October 2026– date –

For weight loss, low-carb and low-fat end up equal at one year (DIETFITS; a 121-RCT meta-analysis). Carbohydrate share and mortality form a U-curve with 50–55% at the bottom. Swapping carbs for animal foods raises mortality (HR 1.18); swapping for plant foods lowers it (HR 0.82). Low-carb's edge in type 2 diabetes is short-term only. Do-it-yourself keto is not recommended.

Moderate-certainty benefit exists only for preventing antibiotic-associated and C. difficile diarrhea (specific strains; no effect in inpatients over 65). Cold prevention, mood, and weight loss in healthy adults show small effects from mostly industry-funded trials. Effects are strain-specific, and taking probiotics after antibiotics may delay recovery (Cell 2018).

Periodontitis is associated with 1.3–1.5× all-cause mortality and 1.2–1.4× dementia, but causation is unproven. The one moderate-certainty causal link is diabetes: periodontal treatment lowers HbA1c by 0.43% (Cochrane 2022). The P. gingivalis Alzheimer's drug failed. Bottom line: keep your teeth, clean between them daily, get checked yearly.

Large cohorts and an umbrella review agree: 2–4 cups a day carries the lowest mortality, cardiovascular, and diabetes risk. Coffee does not trigger atrial fibrillation (RCTs). The exception is severe hypertension. Sleep is the real trade-off — 400 mg six hours before bed cuts sleep by an hour.

The 0.8 g/kg RDA is a floor. International consensus: 1.0–1.2 g/kg after 50, 1.2–1.6 g/kg with resistance training. Healthy kidneys tolerate high protein; CKD and prior cardiovascular disease are different. Protein powder clearly helps only alongside strength training.