Fortunately, when you eat plants, the phytochemicals they contain continue to work their magic in your body.
Whether serving as antioxidants (see page 43 ), mimicking hormones, reducing inflammation, blocking tumor formation, eradicating carcinogens, stimulating enzymes, or destroying bacteria, phytochemicals have hundreds of mechanisms that help to prevent the onset of diseases and fight existing diseases.
Although some phytochemicals are antioxidants, not all antioxidants are phytochemicals.
Some vitamins, such as vitamins C and E, and the mineral selenium also act as antioxidants.
Many factors can affect the quantity of phytochemicals in food as well as their bioavailability. For example, agricultural factors, such as soil, water, climate, and the use of chemicals, influence phytochemical content. Organically grown produce must develop a more robust defense against assailants than plants protected by chemical pesticides, so its phytochemical content is correspondingly higher.
2 , 3 , 4
Conversely, storage methods after harvest can diminish phytochemical concentrations.
Food-refining methods can dramatically reduce phytochemical content, especially when the most phytochemical-rich parts of plants are removed (such as the germ and bran from wheat grains) or when the processing involves exposure to harsh chemicals, heat, or pressure. Food preparation methods, such as cooking, sprouting, fermenting, blending, juicing, and processing, can also significantly affect phytochemical content and bioavailability, in either direction.
Most phytochemicals are more efficiently absorbed from raw foods. For example, the absorption of isothiocyanates can be significantly higher from raw cruciferous vegetables than cooked cruciferous vegetables.
5 , 6 , 7 , 8
In general, cooking foods tends to decrease phytochemical content; the greater the intensity and duration of heat exposure, the more significant the phytochemical losses. Not surprisingly, water-soluble phytochemicals are more readily lost when food is boiled. On the other hand, cooking softens or ruptures plant cell walls, making it easier for the body to extract and absorb certain types of phytochemicals, particularly carotenoids.
9 , 10
For example, more lycopene is bioavailable from cooked tomatoes than from raw tomatoes, and more beta-carotene is bioavailable from cooked carrots than from raw carrots.
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Adding even a small amount of fat from high-fat whole foods, such as avocado, improves carotenoid absorption from foods, whether the foods are raw or cooked.
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The bioavailability of phytochemicals from raw foods can be maximized by reducing the particle size and increasing the surface area of the food by chopping, pureeing, processing, milling, mashing, grating, or chewing well.
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Juicing is even more effective because the process removes the plant’s cell walls, which contain fiber and other components known to reduce the bioavailability of nutrients and phytochemicals. For this reason, some carotenoids, such as alpha-carotene, beta-carotene, and lutein, appear to be more bioavailable from vegetable juice than from raw or cooked vegetables.
22 , 23
Sprouting and fermenting significantly enhance a plant food’s phytochemical content.
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Scientific studies have shown that for a variety of food plants, germinating yields remarkable increases in phytochemicals.
27 , 28 , 29 , 30 , 26 , 7 , 31
This rise in phytochemical content is predictable because the life of a new plant depends on the support and protection from these compounds. One notable example is broccoli sprouts, which were found to contain ten to one hundred times more glucoraphanin (a glucosinolate and the precursor of sulforaphane) than mature broccoli.
26 , 7
Sulforaphane is a potent natural inducer of the body’s detoxifying phase II enzymes, which process and eliminate carcinogens. Sulforaphane has also been shown to be an impressive antimicrobial agent; it’s highly effective against Helicobacter pylori (H. pylori) , an infectious bacteria associated with gastritis, peptic ulcers, and stomach cancer.
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Recent evidence has also shown that broccoli sprouts may improve insulin resistance in patients with type 2 diabetes.
Finally, sulforaphane appears to reduce oxidative stress and tissue damage associated with a variety of disease states.
Maximizing Phytochemicals and Antioxidants in the Diet
While vegetables and fruits are commonly regarded as the primary suppliers of phytochemicals and antioxidants, these compounds are also plentiful in all whole plant foods. The most effective way to maximize phytochemical and antioxidant intake is to fill your plate with a wide variety of colorful plant foods that cover the entire spectrum of the rainbow. For example, red or black rice, quinoa, or beans will typically have more phytochemicals than brown or white rice.
In addition to eating more organic, raw plant foods and breaking them down during food preparation, regularly include sprouted and fermented foods in your diet to boost phytochemical intake. When you do cook, keep cooking times short and temperatures low.
