NDA (II) 2017 General Ability Test · Question 104 of 150

Correct — D, Live microbial food supplement. The Food and Agriculture Organization and the World Health Organization defined probiotics in 2001 as live microorganisms which, when administered in adequate amounts, confer a health benefit on the host, and the international scientific association kept that wording in 2013. Two things in the definition matter for this question: the organisms must be alive, and they are taken in with food or as a supplement. The word itself is built from the Latin pro, for, and the Greek biotikos, fit for life — the exact opposite of antibiotic, which means against life.

• (a)Organic food — Organic is a label about how the crop or animal was farmed — without synthetic fertilisers, pesticides or growth promoters. It says nothing about live microorganisms, and a probiotic need not be organic nor an organic food probiotic.
• (b)Antacid — An antacid is a chemical base such as magnesium hydroxide or sodium bicarbonate that neutralises excess stomach acid. It is a drug acting on pH, with no living organism in it.
• (c)Antibiotic — An antibiotic kills or stops the growth of microbes. A probiotic supplies them. The two words are near opposites, which is precisely why the paper offers this option.

The human gut carries an enormous resident microbial population that helps digest food, makes some vitamins and keeps harmful organisms from taking hold. A probiotic is a preparation of live organisms taken by mouth to support that population. The commonest are bacteria of the genera Lactobacillus and Bifidobacterium, and one yeast, Saccharomyces boulardii. They reach people through fermented foods such as yoghurt, curd, kefir, cheese, kimchi, tempeh and miso, or as capsules, tablets, powders and sachets.

Two neighbouring terms are worth fixing alongside it. A prebiotic is not an organism at all but a food component, typically a non-digestible fibre, that the beneficial microbes feed on. A synbiotic combines the two. In examinations the standard traps are the word antibiotic, which sounds similar and means the reverse, and the claim that probiotic organisms are foreign to the gut — many of them are ordinary residents of it, which is why a 2022 UPSC item rejected exactly that statement. One practical benefit worth remembering is that lactobacilli produce lactase and so help break down milk sugar.

• The FAO and WHO definition, from 2001, is 'live microorganisms which when administered in adequate amounts confer a health benefit on the host'.
• Typical probiotic organisms are Lactobacillus species, Bifidobacterium species and the yeast Saccharomyces boulardii — so probiotics include both bacteria and a yeast.
• A prebiotic is a non-digestible food component that nourishes beneficial gut microbes; a synbiotic combines a probiotic with a prebiotic.
• Curd, yoghurt, kefir, kimchi and miso are fermented foods that carry live cultures; capsules and powders are the supplement form.
• The name comes from Latin pro, 'for', and Greek biotikos, 'fit for life' — the opposite of antibiotic.

• Reading probiotic as a kind of antibiotic because the words rhyme.
• Believing probiotic organisms do not naturally occur in the human gut — many of them do.
• Assuming probiotics are only bacteria; Saccharomyces boulardii is a yeast.

NDA and UPSC ask for the definition, or set two or three statements about what probiotics contain and what they do.

• practice — not a real PYQ

  Which one of the following is a prebiotic rather than a probiotic ?

  • (a)A capsule of live Lactobacillus
  • (b)A non-digestible dietary fibre that beneficial gut bacteria feed on
  • (c)Curd carrying live cultures
  • (d)A sachet of Saccharomyces boulardii

  Answer(b) A non-digestible dietary fibre that beneficial gut bacteria feed on — a prebiotic is food for the microbes, not the microbes themselves.

• practice — not a real PYQ

  Which one of the following organisms used in probiotic preparations is a yeast ?

  • (a)Lactobacillus acidophilus
  • (b)Bifidobacterium bifidum
  • (c)Saccharomyces boulardii
  • (d)Streptococcus thermophilus

  Answer(c) Saccharomyces boulardii — the others are bacteria, which is why probiotics are said to be made of both bacteria and yeast.