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Why the rise in Multiple Sclerosis

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New research may help explain why multiple sclerosis rates have risen sharply in the U.S. and some other countries among women, while rates appear stable in men.The study could also broaden understanding of how environmental influences alter genes to cause a wide range of diseases. The causes of multiple sclerosis (MS) are not well understood, but experts have long suspected that environmental factors trigger the disease in people who are genetically susceptible. In the newly published study, researchers found that women with MS were more likely than men with MS to have a specific genetic mutation that has been linked to the disease.

Women were also more likely to pass the mutation to their daughters than their sons and more likely to share the MS-susceptibility gene with more distant female family members. If genes alone were involved, mothers would pass the MS-related gene to their sons as often as their daughters, said researcher George C. Ebers, MD, of the University of Oxford. Ebers’ research suggests that the ability of environmental factors to alter gene expression — a relatively new field of genetic study known as epigenetics — plays a key role in multiple sclerosis and that this role is gender-specific.

The theory is that environmental influences such as diet, smoking, stress, and even exposure to sunlight can change gene expression and this altered gene expression is passed on for a generation or two. “The idea that the environment would change genes was once thought to be ridiculous,” Ebers says. “Now it is looking like this is a much bigger influence on disease than we ever imagined.”

The study by Ebers and colleagues included 1,055 families with more than one person with MS. Close to 7,100 genes were tested, including around 2,100 from patients with the disease. The researchers were looking for MS-specific alterations in the major histocompatibility complex (MHC) gene region. They found that women with MS were 1.4 times more likely than men with the disease to carry the gene variant linked to disease risk. A total of 919 women and 302 men had the variant in the MHC region, compared to 626 women and 280 men who did not have it.

The study appeared in the Jan. 18 issue of Neurology.

Epigenetics is not evolution. Genetic alterations linked to environmental assaults can be passed down for a generation or two, but DNA usually rights itself over time, Ebers says. “This may explain why we hardly ever see MS in families over more than three generations,” he says. Earlier studies by Ebers and colleagues suggest that vitamin D deficiency may be the environmental stressor that triggers the MS-linked gene alterations. Rates of the disease are highest among people living farthest from the equator, and there is widespread speculation that lack of vitamin D due to low sun exposure may explain this. Other than Ebers’ research team, Orhun Kantarci, MD, of the Mayo Clinic in Rochester, Minn., is one of the few researches studying epigenetics as it relates to multiple sclerosis.

Kantarci calls the new research a potentially important piece of the puzzle to explain the gender difference in MS, but he adds that the research must be replicated. “This study provides more questions than answers, but it is very interesting,” he says. “We are learning that inheritance isn’t as simple as [Gregor] Mendel described.”

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Eating Guidelines for Multiple Sclerosis

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  • Maintain a healthy weight. If unwanted weight loss or weight gain occurs, contact your doctor or dietitian

Reduced mobility can result in overweight or obesity, because you are using fewer calories. Some medications, like steroids and antidepressants can also cause weight gain.

Being underweight and having poor nutrition can be caused by

– reduced mobility and feeling tired, which can make shopping, cooking and eating difficult

– difficulty getting food or drinks to the mouth

– poor appetite, and

– difficulty swallowing.

If you are having any of these symptoms and they are keeping you from eating, discuss your symptoms with your doctor.

  • When you have MS, it is especially important to get the recommended amounts (the Dietary Reference Intakes, or DRIs) of the following vitamins and minerals. If your doctor has diagnosed that you are deficient in any of these, you may be advised to take more. Do not take amounts higher than what is recommended because this can be harmful.

– Calcium and vitamin D. People with MS have a higher risk of low bone mineral density and breaking bones. This may be due to low vitamin D and calcium in the diet, or other factors such reduced physical activity, such as walking. Good food sources of calcium include dairy products (milk, yogurt and cheese), fortified soy and rice beverages, fortified juices, tofu with added calcium and canned fish with the bones. Good food sources of vitamin D include milk, fortified soy and rice beverages, fortified juices, fatty fish, such as salmon, and eggs. If you do not eat these foods daily, you should discuss adding a daily supplement with your doctor or dietitian. 

– Vitamin B12. Vitamin B12 deficiency is common in people with MS. Low levels of vitamin B12 can cause a type of anemia that can make you feel tired. Good food sources of vitamin B12 are dairy products (milk, yogurt and cheese), eggs, meat, fish, poultry, and fortified soy and rice beverages. It is recommended that people over 50 take a vitamin B12 supplement, because as you get older, you don't absorb the vitamin B12 from food very well. The amount of vitamin B12 in a multivitamin is usually enough.

– Zinc and selenium. Zinc and selenium deficiencies are common in people with MS. Zinc is needed for the growth and repair of body cells. Selenium works as an antioxidant to protect body cells from damage. Good food sources of zinc are meat, seafood, dried beans, peas, and lentils, and whole grains. Good food sources of selenium are Brazil nuts, seafood, fish and shellfish, liver and kidney. If these are foods that you don't eat regularly, you may need a supplement. The amounts in a multivitamin mineral supplement are usually enough.

  • Many people with MS try different herbal or nutritional supplements hoping these will improve their symptoms or prevent MS from getting worse. Ginkgo biloba has been studied in people with MS, and while early studies show some benefit, larger studies need to be done before it can be recommended. Gingko biloba has many side effects and shouldn't be taken by people who have bleeding disorders, who are taking blood thinning medication, or who are planning surgery.

Other supplements, including St. John's wort, ginseng, echinacea and valerian, have not been studied in people with MS, so it is not known if they are effective or safe. Because echinacea can stimulate the immune system, it might make MS symptoms worse.

 

Source: Dietitians of Canada. Reproduced with Permission.

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