Rat study bolsters the hypothesis that our bones need more omega-3s — and fewer omega-6 fats — than most Americans consume
And by doing so, they support a growing scientific consensus that the role of calcium in bone health has been exaggerated… at the expense of other, frequently deficient factors.
The scientists used rat pups bred to be omega-3 deficient and X-ray technology to gauge the impact of different fat regimens on the animals' bone mineral content.
For the study, the rats were divided into three groups.
All three groups were fed milk enriched with the common omega-6 fat called LA, plus a tiny amount of one of three different fats or fat mixes:
- Omega-3 DHA (one percent of the milk)
- Omega-6 DPA (one percent of the milk)
- Omega-3 DHA (one percent of the milk) plus Omega-6 DPA (0.4 percent of the milk)
Once the animals reached adulthood, the researchers measured their fatty acid levels and bone mineral content and density.
As they wrote, "[intake of] both [omega-3] DHA and [total omega-3s] strongly correlate to BMC [bone mineral content]” (Li Y et al. 2010).
The results showed that the animals fed extra omega-6 DPA (group 2) "… generally had the lowest BMC [bone mineral content] and BMD [bone mineral density] values.”
They concluded that the outcomes indicate "an indispensible role of DHA in bone health” (Li Y et al. 2010).
Study results appear unsurprising, but welcome
Frankly, while this study supports the role of omega-3s in bone health, the main outcome was not really surprising, since the authors used animals deficient in DHA and simply restored it to them in their food.
And it's also no surprise that—as the authors noted with more emphasis than seems warranted—the group fed omega-6 DPA didn't use it to overcome the omega-3 DHA deficiency inherent to all of these specially bred animals.
Their focus on this rather unremarkable outcome is odd, since there is no reason to believe that omega-6 DPA ever could replace the bone-health functions of omega-3 DHA.
In fact, some of the same researchers have published prior animal research showing that omega-6 fats tend to weaken bone (See "Omega-3s Seen as Stellar Bone-Builders”).
While the new study broke no real ground, it supports earlier research that better demonstrated the importance of omega-3s… and it serves as a welcome reminder of those more compelling findings.
(Click the links below to read our reports on those prior studies.)
Calcium for bone health: Hype versus science
Science suggests that the answer to "Got Milk?” should be, "milk, schmilk”.
For sure, calcium is critical to bone and overall health—and it may play key anti-cancer roles as well.
But the notion that bone health requires copious amounts of dietary calcium defies the evidence.
While some population studies link higher calcium intake with stronger bones, those results mostly come from places (like America) where key bone-health factors are lacking.
In those studies, high-dose calcium is probably compensating for people's otherwise undernourished bone-metabolism systems.
When you account for other bone-health factors—especially people's vitamin D and vitamin K blood levels, and their weight-bearing work or exercise habits—the link between high-dose calcium and reduced risk of bone fractures practically disappears.
The body doesn't seem to need all that much calcium to make strong bones. For example, many cultures where people who eat relatively little calcium have low bone-fracture rates.
Aside from a modest amount of calcium, we also need about a dozen other minerals… as well as key bone-metabolism factors such as vitamin K and omega-3s. And in order for bones to absorb calcium, vitamin D must be present.
More recently, research has been turning up close connections between omega-3s and bone health in animals and humans alike.
And a clinical trial showed that people who ate a planned diet high in omega-3s had stronger bones… see "Omega-3s in Walnuts, Flaxseed, and Greens Boost Bones.”
That trial tested the omega-3 fatty acid found in certain plant foods, called ALA, but actually demonstrated the benefits of the long-chain, "bio-active” omega-3 fats found in our cells and in fish fat (EPA and DHA).
(This is because the human body burns almost all dietary ALA as fuel, and converts from one to 10 percent into essential EPA and DHA. Thus, when you test the bodily effects of consuming a given amount of omega-3 ALA, you're really testing the effects of the much smaller amounts of EPA and DHA the body made from that ALA.)
Our most recent report came from outer space: "NASA Links Omega-3s to Astronauts' Bone Health”, and it was preceded by summaries of two population studies in young males: see "Omega-3s May Build Young Boys' Bones” and "Omega-3s Give Budding Men Better Bones” …in which researchers actually measured blood levels of omega-3s and found that young men with higher blood levels of omega-3s had denser, stronger bones.
- Li Y, Seifert MF, Lim SY, Salem N, Watkins BA. Bone mineral content is positively correlated to n-3 fatty acids in the femur of growing rats. Br J Nutr. 2010 Apr 27:1-12. [Epub ahead of print
- Shen CL, Yeh JK, Rasty J, Li Y, Watkins BA. Protective effect of dietary long-chain n-3 polyunsaturated fatty acids on bone loss in gonad-intact middle-aged male rats. Br J Nutr. 2006 Mar;95(3):462-8.