A Review of Recent Scientific Papers Related to Vegetarianism
I’ve frequently wondered how much calcium is actually in my glass of soymilk since there’s often a layer of sludge left at the bottom of the glass or in the carton. Could this be where most of the calcium ends up? Researchers at Creighton University have raised important concerns about the amount of calcium actually delivered by fortified beverages. They examined four brands of calcium-fortified soymilk and rice milk and eight brands of calcium-fortified orange juice. Beverages were tested and assigned a score based on the amount of calcium in the beverage that did not dissolve (and that probably would not be drunk) and on the likelihood of the calcium in the beverage being absorbed. A score of 100 indicates a source of calcium that would be well absorbed and that would deliver the amount of calcium on the product’s nutrition label. Scores for orange juice ranged from 70 to 99, with most products above 95. Soymilk and rice milk scores ranged from 57.5 to 90. These results suggest that many calcium-fortified beverages do not deliver as much calcium as the label suggests they do. What can consumers do?
Some vegetarians choose to eat a raw foods diet consisting of foods that have not been cooked or processed. Typically, people eating a raw foods diet have a low Body Mass Index (BMI) and are quite lean. This has potential implications for bone health since low body weight and body fat are associated with increased risk of osteoporosis. In addition, raw foods diets are frequently low in calcium. A recent study examined bone health in 18 vegetarians who had been eating a raw foods diet for an average of 3.6 years. The raw foods vegetarians had a lower bone mass in their spine and hips compared to non-vegetarian controls. A lower bone mass is believed to increase risk of developing osteoporosis. However, the raw foods vegetarians did not have a higher rate of bone loss suggesting that, despite a lower bone mass, their bones are of good quality. In addition, the raw foods vegetarians had higher levels of vitamin D, possibly because of greater sun exposure. Additional study is needed to determine whether long-term use of a raw foods diet affects risk of osteoporosis.
Many studies have found that vegetarians have a lower risk of heart disease and type 2 diabetes. Fewer studies have examined vegans. British researchers compared 21 vegans and 25 non-vegetarians who were similar in age and Body Mass Index (BMI). The vegans, all of whom had been vegan for at least 3 years, had diets that were lower in saturated fat and higher in polyunsaturated fat, carbohydrates, and fiber than the non-vegetarians. The vegans had lower blood pressure, lower blood triglyceride levels, and lower fasting blood glucose levels. Vegans also had better pancreatic beta-cell function, which means that they were at lower risk for developing type 2 diabetes. The subjects had similar weights and activity levels; therefore, the differences seen were probably due to dietary factors. These results suggest that a vegan diet can reduce risk of heart disease and type 2 diabetes.
A recent study of more than 55,000 Swedish women agrees with previous studies that suggest vegetarians do have a lower risk of obesity. In this study, women were asked whether they considered themselves to be omnivores, semivegetarians (sometimes eat fish), lactovegetarians, or vegans. Only a small percentage of the women identified themselves as semivegetarian (1.73 percent), lactovegetarian (0.29 percent), or vegan (0.15 percent). Despite these low numbers, there were enough study subjects to see differences among the groups.
The non-vegetarian women were significantly heavier than any of the other groups and had a higher Body Mass Index (BMI). Vegans had the lowest weight. After adjusting for age and other factors, vegans had a 65 percent lower risk of obesity than did omnivores, while lactovegetarians had a 46 percent lower risk and semivegetarians a 48 percent lower risk.
Does this mean all vegetarians are lean? No, not at all, but it does suggest that there is something about vegetarian diets that helps people control their weight.
Some studies have suggested that a higher intake of calcium is associated with weight loss, although other studies do not see any effect of calcium on body weight. A recent intervention study examined if an increase in calcium from dairy products would affect body weight in young women. In this study, 155 healthy, normal-weight women were assigned to one of three groups—their usual diet that contained less than 800 milligrams of calcium per day (control), a diet in which some of the usual foods were replaced with dairy products so that calcium intake was 1,000-1,100 milligrams daily (medium-dairy), or a diet in which more dairy products were used so that calcium intake was 1,300-1,400 milligrams per day (high-dairy). Subjects remained on their assigned diet for a year. The groups had similar calorie intakes. There was no significant difference among the groups in terms of weight change or changes in body fat over the year. These results suggest that simply increasing dairy product consumption, without reducing calorie intake, will not lead to weight reduction.
New research supports the theory that lower sodium diets may promote stronger bones. In a small study of the effects of sodium intake on bone health in 186 adults, a typical American diet was compared to the non-vegetarian DASH (Dietary Approaches to Stop Hypertension) diet at each of three sodium intakes for 30 days. The DASH diet emphasizes fruits, vegetables, and lowfat dairy products and includes whole grains, poultry, fish, and nuts. This diet is low in fats, red meat, and sugar. Levels of two indicators of bone health improved significantly in those study participants on the DASH diet, while those indicators worsened in those on the typical American diet. More importantly, levels of these indicators generally improved as sodium intake decreased, with the best levels seen at an intake of 1,150 milligrams per day.
Diets high in sodium lead to urine high in sodium, which results in high levels of calcium in urine and contributes to an increased loss of calcium. Some studies have suggested that, for every 2,300 milligrams of sodium in the urine, 40 milligrams of calcium are lost. In theory, this would result in the loss of as much as a third of bone mass in just over 20 years if calcium loss was not otherwise addressed.
The study’s authors suggest that calcium, potassium, and magnesium, as well as antioxidants and phytochemicals from fruits and vegetables, along with reduced sodium intake, play a role in supporting bone health.
A diet that emphasizes fruits and vegetables, provides adequate calcium, and is low in sodium has benefits for bone health.
This review of studies examining low-sodium diets was written by Mark Rifkin, MS, Dietetic Intern.
The Vegetarian Journal published here is not the complete issue, but these are excerpts from the published magazine. Anyone who wishes to see everything should subscribe to the magazine.
Thanks to volunteer Stephanie Schueler for converting this article to HTML.
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