Donnerstag, 14. September 2017

Study dump: food groups, vitamin K, sleep, nuts, B12 and phosphate

In the best case we should use epidemiology and nutrition science to guide public health policy through flexible incentives and taxes. Let's be prepared when the time comes and we can make that change real. One day, maybe by sheer luck, some politician will listen to good science. Study dump based on interesting abstracts:

Food group centric view. The author Schwingshackl works or used to work at our Viennese nutrition department. This study is a thing of beauty for everyone interested in epidemiology and our dear friends who suffer from orthorexia and will outlive us all.
A 56% reduction in relative risk for mortality with optimal intakes? Interestingly we should (or could?) see a 75% reduction by very naive multiplication (RR estimated at nadir in Figure 2). At a quick glance I do not see if the authors truly prove diminishing returns or not, though.:


With increasing intake (for each daily serving) of whole grains (RR: 0.92; 95% CI: 0.89, 0.95), vegetables (RR: 0.96; 95% CI: 0.95, 0.98), fruits (RR: 0.94; 95% CI: 0.92, 0.97), nuts (RR: 0.76; 95% CI: 0.69, 0.84), and fish (RR: 0.93; 95% CI: 0.88, 0.98), the risk of all-cause mortality decreased; higher intake of red meat (RR: 1.10; 95% CI: 1.04, 1.18) and processed meat (RR: 1.23; 95% CI: 1.12, 1.36) was associated with an increased risk of all-cause mortality in a linear dose-response meta-analysis. A clear indication of nonlinearity was seen for the relations between vegetables, fruits, nuts, and dairy and all-cause mortality. Optimal consumption of risk-decreasing foods results in [ONLY] 56% reduction of all-cause mortality, whereas consumption of risk-increasing foods is associated with a 2-fold increased risk of all-cause mortality.
Optimal consumption (the smallest serving with significant results and no further substantial change in risk or no further data for larger amounts) of risk-decreasing foods [3 servings whole grains/d (RR = 0.79), 3 servings vegetables/d (RR = 0.89), 3 servings fruit/d (RR = 0.90), 1 serving nuts/d (RR = 0.85), 1 serving legumes/d (RR = 0.90), and 2 servings fish/d (RR = 0.90)] results in a 56% reduction 
Could be a problem:  "We rated the quality of meta-evidence for the 12 food groups. The NutriGrade meta-evidence rating was “very low” for eggs; “low” for refined grains, vegetables, fruits, and SSBs; “moderate” for nuts, legumes, dairy, fish, red meat, and processed meat; and “high” for whole grains"

Schwingshackl, Lukas, et al. "Food groups and risk of all-cause mortality: a systematic review and meta-analysis of prospective studies." The American Journal of Clinical Nutrition 105.6 (2017): 1462-1473.



Vitamin K and health. Sadly a negative finding from EPIC-NL cohort. I am still looking forward to more studies and considering vitamin K about as promising as vitamin D. Still very little research:
Thus far, four studies investigated the association between vitamin K intake and mortality [3,17–19], of which three studies investigated all-cause mortality [3,18,19]. One study suggested that a high vitamin K intake was associated with a reduced risk of all-cause and cause-specific mortality [18], while two other studies were not able to detect an association [3,19]...
After multivariable adjustment, phylloquinone and menaquinones were not associated with all-cause mortality with hazard ratios for the upper vs. the lowest quartile of intake of 1.04 (0.92;1.17) and 0.94 (0.82;1.07) respectively. Neither phylloquinone intake nor menaquinone intake was associated with risk of CVD mortality. Higher intake of long chain menaquinones was borderline significantly associated (ptrend = 0.06) with lower CHD mortality with a HR10μg of 0.86 (0.74;1.00). None of the forms of vitamin K intake were associated with cancer mortality or mortality from other causes.
Zwakenberg, Sabine R., et al. "Vitamin K intake and all-cause and cause specific mortality." Clinical Nutrition 36.5 (2017): 1294-1300.


