Plant Pesticides

Posted by on June 20, 2010 14 comments

I mentioned earlier, when discussing the case of the 88-year-old woman who suffered bok choy poisoning, that most of the toxins in our bodies come from plant foods.

This is a surprise to most, since we have been taught to regard vegetables as healthy, to fear meat and fats, and to fear above all synthetic environmental toxins like pesticides.

Yet the volume of plant toxins which our bodies must deal with from our daily food is remarkable.  Bruce Ames and Lois Gold of the University of California at Berkeley report:

About 99.9% of the chemicals humans ingest are natural. The amounts of synthetic pesticide residues in plant foods are insignificant compared to the amount of natural pesticides produced by plants themselves. Of all dietary pesticides that humans eat, 99.99% are natural: they are chemicals produced by plants to defend themselves against fungi, insects, and other animal predators….

We have estimated that on average Americans ingest roughly 5000 to 10,000 different natural pesticides and their breakdown products. Americans eat about 1500 mg of natural pesticides per person per day, which is about 10,000 times more than the 0.09 mg they consume of synthetic pesticide residues. [1]

They also note that 57% of natural plant compounds tested have proven to be carcinogens in rats and mice, compared to 60% of synthetic compounds tested. In general, plant pesticides are as potently toxic as synthetic pesticides.

Should you run in terror from the supermarket vegetable aisle? No, not at all: it’s better to back away cautiously, to avoid being noticed.  (Just kidding; in fact we recommend eating 1 to 2 pounds of plant foods per day, including vegetables!)  But it’s prudent to diversify your plant food consumption, avoid the most toxic foods like grains and legumes, and cook most vegetables.

[1] Ames BN, Gold LS. Paracelsus to parascience: the environmental cancer distraction. Mutation Research 2000 Jan 17; 447(1):3-13. http://pmid.us/10686303.

The Danger of Plant Foods

Posted by on June 18, 2010 27 comments

Recently, an 88-year-old Chinese woman was brought to the emergency department at New York University’s Tisch Hospital by her family. She had been lethargic and unable to walk or swallow for 3 days. [1]

She had been eating 2 to 3 pounds of raw bok choy daily for several months in the hope that it would help control her diabetes, and the bok choy had poisoned her thyroid. In addition to coma, her symptoms included low body temperature (36 C), a shrunken thyroid, dry skin and coarse hair.  Her life was saved by high doses of intravenous thyroid hormone, but she still needed four weeks in the hospital before she could be moved to a nursing facility.

Remarkably, but not surprisingly in light of how little publicity is given to the dangers of plant toxins, her family wanted to keep feeding her raw bok choy in the hospital! [2]

This episode is a timely reminder that most of the toxins in our bodies come from the plant foods we eat.  Plant toxins can be quite dangerous. 

For good health, exposure to plant toxins should be minimized by:

  1. Cooking most plant foods other than fruits and berries, which are relatively non-toxic.  The heat of cooking destroys many toxins, and renders many others more digestible.
  2. Diversifying plant food sources.  Don’t eat too much of any one plant; rather try to eat modest amounts from many different species.  Live by the toxicologists’ rule, first formulated by Paracelsus:  “The dose makes the poison.”  If you keep the dose of any one toxin low, it will not poison you.
  3. Eliminating the most toxic foods.  These are grains; legumes; oils from grains, legumes, and seed crops; and fructose sugars.

The Paleo principle – it’s healthiest to eat like a caveman – is a good guide to low-toxicity eating.  Paleolithic peoples gathered a wide variety of plants – hundreds of species – and did not eat the Neolithic agricultural crops. Agriculture needs plants that produce an abundance of calorie-rich seeds, but these are precisely the plants that load their seeds with high levels of toxins to discourage herbivores.

Eat like a caveman, and stay out of the hospital!

[1] Chu M, Seltzer TF. Myxedema coma induced by ingestion of raw bok choy. N Engl J Med. 2010 May 20;362(20):1945-6. http://pmid.us/20484407.

[2] http://www.aolhealth.com/2010/05/20/too-much-bok-choy-puts-88-year-old-in-coma/.

