Primary Research · 2005
Oral cyanocobalamin supplementation in older people with vitamin B12 deficiency: a dose-finding trial
Eussen SJ, de Groot LC, Clarke R, et al. · Archives of Internal Medicine, 2005
Key finding
Dose-finding RCT in older adults found 647–1,032 µg/day oral B12 was needed to normalize mild B12 deficiency markers — orders of magnitude above the RDA, supporting high-dose oral as an alternative to injections.
Abstract
PubMed · PMID 15883237 →BACKGROUND: Diet and lifestyle modifications can substantially reduce the risk of type 2 diabetes. While a strong inverse association has been reported between dairy consumption and the insulin resistance syndrome among young obese adults, the relation between dairy intake and type 2 diabetes is unknown. METHODS: We prospectively examined the relation between dairy intake and incident cases of type 2 diabetes in 41,254 male participants with no history of diabetes, cardiovascular disease, and cancer at baseline in the Health Professionals Follow-up Study. RESULTS: During 12 years of follow-up, we documented 1243 incident cases of type 2 diabetes. Dairy intake was associated with a modestly lower risk of type 2 diabetes. After adjusting for potential confounders, including body mass index, physical activity, and dietary factors, the relative risk for type 2 diabetes in men in the top quintile of dairy intake was 0.77 (95% confidence interval [CI], 0.62-0.95; P for trend, .003) compared with those in the lowest quintile. Each serving-per-day increase in total dairy intake was associated with a 9% lower risk for type 2 diabetes (multivariate relative risk, 0.91; 95% CI, 0.85-0.97). The corresponding relative risk was 0.88 (95% CI, 0.81-0.94) for low-fat dairy intake and 0.99 (95% CI, 0.91-1.07) for high-fat dairy intake. The association did not vary significantly according to body mass index (< 25 vs > or = 25 kg/m(2); P for interaction, .57). CONCLUSION: Dietary patterns characterized by higher dairy intake, especially low-fat dairy intake, may lower the risk of type 2 diabetes in men.
Abstract sourced from PubMed, a database of the U.S. National Library of Medicine. Displayed in the authors’ own words for context; our critique is in the sections below.
About the supplement
Vitamin B12 (Cobalamin)
Dose · mechanism · evidence grade · safety →
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How to read a study like this
The same questions worth asking about any research paper, not just this one. Worth a minute even if you trust the grade.
Who was studied, and do you resemble them?
Supplement effects often depend on baseline status. Vitamin D helps people who are deficient; iron helps people who are anemic. A result in people unlike you may not apply to you.
What was measured, and does it matter in daily life?
A study that shows a blood marker moved isn't the same as a study that shows people felt or functioned better. Ask what the outcome means in practice.
How large was the effect — not just whether it was significant.
'Statistically significant' only means the effect is unlikely to be zero. It doesn't tell you the effect is large enough to notice. Look for effect sizes, not just p-values.
Who paid for the trial, and what did they stand to gain?
Industry-funded trials are several times more likely to report positive results than independent ones. It's not usually fraud — it's subtle design and reporting choices. Weight accordingly.
Has anyone else replicated this?
Single positive trials are hypotheses. Replication by independent groups is what turns a hypothesis into reliable evidence. If the only positive trial is the one you're reading, wait.
Does the dose in the trial match what's being sold?
Supplement marketing routinely cites trials that used 5–10× the dose in the product. If the effective dose was 2 g/day and the capsule has 200 mg, expect roughly no effect.
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