[Image: Products made from soybeans]Miso is a thick, high-protein paste made from soybeans, salt and a fermenting agent (usually an Aspergillus mold culture) that is similar in taste and color to soy sauce. Sometimes a grain, such as rice and barley, is fermented with the soybeans for additional flavor. Miso is popular as a soup and breakfast drink in Japan. The fermenting yeast in miso makes it a rich source of vitamin B-12. In addition, research has shown that antioxidant components in miso may inhibit formation of oxidized cholesterol that forms plaque in the arteries (Santiago et al., 1992).
Natto is made of fermented, cooked whole soybeans and offers nutritional values similar to those found in miso. It has a sticky, viscous coating and is strong-smelling, with a cheesy texture. It is used as a spread or in soups.
Tempeh is made of whole, cooked soybeans infused with a culture to form a dense, chewy cake. It is a good source of fiber protein, polyunsaturated fats and lecithin, as well as useful amounts of calcium, iron, magnesium, potassium and some B vitamins.
Soybean sprouts are rich in vitamins A, B and C and are eaten raw in salads or cooked.
Soy sauce, the most widely recognized of soybean foods, is fermented from a mixture of whole soybeans, wheat flour and fermenting agents, such as yeast, for about 18 months. Then the liquid is extracted and processed. Soy sauce adds sodium and flavor to the diet.
Tomato products
Tomatoes contain a chemical, lycopene, which is a carotenoid without any vitamin A activity. It is an antioxidant and removes reactive oxygen species as they develop. Reactive oxygen species are thought to cause degenerative changes seen in chronic diseases of aging such as hypertension, heart disease and cancer.
Lycopene causes the red color of tomatoes. Lycopene is also in other fruits such as guava and watermelon. Tomatoes are the best source of lycopene in the American diet. About 80% of dietary lycopene comes from tomato products. Cooking increases lycopene bioavailability, possibly by breaking the cell walls; cooked tomato products such as tomato sauce and paste are the best sources. Carotenoids are fat soluble and availability of lycopene is increased with some added fat. Foods such as pizza, red pasta sauce and marinara are good sources of lycopene. Lycopene is less available in raw tomato products.
According to the USDA Food Guide, the recommendation is to consume nine fruits and vegetables a day. Higher consumption of fruits and vegetables results in reduced incidence of chronic diseases of aging. Include tomatoes as part of your healthy diet to reduce the risk of prostate and other cancer.
Lycopene has many beneficial effects. In particular, lycopene is thought to help prevent prostate cancer. The American Cancer Institute studied 50,000 health professionals for lycopene intake. There was 16% reduction in the incidence of prostate cancer in those who had the highest lycopene intake compared to those who had much lower lycopene intake. Higher lycopene intake resulted in reduction of other cancers as well. In terms of dietary intake of lycopene containing foods, this translates into consuming tomato products more than twice a week in the high intake group compared to those who consumed tomato products less than once a month.
Onions and garlic
Garlic has chemopreventive, antibiotic, antihypertensive and cholesterol-lowering properties. Even garlic, onion, celery, endive, chives and white wine contain chemicals that fight cancer such as allyl sulfides allicin. Onion and garlic are also thought to lower blood pressure and reduce blood clotting.
Berries
Berries are nutritionally excellent and contain significant amounts of dietary fiber, Vitamin C (ascorbic acid), Vitamin A (beta carotene), B vitamins and minerals. They are also a good source of both soluble and insoluble fiber. Raspberries and blackberries, for example, contain 4-6 grams of fiber per 100 grams. High fiber intakes are believed to help in the prevention of heart disease and colon cancer.
All vegetables with deep red, blue and purple color contain anthocyanins that act as antioxidants. Flavonoids are a category of phytochemicals. There has been a lot of interest in flavonoids because of their beneficial effects. All red and blue berries contain flavonoids. Raspberries are a good source of the flavonoids quercetin and kaempferol. Quercetin is an anticarcinogenic and it acts as an antioxidant to inhibit LDL oxidation. Quercetin and kaempferol prevent lipid peroxidation by several mechanisms. These are: 1. scavenging lipid peroxidation-initiating radicals, 2. binding metal ions, 3. scavenging lipid peroxyl radicals and4. inhibiting enzymatic systems responsible for free radical production. Quercetin may also block the release of histamine and may therefore be beneficial for those suffering from allergies.