Sleep? Two studies arrive at similar conclusions. However, they are easy to misunderstand. These study designs are too weak to tell the whole story, just like body mass index studies. First of all, sleep will be affected by disease just like BMI. Second of all, we have to think about set points again: do you sleep more or less than you need (desire?). Being tired and a short sleeper is absolutely not the same. This mess is really hard to untangle.
We eventually included in our study 40 cohort studies enrolling 2,200,425 participants with 271,507 deaths. A J-shaped association between sleep duration and all-cause mortality was present: compared with 7 h of sleep (reference for 24-h sleep duration), both shortened and prolonged sleep durations were associated with increased risk of all-cause mortality
sleep duration that was either too short or too long was associated with higher risk of all‐cause mortality and cardiovascular events, with the lowest risk at sleep duration of ≈7 hours per day.

Liu, Tong-Zu, et al. "Sleep duration and risk of all-cause mortality: a flexible, non-linear, meta-regression of 40 prospective cohort studies." Sleep medicine reviews 32 (2017): 28-36.

J Am Heart Assoc. 2017 Sep 9;6(9). pii: e005947. doi: 10.1161/JAHA.117.005947. Relationship of Sleep Duration With All-Cause Mortality and Cardiovascular Events: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies. Yin et al.


Ecologic evidence in favour of the Mediterranean diet. Please, remember ecologic studies are weak, weak, weak. I would like to emphasize this.
The "Mediterranean Adequacy Index (MAI, derived from 15 food groups)" correlated "with 50-year all-cause mortality rates in the Seven Countries Study"
Menotti, Alessandro, et al. "BASELINE FATTY ACIDS, FOOD GROUPS, A DIET SCORE AND 50-YEAR ALL-CAUSE MORTALITY RATES. AN ECOLOGICAL ANALYSIS OF THE SEVEN COUNTRIES STUDY." Annals of Medicine just-accepted (2017): 1-21.


Nuts and mortality. More of the same, but important nonetheless. Apparently you only need to eat very small amounts of nuts?
The final analyses included 18 prospective studies. The random-effects summary RRs for high compared with low nut consumption were 0.81 (95% CI: 0.78-0.84) for all-cause mortality (18 studies with 81 034 deaths), 0.75 (95% CI: 0.71-0.79) for CVD mortality (17 studies with 20 381 deaths), ... for stroke mortality (13 studies with 4850 deaths) and 0.87 (95% CI: 0.80-0.93) for cancer mortality (11 studies 21 353 deaths). ...Peanut (5 studies) and tree nut (3 studies) consumption were similarly associated with mortality risks. ... evidence for nonlinear associations between nut consumption and mortality (P-nonlinearity <0.001 for all outcomes except cancer mortality), with mortality risk levelling off at the consumption of about 3 servings per week (12 g d-1).
Chen, Guo-Chong, et al. "Nut consumption in relation to all-cause and cause-specific mortality: a meta-analysis 18 prospective studies." Food & Function (2017).



B12 and sarcopenia? Just a small study. And they did not test methylmalonic acid, arguably the best marker of B12. It is not a terrible study, but it might confuse lay people. (and it will be abused by the likes of LEF to sell B12 supplement. Taking a B12 supplement is not wrong per se but the exaggerated claims by LEF & Co give the industry a terrible reputation.)
Bulut, Esra Ates, et al. "Vitamin B12 deficiency might be related to sarcopenia in older adults." Experimental Gerontology (2017).


Phosphate & vascular calcification. Not that I am the only one but I have championed this hypothesis years ago based on promising data from epidemiology and animal models:
Of the 10 studies located, 8 indicated an association between serum phosphorus and vascular calcification. ... Studies were limited since no randomized controlled trials were available....Due to considerable amounts of phosphorus additives in the food supply, there may be a connection to dietary phosphorus and vascular calcification. Additionally, phosphorus binders may assist in the prevention of vascular calcification but have not been studied in a healthy population.
Sheridan, Kristin, and John V. Logomarsino. "Effects of serum phosphorus on vascular calcification in a healthy, adult population: A systematic review." Journal of Vascular Nursing 35.3 (2017): 157-169.

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