A new study may help answer three questions about human evolution and nutrition.
First, did most of our Paleolithic ancestors eat lots of meat and/or aquatic animals?
If so, was this essential to the development of brains larger and more capable than those of apes?
Last, if seafood-source omega-3s and other animal fats are essential to good health, why are there so many apparently healthy vegans in the world?
We should begin by noting two key facts: omega-3 fatty acids come in two basic forms with hugely different health properties, and these forms occur in two very different kinds of food:
- Very small amounts of a “short-chain” omega-3 called ALA occur in dark leafy greens such as spinach or kale, and more abundantly in walnuts, flaxseed, and canola oil.
- In contrast, “long-chain” omega-3s – primarily DHA and EPA – are unique to fish, shellfish, and algae … and the eggs of chickens that forage on wild greens or get supplemental DHA.
Our cells contain and absolutely require omega-3 DHA and EPA (especially DHA) for most key body functions: vision, thinking, memory, mood control, nerve growth and protection, immune/inflammation control, heart rhythm control, and many metabolic processes.
People do not really need omega-3 ALA … if they get ample DHA from seafood or supplements, from which the body can make adequate EPA.
If they get little or no DHA, the body will convert the ALA it gets from plant foods into EPA and DHA (mostly EPA).
But the body can't make much DHA from EPA, so vegan diets make it hard for the body to make enough DHA from plant foods to enable optimal health. (Wisely, some vegans take algae-source DHA supplements.)
And humans can only convert one to 10 percent of omega-3 ALA into the amounts of omega-3 EPA and DHA required for life and optimal health. (The un-converted 90 to 99 percent of dietary ALA just gets burned up as fuel.)
So it's much easier to ensure adequate levels of essential EPA and DHA by getting them directly from dietary fish and/or fish oil.
And there's another good reason to get plenty of seafood-source DHA and EPA.
Omega-6 overload creates need for more seafood-source omega-3s
This excess of omega-6 fats that makes it even harder for the body to make EPA and DHA from plant-source ALA ... and is also proven proven to drive heart disease, dementia, cancer, and more.
Accordingly, people eating lots of vegetable oil and packaged/processed foods need more omega-3 DHA and EPA from seafood than they otherwise would, just to counterbalance the omega-6 overload.
Humans may be more adaptable than thought
Many apparently healthy, long-lived people consume little or no seafood-source omega-3s (DHA and EPA) … nor did their pregnant/nursing mothers.
How can this be, if DHA and EPA (especially DHA) are so essential and we can't make much from plant-source omega-3 ALA?
Clinical studies suggest that people can adapt to a lack of omega-3 fish fats by raising the rate at which they convert plant-form omega-3 ALA into EPA and DHA (Welch AA et al. 2008; Welch AA et al. 2010).
And researchers have found smaller differences in people's blood levels of EPA and DHA than expected, despite large differences in their intakes of omega-3s.
Now, findings from a renowned team of brain researchers at UCLA shed further light on the apparent ability of some people to thrive despite eating little or no seafood-source omega-3s.
Curcumin boosts conversion of plant-source omega-3s to the seafood kind
The UCLA researchers were led by Fernando Gomez-Pinilla, Ph.D., professor of neurosurgery, integrative biology, and physiology.
His lab has been conducting some of the best research into the effects of curcumin
and seafood-source omega-3s
on brain health and functions.
Turmeric root has long been prized in Asian medicine, and the term “curcumin
” refers to turmeric's trio of yellow-orange, powerfully antioxidant/antiinflammatory pigments.
The UCLA group cited the simple fact that led them to test the effect of curcumin on rat's ability to make of omega-3 DHA from plant-source omega-3 ALA:
“[M]any populations thrive on an entirely plant based diet and are able to obtain adequate levels of DHA to support cognitive development and plasticity” … despite the virtual absence of DHA from their diets.”
We should note that some people fail to thrive on purely vegan diets – possibly for genetic reasons, and/or due to life circumstances that require a broader nutritional base – and eventually abandon them.
This puzzling fact led the UCLA researchers to propose that certain components in plant foods “might enhance the conversion of DHA from omega-3 precursors” (by which they meant omega-3 ALA).
Animal studies link DHA deficiency to cognitive impairment … but that doesn't fit with the ample evidence that, like omnivores, most vegetarians display normal cognitive abilities.