Ellagic acid is another phytochemical present in berries. Ellagic acid is a phenolic compound that gives a food its mouth-puckering feeling. It can act as a flavorant and a colorant while it is also an antioxidant. Ellagic acid may protect plants against microbial infections.
Ellagic acid is an anticarcinogenic by blocking metabolic pathways associated with the development of cancer cells. It is particularly effective in blocking hormone related cancers. Ellagic acid is found in many fruits, but it is exceptionally high in raspberries and blackberries.
Cranberries have been used to treat urinary tract infections, but recent research shows that they may also be useful for preventing breast cancer and reduce stomach ulcers. Cranberries may be useful in lowering LDL cholesterol levels.
Strawberries are high in antioxidants and vitamin C. They are known to fight heart disease and provide a number of vitamins and minerals that support overall human health. Strawberries have 7-75 mg/100 g phytochemicals by weight.
Raspberries are known for their ability to fight cancer because of the phytochemical content and abundant supply of vitamins and minerals. The anthocyanin content ranges between 20-60 mg/100 g of red raspberries.
Other berries such as black raspberries have 214-428 mg/100 g of phytochemicals; blackberries 83-326 mg/100 g; and boysenberries have over 160 mg/100, cranberries 45-100 mg/100 g, and blueberries 25-495 mg/ 100 g.
Citrus fruits
Deep yellow and orange vegetables provide alpha and beta carotenes, antioxidants that help fight cancer.
Fruits that are yellow/orange provide anthoxanthins that protect against cancerous changes. Citrus fruit are full of antioxidants, flavonoids, that have anti-inflammatory and antitumor activity. The flavonoids inhibit tumor cell growth and can activate important detoxifying enzymes. These polyphenols, called limonoids, inhibit tumor formation by stimulating a detoxifying enzyme that catalyzes the formation of less toxic and more water-soluble compounds that can be easily excreted from the body. Polyphenols are the molecules that provide the bitter taste in citrus fruits and tanginess in many fruits and teas.
Citrus pulp, or the white part of the orange peel, is rich in compounds called glucarates. These substances may be beneficial in preventing breast cancer, and they may offer some benefit to women who have severe problems with premenstrual syndrome.
Can I Just Take a Phytochemical Pill?
Phytochemicals are rapidly becoming available for consumers to purchase. Taking these supplements containing phytochemicals will provide only selected components in a concentrated form, but not all of the compounds that occur naturally in the foods. It is important to eat fruits, vegetables and grains instead of simply taking a pill.
How Can I Get More Phytochemicals in My Diet?
Here are some easy ways to increase your intake of phytochemicals:
1. Eat more whole grains. Don't limit your choices to bread, rice and pasta. Try barley, bulgur and wild rice for variety.
2. Eat a variety of vegetables. Broccoli, carrots, greens, winter and summer squashes, green and red peppers, snow peas and red cabbage all are great choices.
3. Eat more fruits and berries. Research shows the average American eats only one serving per day. A glass of juice at breakfast is a good start, but you might want to try bananas or berries on top of your cold cereal as well. Berries make a great dessert.
4. Don't forget herbs and spices. Even though you do not eat much of them, they also contain phytochemicals. Learn to use them more in your cooking.
5. Explore new foods and new recipes.
According to the Journal of Agricultural Food Chemistry (2004), the 20 most antioxidant rich fruits and vegetables are:
- Small red beans (dried).
- Wild blueberries.
- Red Kidney beans.
- Pinto beans.
- Blueberries (cultivated).
- Cranberries.
- Artichokes (cooked).
- Blackberries.
- Prunes.
- Raspberries.
- Strawberries.
- Red Delicious apples.
- Granny Smith apples.
- Pecans.
- Sweet cherries.
- Black plums.
- Russet potatoes (cooked).
- Black beans (dried).
- Plums.
- Gala apples.
There are other easy methods for increasing fruits, vegetables and grains in your diet. Search the following Web sites to learn more about phytochemicals and for recipes and tips on increasing phytochemicals in your diet:
Summary
The best way to get phytochemicals in your diet is to eat a wide variety of fruits, berries, vegetables, legumes, beans and whole grains. Following the recommended number of servings from the Food Guide is the best way to get all of the nutrients and phytochemicals you need.