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OptiBac Probiotics Probiotics

One week flat

Product rated 4.6 from 44 reviews
( Website and brand rated 4.7 from 320 reviews )

£7.24 Excl. UK Taxes

(Approximately US$ 12.38)

In Stock

This is a high quality, short term course of live cultures. 'One week flat' from OptiBac Probiotics is gluten free and therefore may be especially suitable for those with bloating.

7 sachets

What's it for?

A natural bacteria supplement from OptiBac Probiotics to be taken for 7 consecutive days. 

Who's it for?

For those seeking a high quality, short-term live cultures supplement.

Each sachet provides

5 billion live cultures + 0.3g FOS fibres.

OptiBac Probiotics 'One week flat' 

'One week flat' is a food supplement containing natural bacteria (live cultures), in powdered sachets to be taken daily as a one-week course. This can be taken once a month, or as frequently as desired. Please scroll to the bottom of the page to read reviews from our customers who have tried this supplement.

Lactococcus lactis Rosell-1058

Lactococcus lactis Rosell-1058

More about 'One week flat'

Lactobacillus acidophilus Rosell-52: acidophilus is a natural resident of the intestinal microflora; this strain of acidophilus from OptiBac Probiotics has been shown to survive gastric acidity and biliary salts, and to reach the intestines without damage. 

Bifidobacterium bifidum Rosell-71: In-vitro tests suggest that this strain flourishes well with Fructooligosaccharides.

Lactobacillus casei Rosell-215 is of an extensively studied species naturally residing in the intestinal flora; this strain from OptiBac Probiotics has been researched in its ability to resist gastric acidity and bile salts in order to reach your small and large intestines alive.

Lactococcus lactis Rosell-1058 is extracted from the kefir culture, and has been scientifically proven to reach the gut alive.

Fructooligosaccharide fibres (FOS) predominantly settle in the large intestine where they may act as a food source to stimulate the growth of your body's natural bacteria. 

This 7 day course is ideal for those looking for a short term, high quality natural bacteria supplement. 

Background information

Unlike similar foods and supplements containing live cultures, 'One week flat' is free from added sugars and does not contain gluten, and may therefore be suitable for those with bloating.  Abdominal or stomach bloating is thought to be associated with food intolerances, constipation, over-eating, PMS or intestinal gas; leaving the abdomen feeling uncomfortable, full and tight.  If you have poor digestion, waste materials and the gases they produce can remain in the gut for long periods of time, often at high temperatures and pressures.  This causes bloating and stretching of the gut walls beyond their comfortable limits. An imbalance of bacteria in the gut may result in poor digestive health, bloating, production of smelly and uncomfortable gases, and sluggish bowels. This imbalance is known as dysbiosis

Healthcare professionals can see Scientific Research on live cultures and bloating.

Please note: As of May 2014, this product has a new name ('One week flat') in the EU. The ingredients remain the same.


As a natural food supplement 'One week flat' can be given to adults and children from 4 years old & up, with the following recommendations: Take one sachet daily with breakfast for a 7 day course, or as professionally directed.

We highly recommend you take 'One week flat' for 7 consecutive days.  Most customers take this course once a month, but it can taken as often as desired. For more information see our FAQ: How often should I take OptiBac One week flat?

For best results:

  1. Pour an inch of water into a tall glass, leaving plenty of room for swirling.
  2. Shake the sachet well before gently sprinkling in the powder.
  3. Leave powder to dissolve naturally. 
  4. Vigorously swirl the water around in the glass.
  5. Drink, wait, and enjoy the benefits!


It is not recommended to give live cultures to patients who are: severely immunosuppressed, have pancreatitis, are in the Intensive Care Unit, have blood in the stool, have central venous catheters; or to post-surgical patients with open wounds, or infants with short bowel syndrome; unless under a doctor's care.

Full Ingredients

Stabiliser: Maltodextrin; Fructooligosaccharides (FOS); live cultures: (Lactococcus lactis Rosell-1058, Lactobacillus casei Rosell-215, Lactobacillus acidophilus Rosell-52 and Bifidobacterium bifidum Rosell-71).

Each sachet guarantees 5 billion micro-organisms + 0.3g FOS fibres.


Like the rest of the OptiBac Probiotics range, this product does not require refrigeration.  

Store away from direct sunlight.

  • Vegetarian
  • No added sugars
  • Gluten free
  • Yeast free
  • Free from artificial colours
  • Flavourless
  • Suitable in pregnancy
  • Live cultures
  • FOS fibres
  • Natural bacteria

Delivery Options

We endeavour to keep our delivery and shipping rates as fair as possible. There are no extra hidden admin or packaging fees.

Delivery method Price per order
UK Standard Shipping
Usually delivered within 4-7 days
UK First Class Postage
Usually delivered within 1-3 days
UK Next Day Delivery
Choose this option by 2pm Mon-Fri and your order should be with you in 24 hours.
Please only select this option if someone can sign for the order.
International - EU
Please allow 7-10 days for delivery
International - Non-EU
Please allow 7-20 days for delivery
We noticed that you're not inside Europe, so we have removed UK Taxes from the table above.

Orders placed before 2.00pm will be dispatched the same working day.

Free Delivery

We offer free delivery (UK and International) on all orders over £100. This discount will be applied automatically to your basket when you checkout.

Customer Reviews — 44 Reviews

  • Posted by Howard (UK) 1 month ago

    5 stars

    "I suffered from bloating for more than 5 years, with no relief whatsoever.
    My colonics Hydrotherapist recommended OptiBac products, that were spoken highly of at Colonics seminars.
    I purchased One Week Flat, and from day one of the 7 day course, I have had no bloating since.
    I am amazed, speechless and over the moon to be free of bloating, which caused me extreme pain sometimes, it affected me walking or exercising. It affected my relationship with my wife, it gave or worsened lower back pain that I suffer from.
    I am now completely free from bloating, and at risk of sounding dramatic, it has turn my life around :))))))

  • Posted by Kat Turton (Norfolk) 1 month ago

    5 stars

    "Cannot recommend this product enough. I am a chronic IBS sufferer and was going through a bad patch with coming off my pill (super, super bloated). After 3 days I noticed a massive difference and felt so much better in myself. I was expecting the sachets not to taste very pleasant but infact they did not taste of anything so taking them was easy. I've since moved on to the optibac daily which is keeping my IBS under control. Great product."

  • Posted by Annamaria (London) 1 month ago

    5 stars

    "I had a very bad period, my tummy hurt me and I was always going to the toilet, Everything I was eating that hurt me, I ... Read More »"

    Reply from OptiBac Probiotics

    Great news that ‘One week flat’ worked well for you.

    You can certainly try one of our daily probiotics – ‘For every day’ or ‘For every day EXTRA Strength’, and remember it’s also fine to keep taking ‘One week flat’ at regular intervals (some of our customers like it so much they even take it every day!).

  • Find out how we collect our reviews.

    View All 44 Reviews »

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Payment will be taken in British Pound Sterling, but for your information we’ve added estimated prices in US Dollars to each product page. UK taxes have been automatically removed from all product & delivery prices. Nothing else has been modified from the original version of the site.

Kind regards,
The OptiBac Probiotics team