenza A after vaccination. 

Another human trial in 2015 reported that daily consumption of lactobacillus casei resulted in no observable effect on the components of the immune response to influenza vaccination but reduced the duration of upper respiratory symptoms. 

A clinical trial (2011) using another strain of Lactobacillus (Lactobacillus GG) showed that this organism acted as an adjuvant, improving influenza vaccine immunogenicity.

A clinical study published in 2005 (deVrese et al.) utilised two different probiotics, Lactobacillus rhamnosus GG or L. acidophilus CRL431. The probiotics induced significantly higher levels of neutralising antibodies and higher levels of anti-polio serum IgG and IgA after oral polio vaccination.


Bifidobacterium is a highly studied and highly documented probiotic. It is described in more than 300 scientific publications of which more than 130 are reports of clinical studies. Bifidobacterium has been tested in clinical trials since the 1970s (Black,1996). Bifidobacterium has been tested in clinical trials that have included subjects from preterm infants to the elderly, and it has been administered in dosages up to 100 billion CFU/day (Jungersen et al. (2014).

The length of probiotic supplementation during these studies was 2-4 weeks, at a daily probiotic CFU of 1 billion and upwards.

May support bowel function... 

Regular bowel movements, natural transit time and normal stool consistency are part of a well-functioning bowel. However, the boundaries for normal bowel function are wide and vary to a large extent from person to person. The normal range for bowel movements is five to 14 times a week, with outer boundaries of three to 21 times a week.

In a series of randomised, double-blind, placebo-controlled, cross-over trials, bifidobacterium not only showed to have some conclusive impact on adult bowel function, but infants as well.


In a double-blind, randomized, placebo-controlled, cross-over trial, bifidobacterium in fermented milk was given to healthy females in a dosage of 1x109 CFU/day for two weeks (Uchida et al. 2005). In this study, 41 females had an average stool frequency in the bifidobacterium period of 8.8 per two weeks compared to 8.0 in the placebo period. When the subjects were divided into constipation (less than eight times per two weeks) and no constipation tendency groups, stool frequency was significantly higher in the bifidobacterium period compared to the placebo period in the constipation tendency group.


A multicentre, double-blind, placebo-controlled study evaluated the efficacy of a milk formula supplemented with bifidobacterium in the prevention of acute diarrhoea in 90 healthy infants younger than eight months living in residential nurseries or foster care centres. There was a tendency toward a decrease in the incidence of diarrhoea, with 28.3% of the infants receiving bifidobacterium.

May support the body’s immune function. 

A clinical trial reported in 2012 (Holscher et al.) reported that infants consuming formula with Bb12 produced faeces with detectable presence of Bb12 and augmented sIgA concentration. Moreover, Caesarean-delivered infants consuming Bb12 had heightened immune response, evidenced by increased anti-rotavirus- and anti-poliovirus-specific IgA following immunization. These results demonstrate that negative immune-related effects of not breastfeeding and Caesarean delivery can be mitigated by including Bb12 in infant formula, providing infants a safe, dietary, immune-modulating bacterial introduction.

Lactobacillus Casei References

Clinical studies:

1. Jespersen et al., Effect of Lactobacillus paracasei subsp. paracasei, L. casei 431 on immune response to influenza vaccination and upper respiratory tract infections in healthy adult volunteers: a randomized, double blind, placebo-controlled, parallel-group study, Am J Clin Nutr 2015;101:1188–96.

2. Rizzaedini et al., Evaluation of the immune benefits of two probiotic strains Bifidobacterium animalis ssp. lactis, BB-12 ® and Lactobacillus paracasei ssp. paracasei, L. casei 431 ® in an influenza vaccination model: a randomised, double-blind, placebo-controlled study, British Journal of Nutrition 2012;107: 876–84.

3. De Vrese et al., Probiotic bacteria stimulate virus-specific neutralizing antibodies following a booster polio vaccination, Eur J Nutr 2005;44:406–413.


Hill D, Sugrue I, Tobin C, Hill C, Stanton C, Ross RP. The Lactobacillus casei Group: History and Health Related Applications. Front Microbiol. 2018 Sep 10;9:2107. doi: 10.3389/fmicb.2018.02107.

Jungersen M, Wind A, Johansen E, Christensen J E, Stuer-Lauridsen B and Eskesen D. The Science behind the Probiotic Strain Bifidobacterium animalis subsp. lactis BB-12. Microorganisms. 2014 Jun; 2(2): 92–110. doi: 10.3390/microorganisms2020092

Bifidobacterium References

Uchida K, Akashi K, Kusunoki I, Ikeda T, Katano N, Motoshima H, et al. Effect of fermented milk containing Bifidobacterium lactis Bb-12 on stool frequency, defecation, fecal microbiota and safety of excessive ingestion in healthy female students –2nd report. J Nutr Food 2005;8:39-51.

Chouraqui JP, Van Egroo LD, Fichot MC. Acidified milk formula supplemented with bifidobacterium lactis: impact on infant diarrhea in residential care settings. J.Pediatr. Gastroenterol.Nutr. 2004;38:288-292.

Holscher H D, Czerkies L A, Cekola P, et al. Bifidobacterium lactis Bb12 enhances intestinal antibody response in formula-fed infants: a randomized, double-blind, controlled trial. JPEN J. Parenter. Enteral Nutr. 2012;36:106S–117S

Additional bifidobacterium clinical studies and effects on bowel function:

Eskesen D, Jespersen L, Michelsen B, Whorwell PJ, Muller-Lissner S, Morberg CM. Effect of the probiotic strain Bifidobacterium animalis subsp. lactis, BB-12(R), on defecation frequency in healthy subjects with low defecation frequency and abdominal discomfort: a randomised, double-blind, placebo-controlled, parallel-group trial. Br.J.Nutr. 2015:1-9.

Pitkala KH, Strandberg TE, Finne Soveri UH, Ouwehand AC, Poussa T, Salminen S. Fermented cereal with specific bifidobacteria normalizes bowel movements in elderly nursing home residents. A randomized, controlled trial. J.Nutr.Health Aging 2007;11:305-311.

Nishida S, Gotou M, Akutsu S, Ono M, Hitomi Y, Nakamura T, et al. Effect of Yogurt Containing Bifidobacterium lactis BB-12 on Improvement of Defecation and Fecal Microflora of Healthy Female Adults. Milk Science 2004;53:71-80.

Matsumoto M, Imai T, Hironaka T, Kume H, Watanabe M, Benno Y. Effect of Yoghurt with Bifidobacterium lactis LKM512 in Improving Fecal Microflora and Defecation of Healthy Volunteers. Journal of Intestinal Microbiology 2001;14:97-102.