Fish, Not Fish Oil Capsules

Posted by on June 16, 2010 50 comments

Yesterday I recommended eating about a pound a week of salmon or sardines as part of the strategy for achieving an optimal omega-6 to omega-3 ratio.

Yet this is not the way many health-conscious people obtain omega-3 fatty acids.  They buy fish oil capsules. 

The trouble with this approach is that omega-3 fats are chemically fragile:  their carbon double bonds are easily oxidized.  EPA has 5 double bonds and DHA 6 double bonds, so they are the most vulnerable of all dietary fats.  They easily become rancid.

Fish oil capsules often sit on a shelf for months before they are eaten.  If someone offered you the opportunity to eat salmon that had been sitting on a shelf for six months, would you do it?  No? Then why accept the same deal with salmon oil?

In fact, clinical trials have compared eating fish to eating fish oil capsules.  Fish consumption has an excellent record in a number of clinical trials, but fish oil capsule supplements do not. 

In the Diet and Angina Randomized Trial (DART-2), 3114 men with stable angina were followed for 3-9 years. There was a control group, a group advised to eat oily fish like salmon, and a group taking 3 fish oil capsules daily.  There was a significant increase in sudden cardiac death among the subgroup taking fish oil capsules. [1]

So, give up the fish oil capsules:  they’re all too likely to poison you.  Instead, buy some fresh fish.  Poached or baked salmon is an excellent summer dinner.

[1] Burr ML et al. Lack of benefit of dietary advice to men with angina: results of a controlled trial. Eur J Clin Nutr. 2003 Feb;57(2):193-200. http://pmid.us/12571649.

Omega-3 Fats and Cardiovascular Disease

Posted by on June 15, 2010 30 comments

The importance of achieving a good omega-3 to omega-6 ratio has been demonstrated repeatedly in clinical trials and epidemiological studies.  Cardiovascular disease mortality is especially strongly dependent on this ratio [1]:

This plot shows coronary heart disease mortality plotted against the fraction of long polyunsaturated fats in tissue that are omega-6, not omega-3.  It’s best to have around 30% omega-6, 70% omega-3.  But most Americans have around 78% omega-6, 22% omega-3.  Their omega-6 to omega-3 ratio is 9 times the optimum, and CHD mortality is ten-fold higher than is necessary.

Dr. Bill Lands, one of the pioneers in omega-3 and omega-6 science, notes that the tissue ratio is determined by how much of each type of fat is eaten:

There seems to be no ‘corrective’ metabolic response to prevent fatal tissue combinations from being developed. As much as humans might wish for some protective re-adjustment of the metabolic promiscuity, the enzymes seem to continue assembling harmful and harmless combinations in response to supplies ingested – without much regard to or feedback from the consequences. [2]

So it’s important to eat these fats in the right ratio.

How do you do that?  These steps:

  1. Minimize omega-6 fats by:
    • Avoiding most vegetable oils, including soybean oil, corn oil, safflower oil, and canola oil.
    • Using low-omega-6 oils, such as coconut oil, butter, beef tallow, olive oil, and lard, in cooking and dressings and sauces.
    • Regularly eating low-omega-6 red meats, like beef and lamb.
  2. Get sufficient omega-3 fats by eating 1 lb per week of fatty cold-water fish, like salmon or sardines.

These simple dietary changes can reduce your risk of dying from a heart attack by a factor of ten.

Yet how many doctors recommend these steps?  Indeed, many recommend the opposite:  avoiding saturated fats in coconut oil, butter, and beef tallow; avoiding red meats; and eating lots of vegetable oil.

This is a great example of our First Law of Health:  Every conventional dietary recommendation is wrong.

[1] Lands WE. Dietary fat and health: the evidence and the politics of prevention: careful use of dietary fats can improve life and prevent disease. Ann N Y Acad Sci. 2005 Dec;1055:179-92. http://pmid.us/16387724. Lands WE, http://efaeducation.nih.gov/sig/personal.html.  Hat tip Stephan Guyenet, http://wholehealthsource.blogspot.com/2008/09/omega-fats-and-cardiovascular-disease.html.

[2] Lands WE, http://efaeducation.nih.gov/sig/composition%20maintained.pdf.