Drinking vegetable juices can be a practical way to boost antioxidant and phytochemical intake. Enjoy the juice on an empty stomach prior to eating breakfast. Stick to juices that are freshly pressed, and to keep calories down, don’t include fruits and use only small amounts of carrots or beets. A great combination is dark leafy greens, celery, cucumber, ginger, turmeric root, and lemon or lime.
As a general rule, rely on foods, not supplements, for phytochemicals. When phytochemicals are isolated and concentrated, their effects can be vastly different than when they are consumed in whole foods. In some cases, supplements can be harmful. One possible explanation for this is that phytochemicals in foods have synergistic effects that do not occur when the phytochemical is consumed in isolation.
Among the most celebrated phytochemical and antioxidant superstars are dark-green leafy vegetables, cruciferous vegetables, sprouts, purple and blue fruits, herbs and spices, deeply colored legumes, nuts and seeds, garlic, cocoa beans, citrus fruits, tea, and tomatoes.
Remember, the absorption of fat-soluble nutrients is enhanced when a source of fats is consumed, although only small amounts are needed.
Higher-fat foods, such as nuts and seeds, are the richest sources of the important antioxidant vitamin E.
Table 7.1 (below) highlights the phytochemical and antioxidant superstars for fighting diabetes, along with their sources and mechanisms of action.
Incorporate a variety of these foods into your daily diet!
TABLE 7.1. Phytochemical and Antioxidant Superstars for Fighting Diabetes
PHYTOCHEMICAL/ ANTIOXIDANT
FOOD SOURCES
MECHANISM OF ACTION
Allicin
Garlic
Onions
Leeks
May improve blood glucose.
May improve cardiovascular risk factors.
Anthocyanins
Berries (acai, raspberries, blueberries, black
currants, blackberries)
Cherries
Eggplant
Red and purple cabbage
Black plums
Purple sweet potatoes
Pecans
Antioxidant.
Anti-inflammatory.
Reduce insulin resistance.
Bioflavonoids (e.g., hesperidin and naringin)
Citrus fruits Peppers
Peppermint Broccoli
Anti-inflammatory.
May prevent the progression of hyperglycemia.
Capsaicin
Hot chiles Sweet peppers
Increases energy expenditure. Enhances insulin response.
Reduces inflammation and lipid oxidation. Promotes weight loss.
Carotenoids
Orange, yellow, and red vegetables Dark-green vegetables
Antioxidant.
Enhance insulin sensitivity.
Some carotenoids are associated with reduced diabetes risk.
Catechins
Tea (green, matcha, black, white, and fruit) Fresh fruit (apples, apricots, cherries, peaches, berries) Cocoa
Broad beans, fava beans Some nuts
Reduce insulin resistance.
Increase glucose uptake.
May improve diabetic wound healing.
Curcumin
Turmeric
Anti-inflammatory.
Anti-obesity.
Gingerol
Ginger
May suppress formation of advanced glycation end products.
Improves blood glucose levels and glucose tolerance.
Isoflavones
Soybeans
May improve beta cell function and insulin sensitivity.
Proanthocyanidins
Almonds, hazelnuts, peanuts, pecans, pistachios (much higher in raw than roasted)
Anti-inflammatory.
Antioxidant.
May improve glucose uptake.
Quercetin
Apples Broccoli
Onions, scallions Tea
Anti-inflammatory.
Antioxidant.
May improve blood glucose levels and insulin production.
May lower triglycerides and cholesterol.
Resveratrol
Grapes, grape juice Peanuts, pistachios
Some berries Red wine
Reduces fasting blood glucose.
Reduces insulin resistance.
Sulforaphane
Broccoli sprouts Broccoli
Improves fasting glucose in people with poorly controlled type 2 diabetes.
Source
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CHEMICAL CONTAMINANTS: HIDDEN HARMS IN FOOD
C hemical contaminants, both those that get into food through the environment and products of high-temperature cooking, can wreak havoc in your body. They can promote oxidative stress, fuel inflammation, promote fat accumulation (by disrupting hormones), and damage vital organs, DNA, and the central nervous system. All of these effects increase the risk of type 2 diabetes and its complications.
Reducing exposure to these compounds is an important step toward correctly abnormalities of metabolism. (See pages 49 , 50 in