SCIENTIFIC UPDATE
By Reed Mangels, PhD, RD
Vegans and Heart Disease
We've all heard of cholesterol, LDL cholesterol, and HDL cholesterol. High concentrations of total cholesterol and LDL cholesterol in our blood are associated with a higher risk for heart disease, and high concentrations of HDL cholesterol are associated with a lower risk of heart disease. Other particles that appear in our blood also affect heart disease risk. High amounts of a particle called Apo A-1 are correlated with reduced risk and high amounts of Apo B are associated with a higher risk.
A large study in the United Kingdom looked at concentrations of these substances in vegetarians, vegans, fish-eaters, and meat-eaters. There were about 400 people in each dietary group. As has been seen in other studies, vegans had a lower BMI and ate fewer calories. Vegans had the lowest intake of saturated fat and the highest intake of polyunsaturated fat. Not surprisingly, vegans had the lowest concentrations of total cholesterol, LDL cholesterol, and Apo B. Some of the difference was probably due to vegans' lower weight, but most of the difference in levels of cholesterol and Apo B in blood was due to dietary differences. These lower concentrations suggest that vegans have a lower risk of heart disease than do vegetarians, meat-eaters, or fish-eaters.
Bradbury KE, Crowe FL, Appleby PN, Schmidt JA, Travis RC, Key TJ. 2014. Serum concentrations of cholesterol, apolipoprotein A-1 and apolipoprotein B in a total of 1694 meat-eaters, fish-eaters, vegetarians and vegans. Eur J Clin Nutr. 68:178-83.
Vegetarian Diets and Blood Pressure
A group of researchers recently combined the results of more than 30 observational studies and 7 clinical trials to assess the effect of a vegetarian diet on blood pressure. High blood pressure, also called hypertension, affects close to one third of adults in the United States. High blood pressure can cause heart attacks, kidney failure, and stroke.
When the results from all the studies were combined, vegetarians clearly had lower blood pressure than did nonvegetarians. Additionally, when nonvegetarians ate a vegetarian diet, their blood pressure decreased. The reduction in blood pressure associated with a vegetarian diet was similar to what would be seen if people reduced their sodium intake or lost about 10 pounds. The extent of blood pressure reduction associated with a vegetarian diet would be expected to reduce the risk of death from heart disease by 9% and from stroke by 14%. Vegetarians tend to be leaner than nonvegetarians and this may partially explain why vegetarians tend to have lower blood pressure. Only a part of the difference in blood pressure can be explained by weight, however. Other factors in a vegetarian diet that could improve blood pressure include higher potassium intakes and lower saturated fat intakes.
Yokoyama Y, Nishimura K, Barnard ND, et al. 2014.Vegetarian diets and blood pressure: a meta-analysis. JAMA Intern Med. [Epub ahead of print].
Medications in the United Kingdom Frequently Contain Animal-Derived Ingredients
It can be challenging to find out whether or not medications contain animal products. Researchers in the UK examined the 100 most commonly prescribed drugs in primary care. Close to 75% contained lactose, gelatin, or magnesium stearate, all substances that may be derived from animals. Lactose is derived from cows' milk, gelatin from cows or pigs or occasionally fish, and magnesium stearate may be from cows, pigs, or sheep as well as from non-animal sources. Magnesium stearate was identified as coming from vegetable sources in 31 out of 49 products, 4 products contained animal-derived magnesium stearate, and the remainder did not indicate the source of magnesium stearate. Drug manufacturers in the European Union are not allowed to indicate whether or not their products are suitable for vegetarians or vegans. The study authors call for greater disclosure of animal content in medications and say that the ultimate solution would be to eliminate animal-derived products where possible from medications. Information about animal ingredients in medications is not commonly available in the US; concerns should be discussed with your health care provider.
Tatham KC, Patel KP. 2014. Suitability of common drugs for patients who avoid animal products. BMJ. [Epub before print].
Not Every Country Has a Dairy Group
In addition to providing a fascinating and thorough explanation of dietary trends worldwide, the Future Diets, Implications for Agriculture and Food Prices report, produced by the independent think tank Overseas Development Institute (ODI), presents examples of dietary guidance from other countries. This guidance is like MyPlate in the U.S. It was interesting to see how other countries describe food groups. For example, MyPlate has a Protein group.
Here's what other countries use:
- Pulses - India [pulses is another word for legumes or dried beans]
- Legumes and animal origin foods - Mexico
- Fish and meat dishes (meat, fish, egg and soybean dishes) - Japan
Where MyPlate has a Dairy group, other countries have the following:
- Milks and pulses (with a picture showing tofu and other soy products) - China
- Only a notation that a ½ serving from the meat and alternatives group should come from dairy or other high calcium products - Singapore
- No specific group - Mexico
Read more of this intriguing report.
Prevalence of Obesity
The newest findings on the prevalence of obesity among children in the US are positive and negative. The positive results are that there has been a significant decrease in obesity in preschool-age children (2-5 years). Since 2003-2004, the prevalence of obesity in this age group dropped from close to 14% to about 8%. This is good news! On the negative side, overweight and obesity rates in children are still too high. About 18% of 6-11-year-olds are obese and 20.5% of 12-19-year-olds are obese. Overall, 31.8% of 2-19 year olds are either overweight or obese and 16.9% are obese. These results suggest that we need to curtail this epidemic of overweight and obese children and teens.
Ogden CL, Carroll MD, Kit BK, Flegal KM. 2014.Prevalence of childhood and adult obesity in the United States, 2011-2012. JAMA. 311:806-14.
Vegetarians Have Lower Risk of Hip Fractures
Fracturing a hip is something most people would prefer to avoid. Dietary patterns appear to affect the risk of hip fracture. In a study of more than 62,000 Chinese men and women, those whose diets were highest in fruits, vegetables, and soy products had the lowest risk of breaking a hip. Their risk was 21-34% lower than those whose diet was lower in fruits, vegetables, and soy products. In addition to potential benefits with regard to bone health, this eating style also reduces the risk of heart disease and diabetes.
Dai Z, Butler LM, van Dam RM, Ang L-W, Yuan J-M, Koh W-P. 2014. Adherence to a vegetable-fruit-soy dietary pattern or the Alternative Healthy Eating Index is associated with lower hip fracture risk among Singapore Chinese. J Nutr. [Epub ahead of print].
High School Food Choices May Have Lasting Effects
Colorectal adenomas are precancerous polyps. They can become cancerous if they are not removed. Researchers wondered if dietary factors increased the risk of developing these adenomas. They asked more than 17,000 women, aged 34-51 years, to remember foods they ate in high school and as adults. Women whose high school diets were high in vegetables, fruits, and fish had a low risk of developing a rectal adenoma (precursor of rectal cancer) as adults. Women whose high school diets were high in red meat, processed meat, desserts, and other sweets had a higher risk of developing rectal adenomas as adults. The risk was especially high in women who ate more red or processed meat and sweets during both high school and adulthood.
Nimptsch K, Malik VS, Fung TT, et al. 2014, Dietary patterns during high school and risk of colorectal adenoma in a cohort of middle-aged women. Int J Cancer.134:2458-67.
