title: Cheese 'refinement' with whey B-vitamin removal during precipitation potentially induces temporal 'functional' dietary shortage: homocysteine as a biomarker.
abstract: Cottage cheese 'refinement' with massive B-vitamin losses (≈70-84%) through whey removal during precipitation may potentially induce an acute imbalance between protein/methionine load and temporal inadequacy/shortage of nutrients critical for their metabolism, i.e. B6 and B12. The temporal effect of cottage cheese consumption was evaluated using increased plasma homocysteine as a B-vitamin shortage marker. In a double-blind study, healthy, normal-weight (BMI = 22-27), premenopausal women aged 25-45 years were first given a methionine load (100 mg kg(-1), n = 15), then cottage cheese alone (500 g, ≈50 g protein, ≈1200 mg methionine, n = 49) at breakfast, and then with added B6 (2 mg, n = 8) and/or B6 + folate (1 mg + 200 mcg, n = 7). Plasma homocysteine was measured preprandially (t0) and then postprandially 5 h (t5) and ≥6-24 h. Cheese-induced homocysteine increased 28.7% (p ≤ 0.001), ≈60% of the free methionine response, remaining higher through ≥6-8 h. Co-supplementation with B6 reduced the Hcy increase by 45.0% (to 14.9%, p = 0.025), and that with B6 + folate reduced the Hcy increase by 72.3% (to 7.5%, p = 0.556, NS). Homocysteine increased more in participants with lower baselines (<5 μM vs. ≥5 μM, p ≤ 0.001) following cheese, ≈3-fold (54.8% vs. 18.5%) or methionine, 47.3% (266.7% vs. 181.1%). Cheese B-vitamin depletion - i.e. to B6 ≈ 2.0-4.0 μg g(-1) protein, far below women's metabolic requirement (15-20 μg g(-1)) - appeared to induce acute relative shortage compared to methionine/protein loads, exemplified by greater homocysteine increases than with other animal proteins (previous data), more so with lower baseline homocysteine. Smaller increases following re-supplementation demonstrated potential for 'functional fortification'/co-supplementation. Unnoted cheese 'refinement', like white bread, potentially induces episodic vitamin shortage effects, warranting consideration for acute/cumulative implications, alternative processing/supplementation technologies, and food combinations, especially for at-risk populations (i.e. with genetic, hormonal/gender, or aging-related predispositions), and for cardiovascular, bone, and brain health.
authors.affiliation: Institute for Nutrition Research, Office: 5 Kehilat Jitomir, Tel Aviv 69405, Israel. nivnet@inter.net.il.
authors.forename: N
authors.initials: N
authors.lastname: Shapira
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood*; D015992:Body Mass Index; D002611:Cheese / Q000032:analysis*; D004032:Diet; D019587:Dietary Supplements; D023381:Endpoint Determination; D005260:Female; D005492:Folic Acid / Q000097:blood; D064368:Healthy Volunteers; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D007557:Israel; D008715:Methionine / Q000008:administration & dosage; D008875:Middle Aged; D025101:Vitamin B 6 / Q000008:administration & dosage; D014803:Vitamin B Complex / Q000008:administration & dosage*
chemical_list: D015415:Biomarkers; D006710:Homocysteine; D014803:Vitamin B Complex; D025101:Vitamin B 6; D005492:Folic Acid; D008715:Methionine