Questions & explanations
1. What is lactose intolerance in children?
Lactose intolerance means the body cannot digest lactose, a sugar in milk, because it lacks enough lactase enzyme. Primary lactose intolerance develops slowly after age 2-3 when lactase production naturally drops. Secondary lactose intolerance happens after an illness like gastroenteritis that damages the gut lining, and it is temporary. Symptoms include bloating, gas, diarrhea, and stomach pain after eating dairy. The hydrogen breath test measures hydrogen in breath after drinking lactose; high levels mean poor digestion. Management involves avoiding lactose or using lactase enzyme drops or lactose-free milk. Most children with primary intolerance can still eat small amounts of yogurt or hard cheese.
2. What factors determine the choice of enteral formula for a child?
The formula must be appropriate for the child's age: infants need breast milk or infant formula, while older children can use pediatric formulas. For children with specific diseases, there are special formulas: for example, a child with cow's milk allergy needs a hypoallergenic formula with broken-down proteins. A child with kidney disease may need a formula with lower protein and electrolytes. The formula's calorie density can be adjusted: standard is 1 kcal/mL, but some children need higher calorie (1.5-2 kcal/mL) to gain weight. The formula should also provide enough vitamins and minerals. A dietitian calculates the exact amount needed based on the child's weight and growth goals.
3. What are ACTN3, ACE, and PPARGC1A in the context of sports performance?
These are genes that have common variants (versions) linked to athletic traits. ACTN3 is called the 'speed gene' because a variant (R577X) is associated with fast-twitch muscle fibers and sprint performance. ACE (angiotensin-converting enzyme) has an insertion/deletion variant that affects blood flow and oxygen delivery; the I allele is linked to endurance. PPARGC1A (PGC-1α) is a gene that regulates mitochondria and energy metabolism; a variant (Gly482Ser) may influence endurance capacity. Having certain variants does not guarantee success but can give a slight advantage in specific sports. Most people have a mix of variants, so training and environment matter more.
4. An athlete discovers they have the ACTN3 XX genotype. Should they change their training focus from sprinting to endurance? Explain.
No, they should not change their training focus based solely on this gene variant. The XX genotype means they lack α-actinin-3, but many elite sprinters have been found with XX genotype, though less commonly. The effect of ACTN3 on performance is small, and training can overcome genetic differences. Sprinting success depends on many factors like technique, power training, and muscle fiber recruitment. The athlete should continue training for their chosen sport and not let a single gene discourage them. Genetic information is best used for general awareness, not to dictate training direction. Focus on consistent, smart training and proper nutrition instead.
5. Compare the potential benefits of probiotics versus a fiber-rich diet for an athlete's gut health.
Probiotics add live beneficial bacteria directly to the gut, while fiber feeds the bacteria already there. Probiotics may help restore gut balance after antibiotics or illness, and some strains can reduce exercise-induced gut symptoms. Fiber, on the other hand, promotes long-term diversity and produces short-chain fatty acids that have anti-inflammatory effects. For an athlete, a fiber-rich diet is more sustainable and supports overall gut health. Probiotics can be a short-term boost but are not a replacement for fiber. Ideally, athletes should eat plenty of fiber and consider probiotics for specific issues like traveler's diarrhea or after antibiotics.
6. Why might a child with severe reflux need continuous tube feeding instead of bolus?
Continuous feeding delivers formula at a slow, steady rate, which keeps the stomach partially filled and reduces pressure that can trigger reflux. Bolus feeding gives a large volume quickly, which can distend the stomach and cause the lower esophageal sphincter to relax, allowing stomach contents to flow back up. With continuous feeding, the stomach is never too full, so reflux episodes are less frequent. The slow rate also helps the formula move through the stomach more smoothly. This approach is especially helpful for children with gastroesophageal reflux disease (GERD) who vomit often. It can improve comfort and reduce the risk of aspiration.
7. What is the difference between stunting and wasting?
Stunting is chronic undernutrition that makes a child short for their age, while wasting is acute undernutrition that makes a child thin for their height. Stunting develops over months or years, while wasting can happen quickly (weeks). Stunting is harder to reverse after age 2, but wasting can be treated with intensive feeding. Both can occur in the same child. Stunting reflects long-term poor diet and infections, while wasting reflects recent food shortage or illness. Both increase the risk of death and developmental delays. Prevention strategies differ: stunting requires long-term nutrition, wasting needs immediate food and health care.
8. What are common complications of enteral tube feeding in children and how can they be managed?
Common complications include tube blockage, which can be prevented by flushing the tube with water before and after feedings. Diarrhea or constipation may occur from the formula; switching to a fiber-containing formula or adjusting the feeding rate can help. The tube can become dislodged or the skin around a G-tube can get infected; keep the site clean and dry. Aspiration (formula going into the lungs) is a serious risk; keep the child's head elevated during feeds and check tube position before each use. Nausea or bloating can be reduced by feeding more slowly or using a continuous pump. Always report any problems to the healthcare team.
9. An athlete consumes a high-nitrate meal but does not experience performance improvements. What factors could explain this inter-individual variability?
Several factors can affect the response. The oral microbiome composition varies between people; some have fewer nitrate-reducing bacteria. Genetics also play a role in how efficiently nitrate is converted and used. The athlete's baseline fitness level matters: well-trained athletes may see smaller benefits because their bodies already use nitric oxide efficiently. The timing of intake relative to exercise is important; nitrate needs 2-3 hours to peak in blood. Also, the dose and form of nitrate (e.g., whole food vs. supplement) can influence absorption. Finally, if the athlete uses mouthwash or has gum disease, conversion is impaired.
10. How can you tell primary from secondary lactose intolerance in a child?
Primary lactose intolerance is genetic and appears gradually after age 2-3, with symptoms worsening over years. Secondary lactose intolerance starts suddenly after a gut infection or inflammation, and it is temporary, lasting weeks to months. In primary, symptoms are triggered by any lactose-containing food, while in secondary, symptoms are linked to the recent illness. A hydrogen breath test can confirm both, but the history helps tell them apart. For secondary, treating the underlying cause often resolves the intolerance. Primary intolerance requires lifelong dietary changes, but secondary usually improves once the gut heals.
11. Compare the effectiveness of dietary nitrate from beetroot juice between two individuals: one with a healthy oral microbiome and one who uses mouthwash regularly.
The individual with a healthy oral microbiome will likely get a greater increase in nitric oxide and improved blood flow, leading to better endurance performance. The mouthwash user will have reduced nitrate conversion, so the performance benefit will be smaller or absent. However, other factors like diet, training, and genetics also influence the response. The difference can be significant in controlled studies, but in real life, the effect size varies. To maximize nitrate benefits, maintain good oral hygiene without overusing antibacterial products. Brushing teeth is fine, but avoid antiseptic mouthwash around nitrate intake.
12. How does food insecurity contribute to multiple micronutrient deficiencies?
Food insecurity means people do not always have enough food or cannot afford a variety of healthy foods. When diets are limited to a few cheap staples like white rice or cassava, they lack many vitamins and minerals. For example, a diet of mostly rice provides energy but little vitamin A, iron, or zinc. This can lead to several deficiencies at the same time, such as vitamin A deficiency causing night blindness and iron deficiency causing anemia. Food-insecure families often cannot buy fruits, vegetables, or animal products, so they miss many nutrients. Improving access to diverse foods is key to preventing these deficiencies.