Comparisons

We compare to answer a question, not to crown a winner. Where no head-to-head study exists, we say so.

Yogurt vs kefir

Both are fermented milks. Yogurt has a 108-study systematic review (lactose tolerance causal; other outcomes associations). [1] Kefir has a 16-study review of trials, mostly at high risk of bias. [2] No head-to-head study was found. See Yogurt, Kefir.

Kimchi vs sauerkraut

Both are salted fermented cabbage. Kimchi has small trials on weight, glucose and lipids; sauerkraut has one 87-person crossover trial on the gut microbiome. [3][4][5] Both are salty and are listed by Mayo Clinic for MAOI users. [6] No direct comparison was found.

Flaxseed vs chia

Flaxseed: meta-analysis shows lower apolipoprotein B (high heterogeneity). [7] Chia: lower C-reactive protein in a 4-trial meta-analysis. [8] Different outcomes, so no winner. See Flaxseed, Chia.

Oats vs barley

Both supply beta-glucan; the FDA claim covers both. [9] Oats have a meta-analysis (LDL -0.25 mmol/L at 3 g beta-glucan a day). [10] Barley has a smaller trial base. [11] Barley contains gluten.

Whole fruit vs juice

Juice has less fiber. In cohorts, 100% juice was not associated with type 2 diabetes, non-100% juice was (RR 1.15), and juice lacked the beneficial association seen for whole fruit. [12] Juice trials exist for pomegranate and beet. [13][14]

Cocoa vs dark chocolate

Cocoa: a 31-trial meta-analysis found lower LDL (-9.47 mg/dL) and systolic pressure (-2.52 mmHg). [15] See Cacao. Proper evidence for chocolate bars was not found: chocolate adds sugar and fat, and trial products are often cocoa or cocoa extract, not bars. [16]

Green tea vs black tea

A review pooled green and black tea for blood pressure. [17] Black tea lowered LDL in a meta-analysis. [18] See Green tea. No head-to-head result was found.

Soy foods vs soy supplements

Trials of soy protein support small LDL reductions. [19] Proper evidence comparing foods with isoflavone supplements was not found.

Fermented foods vs probiotic supplements

ISAPP separates them: a probiotic needs a defined strain with a shown benefit. [20][21] Supplement trials are strain specific, for example in irritable bowel syndrome. [22]

Fortified foods vs supplements

FDA's fortification policy applies to conventional foods and not to supplements. [23] Proper evidence comparing them was not found.

Fish as food vs fish-oil capsules

They are different products; the observational fish studies do not test capsules. [24]