Are frozen vegetables processed food?

The answer is Yes.

Frozen vegetables are processed through the following steps (Ref 1):

Harvest - Factory receiving and quality checks - Sifting and Washing - Blanching - Freezing - Weighing and Bagging - Quality Control - Delivery

The current industry standard of blanching is set at 86ºC. Take an example of broccoli. Blanching practically kills enzyme myrosinase, which is necessary to form sulforaphane, one of the powerful cancer-preventive compounds in broccoli.

However, Illinois scientists (Ref 2) suggest either lowering the temperature to 76ºC or adding 0.25 percent of Daikon radish on the frozen broccoli. The first remedy help preserve 82% of the enzyme. And the second one works by adding the enzyme myrosinase from Daikon radish onto the frozen broccoli to form sulforaphane.

In addition to Daikon radish, cabbage, arugula, watercress, horseradish also contain myrosinase. So sprinkle a tiny amount of these raw vegetables to frozen cooked broccoli and you will still get the cancer fighting phytochemical sulforaphane.

Purslane, weed, food or medicine?

I have tried to grow a garden in Salinas of Santa Elena in Ecuador recently. It never occurred to me that it would be that difficult. The temperature is perfect for growing things, around 25 degree Celsius and I water them everyday. However, the ground is extremely salty, as the house sits ocean front. In addition, Salinas, meaning saltworks in Spanish, has been farming salt for many years, thus making it even more salty than other ocean front places.

However, there is one weed that grows extremely well. Even though I plug out some everyday, I just cannot keep up with their growth.

Now I am back in Canada, spending too much time on the internet. I came across some articles regarding edible weeds. Voila, the weed that bothered me so much is called purslane (Verdolaga in Spanish, Portulaca oleracea in Latin) and packed with nutrition. So next time I am in my house in Salinas, instead of trying to eliminate them, I will just eat the weed.

Nutrients and medicinal properties:

1. Purslane contains more omega 3 fatty acids (in the form of alpha-linolenic acid) than any other leafy plant.

2. The two types of betalain alkaloid pigments, the reddish betacyanins (visible in the coloration of the stems) and the yellow betananthins (noticeable in the flowers and the slight yellowish tint of the leaves), have been found to have antimutagenic properties in laboratory studies (a good review of natural antimutagenes can be found here).

3. It is a good source of vitamins and dietary minerals, especially vitamin A, C, E and magnesium, calcium, potassium and iron.

4. Could be a good candidate for anti-aging research, as it contains dopamine and DOPA. Betacyanins isolated from Purslane improved cognition in aged mice.

Harvesting:

The last inch or two of the leafy stem will be the most tender. When stressed by drought, which is where they are in my garden under normal circumstance, purslane switches to a different photosynthesis pathway: the leaves trap carbon dioxide at night and convert them into malic acid (the sour taste of the apple). Under the sun, malic acid is converted into glucose. So when you harvest early in the morning, the leaves are significantly more tangy than harvest in the late afternoon, which have more glucose.

How to eat purslane?

1. Add them in salads

2. Stir fry them with chicken, pork or shrimp

3.Use them as garnish in ceviche

4. Cook them in a soup

I cannot wait to try them.

Tofu

Tofu is made by coagulating soymilk. It has been eaten for its high protein content for at least two thousand years in Asia. It is popular among vegetarians for the completeness of soy protein (it is the only plant protein that contains all the essential amino acid for humans).

Even though the health benefits of tofu consumption are controversial, researchers have shown that tofu intake reduces cancer risk. 

The amount of tofu necessary to protect against cancer

is <1 serving, or 228 g (1 cup)/day compared with infrequent

consumption.

The health benefit of eating tofu might be due to the presence of BBI (Bowman-Birk inhibitors) and their variants, which are a class of naturally-occurring protease inhibitors. BBI has shown to stop breast cancercells from dividing in a laboratory dish. It may also have anti-inflammatory properties.

In addition to soybeans, BBI and their variants are found in other legumes such as mung bean, lentil, pea and chickpea etc.

Gender differences in cancer risks

In this bbc report on cancer risks, women and men are put in different category:



I consider this a progress. Next level of differences are in different ethnic groups. And once we have all our genomes sequences, we shall know our risks by genome types.

