Nutrition 331: Nutrition for Health
Study Guide: Unit 14
Vegetarian Diets, Alcohol, and Caffeine
Throughout this course, we touched on vegetarian diets and considered the health effects of alcohol and caffeine. This unit explores vegetarian diets more thoroughly and summarizes our current knowledge about caffeine and alcohol.
After completing this unit, you should be able to
- identify appropriate food choices to include or exclude from both lacto-ovo-vegetarian and vegan diets.
- discuss health benefits of vegetarian and vegan diets.
- discuss nutrients that may be inadequate in lacto-ovo-vegetarian or vegan diets, and suggest solutions to address these inadequacies.
- discuss life cycle stages where a vegetarian or vegan diet may not meet nutrient needs.
- list the health consequences associated with excess alcohol consumption, and discuss health benefits associated with moderate alcohol consumption.
- identify significant dietary sources of caffeine, and discuss the effect of caffeine on health.
Section 1 Vegetarian Diets
Read pages 237–243, “Controversy 6: Vegetarians and Meat-Containing Diets: What Are the Benefits and Pitfalls?” of Chapter 6 “The Proteins and Amino Acids.”
The textbook provides a good summary of vegetarian diets, terms used to describe vegetarians and their diets, and the health benefits of avoiding animal products in the diet. The textbook also considers the dietary needs in critical periods of the life cycle, including pregnancy, infancy, childhood, and adolescence, and discusses nutrients that may be of special concern in stages of rapid growth or during serious illness.
Vegetarians eat plant-based foods but eliminate some or all foods that come from animals. Lacto-ovo-vegetarians avoid meat and seafood, but include eggs and dairy products in their diets. Vegans (pronounced vay-guns or vee-guns) are the strictest vegetarian group. They eat only foods derived from plant sources. Other vegetarian terms can be found in Table C6‑1 (p. 238).
What is the effect of eating a vegetarian diet on overall health? This question has been challenging to answer, because it is difficult to disentangle the various lifestyle factors that cluster together. The following study illustrates the problem and the best attempt so far to come up with credible answers.
The largest study done on the relationship between meat consumption and risk of death was carried out on half a million Americans who were 50–71 years old at the start of the study (Sinha et al., 2009). Over the next 10 years, roughly 50,000 of the men and 23,300 of the women died. The researchers analyzed the relationship between meat consumption and mortality in detail. One clear finding was that meat eaters had a higher risk of death during the period of observation than did those who ate little or no meat. But the study also reported that meat eaters typically have an unhealthy lifestyle: they smoke more, exercise less, weigh more, and eat a poorer diet. Conversely, the people who eat little meat tend to follow a much healthier lifestyle. Under these circumstances, it is problematic to unravel how much of the association between meat and poor health is truly caused by eating meat and how much is merely guilt by association. This problem is common in cohort studies (see Section 5 of Unit 2 for a discussion of this). The researchers used statistical analysis to allow for the effects of an unhealthy lifestyle and thereby attempted to estimate the real relationship between meat consumption and risk of death.
When the researchers compared the extreme quintiles (i.e., the subjects who were in the highest and lowest fifths for consumption), the heavy meat eaters had about a 20–30% higher risk of death. These extra deaths were split between cancer and cardiovascular disease.
This study provides strong evidence that large sections of the population would be healthier if they ate less red meat—eating chicken or fish is preferable. The study fails to clarify, however, why meat has a negative effect on health. An important reason is probably because when people eat less meat, they tend to replace it with extra servings of healthier foods, such as vegetables. Meat may also contain unhealthy substances.
For people who are omnivores, it is a challenge to imagine meals and snacks without meat, fish, poultry, milk, cheese, and eggs. This section demonstrates what a lacto-ovo-vegetarian’s diet might look like.
Canada’s Food Guide is useful for identifying suitable food choices for both vegetarians and omnivores. Lacto-ovo-vegetarians will consume dairy products, so their needs for calcium, riboflavin, vitamin D, and protein can be met if dairy products are consumed in adequate quantities. Meat and Alternatives choices for lacto-ovo-vegetarians include eggs, cooked beans, peas, lentils, tofu, nuts, seeds, and nut butters (e.g., peanut butter). Lacto-ovo-vegetarians choose snack foods with care so as to avoid products containing meat or fish.
Vegans also eliminate dairy products and eggs from their diets. As milk, cheese, and eggs (a meat alternative) are pervasive in Canadian foods, it’s hard to imagine life without these ingredients. Items like cakes, muffins, pancakes, and puddings may be acceptable to the lacto-ovo-vegetarian, but usually do not fit a vegan diet unless the recipes eliminate eggs and substitute soy products for cow milk products.
Vegans need to select calcium-rich foods often and consistently. Vegetarian recommendations for calcium suggest a minimum of eight calcium-rich foods per day. Serving sizes, slightly different from Canada’s Food Guide, are
- calcium-fortified fruit juice (125mL);
- figs (5);
- bok choy, broccoli, collards, Chinese cabbage, kale, or mustard greens (250mL cooked or 500mL raw);
- almonds (60mL);
- cooked soybeans, including tofu (125mL); and
- fortified soy milk (125mL).
Vegan diets may not contain enough vitamin D. Fortified soy milk provides a suitable supplementary source of vitamin D. If a vegan does not consume 500mL of fortified soy milk per day, he or she should consider a vitamin D supplement. Note that 500mL of fortified soy milk equals four servings of calcium-rich food, according to the list above.
The following two menus offer examples of how vegetarian meals and snacks may be planned. The healthy vegetarian will explore cuisines from around the world that include beans, peas, lentils, nuts, and seeds. Notice how the minimum of two servings of Meat and Alternatives are met and, for the vegan, notice the calcium-rich foods.
