"Vegetarians and Stroke Risk Factors —Omega 3s?"
In my last video we started to explore
“What might explain the higher stroke risk in vegetarians?”
found in the EPIC Oxford study. Lower risk of heart disease,
and lower risk of cardiovascular disease overall, but higher risk of stroke.
We looked into vitamin D levels as a potential mechanism,
but that didn’t seem to be the case. What about long-chain omega 3s,
the fish fats like EPA and DHA, found, not surprisingly,
in markedly lower levels in vegetarians and vegans?
About 30% lower in vegetarians and more like half as low in vegans.
But according to the most extensive systematic assessment
of effects of omega-3 fats on cardiovascular health to date,
there is no benefit for stroke, combining 28 randomized controlled trials.
In fact, there was evidence that taking fish oil didn’t help
with heart disease or overall mortality either.
This may be because on one hand the omega 3s may be helping,
but the mercury in fish may be making things worse.
That’s the constant challenge among public health professionals,
balancing the benefits with the contaminant risks.
For example, dietary exposure to PCBs may be associated
with increased risk of stroke. In this study, for instance,
neither ﬁsh nor intake of PCBs was related to stroke risk.
However, at the same ﬁsh intake, dietary PCBs were associated
with an increased risk of stroke;
so, the PCB pollutants may be masking the fish benefit.
Thus, if we had a time machine and could go back
before the industrial revolution and find that ﬁsh
in an unpolluted state it might protect against stroke,
but looking at the data, if fish really was protective
then we might expect that the pescatarians, those who eat fish,
but no other meat, to be down here or something,
since they would have the fish benefit without the meat risk,
but no, they’re stuck out here.
So, it doesn’t seem to be the omega 3s either.
Let’s take a closer look at what the vegetarians were actually eating.
When it comes to plant-based diets for cardiovascular disease prevention,
all plant foods are not created equal.
There are basically two types of vegetarians:
those that do it for their health, and those that do it
for ethical reasons, like global warming, or animals.
And they tend to eat different diets.
For example, health vegans tend to eat more fruit and less sweets.
You don’t tend to see those doing it for health
chowing down on vegan doughnuts.
In the United States, the primary motivations
for meat reduction are health and cost.
A middle-class American family is four times more
likely to reduce meat for health reasons compared to
environmental or animal welfare concerns.
But in the UK, where the stroke study was done,
the #1 reason given for becoming vegetarian or vegan is ethics.
We know plant-based diets that emphasize higher intakes of plant foods
and lower intakes of animal foods, are associated with a lower risk
of incident cardiovascular disease, a lower risk of dying
from all causes put together, but that’s only for healthy plant foods.
Eating lots of Wonder Bread, soda, and apple pie
isn’t going to be doing you many favors.
For all types of plant-based diets it’s crucial that the choice
of plant foods is given careful consideration.
We should be choosing whole grains over reﬁned grains,
whole fruits, avoiding trans fats, and added sugars.
Could it be that the veggie Brits were just eating more chips?
We’ll find out, next.