In the previous video, I discussed some faulty logic used by a raw food website. This video
will focus on the health risks and benefits to a classic raw vegan diet. I want to repeat
that the criteria for raw foodism is 75% or more uncooked foods.
I have the benefit of having read the responses to my previous video prior to making this
one. One of the sites that embedded my video was Thirty Bananas a Day, and they asked "Can
we post some video responses to this guy?" This is a raw foodism website, and I found
it very useful for the kinds of experiences most people have when starting this diet.
I'll come back to that later. I was reassured to see that I pissed off most of them, and
they responded with emotion-based attacks I would have expected. One person suspected
I was a shill of some sort. What I was most pleased to see were several respondents who
thought I made good points, even if they disagreed in the fundamentals. I can live with that.
I don't claim to have all the answers.
Let's start with risks. What are the possible negative health implications of raw food dieting?
I'm going to list them off: Risk 1. Tooth decay. This is not to be scoffed
at. Some long term raw foodists apparently have very bad teeth. Here's a picture of impact
damage to a molar. A German study of long-term raw foodists found a significant increase
in tooth erosion compared to controls. 61% of the raw food group had severe erosion on
at least one tooth compared to only 32% of controls. Two theories have been advanced
to explain this. One, that the high acidity of plant products like orange juice is dissolving
enamel. Two, that the abrasive roughage and fiber, and the sheer bulk of the food accelerates
enamel decay. It's also common for a vegan to have calcium deficiency, which can further
complicate dental health.
Risk 2. Underweight. If you're looking to lose weight, then a high bulk, low calorie
diet might be a good way to do so. If you're already a healthy weight, you may find it
a challenge to eat sufficient calories on a raw food diet. A German questionnaire study
found that 15% of men, and 25% of women on a vegan raw food regimen were classified as
underweight. The longer they had been on the diet, and the higher the percentage raw, the
more likely they were to be underweight. The weight loss averaged 10 kilograms for men,
and 12 kilograms for women. That's around 25 pounds to my fellow Americans.
Risk 3. Amenorrhea. From the same German study, about 30% of women on raw food regimens stopped
getting their periods. Again, this was correlated with percent of raw, and duration of diet.
From these two factors, underweight and amenorrhea, this study concludes: "a very strict raw food
diet cannot be recommended on a long-term basis"
Risk 4. Nutrient deficiency. Vegan raw foodists need to supplement heavily to overcome the
nutrient deficiencies in their diet. Especially vitamin B12, iron, zinc, selenium, calcium,
and vitamin D. This can be overcome by very careful planning of meals, but it's still
going to be a challenge to get high quality protein. Remember that many legumes are poisonous
without cooking, so nuts and seeds have to play a big role in providing protein, and
a variety are needed to provide complete amino acid coverage. My own advice for raw foodists:
that 25% of your diet that isn't raw should be lean meats or cooked beans.
Risk 5. Bone loss. There's a significant difference in controls and raw foodists at key points
in skeletal bone mass. One study suggests that this may not be a sign of degradation,
but mostly just a response to the weight loss, because the markers of bone loss are stable.
The risk of osteoporosis or fractures wasn't measured, and since this is a fairly new trendy
diet, the clinically important results may not be obvious for a few decades, long after
raw food is no longer the "in" thing.
I'll combine 6, 7 and 8. Bloating, nausea, and vomiting. These are very common. When
you start this rigorous diet, your body will have a difficult time adjusting to all the
fiber. You'll become bloated and you'll have digestive problems. Scanning through the blogs
and websites, all the new raw foodists complain about feeling terrible. Experienced users
reassure them that they'll feel better after a few weeks. I'm going to come back to these
three in the very end.
Risk 9. Risk of infection or poisoning. Cooking kills bacteria, viruses, and actually decreases
the amount of pesticide residues on fruits and vegetables. I've never advocated 100%
cooked, but eating raw vegetables is associated with some risks. Many of you will remember
the E coli and salmonella issues with raw spinach and peanut butter. Home-made fermented
foods carry a risk of botulism and well... name a food-born pathogen. I don't want to
oversell this, because the risks are very low, I just think it needs to be on this list.
One of the reason we process foods is to make them safer.
Now let's switch focus to the benefits of raw food dieting vs. the standard omnivorous
American type diet. For the most part, they're the same benefits one gets from any vegan
diet. I'll try to point out any differential benefits.
Benefit 1. Decreased cholesterol.
It's well known that increased fruit and vegetable consumption is protective for heart disease,
diabetes, and cancer. In fact, a single extra serving of fruit or veg per day may reduce
risk of ischemic stroke by 6%. Note to my American colleagues: french fries don't count.
