Signs of bone conservation were seen in men and women who reported higher omega-3 intake; NASA team proposes a plausible explanation and calls for controlled trials
Getting adequate calcium is critical of course, but research shows that we don't need as much of the mineral as the Dairy Council would like us to think.
In fact, most Americans get more than enough calcium, but they lack vitamin D, which is essential for getting calcium into our bones. (They may also lack other essential bone nutrients, such as vitamin K from leafy greens.)
We covered some recent findings in "Omega-3s May Build Young Boys' Bones” and "Omega-3s Seen as Stellar Bone-Builders”.
Now, the NASA-based authors of a small observational study report that astronauts who reported eating the most fish suffered the least bone loss in outer space.
As they wrote, "…higher consumption of fish (a rich source of omega-3 fatty acids) was associated with reduced loss of bone mineral density after [space] flight” (Zwart SR et al. 2009).
Omega-3-rich diets linked to stronger bones in astronauts
To gauge the effects of omega-3s on bone strength in space, NASA nutritional biochemist Sara Zwart, Ph.D., and her colleagues measured expression of the gene that prompts creation of the protein complex called NF-kappaB.
NF-kappaB is a gene "switch” linked to inflammation, bone resorption, muscle wastage, and weaker immune health.
Previous tests have shown that NF-kappaB levels can rise five-fold in astronauts following periods of spaceflight… probably as part of the body's incompletely understood reaction to weightlessness.
As Dr. Zwart's team wrote, "We now have evidence that NF-kappaB is activated after short-duration spaceflight, and therefore inhibition of NF-kappaB activation could have many beneficial downstream effects to counteract the negative effects of spaceflight on bone, muscle, and immune function.” (Zwart SR et al. 2009)
Chronic over-activation of NF-kappaB is linked closely to the excess of starches, sugars, and omega-6 fatty acids in the American diet.
As the NASA team noted, and as we reported in another context last week, dietary omega-3s decrease activation of NF-kappaB in our cells, as do the polyphenol-type antioxidants that abound in berries and other colorful plant foods.
The researchers recruited 10 astronauts—seven men and three women—and drew blood samples before and after they spent 12-16 days on a Space Shuttle.
They also acquired blood test and bone strength data from astronauts on longer spaceflights and Russia's Mir space station.
The astronauts' dietary intakes of various foods were determined using questionnaires, and they underwent bone exams before and after missions.
And the analysis linked higher fish intakes to reduced bone loss during weightlessness.
As they wrote, "Together, these data provide mechanistic cellular and preliminary human evidence of the potential for EPA to counteract bone loss associated with spaceflight” (Zwart SR et al. 2009).
And they went on to wax enthusiastic about the broader promise of omega-3s as critical nutritional supports for spaceflight:
"Beyond muscle, bone, and immune function, the role of n-3 fatty acids in cancer prevention is currently being investigated in animal models of spaceflight radiation effects, with positive results.""Thus, there is a good possibility that something as simple as a menu change to increase fish intake might serve as a countermeasure to help mitigate risks related to bone, muscle, immune function, and potentially even radiation” (Zwart SR et al. 2009).
Many Americans show excessive levels of NF-kappB, thanks to diet and lifestyle factors that activate the pro-inflammatory, bone-sapping gene switch, which, when it's over activated, adversely affects many organs and functions.
If omega-3s are good for astronauts because they suppress NF-kappaB, there's reason to think they should benefit the earthbound as well.
- Chapkin RS, Kim W, Lupton JR, McMurray DN. Dietary docosahexaenoic and eicosapentaenoic acid: emerging mediators of inflammation. Prostaglandins Leukot Essent Fatty Acids. 2009 Aug-Sep;81(2-3):187-91. Epub 2009 Jun 6. Review.”
- González-Ramos R, Van Langendonckt A, Defrère S, Lousse JC, Colette S, Devoto L, Donnez J. Involvement of the nuclear factor-kappaB pathway in the pathogenesis of endometriosis. Fertil Steril. 2010 Feb 24. [Epub ahead of print]
- Zwart SR, Pierson D, Mehta S, Gonda S, Smith SM. Capacity of Omega-3 Fatty Acids or Eicosapentaenoic Acid to Counteract Weightlessness-Induced Bone Loss by Inhibiting NF-kappaB Activation: From Cells to Bed Rest to Astronauts. J Bone Miner Res. 2009 Oct 29. [Epub ahead of print]