UPSC Prelims 2022 Q38: Probiotics — Explained
Consider the following statements in respect of probiotics:
1. Probiotics are made of both bacteria and yeast.
2. The organisms in probiotics are found in foods we ingest but they do not naturally occur in our gut.
3. Probiotics help in the digestion of milk sugars.
Which of the statements given above is/are correct?
- 1 only
- 2 only
- 1 and 3
- 2 and 3
Answer: (c) 1 and 3
Statement-wise explanation
- 1: correct — The FAO/WHO expert consultation (2001) defines probiotics as live micro-organisms that, given in adequate amounts, confer a health benefit on the host. The definition is not limited to bacteria. Most commercial probiotics are lactic acid bacteria such as Lactobacillus and Bifidobacterium. The yeast Saccharomyces boulardii, first isolated from lychee and mangosteen in 1923, is a widely used non-bacterial probiotic. So probiotics include both bacteria and yeast.
- 2: incorrect — The main probiotic groups, Lactobacillus and Bifidobacterium, are normal residents of the human gastrointestinal tract. Lactobacilli also live naturally in the urinary and genital tracts. Probiotics are given to add to or restore this native gut flora, often after antibiotics have upset it. The claim that these organisms do not naturally occur in our gut is therefore false. A few strains, such as the yeast S. boulardii, pass through the gut without settling there, but that does not save a statement written as a general rule.
- 3: correct — Many lactic acid bacteria make beta-galactosidase (lactase), the enzyme that splits lactose (milk sugar) into glucose and galactose. The yogurt cultures Lactobacillus bulgaricus and Streptococcus thermophilus are accepted as probiotics because they ease lactose maldigestion. Trials with some Bifidobacterium strains show the same effect. So probiotics help in digesting milk sugars, though the benefit depends on the strain.
How to eliminate
Statement 2 is the easiest one to judge. Basic biology says 'good bacteria' such as Lactobacillus already live in the human gut, and probiotics are taken to top them up. The phrase 'do not naturally occur in our gut' is a sweeping negative, which UPSC often uses to make a statement false. Once Statement 2 is out, options (b) and (d) go, leaving (a) '1 only' and (c) '1 and 3'. Statement 3 settles it, and everyday knowledge is enough: curd and yogurt are made by lactic acid bacteria that ferment milk sugar, and people with lactose intolerance often tolerate curd better than milk. That points to (c). If you doubted Statement 1, the option structure helps: every option that keeps Statement 2 out (a, c) also keeps Statement 1 in. The fact to remember is that the probiotic yeast Saccharomyces boulardii exists.
Know more
Probiotics are live micro-organisms which, when administered in adequate amounts, confer a health benefit on the host. This is the FAO/WHO definition from 2001. Three conditions follow from it: the organism must be alive, must be given in an adequate dose, and must have a proven benefit. That benefit is strain-specific. One Lactobacillus strain may work while another of the same species does not.
Common probiotic organisms
| Group | Examples | Natural home |
|---|---|---|
| Lactic acid bacteria | Lactobacillus acidophilus, L. rhamnosus, L. bulgaricus | Gut, curd, fermented foods |
| Bifidobacteria | Bifidobacterium lactis, B. longum | Gut (abundant in infants) |
| Other bacteria | Streptococcus thermophilus, Bacillus spp. | Yogurt cultures, soil, spores |
| Yeast | Saccharomyces boulardii | Tropical fruit; passes through the gut without settling |
How they help: they compete with pathogens for space and nutrients, make lactic acid and antimicrobial substances, strengthen the gut lining, modulate immunity, and supply enzymes such as beta-galactosidase (lactase) for lactose digestion.
Related terms UPSC can mix up
| Term | Meaning |
|---|---|
| Prebiotic | Non-digestible food (e.g., inulin, fibre) that feeds good gut microbes |
| Synbiotic | Probiotic plus prebiotic together |
| Postbiotic | Inactivated microbes or their products that still give a benefit |
| Gut microbiome | The whole community of microbes and their genes in the intestine |
India context: In 2011, ICMR and the Department of Biotechnology issued Guidelines for Evaluation of Probiotics in Food. FSSAI regulates probiotic foods under its nutraceutical and health-supplement regulations. Traditional Indian fermented foods such as curd, idli-dosa batter and kanji are natural sources of lactic acid bacteria.