So we shouldn't be too surprised that raw vegan diet decreases cholesterol in at least
one study. Unfortunately, it decreases both the good and bad forms, HDL and LDL, so the
benefit is somewhat reduced. Part of this is related to the Vitamin B12 deficiency,
which is associated with increased heart disease risk. Although supplementation is recommended,
over half the raw vegans in this study had a functional B12 deficiency, so it's a common
problem. This effect may actually outweigh the benefits from increase fruit and vegetables,
so if you must eat raw, make sure your B12 levels are sufficient. It's worth noting that
several studies have shown that lacto-ovo-vegetarians, those that eat eggs and dairy, actually have
lower heart disease risk than full vegans, and this study may explain why.
Benefit 2. Decreased inflammation.
This is one of the clearest benefits. Cooked foods are much more likely to stimulate the
immune system to cause an inflammatory response. This is important in food allergy and in inflammatory
intestinal diseases like colitis. There seems to be a general decrease in immune markers
for inflammation, which should be good for arthritis and fibromyalgia. Some studies find
a subjective response in these conditions, others don't. I'll come back to that.
Benefit 3. Probiotics
It's relatively clear that eating foods fermented with lactobacillus has a probiotic effect.
Good bacteria colonize the gut, and that can cause some good things to happen, like better
digestive health, and decreased colon cancer risk. The effect is very temporary, as we
are finding all probiotics to be, when you stop eating lactobacillus, your flora almost
immediately reverts to the previous condition. Increased fiber consumption is usually associated
with decreased colon cancer risk, although I couldn't find any studies confirming that
specifically for raw foods.
Benefit 4. Weight loss
This fits in both benefit and risk, but weight loss can be beneficial for the obese or overweight.
Because of the difficulty of getting enough calories from raw plant sources, this would
certainly seem to be a fast way to drop a lot of weight while feeling quite full.
Benefit 5. A raw vegan diet is very low in sodium, and usually doesn't include the added
salt that may come with processing. One study measured a hypotensive effect, a lowering
of blood pressure, for people who ate raw vegan. I think this might be one of the most
differential benefits of raw vs. cooked vegan diets, because we usually add salt during
cooking and preparing foods. I don't have any citations on that, so take it with a grain
of salt... pun intended. It would be nice to see more studies done on this topic.
Benefit 6. Lastly, according to one study, a raw vegan diet may have increased antioxidants
compared to omnivorous cooked diet, which is good for overall health, cancer risk, diabetes,
and lots of other chronic conditions. However, the favorable comparison is from raw and vegan
to omnivore and cooked.
When we look at another study, that compares matched vegan diets, but simply puts one of
the two plates into the microwave for 2 minutes, the benefits were the same for the cooked
vegan and uncooked vegan over a period of one week. The raw vs. cooked didn't have much
of an effect on markers of health status. This is an important study, but unfortunately
it's in German and not in a journal I can locate, so I'm having to rely on the PubMed
abstract. But this type of study is exactly what we need... to see if cooking is really
as toxic as the raw foodists claim. I'd like to see it repeated over longer periods of
time and with larger populations, because it would seem to address my primary suspicion,
that uncooked is less important than high vegetable and fruit, in any form.
I want to examine in more depth a particular study, because it deals with one final issue
that needs to be addressed: The discomfort and difficulty of this diet.
You recall that I mentioned the bloating, diarrhea, vomiting and general digestive distress?
That's a problem if this diet really does have net benefit. It's hard to keep people
on it. That's what I found most striking about one study on rheumatoid arthritis. The study
started with 22 patients in the raw food group, but 8 dropped out because of nausea, diarrhea,
and difficulties with the taste. Only 5 of the 22 would agree to drink the fermented
wheat drink supplement because of the taste, and by the end of the 3 month study, only
one person was still able to stomach it. 9 of the 22 had deviations from the diet more
than once a day. Half of the raw food group simply couldn't finish the three month study
period.
The outcome of the study was fairly neutral. The raw dieters lost weight, in spite of eating
calorie-matched diets, they had subjective relief of their RA symptoms, but none of the
objective criteria improved. The authors conclude that there may be some placebo effect from
what patients perceived as a mystical diet. As we discovered in previous videos, the more
intense the sensation, the more the placebo effect works. Is there something like that
at work here? I don't know, but what really strikes me is how unpleasant this diet is
to new people.
How can anything that's all natural and good for you cause so much discomfort and be so
difficult to stay on. Perhaps our bodies are suggesting that we maintain a little more
diversity and balance. It's not a useful diet if you can't adhere to it, obviously.
If you're really thinking about trying out this diet, I have one and only one bit of
advice for you. Talk with a health care professional first. The sheer amount of bad information
on the Internet makes it unreliable as a basis for health advice. The way people get talked
into these types of trendy new diets is usually peer pressure, curiousity, and a steady stream
of misinformation. My only goal with this video was to lay out what I see as the real
risks and benefits. My final summary from what I have read is that you probably get
all the benefits of a raw food diet just by eating a cooked vegan diet, with the one exception
that raw food is usually quite low in sodium. However, there are going to be risks with
any diet, and if your body is trying to tell you something, you might try listening to
it.
Good health, and thanks for watching.