SCIENTIFIC UPDATE
By Reed Mangels, PhD, RD
Animal-Derived Products In Health Care
A recent article in a British journal devoted to medical ethics discussed an issue
that is rarely addressed — namely, the use of animal-derived components in
medical practice. Products from medications to surgical dressings, to anesthesia,
and to implants may contain animal products and/or have been tested on animals. With
the growing number of vegans in the UK as well as the increased population of those
whose religious background proscribes use of animal-derived products, health care
professionals are more likely to be asked about the source of ingredients in
medications, medical dressings, and devices.
The authors ask, "...what information should or should not be disclosed to patients about the products being used to treat them?" For example, if there is no viable alternative to an animal-derived medication and a vegan patient asks about the medication's origin, should the physician tell the patient that the medication is derived from an animal, knowing that this may lead to the patient's refusing the potentially life-saving medication? What if the patient doesn't ask? Is the physician obliged to tell the patient that the medication is animal-derived? Of course, there is also the issue that it's difficult or impossible to know about the constituents of every medication, dressing, and device. Just as in foods, medications may contain preservatives, stabilizing agents, flavors, and colors that can change over time.
The authors use principles of bioethics to examine these questions and conclude:
- "Clinicians should not presume patients are uninterested but rather ascertain if the use of animal-derived constituents is an issue for them. If so, they should, as far as possible, disclose the use of known animal-derived constituents in the patient's care to ensure their concerns are adequately catered for."
- "Clinicians...will need to communicate that insufficient information exists regarding the constituents in every product they are using, and so it is possible that some products may still contain animal-derived constituents. Any more than this may not be practicable until there have been significant changes in product labelling."
- Patients should be informed if a suitable non-animal derived alternative product exists and, if it does, about the risks and benefits of use of this alternative.
- The health care system has an obligation to ensure that alternative products are available where possible, at least for commonly used products.
- "In instances where a patient...refuses treatment because of unavoidable animal-derived constituents, the patient's wishes must be respected, provided they have capacity to make an informed choice."
We suspect that this is only the beginning of discussions of this complex issue.
Rodger D, Blackshaw, BP. Using animal-derived constituents in anaesthesia and surgery: the case for disclosing to patients. BMC Med Ethics. 2019 Feb 18;20(1):14.
"Healthy Plant Foods" Associated With Less Weight Gain Over
Time
A recent study compared weight change in those eating more "healthy plant foods"
compared to those eating "less healthy plant foods" or more animal products. Healthy
plant foods included whole grains, beans, fruits, vegetables, nuts, and vegetable
oils. Less healthy plant foods included fruit juices, desserts, sugar-sweetened
beverages, refined grains, and potatoes. Eating habits and weight gain over 20 years
of more than 125,000 men and women were assessed. Most gained weight but those
eating more "healthy plant foods" gained substantially less weight than those eating
more "less healthy plant foods" or more animal products.
Satija A, Malik V, Rimm EB, et al. Changes in intake of plant-based diets and weight change: results from 3 prospective cohort studies. Am J Clin Nutr. 2019;110:574-582.
Eat an Apple Every Day...
An estimated 14% of Americans age 71 or older have dementia, a general term for a
decline in mental ability severe enough to interfere with daily life. There is
currently no effective treatment for dementia, and so some researchers are focusing
on slowing or preventing the reduced mental function that appears in some people in
middle age and increases their risk of dementia. Diet is a promising area of
research. One study first examined more than 3,000 men and women when they were
18-30 years old. Over the next 25 years, researchers tracked what subjects ate and
measured their cognitive function using standardized tests. Subjects who ate the
most fruits and vegetables had better cognitive function when they were middle-aged
compared to those who ate the least. This was particularly true for those eating the
most whole vegetables and whole fruits, as opposed to vegetable or fruit juice. In
this study, potatoes were not counted as vegetables. The group eating the most
vegetables averaged 6.5 servings per day and were compared to the group averaging 1
serving a day. The group eating the most fruit averaged 3.4 servings per day; the
group eating the least fruit averaged less than half a serving per day. Tomatoes,
dark green vegetables (like kale), deep-yellow/orange vegetables (like carrots and
winter squash), avocados, and guacamole were the vegetable sub-groups that had the
strongest association with better mental function. These results add to the list of
health benefits offered by fruits and vegetables.
Mao X, Chen C, Xun P, et al. Intake of vegetables and fruits through young adulthood is associated with better cognitive function in midlife in the US general population. J Nutr. 2019;149:1424-33.
Heart Disease and Stroke In Vegetarians
A recently published study from the UK examined more than 48,000 vegans,
vegetarians, fish eaters, and meat eaters, and their risk of heart disease and
stroke over an 18-year period. Because of the relatively small number of vegans,
they were combined with lacto vegetarians and lacto-ovo vegetarians into a group
called "vegetarians." The vegetarians (including vegans) had a 22% lower risk of
heart disease than the meat eaters; fish eaters had a 13% lower risk than the meat
eaters. According to the study's authors, these results suggest that if 1,000 meat
eaters were compared to 1,000 vegetarians, over a 10-year period, there would be 10
fewer cases of heart disease in the vegetarians.
In contrast, vegetarians (including vegans) had a higher risk of a kind of stroke called hemorrhagic stroke and of stroke overall than did meat eaters. This suggests that if 1,000 meat eaters were compared to 1,000 vegetarians, over a 10-year period, there would be three more cases of stroke in vegetarians than in meat eaters. There are two main types of stroke — ischemic and hemorrhagic. Ischemic strokes are more common (87% of all strokes) and are due to a blood clot blocking blood flow to the brain. Hemorrhagic strokes are caused by a weakened blood vessel rupturing and bleeding into the brain.
When vegans were examined separately, they had a lower risk of heart disease than meat eaters but a higher risk for stroke, although neither estimate was statistically significant, possibly due to the small number of cases in vegans.
This study's results are similar to other studies that have reported a reduced risk of heart disease or of dying from heart disease in vegetarians. Up until now, studies of strokes in vegetarians have looked only at the risk of dying from stroke and found no significant difference of dying from stroke by diet group.
The study's authors note that vegetarians and vegans in this study have lower blood levels of vitamins, and omega-3 fatty acids than do meat eaters and wonder if these differences could have contributed to the higher risk of stroke seen in this study.
There were only small differences in saturated fat and fiber intake between the vegetarian and meat-eating groups. Additional research should be done using groups with larger differences in intakes of saturated fat and fiber.
If other large studies have similar results, it will be important to identify dietary changes vegetarians can make to reduce their risk of stroke without affecting their already reduced risk of heart disease. While we don't know if lower blood levels of vitamin B12, vitamin D, and omega-3 fatty acids were related to the higher risk of stroke, we do know that having enough of these nutrients is important for good health.
Tong TYN, Appleby PN, Bradbury KE, et al. Risks of ischaemic heart disease and stroke in meat eaters, fish eaters, and vegetarians over 18 years of follow-up: results from the prospective EPIC-Oxford study. BMJ. 2019;366:l4897.
