This last morning of the congress was devoted to the issue of the environment and how diet choices can impact greenhouse gases, fossil fuel use, water use and efficiency of energy use. The Chair of Nutrition at Loma Linda University's School of Public Health, Joan Sabate, M.D. Dr.P.H., was the plenary speaker and he tried to help us grasp the multilayered definition of sustainability. It addresses ecology, he said, health for the present and future generations, optimizing natural and human resources, and a low environmental impact. Our modern food system has become a way to convert fuel to edible forms. On average, food requires 10 times the energy to produce as the amount of energy that we get from eating it. Meat production uses considerably more energy than plant foods. The ratio of energy in to energy out for meat is 25:1, for plant food it is 2:1. Neither one is sustainable in the long run, but plant foods are closer to the target. Harry Aikins of the Netherlands described meat as a luxury protein. About 40% of global grain and 70% of soy production is used to feed livestock. It takes about 6 kg of plant protein to yield 1 kg of animal protein and animal protein requires 50 fold more water to produce. The world population is expected to plateau out at about 9 billion people by 2050 and he stated that we are expected to need 60% more food to meet the demand. He suggested that consumer change is slower than it needs to be and instead of carrot and stick incentives, he suggests (somewhat tongue in cheek) carrot and nuke. The message of his final slide is that “urgency is severely underestimated!”
I really enjoyed Samuel Soret of the Geoinformatics program at Loma Linda. His job was to talk about greenhouse gases and global warming. He and his co-investigators are involved in calculating the carbon footprint of various diet patterns. He states that there is a 500 kg per year difference in greenhouse gas production between a vegetarian diet and a non-vegetarian diet. If a meat eater becomes a semi-vegetarian, that person will reduce their GHG by 21% and if he or she becomes vegetarian it will be reduced by 30%. If 100 non-vegetarians become vegetarian, they will offset the manufacture of four Mercedes-S class cars. The trend pattern for mortality is just the same as the graph pattern for greenhouse gases. The message was that you can improve your own health and the health of the planet by your diet choices. They are also calculating the carbon footprint of the production of meat analogues and plan to publish a paper next year.
No conference on vegetarian nutrition would be complete without addressing several of the nutrients of concern for vegetarians. The most obvious of these is vitamin B12. Ella Haddad, a long time professor at Loma Linda addressed this issue is a comprehensive way that will certainly give me new material to update my own lecture for my class in nutrition. Borderline deficiency of B12 is more common than blatant deficiency. It is common both in developed and developing countries. It is so common as people get older that Dr. Haddad recommended that all people over 50 either consume food fortified with B12, or take a supplement. It is also a risk for vegans and studies on vegan children have shown deficiencies from 25-86%. The ultimate source of B12 is synthesis by bacteria (which is why it is found in animal proteins—better substrate for bacteria). Soy milk fortified with B12 should probably be a regular part of their diet. An interesting note at the end of the presentation was that a high dose of B12 may improve neurologic function even in the absence of obvious deficiency. In one of the short oral presentations, a young man from Germany introduced us to a vitamin B12 enriched toothpaste that has been formulated for vegans. His data showed a definite benefit in raising B12 levels just by brushing teeth with this product.
Reed Mangels of the Vegetarian Resource Group took on the subject of bone nutrients. Calcium is only one of a long list including magnesium, potassium, phosphorus, vitamin D, vitamin C, Folate, B12, Boron, and protein. Fruits and vegetables as a group along with weight-bearing exercise and certain hormones also impact bone density. I was glad to see her take on the protein and calcium conundrum. It has been known for at least 40 years that when a person consumes high amounts of protein, their urinary excretion of calcium goes up quite significantly. It was assumed that this would impact bone density and bone strength. It has become clear from more recent studies that low protein intake is harmful to bone. Vegetarian women who have higher protein intake have lower risk of bone fracture. The explanation may be that calcium is absorbed at higher rates with higher protein intake. The urinary excretion may not be from bone, but from the extra absorption that happens with higher protein. The organizations that have recommended daily intakes, have a range of calcium recommendations from 700 to 1200 mg so there is not consensus on how much is required. In the EPIC-Oxford study (European Prospective Investigation into Cancer and Nutrition) the vegans in the group had a 30% higher risk of fracture than the other diet categories in their study. However, when they dropped out everyone whose calcium intake was below approximately 550mg and recalculated it , that extra fracture risk disappeared. Reed Mangels suggested that it is prudent to follow the recommended daily allowances of 1000-1200 mg for adults, depending on age and menstrual status. The use of calcium fortified non-dairy milks and orange juice, calcium precipitated tofu, oranges, green leafy vegetables, some kinds of beans all have enough to bring intake up to the recommended amount.
Have you heard of epigenetics? The epigenome consists of chemical compounds that modify, or mark, the genome in a way that tells it what to do, where to do it and when to do it. One of our speakers, John Kelly, M.D presented some fascinating information today about the impact of nutrition and exercise on the epigenome which in turn determines the expression of our genes. The studies he cited were done on mice and demonstrated that a mother’s diet before and during pregnancy can switch genes on or off in a protective way. In one study the switched off gene continued in its modified form through three or four generations of mice. In an unpublished study from Surrey University, one week of sleep deprivation switched off hundreds of genes. At least in animal studies, it appears that parents' lifestyle choices can impact their offspring. Randy Jirtle, Ph.D., an epigenetics researcher, is quoted as saying that ”nutrition is not a fleeting affair. We are quite literally what we eat, as well as what our parents and grandparents ate.”
In the closing remarks, we found out that this year’s congress ended up with 827 attendees. That’s up from about 350 at the first vegetarian congress. There will be another in about five years—I hope to be there again.
—Vicki Saunders, M.S., is an instructor of nutrition at Pacific Union College and is the past-president of the Seventh-day Adventist Dietetic Association.
This is a companion discussion topic for the original entry at http://spectrummagazine.org/node/5117