關於營養的6個謠言（下）【生肉】

關於營養的6個謠言（下）【生肉】

Nutrition Misfires

Misfire #4

Juicing is the best way to get your fruit and veggies.

There』s a juice for every day of the week, and your clients have probably tried them all: green juice, detox juice, and juices infused with ginger and turmeric. Recent research has shown that juices are an effective way to increase vitamins, minerals and phytonutrients in the diet (Zheng 2017). In the U.S., most people don』t eat enough fruit or vegetables and may miss out on the nutrients they provide: vitamins A and C, potassium, fiber, phytonutrients, and more.

But is drinking juice better than eating the fruits and vegetables they were squeezed from? No one is arguing that we should drink juice instead of eating whole produce. Juicers usually remove fiber, but fiber is important for digestive health and cholesterol reduction, and it helps keep blood sugar under control. 「You may be tossing out some of the great things we eat fruits and veggies for in the first place,」 says Kirchherr.

Calories are another consideration. 「How many whole oranges are you using for that glass of orange juice? Five? Six? Would you ever sit down and eat that many whole oranges?」 asks Kirchherr. You are probably consuming a lot more calories from juice than you would if you were eating the whole fruit. Barratt tells her clients, 「It is much more economical and nutritious to eat whole fruits and vegetables in smoothies, salads, soups and stir-fries.」

Misfire #5

Nutrition Facts labels on foods tell me all I need to know about the foods.

「Most of us want a super-simple way to manage the information about things we eat and drink,」 says Kirchherr. She recommends using 5% (low in a nutrient) and 20% (high in a nutrient) of the Daily Value as a quick guide. (The Daily Value indicates how much of a nutrient a single serving of the food contributes to an average daily diet of 2,000 calories.) Trying to reduce sodium? Look for 5% or less of the Daily Value. Trying to increase fiber? Go for 20% or more.

However, Kirchherr cautions, 「The Nutrition Facts label provides context in terms of calories and nutrition, but the ingredient list gives us more detail about the product. Focusing on one or the other doesn』t give the full nutrition picture.」 McManus explains that, for example, fiber is often added to white bread, which boosts the number of grams of fiber on the Nutrition Facts label but doesn』t make white bread as nutritious as whole-wheat bread. Whole-wheat bread lists whole-wheat flour as the first ingredient and contains more vitamins, minerals and phytonutrients, which don』t all appear on the Nutrition Facts label. In addition, says McManus, 「Research

Also, as McManus reminds clients, 「Many of the healthiest foods (fresh fruit, vegetables, fish, poultry, whole grains, nuts and seeds bought in bulk) do not have Nutrition Facts labels.」

Key changes to nutritional labels. By the way, Nutrition Facts labels are changing to be clearer about the number of calories per serving and to reflect current scientific knowledge about nutrients of concern for Americans. There is an overview of the changes at fda.gov/downloads/food/labelingnutrition/ucm511646.pdf.

Misfire #6

Vitamins and minerals are essential for health, so I should take a lot of them.

If you get less than enough iron, you become anemic; too little vitamin C, and you get scurvy. Vitamins and minerals are critical for good health, but the message for clients, says Kirchherr, is 「bigger isn』t always better. This is true for things that are good for us, too.」 We can』t easily get rid of excess vitamins stored in fat, such as fat-soluble vitamins A, D, E and K. The B vitamins and vitamin C, on the other hand, are water-soluble, and we excrete what we can』t absorb, so taking an excess of those may mean you are essentially flushing the money you paid for them down the toilet.

While a multivitamin and mineral supplement containing around 100% of the Daily Values may be low risk and could make up for nutrients missing in the diet (Ward 2014), we have little research on the long-term effects of large doses of vitamins, minerals and other dietary supplements. In the U.S., laws do not require the Food and Drug Administration to verify safety or effectiveness before dietary supplements are marketed to consumers (NIH 2011). And don』t assume that because a supplement is popular, it is also effective. Many people believe that taking large doses of vitamin C will prevent them from getting colds, but the scientific evidence doesn』t support that belief (PubMed Health 2017).

To avoid nutrition misfires, we need to help clients scratch the surface and see there is more to every nutrition topic than just a sound bite. Kirchherr wisely reminds us, 「Extremes, like 『always』 and 『never,』 don』t work in food and nutrition.」 Perhaps that should be our first message to clients.

6 KEY TIPS FOR CLIENTS

1. Sugar and carbs. Reduce added sugar, not the sugar occurring naturally in fruit or all carbohydrates. Limit intake of added sugars and refined grains, but enjoy whole foods.
2. Vegetarian or meat? 「Plant-based eating」 means eating mostly foods from plants (legumes, healthy oils like olive oil, nuts, seeds, whole grains, fruits and vegetables), but it allows for more flexibility than a vegetarian diet and can include fish, eggs, dairy and some meats.
3. Gluten, yes or no? Don』t avoid gluten unless you have celiac disease or another medical condition. Avoid white bread, pizza, cakes, cookies and other less healthy sources of gluten, but eat more nutrient-dense breads made with whole-grain flours and intact whole grains like barley and quinoa.
4. Juice or whole fruit? Juices provide nutrition, but they eliminate fiber and increase calorie intake. Eat whole fruits and vegetables instead, since it』s more economical and provides all the nutrient values, including fiber, with fewer calories.
5. Nutrition Facts labels. These are only part of the story; search the list of ingredients as well. On the label, consider 5% of the Daily Value as low in nutrients and 20% as high. Remember that some of the healthiest foods, like fruits, fish and bulk nuts, do not have labels.
6. Vitamins and minerals. Supplements containing around 100% of Daily Values may be helpful and low risk, but more is not always better. Keep in mind that excess fat-soluble vitamins are retained in the body, and water-soluble nutrients are flushed away.

References

Appleby, P.N., and Key, T.J., 2016. The long-term health of vegetarians and vegans. Proceedings of the Nutrition Society, 75, 287–93.

NIH (National Institutes of Health Office of Dietary Supplements). 2011. Dietary supplements: Background information. Accessed July 15, 2018: ods.od.nih.gov/factsheets/DietarySupplements-HealthProfessional/.

PubMed Health. 2017. Common colds: Does vitamin C keep you healthy? Accessed July 15, 2018: ncbi.nlm.nih.gov/pubmedhealth/PMH0072728/.

Ward, E. 2014. Addressing nutritional gaps with multivitamin and mineral supplements. Nutrition Journal, 13, 72.

Zheng, J., et al. 2017. Effects and mechanisms of fruit and vegetable juices on cardiovascular diseases. International Journal of Molecular Sciences, 18, 555. doi:10.3390/ijms18030555.

作者：Sanna Delmonico, MS, RDN, CHES