This discrepancy lead the UCLA team to look for components in plant foods that might increase the synthesis of omega-3 DHA from plant-source omega-3 ALA, and raise DHA levels in the brain.
Study produced intriguing findings
The UCLA team divided rats into four groups:
- Control diet – regular rat chow
- Curcumin diet – rat chow plus added curcumin
- Omega-3 ALA diet – rat chow plus added ALA
- Omega-3 ALA + Curcumin diet – rat chow plus ALA and curcumin
The results were enlightening … and heartening as far as vegans' ability to stay reasonably healthy without seafood or omega-3 supplements:
First, the ALA + Curcumin group developed the highest brain levels of DHA. (Wu A et al. 2014).
Second, they found that curcumin boosted the levels of enzymes involved in the synthesis of DHA from ALA – such as FADS2 and elongase 2 – in both liver and brain tissue.
The ALA + Curcumin diet also produced the lowest levels of anxiety-like behavior among all of the animals … a benefit also seen in human studies testing the effects of omega-3 DHA and EPA on mood.
The UCLA team came to an obvious conclusion:
“These findings have important implications for human health and the prevention of cognitive disease, particularly for populations eating a plant-based diet or who do not consume fish, a primary source of DHA, since DHA is essential for brain function and its deficiency is implicated in many types of neurological disorders.”
In addition to its beneficial effects on the enzymes used to convert ALA to DHA, the researchers proposed that some of the curcumin-induced increases in DHA levels might stem from curcumin's well-documented and particularly potent antioxidant and anti-inflammatory effects.
Oxidative stress is proven to suppress the enzymes involved in DHA synthesis, and curcumin
is proven to reduce oxidative stress in the body.
Curcumin may be just one omega-3-conversion ally in plant foods
The authors proposed that the effect of curcumin may just be the tip of an iceberg.
And their idea would explain why vegetarian (no meat or seafood) and vegan (no meat, seafood, or dairy) diets appear remarkably healthful, despite lack of seafood.
As they wrote, “This study has significant implications for the ongoing debate between those in the ancestral nutrition (e.g. Paleo diet) versus plant-based (e.g. vegan) philosophical camps.”
It's worth quoting at length from the discussion section of their paper (Wu A et al. 2014):
- “According to prevalent beliefs regarding our recent evolutionary history as hunter-and-gatherers, interrupted only 10,000 years ago during the transition from the Paleolithic (Stone Age) to Neolithic cultural modes, we require a certain amount and type of animal food in order thrive.”
- “If this new research is found to be relevant to human nutrition, our suboptimal genetic potential to convert plant derived omega-3 fats to DHA may be mitigated or compensated for with the use of special ‘plant allies' such as turmeric.”
- “Indeed, a growing body of research now indicates that many of our supposed genetic limitations are compensated for epigenetically through microbes in our body that help us to generate vitamins, fatty acids, enzymes, immune compounds, neurotransmitters, etc., which our eukaryotic cells alone are incapable of meeting the sufficient demand for.”
- “Ultimately, this research sheds light on just how little we still know about our metabolic needs and capabilities and the profound complementarity and dialog that occurs between the animal and plant kingdoms in the realm of nutrition – a field of study still in its infancy.”
This is intriguing, important stuff … stay tuned for research updates as they occur.
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- Welch, A.A., Bingham, S.A., Ive, J., et al. (2006) Dietary fish intake and plasma phospholipid n-3 polyunsaturated fatty acid concentrations in men and women in the European Prospective Investigation into Cancer-Norfolk United Kingdom cohort. Am. J. Clin. Nutr. 84, 1330-1339.
- Welch, A.A., McTaggart, A., Mulligan, A.A., et al. (2001) DINER (Data Into Nutrients for Epidemiological Research) - a new data-entry program for nutritional analysis in the EPIC-Norfolk cohort and the 7-day diary method. Public Health Nutr. 4, 1253-1265.
- Wu A, Noble EE, Tyagi E, Ying Z, Zhuang Y, Gomez-Pinilla F. Curcumin boosts DHA in the brain: Implications for the prevention of anxiety disorders. Biochim Biophys Acta. 2014 Dec 27. pii: S0925-4439(14)00377-9. doi: 10.1016/j.bbadis.2014.12.005. [Epub ahead of print]
s of neurological disorders.