However, everything is a leap of faith. So take the report as true if you are willing to believe in today's statistical method. Otherwise, disregard it and go on living your way of life, whatever it might be.

Leptin, Living Environment and Cancer

Cancer is not only influenced by its micro-environment but also by a broader environment, according to a new study led by researchers at The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute (see here).

In this study, the scientists showed that tumors (melanoma and colon cancer) of mice in an enriched housing (20 mice in large containers equipped with toys, hiding places and running wheels, along with unlimited food and water as compared to control group) were 80 percent smaller than those in control animals (5 in smaller, standard containers with no toys but with unlimited food and water) within six weeks. Almost 20 percent of the animals in the enriched group had no visible tumors at all. Control animals, on the other hand, all had visible tumors.

"The anti-cancer effect we observed in this study was not due simply to increased activity by the animals, but rather it was induced by social and physical challenges that are associated with the release of stress hormones from the adrenal gland.” said During, one of the authors.

The same effect can be mimicked by blocking leptin or by activating HAS (hypothalamic-sympathoneural-adipocyte) pathway, which in turn lower the serum leptin level.

Leptin is a hormone that is primarily produced in a type of fat tissue called white adipose tissue. The level of circulating leptin is directly proportional to the total amount of fat in the body, in another word, higher amount of body fat means higher amount of circulating leptin.

Leptin is a circulating signal that reduces appetite. The absence of a leptin (or its receptor) leads to uncontrolled food intake and resulting obesity. However, in general, obese people have an unusually high circulating concentration of leptin (1), leading to the conclusion that these people are resistant to leptin.

Fasting or following a very-low-calorie-diet, on the other hand, lowers leptin levels (2).

Studies published recently suggest that the consumption of high amounts of fructose causes leptin resistance and elevated triglycerides in rats. Rats fed high-fructose diet subsequently ate more and gained more weight than controlled rats fed a high fat, high calorie diet (3). In North America, consumer foods and products typically use high-fructose corn syrup as a sugar substitute. In the United States, it has become very common in processed foods and beverages, including soft drinks, yogurt, industrial bread, cookies, salad dressing, and tomato soup (4).

What does it all mean?

I always believed that obesity was not caused solely by over-eating. If anyone has ever been to Guangzhou, China, it is easy to see that people there eat a lot and still stay skinny. Therefore, it must be foods that we in North America repeatedly eat that people there do not eat (or the other way around) that is making us gain weight. Refined sugar is probably one of the foods.

(1) Considine RV, Sinha MK, Heiman ML, Kriauciunas A, Stephens TW, Nyce MR, Ohannesian JP, Marco CC, McKee LJ & Bauer TL (1996). "Serum Immunoreactive-Leptin Concentrations in Normal-Weight and Obese Humans". N Engl J Med 334 (5): 292–295.

(2):
• Dubuc G, Phinney S, Stern J, Havel P (1998). "Changes of serum leptin and endocrine and metabolic parameters after 7 days of energy restriction in men and women". Metab. Clin. Exp. 47 (4): 429–34.
• Pratley R, Nicolson M, Bogardus C, Ravussin E (1997). "Plasma leptin responses to fasting in Pima Indians". Am. J. Physiol. 273 (3 Pt 1): E644–9.
• Weigle D, Duell P, Connor W, Steiner R, Soules M, Kuijper J (1997). "Effect of fasting, refeeding, and dietary fat restriction on plasma leptin levels". J. Clin. Endocrinol. Metab. 82 (2): 561–5.

(3):
• Vasselli JR (November 2008). "Fructose-induced leptin resistance: discovery of an unsuspected form of the phenomenon and its significance. Focus on "Fructose-induced leptin resistance exacerbates weight gain in response to subsequent high-fat feeding," by Shapiro et al.". Am. J. Physiol. Regul. Integr. Comp. Physiol. 295 (5): R1365–9.
• Shapiro A, Mu W, Roncal C, Cheng KY, Johnson RJ, Scarpace PJ (November 2008).
“Frutose-induced leptin resistance exacerbates weight gain in response to subsequent high-fat feeding. Am. J. Physiol. Regul. Integr. Comp. Physiol. 295 (5): R1370–5.

(4) Warner, Melanie (July 2, 2006). “A Sweetener With a Bad Rap”. The New York Times.