Sample Lacto-Ovo-Vegetarian Menu
pasta and bean salad
oil and vinegar salad dressing
whole-grain bread with margarine
fresh vegetables with yogourt dip
lentil, rice, and vegetable casserole with cheese topping
cake or cookies
popcorn with margarine
crackers and cheese
Sample Vegan Menu
lettuce and tomato
olive oil and lemon salad dressing
rice and vegetable casserole with sesame seeds on kale
whole-grain bread with almond butter
ginger cookies (with egg replacement)
nacho chips with salsa
calcium-fortified fruit juice
* Blended chickpeas and tahini (ground sesame seeds) with spices and herbs, formed into patties and fried
** Salad with parsley, tomato, and bulgur (a type of wheat)
Section 2 Alcohol
Read pages 102–111, “Controversy 3: Alcohol and Nutrition: Do the Benefits Outweigh the Risks?” of Chapter 3: “The Remarkable Body.”
You will not be tested on Table C3‑1, and on the sections, “Alcohol Arrives in the Brain,” “The Liver Metabolizes Alcohol,” and “The Hangover.”
Evidence indicates that alcohol can have both beneficial and harmful effects on health (Temple, 2016). Negative health effects of alcohol include the following:
- hypertension: A relationship between alcohol consumption (in excess of four drinks per day) and hypertension has been clearly demonstrated.
- increased risks for developing cancer: In cancer of the throat and esophagus, alcohol greatly increases the carcinogenic action of smoking; alcohol also increases the risk for cancer of the breast.
- cirrhosis of the liver
- harm to a fetus during pregnancy: Fetal alcohol syndrome is the leading identified cause of mental retardation in the Western world; it may also cause growth retardation and congenital abnormalities.
- physical injury or death as a result of alcohol-induced traffic accidents and violence
On the positive side, many case-control and cohort studies have demonstrated that alcohol is associated with a reduced risk of coronary heart disease (CHD) of at least 20%. Studies have mostly indicated that it is alcohol that protects against CHD rather than a particular type of alcoholic beverage such as wine. Since CHD is the second leading cause of death in Canada, the possible preventive action of alcohol is potentially important.
As a result of opposing effects on health, the relationship between alcohol intake and mortality is U‑shaped: moderate drinkers (i.e., those who consume about 0.5 to 1.5 drinks daily) have the lowest total mortality. People consuming alcohol at about that level appear to have a reduced risk of death from CHD, and this reduction exceeds the increase in deaths from other causes. However, heavier drinking leads to a rapid increase in alcohol-related deaths.
The textbook strongly emphasizes the harm caused by alcohol. However, research has also uncovered several surprising benefits of moderate alcohol consumption, with indications of protection against hypertension, gallstones, type 2 diabetes, chronic obstructive pulmonary disease, and impotence. In older adults, moderate alcohol consumption appears to preserve cognitive function. The benefits of alcohol are seen most clearly when alcohol is consumed in small quantities, such as a glass of wine with dinner, rather than as binge drinking (Temple, 2016). That is, drinking a six-pack of beer on Saturday night is not the same as having a glass of wine with dinner every night.
From a nutrition perspective, ideal alcohol intake is moderate, responsible consumption that helps prevent CHD, stroke, and other illnesses, while minimizing the problems that go with alcohol. A moderate intake translates to about one-half to one drink per day for women, and 1.5 (or two at the most) for men. The positives and negatives of alcohol depend on age. As the textbook mentions (p. 111), the dangers tend to affect young people, whereas risk reduction for CHD and other health problems becomes apparent after the age of 50.
Alcohol recommendations are established differently from nutrients and other dietary components that have been discussed in this course. Alcohol has the potential to be abused or to be become addictive. This factor as well as the legal drinking age means that a minimum amount of alcohol cannot be included in nutrition recommendations. Abstinence is a healthy choice for adults and is highly recommended for pregnant and breastfeeding women.
Section 3 Coffee and Caffeine
Coffee and caffeine are consumed by Canadians in enormous quantities but yet are linked to very few ill effects. Large cohort studies carried out with 20 years of follow-up have shown no evidence that heavy consumers of coffee are at increased risk of death, even at an intake of 3 cups per day (Cavalli & Tavani, 2016). Coffee seems to have a negligible effect on risk of cancer and cardiovascular disease. Caffeine is a stimulant. This is helpful for improving concentration and mental functioning, but may cause insomnia when consumed late in the day.
Table C14‑4 in the textbook (p. 650) states the caffeine content of popular beverages. As you can see, tea has about two-thirds as much caffeine as coffee does. Cola beverages and iced tea are other sources of caffeine. As a result, children can suffer from caffeine-induced sleeplessness, restlessness, even though most children do not drink coffee. The textbook states the recommended upper limit for caffeine intake in children (see Fig. 13.9, p. 581).
The textbook recommends limiting caffeine to 300mg caffeine per day (equivalent to two cups of coffee) for women who are pregnant or breastfeeding (see Fig. 13.9, p. 581). This recommendation seems prudent.
A type of beverage that has become popular in recent years, especially among adolescents, is “energy drinks.” Examples include Red Bull and Monster Energy. Such products are consumed for perceived enhancements in mental acuity, wakefulness, and physical performance. Most brands have a caffeine content similar to tea and coffee. However, some brands have a high content of caffeine—as much as 300 to 500mg per container (Reissig et al., 2009).
Bear in mind that tea and coffee are more than just caffeine and water. There is growing evidence that the phytochemicals in tea (i.e., black tea) may protect against heart disease. Studies on coffee have not suggested this benefit.