Effekt av långvarig kalorirestriktion på benhälsa

[King Grub]

Although caloric restriction (CR) could delay biologic aging in humans, it is unclear if this would occur at the cost of significant bone loss. We evaluated the effect of prolonged CR on bone metabolism and bone mineral density (BMD) in healthy younger adults. Two-hundred eighteen non-obese (body mass index [BMI] 25.1 ± 1.7 kg/m(2) ), younger (age 37.9 ± 7.2 years) adults were randomly assigned to 25% CR (CR group, n = 143) or ad libitum (AL group, n = 75) for 2 years. Main outcomes were BMD and markers of bone turnover. Other outcomes included body composition, bone-active hormones, nutrient intake, and physical activity. Body weight (-7.5 ± 0.4 versus 0.1 ± 0.5 kg), fat mass (-5.3 ± 0.3 versus 0.4 ± 0.4 kg), and fat-free mass (-2.2 ± 0.2 versus -0.2 ± 0.2 kg) decreased in the CR group compared with AL (all between group p < 0.001). Compared with AL, the CR group had greater changes in BMD at 24 months: lumbar spine (-0.013 ± 0.003 versus 0.007 ± 0.004 g/cm(2) ; p < 0.001), total hip (-0.017 ± 0.002 versus 0.001 ± 0.003 g/cm(2) ; p < 0.001), and femoral neck (-0.015 ± 0.003 versus -0.005 ± 0.004 g/cm(2) ; p = 0.03). Changes in bone markers were greater at 12 months for C-telopeptide (0.098 ± 0.012 versus 0.025 ± 0.015 μg/L; p < 0.001), tartrate-resistant acid phosphatase (0.4 ± 0.1 versus 0.2 ± 0.1 U/L; p = 0.004), and bone-specific alkaline phosphatase (BSAP) (-1.4 ± 0.4 versus -0.3 ± 0.5 U/L; p = 0.047) but not procollagen type 1 N-propeptide; at 24 months, only BSAP differed between groups (-1.5 ± 0.4 versus 0.9 ± 0.6 U/L; p = 0.001). The CR group had larger increases in 25-hydroxyvitamin D, cortisol, and adiponectin and decreases in leptin and insulin compared with AL. However, parathyroid hormone and IGF-1 levels did not differ between groups. The CR group also had lower levels of physical activity. Multiple regression analyses revealed that body composition, hormones, nutrients, and physical activity changes explained ∼31% of the variance in BMD and bone marker changes in the CR group. Therefore, bone loss at clinically important sites of osteoporotic fractures represents a potential limitation of prolonged CR for extending life span. Further long-term studies are needed to determine if CR-induced bone loss in healthy adults contributes to fracture risk and if bone loss can be prevented with exercise.

J Bone Miner Res. 2016 Jan;31(1):40-51. Effect of Two-Year Caloric Restriction on Bone Metabolism and Bone Mineral Density in Non-Obese Younger Adults: A Randomized Clinical Trial.

http://onlinelibrary.wiley.com/doi/10.1002/jbmr.2701/abstract;jsessionid=AA75EF70CC922FDB43FEE717F8A0BF 10.f02t03

[Gerdler]

Detta är ju jätteintressant. Om de hade tränat lite styrketräning så hade de kanske kunnat behålla sina ben.

Jag tänker mig att någon som styrketränar ett par gånger i veckan från 20-90 års ålder kommer ha en bendensitet som räcker och blir över, så då kan man offra lite bendensitet för att hålla telomererna fräscha.

Det fanns nån annan idé om att man kunde varva perioder med CR och få stor del av nyttan på bara en kort CR då och då. De talade om det i somras på radion och det var ny forskning som låg bakom. Jag har däremot inte hittat varken radioprogrammet eller forskningen som ligger bakom så de kanske bara svamlade?

[KlopFer]

När jag ser den där texten ser mina ögon ut så här :Virro

[Gerdler]

Det du behöver ta fasta på är:

Multiple regression analyses revealed that body composition, hormones, nutrients, and physical activity changes explained ∼31% of the variance in BMD and bone marker changes in the CR group. Therefore, bone loss at clinically important sites of osteoporotic fractures represents a potential limitation of prolonged CR for extending life span.
Det betyder som jag förstår det att merparten av förlusten av benmassa kommer som resultat av kalorirestriktionen i sig ts från av andra faktorer. Det betyder alltså att man kommer bli som Mr Glass i unbreakable även om man kanske blir gammal med CR.

Mer om CR diskuterades i Tyngre Rubriker nyligen:
http://tyngre.se/podcasts/tyngre-rubriker/barnfetma-kalorirestriktion-och-johaugs-positiva-dopingprov/

Så telomererna håller längre, blodkärlen håller längre, man får bättre insulinkänslighet, och levern mår bättre, men benen mår sämre.